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• Running 32 bit assembly code on a 64 bit Linux & 64 bit Processor : Expalin the anomaly.

  - by claws

  Hello, I'm in an interesting problem.I forgot I'm using 64bit machine & OS and wrote a 32 bit assembly code. I don't know how to write 64 bit code. This is the x86 32-bit assembly code for Gnu Assembler (AT&T syntax) on Linux. #include <asm/unistd.h> #include <syscall.h> #define STDOUT 1 .data hellostr: .ascii "hello wolrd\n"; helloend: .text .globl _start _start: movl $(SYS_write) , %eax //ssize_t write(int fd, const void *buf, size_t count); movl $(STDOUT) , %ebx movl $hellostr , %ecx movl $(helloend-hellostr) , %edx int $0x80 movl $(SYS_exit), %eax //void _exit(int status); xorl %ebx, %ebx int $0x80 ret Now, This code should run fine on a 32bit processor & 32 bit OS right? As we know 64 bit processors are backward compatible with 32 bit processors. So, that also wouldn't be a problem. The problem arises because of differences in system calls & call mechanism in 64-bit OS & 32-bit OS. I don't know why but they changed the system call numbers between 32-bit linux & 64-bit linux. asm/unistd_32.h defines: #define __NR_write 4 #define __NR_exit 1 asm/unistd_64.h defines: #define __NR_write 1 #define __NR_exit 60 Anyway using Macros instead of direct numbers is paid off. Its ensuring correct system call numbers. when I assemble & link & run the program. Its not printing helloworld. In gdb its showing: Program exited with code 01. I don't know how to debug in gdb. using tutorial I tried to debug it and execute instruction by instruction checking registers at each step. its always showing me "program exited with 01". It would be great if some on could show me how to debug this. (gdb) break _start Note: breakpoint -10 also set at pc 0x4000b0. Breakpoint 8 at 0x4000b0 (gdb) start Function "main" not defined. Make breakpoint pending on future shared library load? (y or [n]) y Temporary breakpoint 9 (main) pending. Starting program: /home/claws/helloworld Program exited with code 01. (gdb) info breakpoints Num Type Disp Enb Address What 8 breakpoint keep y 0x00000000004000b0 <_start> 9 breakpoint del y <PENDING> main I tried running strace. This is its output: execve("./helloworld", ["./helloworld"], [/* 39 vars */]) = 0 write(0, NULL, 12 <unfinished ... exit status 1> Explain the parameters of write(0, NULL, 12) system call in the output of strace? What exactly is happening? I want to know the reason why exactly its exiting with exitstatus=1? Can some one please show me how to debug this program using gdb? Why did they change the system call numbers? Change this program appropriately so that it can run correctly on this machine.

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• How to use pipes for nonblocking IPC (UART emulation)

  - by codebauer

  I would like to write some test/emulation code that emulates a serial port connection. The real code looks like this: DUT <- UART - testtool.exe My plan is to use create a test application (CodeUnderTest.out) on linux that forks to launch testool.out with two (read & write) named pipes as arguments. But I cannot figure out how to make all the pipe IO non-blocking! The setup would look like this:. CodeUnderTest.out <- named pipes - testTool.out (lauched from CodeUnderTest.out) I have tried opening the pipes as following: open(wpipe,O_WRONLY|O_NONBLOCK); open(rpipe,O_RDONLY|O_NONBLOCK); But the write blocks until the reader opens the wpipe. Next I tried the following: open(wpipe,O_RDWR|O_NONBLOCK); open(rpipe,O_RDONLY|O_NONBLOCK); But then the reader of the first message never gets any data (doesn't block though) I also tried adding open and close calls around each message, but that didn't work either... Here is some test code: #include <stdio.h> #include <sys/types.h> #include <unistd.h> #include <fcntl.h> pid_t pid; char* rpipe, *wpipe,*x; FILE *rh,*wh; int rfd,wfd; void openrpipe( void ) { rfd = open(rpipe,O_RDONLY|O_NONBLOCK); rh = fdopen(rfd,"rb"); printf("%sopeningr %x\n",x,rh); } void openwpipe( void ) { //Fails when reader not already opened //wfd = open(wpipe,O_WRONLY|O_NONBLOCK); wfd = open(wpipe,O_RDWR|O_NONBLOCK); wh = fdopen(wfd,"wb"); printf("%sopeningw %x\n",x,wh); } void closerpipe( void ) { int i; i = fclose(rh); printf("%sclosingr %d\n",x,i); } void closewpipe( void ) { int i; i = fclose(wh); printf("%sclosingw %d\n",x,i); } void readpipe( char* expect, int len) { char buf[1024]; int i=0; printf("%sreading\n",x); while(i==0) { //printf("."); i = fread(buf,1,len,rh); } printf("%sread (%d) %s\n",x,i,buf); } void writepipe( char* data, int len) { int i,j; printf("%swriting\n",x); i = fwrite(data,1,len,rh); j = fflush(rh); //No help! printf("%sflush %d\n",x,j); printf("%swrite (%d) %s\n",x,i,data); } int main(int argc, char **argv) { rpipe = "readfifo"; wpipe = "writefifo"; x = ""; pid = fork(); if( pid == 0) { wpipe = "readfifo"; rpipe = "writefifo"; x = " "; openrpipe(); openwpipe(); writepipe("paul",4); readpipe("was",3); writepipe("here",4); closerpipe(); closewpipe(); exit(0); } openrpipe(); openwpipe(); readpipe("paul",4); writepipe("was",3); readpipe("here",4); closerpipe(); closewpipe(); return( -1 ); } BTW: To use the testocd above you need to pipes in the cwd: mkfifo ./readfifo mkfifo ./writefifo

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• how to solve unhandled exception error when using visual C++ 2008?

  - by make

  Hi, Could someone please help me to solve unhandled exception error when using visual C++ 2008? the error is displayed as follow: Unhandled exception at 0x00411690 in time.exe: 0xC0000005: Access violation reading location 0x00000008 Actually when I used visual c++ 6 in the past, there weren't any error and the program was running fine. But now ehen I use visual 2008, I am getting this Unhandled exception error. Here is the program: #include <stdio.h> #include <stdlib.h> #include <time.h> #ifdef _WIN32 // #include <winsock.h> #include <windows.h> #include "stdint.h" // typedef __int64 int64_t // Define it from MSVC's internal type // typedef unsigned __int32 uint32_t #else #include <stdint.h> // Use the C99 official header #include <sys/time.h> #include <unistd.h> #endif #if defined(_MSC_VER) || defined(_MSC_EXTENSIONS) #define DELTA_EPOCH_IN_MICROSECS 11644473600000000Ui64 #else #define DELTA_EPOCH_IN_MICROSECS 11644473600000000ULL #endif struct timezone { int tz_minuteswest; /* minutes W of Greenwich */ int tz_dsttime; /* type of dst correction */ }; #define TEST #ifdef TEST uint32_t stampstart(); uint32_t stampstop(uint32_t start); int main() { uint32_t start, stop; start = stampstart(); /* Your code goes here */ stop = stampstop(start); return 0; } #endif int gettimeofday(struct timeval *tv, struct timezone *tz) { FILETIME ft; unsigned __int64 tmpres = 0; static int tzflag = 0; if (NULL != tv) { GetSystemTimeAsFileTime(&ft); tmpres |= ft.dwHighDateTime; tmpres <<= 32; tmpres |= ft.dwLowDateTime; tmpres /= 10; /*convert into microseconds*/ /*converting file time to unix epoch*/ tmpres -= DELTA_EPOCH_IN_MICROSECS; tv->tv_sec = (long)(tmpres / 1000000UL); tv->tv_usec = (long)(tmpres % 1000000UL); } if (NULL != tz) { if (!tzflag) { _tzset(); tzflag++; } tz->tz_minuteswest = _timezone / 60; tz->tz_dsttime = _daylight; } return 0; } uint32_t stampstart() { struct timeval tv; struct timezone tz; struct tm *tm; uint32_t start; gettimeofday(&tv, &tz); tm = localtime(&tv.tv_sec); printf("TIMESTAMP-START\t %d:%02d:%02d:%d (~%d ms)\n", tm->tm_hour, tm->tm_min, tm->tm_sec, tv.tv_usec, tm->tm_hour * 3600 * 1000 + tm->tm_min * 60 * 1000 + tm->tm_sec * 1000 + tv.tv_usec / 1000); start = tm->tm_hour * 3600 * 1000 + tm->tm_min * 60 * 1000 + tm->tm_sec * 1000 + tv.tv_usec / 1000; return (start); } uint32_t stampstop(uint32_t start) { struct timeval tv; struct timezone tz; struct tm *tm; uint32_t stop; gettimeofday(&tv, &tz); tm = localtime(&tv.tv_sec); stop = tm->tm_hour * 3600 * 1000 + tm->tm_min * 60 * 1000 + tm->tm_sec * 1000 + tv.tv_usec / 1000; printf("TIMESTAMP-END\t %d:%02d:%02d:%d (~%d ms) \n", tm->tm_hour, tm->tm_min, tm->tm_sec, tv.tv_usec, tm->tm_hour * 3600 * 1000 + tm->tm_min * 60 * 1000 + tm->tm_sec * 1000 + tv.tv_usec / 1000); printf("ELAPSED\t %d ms\n", stop - start); return (stop); } thanks for your replies:

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• c - fork() and wait()

  - by Joe

  Hi there, I need to use the fork() and wait() functions to complete an assignment. We are modelling non-deterministic behaviour and need the program to fork() if there is more than one possible transition. In order to try and work out how fork and wait work, I have just made a simple program. I think I understand now how the calls work and would be fine if the program only branched once because the parent process could use the exit status from the single child process to determine whether the child process reached the accept state or not. As you can see from the code that follows though, I want to be able to handle situations where there must be more than one child processes. My problem is that you seem to only be able to set the status using an _exit function once. So, as in my example the exit status that the parent process tests for shows that the first child process issued 0 as it's exit status, but has no information on the second child process. I tried simply not _exit()-ing on a reject, but then that child process would carry on, and in effect there would seem to be two parent processes. Sorry for the waffle, but I would be grateful if someone could tell me how my parent process could obtain the status information on more than one child process, or I would be happy for the parent process to only notice accept status's from the child processes, but in that case I would successfully need to exit from the child processes which have a reject status. My test code is as follows: #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> #include <sys/wait.h> int main(void) { pid_t child_pid, wpid, pid; int status = 0; int i; int a[3] = {1, 2, 1}; for(i = 1; i < 3; i++) { printf("i = %d\n", i); pid = getpid(); printf("pid after i = %d\n", pid); if((child_pid = fork()) == 0) { printf("In child process\n"); pid = getpid(); printf("pid in child process is %d\n", pid); /* Is a child process */ if(a[i] < 2) { printf("Should be accept\n"); _exit(1); } else { printf("Should be reject\n"); _exit(0); } } } if(child_pid > 0) { /* Is the parent process */ pid = getpid(); printf("parent_pid = %d\n", pid); wpid = wait(&status); if(wpid != -1) { printf("Child's exit status was %d\n", status); if(status > 0) { printf("Accept\n"); } else { printf("Complete parent process\n"); if(a[0] < 2) { printf("Accept\n"); } else { printf("Reject\n"); } } } } return 0; } Many thanks Joe

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• Socket in C: recv overwrite a char[]

  - by Possa

  Hi all, I'm trying to make a little client-server script like many others that I've done in the past. But in this one I have a problem. It is better if I post the code and the output it give me. Code: #include <mysql.h> //not important now #include <stdlib.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <signal.h> #include <string.h> //constant definition #define SERVER_PORT 2121 #define LINESIZE 21 //global var definition char victim_ip[LINESIZE], file_write[LINESIZE], hacker_ip[LINESIZE]; //function void leggi (int); //not use now for debugging purpose //void scriviDB (); //not important now main () { int sock, client_len, fd; struct sockaddr_in server, client; // transport end point if((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) { perror("system call socket fail"); exit(1); } server.sin_family = AF_INET; server.sin_addr.s_addr = inet_addr("10.10.10.1"); server.sin_port = htons(SERVER_PORT); // binding address at transport end point if (bind(sock, (struct sockaddr *)&server, sizeof server) == -1) { perror("system call bind fail"); exit(1); } //fprintf(stderr, "Server open: listening.\n"); listen(sock, 5); /* managae client connection */ while (1) { client_len = sizeof(client); if ((fd = accept(sock, (struct sockaddr *)&client, &client_len)) < 0) { perror("accepting connection"); exit(1); } strcpy(hacker_ip, inet_ntoa(client.sin_addr)); printf("1 %s\n", hacker_ip); //debugging purpose //leggi(fd); ////////////////////////// //receive client recv(fd, victim_ip, LINESIZE, 0); victim_ip[sizeof(victim_ip)] = '\0'; printf("2 %s\n", hacker_ip); //debugging purpose recv(fd, file_write, LINESIZE, 0); file_write[sizeof(file_write)] = '\0'; printf("3 %s\n", hacker_ip); //debugging purpose printf("%s@%s for %s\n", file_write, victim_ip, hacker_ip); //send to client send(fd, hacker_ip, 40, 0); //now is hacker_ip for debug ///////////////////////// close(fd); }//end while exit(0); } //end main Client send string: ./send -i 10.10.10.4 -f filename.ext so the script send -i (IP) and -f (FILE) at the server. Here's my output server side: 1 10.10.10.6 2 10.10.10.6 3 [email protected] for As you can see the printf(3) and the printf(ip,file,ip) fail. I don't know how and where but someone overwrite my hacker_ip string. Thanks for your help! :)

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• Warning: comparison with string literals results in unspecified behaviour

  - by nunos

  So I starting the project of writing a simplified sheel for linux in c. I am not at all proficient with c nor with Linux that's exactly the reason I decided it would be a good idea. Starting with the parser, I have already encountered some problems. The code should be straightforward that's why I didn't include any comments. I am getting a warning with gcc: "comparison with string literals results in unspecified behaviour" at the lines commented with "WARNING HERE" (see code below). I have no idea why this causes an warning, but the real problem is that even though I am comparing an "<" to an "<" is doesn't get inside the if... I am looking for an answer for the problem explained, however if there's something that you see in the code that should be improved please say so. Just take in mind I am not that proficient and that this is still a work in progress (or better yet, a work in start). Thanks in advance. #include <stdio.h> #include <unistd.h> #include <string.h> typedef enum {false, true} bool; typedef struct { char **arg; char *infile; char *outfile; int background; } Command_Info; int parse_cmd(char *cmd_line, Command_Info *cmd_info) { char *arg; char *args[100]; int i = 0; arg = strtok(cmd_line, " \n"); while (arg != NULL) { args[i] = arg; arg = strtok(NULL, " \n"); i++; } int num_elems = i; cmd_info->infile = NULL; cmd_info->outfile = NULL; cmd_info->background = 0; int iarg = 0; for (i = 0; i < num_elems; i++) { if (args[i] == "&") //WARNING HERE return -1; else if (args[i] == "<") //WARNING HERE if (args[i+1] != NULL) cmd_info->infile = args[i+1]; else return -1; else if (args[i] == ">") //WARNING HERE if (args[i+1] != NULL) cmd_info->outfile = args[i+1]; else return -1; else cmd_info->arg[iarg++] = args[i]; } cmd_info->arg[iarg] = NULL; return 0; } void print_cmd(Command_Info *cmd_info) { int i; for (i = 0; cmd_info->arg[i] != NULL; i++) printf("arg[%d]=\"%s\"\n", i, cmd_info->arg[i]); printf("arg[%d]=\"%s\"\n", i, cmd_info->arg[i]); printf("infile=\"%s\"\n", cmd_info->infile); printf("outfile=\"%s\"\n", cmd_info->outfile); printf("background=\"%d\"\n", cmd_info->background); } int main(int argc, char* argv[]) { char cmd_line[100]; Command_Info cmd_info; printf(">>> "); fgets(cmd_line, 100, stdin); parse_cmd(cmd_line, &cmd_info); print_cmd(&cmd_info); return 0; }

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• Help with simple linux shell implementation

  - by nunos

  I am implementing a simple version of a linux shell in c. I have succesfully written the parser, but I am having some trouble forking out the child process. However, I think the problem is due to arrays, pointers and such, because just started C with this project and am not still very knowledgable with them. I am getting a segmentation fault and don't know where from. Any help is greatly appreciated. #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <sys/wait.h> #include <sys/types.h> #define MAX_COMMAND_LENGTH 250 #define MAX_ARG_LENGTH 250 typedef enum {false, true} bool; typedef struct { char **arg; char *infile; char *outfile; int background; } Command_Info; int parse_cmd(char *cmd_line, Command_Info *cmd_info) { char *arg; char *args[MAX_ARG_LENGTH]; int i = 0; arg = strtok(cmd_line, " "); while (arg != NULL) { args[i] = arg; arg = strtok(NULL, " "); i++; } int num_elems = i; if (num_elems == 0) return -1; cmd_info->infile = NULL; cmd_info->outfile = NULL; cmd_info->background = 0; int iarg = 0; for (i = 0; i < num_elems-1; i++) { if (!strcmp(args[i], "<")) { if (args[i+1] != NULL) cmd_info->infile = args[++i]; else return -1; } else if (!strcmp(args[i], ">")) { if (args[i+1] != NULL) cmd_info->outfile = args[++i]; else return -1; } else cmd_info->arg[iarg++] = args[i]; } if (!strcmp(args[i], "&")) cmd_info->background = true; else cmd_info->arg[iarg++] = args[i]; cmd_info->arg[iarg] = NULL; return 0; } void print_cmd(Command_Info *cmd_info) { int i; for (i = 0; cmd_info->arg[i] != NULL; i++) printf("arg[%d]=\"%s\"\n", i, cmd_info->arg[i]); printf("arg[%d]=\"%s\"\n", i, cmd_info->arg[i]); printf("infile=\"%s\"\n", cmd_info->infile); printf("outfile=\"%s\"\n", cmd_info->outfile); printf("background=\"%d\"\n", cmd_info->background); } void get_cmd(char* str) { fgets(str, MAX_COMMAND_LENGTH, stdin); str[strlen(str)-1] = '\0'; //apaga o '\n' do fim } pid_t exec_simple(Command_Info *cmd_info) { pid_t pid = fork(); if (pid < 0) { perror("Fork Error"); return -1; } if (pid == 0) { execvp(cmd_info->arg[0], cmd_info->arg); perror(cmd_info->arg[0]); exit(1); } return pid; } int main(int argc, char* argv[]) { while (true) { char cmd_line[MAX_COMMAND_LENGTH]; Command_Info cmd_info; printf(">>> "); get_cmd(cmd_line); if ( (parse_cmd(cmd_line, &cmd_info) == -1) ) return -1; parse_cmd(cmd_line, &cmd_info); if (!strcmp(cmd_info.arg[0], "exit")) exit(0); pid_t pid = exec_simple(&cmd_info); waitpid(pid, NULL, 0); } return 0; } Thanks.

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• C - Error with read() of a file, storage in an array, and printing output properly

  - by ns1

  I am new to C, so I am not exactly sure where my error is. However, I do know that the great portion of the issue lies either in how I am storing the doubles in the d_buffer (double) array or the way I am printing it. Specifically, my output keeps printing extremely large numbers (with around 10-12 digits before the decimal point and a trail of zeros after it. Additionally, this is an adaptation of an older program to allow for double inputs, so I only really added the two if statements (in the "read" for loop and the "printf" for loop) and the d_buffer declaration. I would appreciate any input whatsoever as I have spent several hours on this error. #include <stdio.h> #include <fcntl.h> #include <sys/types.h> #include <unistd.h> #include <string.h> struct DataDescription { char fieldname[30]; char fieldtype; int fieldsize; }; /* ----------------------------------------------- eof(fd): returns 1 if file `fd' is out of data ----------------------------------------------- */ int eof(int fd) { char c; if ( read(fd, &c, 1) != 1 ) return(1); else { lseek(fd, -1, SEEK_CUR); return(0); } } void main() { FILE *fp; /* Used to access meta data */ int fd; /* Used to access user data */ /* ---------------------------------------------------------------- Variables to hold the description of the data - max 10 fields ---------------------------------------------------------------- */ struct DataDescription DataDes[10]; /* Holds data descriptions for upto 10 fields */ int n_fields; /* Actual # fields */ /* ------------------------------------------------------ Variables to hold the data - max 10 fields.... ------------------------------------------------------ */ char c_buffer[10][100]; /* For character data */ int i_buffer[10]; /* For integer data */ double d_buffer[10]; int i, j; int found; printf("Program for searching a mini database:\n"); /* ============================= Read in meta information ============================= */ fp = fopen("db-description", "r"); n_fields = 0; while ( fscanf(fp, "%s %c %d", DataDes[n_fields].fieldname, &DataDes[n_fields].fieldtype, &DataDes[n_fields].fieldsize) > 0 ) n_fields++; /* --- Prints meta information --- */ printf("\nThe database consists of these fields:\n"); for (i = 0; i < n_fields; i++) printf("Index %d: Fieldname `%s',\ttype = %c,\tsize = %d\n", i, DataDes[i].fieldname, DataDes[i].fieldtype, DataDes[i].fieldsize); printf("\n\n"); /* --- Open database file --- */ fd = open("db-data", O_RDONLY); /* --- Print content of the database file --- */ printf("\nThe database content is:\n"); while ( ! eof(fd) ) { /* ------------------ Read next record ------------------ */ for (j = 0; j < n_fields; j++) { if ( DataDes[j].fieldtype == 'I' ) read(fd, &i_buffer[j], DataDes[j].fieldsize); if ( DataDes[j].fieldtype == 'F' ) read(fd, &d_buffer[j], DataDes[j].fieldsize); if ( DataDes[j].fieldtype == 'C' ) read(fd, &c_buffer[j], DataDes[j].fieldsize); } double d; /* ------------------ Print it... ------------------ */ for (j = 0; j < n_fields; j++) { if ( DataDes[j].fieldtype == 'I' ) printf("%d ", i_buffer[j]); if ( DataDes[j].fieldtype == 'F' ) d = d_buffer[j]; printf("%lf ", d); if ( DataDes[j].fieldtype == 'C' ) printf("%s ", c_buffer[j]); } printf("\n"); } printf("\n"); printf("\n"); } Post edits output: 16777216 0.000000 107245694331284094976.000000 107245694331284094976.000000 Pi 33554432 107245694331284094976.000000 2954938175610156848888276006519501238173891974277081114627768841840801736306392481516295906896346039950625609765296207682724801406770458881439696544971142710292689518104183685723154223544599940711614138798312668264956190761622328617992192.000000 2954938175610156848888276006519501238173891974277081114627768841840801736306392481516295906896346039950625609765296207682724801406770458881439696544971142710292689518104183685723154223544599940711614138798312668264956190761622328617992192.000000 Secret Key 50331648 2954938175610156848888276006519501238173891974277081114627768841840801736306392481516295906896346039950625609765296207682724801406770458881439696544971142710292689518104183685723154223544599940711614138798312668264956190761622328617992192.000000 -0.000000 -0.000000 The number E Expected Output: 3 rows of data ending with the number "e = 2.18281828" To reproduce the problem, the following two files need to be in the same directory as the lookup-data.c file: - db-data - db-description

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• Why won't xattr PECL extension build on 12.10?

  - by Dan Jones

  I was using the xattr pecl extension in 12.04 (in fact, I think since 10.04) without problem. Not surprisingly, I had to reinstall it after upgrading to 12.10 because of the new version of PHP. But now it fails to build, and I can't figure out why. Other PECL extensions have built fine. And I have libattr1 and libattr1-dev installed. Here's the output from the build: downloading xattr-1.1.0.tgz ... Starting to download xattr-1.1.0.tgz (5,204 bytes) .....done: 5,204 bytes 3 source files, building running: phpize Configuring for: PHP Api Version: 20100412 Zend Module Api No: 20100525 Zend Extension Api No: 220100525 libattr library installation dir? [autodetect] : building in /tmp/pear/temp/pear-build-rootdSMx0G/xattr-1.1.0 running: /tmp/pear/temp/xattr/configure --with-xattr checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for a sed that does not truncate output... /bin/sed checking for cc... cc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether cc accepts -g... yes checking for cc option to accept ISO C89... none needed checking how to run the C preprocessor... cc -E checking for icc... no checking for suncc... no checking whether cc understands -c and -o together... yes checking for system library directory... lib checking if compiler supports -R... no checking if compiler supports -Wl,-rpath,... yes checking build system type... x86_64-unknown-linux-gnu checking host system type... x86_64-unknown-linux-gnu checking target system type... x86_64-unknown-linux-gnu checking for PHP prefix... /usr checking for PHP includes... -I/usr/include/php5 -I/usr/include/php5/main -I/usr/include/php5/TSRM -I/usr/include/php5/Zend -I/usr/include/php5/ext -I/usr/include/php5/ext/date/lib checking for PHP extension directory... /usr/lib/php5/20100525 checking for PHP installed headers prefix... /usr/include/php5 checking if debug is enabled... no checking if zts is enabled... no checking for re2c... re2c checking for re2c version... 0.13.5 (ok) checking for gawk... gawk checking for xattr support... yes, shared checking for xattr files in default path... found in /usr checking for attr_get in -lattr... yes checking how to print strings... printf checking for a sed that does not truncate output... (cached) /bin/sed checking for fgrep... /bin/grep -F checking for ld used by cc... /usr/bin/ld checking if the linker (/usr/bin/ld) is GNU ld... yes checking for BSD- or MS-compatible name lister (nm)... /usr/bin/nm -B checking the name lister (/usr/bin/nm -B) interface... BSD nm checking whether ln -s works... yes checking the maximum length of command line arguments... 1572864 checking whether the shell understands some XSI constructs... yes checking whether the shell understands "+="... yes checking how to convert x86_64-unknown-linux-gnu file names to x86_64-unknown-linux-gnu format... func_convert_file_noop checking how to convert x86_64-unknown-linux-gnu file names to toolchain format... func_convert_file_noop checking for /usr/bin/ld option to reload object files... -r checking for objdump... objdump checking how to recognize dependent libraries... pass_all checking for dlltool... no checking how to associate runtime and link libraries... printf %s\n checking for ar... ar checking for archiver @FILE support... @ checking for strip... strip checking for ranlib... ranlib checking for gawk... (cached) gawk checking command to parse /usr/bin/nm -B output from cc object... ok checking for sysroot... no checking for mt... mt checking if mt is a manifest tool... no checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking for dlfcn.h... yes checking for objdir... .libs checking if cc supports -fno-rtti -fno-exceptions... no checking for cc option to produce PIC... -fPIC -DPIC checking if cc PIC flag -fPIC -DPIC works... yes checking if cc static flag -static works... yes checking if cc supports -c -o file.o... yes checking if cc supports -c -o file.o... (cached) yes checking whether the cc linker (/usr/bin/ld -m elf_x86_64) supports shared libraries... yes checking whether -lc should be explicitly linked in... no checking dynamic linker characteristics... GNU/Linux ld.so checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... no configure: creating ./config.status config.status: creating config.h config.status: executing libtool commands running: make /bin/bash /tmp/pear/temp/pear-build-rootdSMx0G/xattr-1.1.0/libtool --mode=compile cc -I. -I/tmp/pear/temp/xattr -DPHP_ATOM_INC -I/tmp/pear/temp/pear-build-rootdSMx0G/xattr-1.1.0/include -I/tmp/pear/temp/pear-build-rootdSMx0G/xattr-1.1.0/main -I/tmp/pear/temp/xattr -I/usr/include/php5 -I/usr/include/php5/main -I/usr/include/php5/TSRM -I/usr/include/php5/Zend -I/usr/include/php5/ext -I/usr/include/php5/ext/date/lib -DHAVE_CONFIG_H -g -O2 -c /tmp/pear/temp/xattr/xattr.c -o xattr.lo libtool: compile: cc -I. -I/tmp/pear/temp/xattr -DPHP_ATOM_INC -I/tmp/pear/temp/pear-build-rootdSMx0G/xattr-1.1.0/include -I/tmp/pear/temp/pear-build-rootdSMx0G/xattr-1.1.0/main -I/tmp/pear/temp/xattr -I/usr/include/php5 -I/usr/include/php5/main -I/usr/include/php5/TSRM -I/usr/include/php5/Zend -I/usr/include/php5/ext -I/usr/include/php5/ext/date/lib -DHAVE_CONFIG_H -g -O2 -c /tmp/pear/temp/xattr/xattr.c -fPIC -DPIC -o .libs/xattr.o /tmp/pear/temp/xattr/xattr.c:50:1: error: unknown type name 'function_entry' /tmp/pear/temp/xattr/xattr.c:51:2: warning: braces around scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: (near initialization for 'xattr_functions[0]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: initialization makes integer from pointer without a cast [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: (near initialization for 'xattr_functions[0]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: error: initializer element is not computable at load time /tmp/pear/temp/xattr/xattr.c:51:2: error: (near initialization for 'xattr_functions[0]') /tmp/pear/temp/xattr/xattr.c:51:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: (near initialization for 'xattr_functions[0]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: (near initialization for 'xattr_functions[0]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: (near initialization for 'xattr_functions[0]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:51:2: warning: (near initialization for 'xattr_functions[0]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: braces around scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: (near initialization for 'xattr_functions[1]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: initialization makes integer from pointer without a cast [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: (near initialization for 'xattr_functions[1]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: error: initializer element is not computable at load time /tmp/pear/temp/xattr/xattr.c:52:2: error: (near initialization for 'xattr_functions[1]') /tmp/pear/temp/xattr/xattr.c:52:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: (near initialization for 'xattr_functions[1]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: (near initialization for 'xattr_functions[1]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: (near initialization for 'xattr_functions[1]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:52:2: warning: (near initialization for 'xattr_functions[1]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: braces around scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: (near initialization for 'xattr_functions[2]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: initialization makes integer from pointer without a cast [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: (near initialization for 'xattr_functions[2]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: error: initializer element is not computable at load time /tmp/pear/temp/xattr/xattr.c:53:2: error: (near initialization for 'xattr_functions[2]') /tmp/pear/temp/xattr/xattr.c:53:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: (near initialization for 'xattr_functions[2]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: (near initialization for 'xattr_functions[2]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: (near initialization for 'xattr_functions[2]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:53:2: warning: (near initialization for 'xattr_functions[2]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: braces around scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: (near initialization for 'xattr_functions[3]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: initialization makes integer from pointer without a cast [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: (near initialization for 'xattr_functions[3]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: error: initializer element is not computable at load time /tmp/pear/temp/xattr/xattr.c:54:2: error: (near initialization for 'xattr_functions[3]') /tmp/pear/temp/xattr/xattr.c:54:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: (near initialization for 'xattr_functions[3]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: (near initialization for 'xattr_functions[3]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: (near initialization for 'xattr_functions[3]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:54:2: warning: (near initialization for 'xattr_functions[3]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: braces around scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: (near initialization for 'xattr_functions[4]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: initialization makes integer from pointer without a cast [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: (near initialization for 'xattr_functions[4]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: error: initializer element is not computable at load time /tmp/pear/temp/xattr/xattr.c:55:2: error: (near initialization for 'xattr_functions[4]') /tmp/pear/temp/xattr/xattr.c:55:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: (near initialization for 'xattr_functions[4]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: (near initialization for 'xattr_functions[4]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: (near initialization for 'xattr_functions[4]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:55:2: warning: (near initialization for 'xattr_functions[4]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: braces around scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: (near initialization for 'xattr_functions[5]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: initialization makes integer from pointer without a cast [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: (near initialization for 'xattr_functions[5]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: (near initialization for 'xattr_functions[5]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: excess elements in scalar initializer [enabled by default] /tmp/pear/temp/xattr/xattr.c:56:2: warning: (near initialization for 'xattr_functions[5]') [enabled by default] /tmp/pear/temp/xattr/xattr.c:67:2: warning: initialization from incompatible pointer type [enabled by default] /tmp/pear/temp/xattr/xattr.c:67:2: warning: (near initialization for 'xattr_module_entry.functions') [enabled by default] /tmp/pear/temp/xattr/xattr.c: In function 'zif_xattr_set': /tmp/pear/temp/xattr/xattr.c:122:49: error: 'struct _php_core_globals' has no member named 'safe_mode' /tmp/pear/temp/xattr/xattr.c:122:92: error: 'CHECKUID_DISALLOW_FILE_NOT_EXISTS' undeclared (first use in this function) /tmp/pear/temp/xattr/xattr.c:122:92: note: each undeclared identifier is reported only once for each function it appears in /tmp/pear/temp/xattr/xattr.c: In function 'zif_xattr_get': /tmp/pear/temp/xattr/xattr.c:171:49: error: 'struct _php_core_globals' has no member named 'safe_mode' /tmp/pear/temp/xattr/xattr.c:171:92: error: 'CHECKUID_DISALLOW_FILE_NOT_EXISTS' undeclared (first use in this function) /tmp/pear/temp/xattr/xattr.c:187:2: warning: passing argument 4 of 'attr_get' from incompatible pointer type [enabled by default] In file included from /tmp/pear/temp/xattr/xattr.c:37:0: /usr/include/attr/attributes.h:122:12: note: expected 'int *' but argument is of type 'size_t *' /tmp/pear/temp/xattr/xattr.c:198:3: warning: passing argument 4 of 'attr_get' from incompatible pointer type [enabled by default] In file included from /tmp/pear/temp/xattr/xattr.c:37:0: /usr/include/attr/attributes.h:122:12: note: expected 'int *' but argument is of type 'size_t *' /tmp/pear/temp/xattr/xattr.c: In function 'zif_xattr_supported': /tmp/pear/temp/xattr/xattr.c:243:49: error: 'struct _php_core_globals' has no member named 'safe_mode' /tmp/pear/temp/xattr/xattr.c:243:92: error: 'CHECKUID_DISALLOW_FILE_NOT_EXISTS' undeclared (first use in this function) /tmp/pear/temp/xattr/xattr.c: In function 'zif_xattr_remove': /tmp/pear/temp/xattr/xattr.c:288:49: error: 'struct _php_core_globals' has no member named 'safe_mode' /tmp/pear/temp/xattr/xattr.c:288:92: error: 'CHECKUID_DISALLOW_FILE_NOT_EXISTS' undeclared (first use in this function) /tmp/pear/temp/xattr/xattr.c: In function 'zif_xattr_list': /tmp/pear/temp/xattr/xattr.c:337:49: error: 'struct _php_core_globals' has no member named 'safe_mode' /tmp/pear/temp/xattr/xattr.c:337:92: error: 'CHECKUID_DISALLOW_FILE_NOT_EXISTS' undeclared (first use in this function) make: *** [xattr.lo] Error 1 ERROR: `make' failed There seem to be a few errors, but I can't make heads or tails of them. Does this just not work properly in 12.10? That would be a big problem for me.

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• how to clear stack after stack overflow signal occur

  - by user353573

  In pthread, After reaching yellow zone in stack, signal handler stop the recursive function by making it return however, we can only continue to use extra area in yellow zone, how to clear the rubbish before the yellow zone in the thread stack ? (Copied from "answers"): #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <setjmp.h> #include <sys/mman.h> #include <unistd.h> #include <assert.h> #include <sys/resource.h> #define ALT_STACK_SIZE (64*1024) #define YELLOW_ZONE_PAGES (1) typedef struct { size_t stack_size; char* stack_pointer; char* red_zone_boundary; char* yellow_zone_boundary; sigjmp_buf return_point; size_t red_zone_size; } ThreadInfo; static pthread_key_t thread_info_key; static struct sigaction newAct, oldAct; bool gofromyellow = false; int call_times = 0; static void main_routine(){ // make it overflow if(gofromyellow == true) { printf("return from yellow zone, called %d times\n", call_times); return; } else { call_times = call_times + 1; main_routine(); gofromyellow = true; } } // red zone management static void stackoverflow_routine(){ fprintf(stderr, "stack overflow error.\n"); fflush(stderr); } // yellow zone management static void yellow_zone_hook(){ fprintf(stderr, "exceed yellow zone.\n"); fflush(stderr); } static int get_stack_info(void** stackaddr, size_t* stacksize){ int ret = -1; pthread_attr_t attr; pthread_attr_init(&attr); if(pthread_getattr_np(pthread_self(), &attr) == 0){ ret = pthread_attr_getstack(&attr, stackaddr, stacksize); } pthread_attr_destroy(&attr); return ret; } static int is_in_stack(const ThreadInfo* tinfo, char* pointer){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->stack_pointer + tinfo->stack_size); } static int is_in_red_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->red_zone_boundary){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->red_zone_boundary); } } static int is_in_yellow_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->yellow_zone_boundary){ return (tinfo->red_zone_boundary <= pointer) && (pointer < tinfo->yellow_zone_boundary); } } static void set_yellow_zone(ThreadInfo* tinfo){ int pagesize = sysconf(_SC_PAGE_SIZE); assert(pagesize > 0); tinfo->yellow_zone_boundary = tinfo->red_zone_boundary + pagesize * YELLOW_ZONE_PAGES; mprotect(tinfo->red_zone_boundary, pagesize * YELLOW_ZONE_PAGES, PROT_NONE); } static void reset_yellow_zone(ThreadInfo* tinfo){ size_t pagesize = tinfo->yellow_zone_boundary - tinfo->red_zone_boundary; if(mmap(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0) == 0){ perror("mmap failed"), exit(1); } mprotect(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE); tinfo->yellow_zone_boundary = 0; } static void signal_handler(int sig, siginfo_t* sig_info, void* sig_data){ if(sig == SIGSEGV){ ThreadInfo* tinfo = (ThreadInfo*) pthread_getspecific(thread_info_key); char* fault_address = (char*) sig_info->si_addr; if(is_in_stack(tinfo, fault_address)){ if(is_in_red_zone(tinfo, fault_address)){ siglongjmp(tinfo->return_point, 1); }else if(is_in_yellow_zone(tinfo, fault_address)){ reset_yellow_zone(tinfo); yellow_zone_hook(); gofromyellow = true; return; } else { //inside stack not related overflow SEGV happen } } } } static void register_application_info(){ pthread_key_create(&thread_info_key, NULL); sigemptyset(&newAct.sa_mask); sigaddset(&newAct.sa_mask, SIGSEGV); newAct.sa_sigaction = signal_handler; newAct.sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK; sigaction(SIGSEGV, &newAct, &oldAct); } static void register_thread_info(ThreadInfo* tinfo){ stack_t ss; pthread_setspecific(thread_info_key, tinfo); get_stack_info((void**)&tinfo->stack_pointer, &tinfo->stack_size); printf("stack size %d mb\n", tinfo->stack_size/1024/1024 ); tinfo->red_zone_boundary = tinfo->stack_pointer + tinfo->red_zone_size; set_yellow_zone(tinfo); ss.ss_sp = (char*)malloc(ALT_STACK_SIZE); ss.ss_size = ALT_STACK_SIZE; ss.ss_flags = 0; sigaltstack(&ss, NULL); } static void* thread_routine(void* p){ ThreadInfo* tinfo = (ThreadInfo*)p; register_thread_info(tinfo); if(sigsetjmp(tinfo->return_point, 1) == 0){ main_routine(); } else { stackoverflow_routine(); } free(tinfo); printf("after tinfo, end thread\n"); return 0; } int main(int argc, char** argv){ register_application_info(); if( argc == 2 ){ int stacksize = atoi(argv[1]); pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setstacksize(&attr, 1024 * 1024 * stacksize); { pthread_t pid0; ThreadInfo* tinfo = (ThreadInfo*)calloc(1, sizeof(ThreadInfo)); pthread_attr_getguardsize(&attr, &tinfo->red_zone_size); pthread_create(&pid0, &attr, thread_routine, tinfo); pthread_join(pid0, NULL); } } else { printf("Usage: %s stacksize(mb)\n", argv[0]); } return 0; } C language in linux, ubuntu

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• how do i install PHP with JSON and OAuth on Mac Snow Leopard?

  - by meilas

  i want to use the dropbox api via this library http://code.google.com/p/dropbox-php/ i installed MAMP then I tried "sudo pecl install oauth" but I got downloading oauth-1.0.0.tgz ... Starting to download oauth-1.0.0.tgz (42,834 bytes) ............done: 42,834 bytes 6 source files, building running: phpize Configuring for: PHP Api Version: 20090626 Zend Module Api No: 20090626 Zend Extension Api No: 220090626 building in /var/tmp/pear-build-root/oauth-1.0.0 running: /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/configure checking for grep that handles long lines and -e... /usr/bin/grep checking for egrep... /usr/bin/grep -E checking for a sed that does not truncate output... /opt/local/bin/gsed checking for cc... cc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether cc accepts -g... yes checking for cc option to accept ISO C89... none needed checking how to run the C preprocessor... cc -E checking for icc... no checking for suncc... no checking whether cc understands -c and -o together... yes checking for system library directory... lib checking if compiler supports -R... no checking if compiler supports -Wl,-rpath,... yes checking build system type... i686-apple-darwin10.4.0 checking host system type... i686-apple-darwin10.4.0 checking target system type... i686-apple-darwin10.4.0 checking for PHP prefix... /usr checking for PHP includes... -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib checking for PHP extension directory... /usr/lib/php/extensions/no-debug-non-zts-20090626 checking for PHP installed headers prefix... /usr/include/php checking if debug is enabled... no checking if zts is enabled... no checking for re2c... no configure: WARNING: You will need re2c 0.13.4 or later if you want to regenerate PHP parsers. checking for gawk... gawk checking for oauth support... yes, shared checking for cURL in default path... found in /usr checking for ld used by cc... /usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld checking if the linker (/usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld) is GNU ld... no checking for /usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld option to reload object files... -r checking for BSD-compatible nm... /usr/bin/nm checking whether ln -s works... yes checking how to recognise dependent libraries... pass_all checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking dlfcn.h usability... yes checking dlfcn.h presence... yes checking for dlfcn.h... yes checking the maximum length of command line arguments... 196608 checking command to parse /usr/bin/nm output from cc object... rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory ok checking for objdir... .libs checking for ar... ar checking for ranlib... ranlib checking for strip... strip rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory checking if cc static flag works... rm: conftest.dSYM: is a directory yes checking if cc supports -fno-rtti -fno-exceptions... rm: conftest.dSYM: is a directory no checking for cc option to produce PIC... -fno-common checking if cc PIC flag -fno-common works... rm: conftest.dSYM: is a directory yes checking if cc supports -c -o file.o... rm: conftest.dSYM: is a directory yes checking whether the cc linker (/usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld) supports shared libraries... yes checking dynamic linker characteristics... darwin10.4.0 dyld checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... no creating libtool appending configuration tag "CXX" to libtool configure: creating ./config.status config.status: creating config.h running: make /bin/sh /private/var/tmp/pear-build-root/oauth-1.0.0/libtool --mode=compile cc -I. -I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth -DPHP_ATOM_INC -I/private/var/tmp/pear-build-root/oauth-1.0.0/include -I/private/var/tmp/pear-build-root/oauth-1.0.0/main -I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib -DHAVE_CONFIG_H -g -O2 -Wall -g -c /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c -o oauth.lo mkdir .libs cc -I. "-I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth" -DPHP_ATOM_INC -I/private/var/tmp/pear-build-root/oauth-1.0.0/include -I/private/var/tmp/pear-build-root/oauth-1.0.0/main "-I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth" -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib -DHAVE_CONFIG_H -g -O2 -Wall -g -c "/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c" -fno-common -DPIC -o .libs/oauth.o In file included from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/php_oauth.h:47, from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c:14: /usr/include/php/ext/pcre/php_pcre.h:29:18: error: pcre.h: No such file or directory In file included from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/php_oauth.h:47, from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c:14: /usr/include/php/ext/pcre/php_pcre.h:37: error: expected '=', ',', ';', 'asm' or 'attribute' before '*' token /usr/include/php/ext/pcre/php_pcre.h:38: error: expected '=', ',', ';', 'asm' or 'attribute' before '*' token /usr/include/php/ext/pcre/php_pcre.h:44: error: expected specifier-qualifier-list before 'pcre' make: * [oauth.lo] Error 1 ERROR: `make' failed

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• How do I install PHP with JSON and OAuth on Mac Snow Leopard?

  - by meilas

  I want to use the Dropbox API via this library, http://code.google.com/p/dropbox-php/. I installed MAMP, and then I tried sudo pecl install oauth but I got the following. >>>> downloading oauth-1.0.0.tgz ... Starting to download oauth-1.0.0.tgz (42,834 bytes) ............done: 42,834 bytes 6 source files, building running: phpize Configuring for: PHP Api Version: 20090626 Zend Module Api No: 20090626 Zend Extension Api No: 220090626 building in /var/tmp/pear-build-root/oauth-1.0.0 running: /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/configure checking for grep that handles long lines and -e... /usr/bin/grep checking for egrep... /usr/bin/grep -E checking for a sed that does not truncate output... /opt/local/bin/gsed checking for cc... cc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether cc accepts -g... yes checking for cc option to accept ISO C89... none needed checking how to run the C preprocessor... cc -E checking for icc... no checking for suncc... no checking whether cc understands -c and -o together... yes checking for system library directory... lib checking if compiler supports -R... no checking if compiler supports -Wl,-rpath,... yes checking build system type... i686-apple-darwin10.4.0 checking host system type... i686-apple-darwin10.4.0 checking target system type... i686-apple-darwin10.4.0 checking for PHP prefix... /usr checking for PHP includes... -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib checking for PHP extension directory... /usr/lib/php/extensions/no-debug-non-zts-20090626 checking for PHP installed headers prefix... /usr/include/php checking if debug is enabled... no checking if zts is enabled... no checking for re2c... no configure: WARNING: You will need re2c 0.13.4 or later if you want to regenerate PHP parsers. checking for gawk... gawk checking for oauth support... yes, shared checking for cURL in default path... found in /usr checking for ld used by cc... /usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld checking if the linker (/usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld) is GNU ld... no checking for /usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld option to reload object files... -r checking for BSD-compatible nm... /usr/bin/nm checking whether ln -s works... yes checking how to recognise dependent libraries... pass_all checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking dlfcn.h usability... yes checking dlfcn.h presence... yes checking for dlfcn.h... yes checking the maximum length of command line arguments... 196608 checking command to parse /usr/bin/nm output from cc object... rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory ok checking for objdir... .libs checking for ar... ar checking for ranlib... ranlib checking for strip... strip rm: conftest.dSYM: is a directory rm: conftest.dSYM: is a directory checking if cc static flag works... rm: conftest.dSYM: is a directory yes checking if cc supports -fno-rtti -fno-exceptions... rm: conftest.dSYM: is a directory no checking for cc option to produce PIC... -fno-common checking if cc PIC flag -fno-common works... rm: conftest.dSYM: is a directory yes checking if cc supports -c -o file.o... rm: conftest.dSYM: is a directory yes checking whether the cc linker (/usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld) supports shared libraries... yes checking dynamic linker characteristics... darwin10.4.0 dyld checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... no >>>> creating libtool appending configuration tag "CXX" to libtool configure: creating ./config.status config.status: creating config.h running: make /bin/sh /private/var/tmp/pear-build-root/oauth-1.0.0/libtool --mode=compile cc -I. -I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth -DPHP_ATOM_INC -I/private/var/tmp/pear-build-root/oauth-1.0.0/include -I/private/var/tmp/pear-build-root/oauth-1.0.0/main -I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib -DHAVE_CONFIG_H -g -O2 -Wall -g -c /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c -o oauth.lo mkdir .libs cc -I. "-I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth" -DPHP_ATOM_INC -I/private/var/tmp/pear-build-root/oauth-1.0.0/include -I/private/var/tmp/pear-build-root/oauth-1.0.0/main "-I/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth" -I/usr/include/php -I/usr/include/php/main -I/usr/include/php/TSRM -I/usr/include/php/Zend -I/usr/include/php/ext -I/usr/include/php/ext/date/lib -DHAVE_CONFIG_H -g -O2 -Wall -g -c "/private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c" -fno-common -DPIC -o .libs/oauth.o In file included from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/php_oauth.h:47, from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c:14: /usr/include/php/ext/pcre/php_pcre.h:29:18: error: pcre.h: No such file or directory In file included from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/php_oauth.h:47, from /private/var/tmp/apache_mod_php/apache_mod_php-53~1/Build/tmp/pear/temp/oauth/oauth.c:14: /usr/include/php/ext/pcre/php_pcre.h:37: error: expected '=', ',', ';', 'asm' or '__attribute__' before '*' token /usr/include/php/ext/pcre/php_pcre.h:38: error: expected '=', ',', ';', 'asm' or '__attribute__' before '*' token /usr/include/php/ext/pcre/php_pcre.h:44: error: expected specifier-qualifier-list before 'pcre' make: *** [oauth.lo] Error 1 ERROR: `make' failed </block>

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• Ethernet Communication Error

  - by SivaKumar

  Hi, I wrote a program to query the status of the Ethernet printer for that i created a TCP Stream Socket and i send the query command to the printer.In case of Error less condition it returns No error status but in error case its getting hang at recv command.Even i used Non blocking now the recv command returns nothing and error set as Resource temporarily unavailable. code: #include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <unistd.h> #include <arpa/inet.h> #include <errno.h> #include <stdlib.h> #include <fcntl.h> #include <sys/ioctl.h> #include <sys/socket.h> #include <signal.h> #include <termios.h> #include <poll.h> #include <netinet/tcp.h> #include <stdarg.h> int main() { int ConnectSocket,ConnectSocket1,select_err,err,nRet,nBytesRead; struct timeval waitTime = {10,30}; fd_set socket_set; unsigned char * dataBuf = NULL; unsigned char tempVar, tempVar1, tempVar2, tempVar3; char reset[] = "\033E 2\r"; char print[] = "\033A 1\r"; char buf[1024]={0}; ConnectSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); printf("The Socket ID is %d\n",ConnectSocket); if (ConnectSocket < 0) { perror("socket()"); return 0; } struct sockaddr_in clientService; clientService.sin_family = AF_INET; clientService.sin_addr.s_addr = inet_addr("192.168.0.129"); //Printer IP clientService.sin_port = htons( 9100); // Printer Port if ( connect( ConnectSocket, (struct sockaddr*) &clientService, sizeof(clientService) ) == -1) { perror("connect()"); close(ConnectSocket); return -1; } /* if((nRet = ioctl(ConnectSocket , FIONREAD, &nBytesRead) == -1)) { perror("ioctl()"); } perror("ioctl()"); */ FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); do { errno=0; select_err = select(ConnectSocket+1, NULL, &socket_set, NULL, &waitTime); }while(errno==EINPROGRESS); if (-1 == select_err || 0 == select_err) { int optVal = 0; int optLen = sizeof(optVal); if(select_err == -1) { perror("select() write-side"); } else { //Timeout errno=0; err = getsockopt(ConnectSocket, SOL_SOCKET, SO_ERROR, (char*)&optVal, &optLen); printf("the return of the getsockopt is %d\n",err); printf("the opt val is %s\n",(char*)optVal); perror("getsockopt()"); if(err == -1) { perror("getsockopt() write-side"); } } printf("Select Failed during write - ConnectSocket: %d\n", ConnectSocket); //close(ConnectSocket); return -1; } err = send(ConnectSocket,print,sizeof(print)-1, 0); printf("\n No of Bytes Send is %d\n",err); if(err == -1 || err ==0) { perror("send()"); //close(ConnectSocket); return -1; } FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); do { errno=0; select_err = select(ConnectSocket+1, NULL, &socket_set, NULL, &waitTime); }while(errno==EINPROGRESS); if (-1 == select_err || 0 == select_err) { printf("Select Failed during write - ConnectSocket: %d\n", ConnectSocket); return -1; } err = send(ConnectSocket,reset,sizeof(reset)-1, 0); printf("\n No of Bytes Send is %d\n",err); if(err == -1 || err ==0) { perror("send()"); //close(ConnectSocket); return -1; } FD_ZERO(&socket_set); FD_SET(ConnectSocket, &socket_set); printf("i am in reading \n"); select_err = select(ConnectSocket+1, &socket_set, NULL, NULL, &waitTime); printf("the retun of the read side select is %d \n",select_err); perror("select()"); if (-1 == select_err|| 0 == select_err) { printf("Read timeout; ConnectSocket: %d\n", ConnectSocket); close(ConnectSocket); perror("close()"); return -1; } printf("Before Recv\n"); nBytesRead = recv(ConnectSocket , buf, 1024, 0); printf("No of Bytes read is %d\n",nBytesRead); printf("%s\n",buf); if(nBytesRead == -1) { perror("recv()"); close(ConnectSocket); perror("clode()"); return -1; } close(ConnectSocket); return 1; }

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• Help with malloc and free: Glibc detected: free(): invalid pointer

  - by nunos

  I need help with debugging this piece of code. I know the problem is in malloc and free but can't find exactly where, why and how to fix it. Please don't answer: "Use gdb" and that's it. I would use gdb to debug it, but I still don't know much about it and am still learning it, and would like to have, in the meanwhile, another solution. Thanks. #include <stdio.h> #include <stdlib.h> #include <ctype.h> #include <unistd.h> #include <string.h> #include <sys/wait.h> #include <sys/types.h> #define MAX_COMMAND_LENGTH 256 #define MAX_ARGS_NUMBER 128 #define MAX_HISTORY_NUMBER 100 #define PROMPT ">>> " int num_elems; typedef enum {false, true} bool; typedef struct { char **arg; char *infile; char *outfile; int background; } Command_Info; int parse_cmd(char *cmd_line, Command_Info *cmd_info) { char *arg; char *args[MAX_ARGS_NUMBER]; int i = 0; arg = strtok(cmd_line, " "); while (arg != NULL) { args[i] = arg; arg = strtok(NULL, " "); i++; } num_elems = i;precisa em free_mem if (num_elems == 0) return 0; cmd_info->arg = (char **) ( malloc(num_elems * sizeof(char *)) ); cmd_info->infile = NULL; cmd_info->outfile = NULL; cmd_info->background = 0; bool b_infile = false; bool b_outfile = false; int iarg = 0; for (i = 0; i < num_elems; i++) { if ( !strcmp(args[i], "<") ) { if ( b_infile || i == num_elems-1 || !strcmp(args[i+1], "<") || !strcmp(args[i+1], ">") || !strcmp(args[i+1], "&") ) return -1; i++; cmd_info->infile = malloc(strlen(args[i]) * sizeof(char)); strcpy(cmd_info->infile, args[i]); b_infile = true; } else if (!strcmp(args[i], ">")) { if ( b_outfile || i == num_elems-1 || !strcmp(args[i+1], ">") || !strcmp(args[i+1], "<") || !strcmp(args[i+1], "&") ) return -1; i++; cmd_info->outfile = malloc(strlen(args[i]) * sizeof(char)); strcpy(cmd_info->outfile, args[i]); b_outfile = true; } else if (!strcmp(args[i], "&")) { if ( i == 0 || i != num_elems-1 || cmd_info->background ) return -1; cmd_info->background = true; } else { cmd_info->arg[iarg] = malloc(strlen(args[i]) * sizeof(char)); strcpy(cmd_info->arg[iarg], args[i]); iarg++; } } cmd_info->arg[iarg] = NULL; return 0; } void print_cmd(Command_Info *cmd_info) { int i; for (i = 0; cmd_info->arg[i] != NULL; i++) printf("arg[%d]=\"%s\"\n", i, cmd_info->arg[i]); printf("arg[%d]=\"%s\"\n", i, cmd_info->arg[i]); printf("infile=\"%s\"\n", cmd_info->infile); printf("outfile=\"%s\"\n", cmd_info->outfile); printf("background=\"%d\"\n", cmd_info->background); } void get_cmd(char* str) { fgets(str, MAX_COMMAND_LENGTH, stdin); str[strlen(str)-1] = '\0'; } pid_t exec_simple(Command_Info *cmd_info) { pid_t pid = fork(); if (pid < 0) { perror("Fork Error"); return -1; } if (pid == 0) { if ( (execvp(cmd_info->arg[0], cmd_info->arg)) == -1) { perror(cmd_info->arg[0]); exit(1); } } return pid; } void type_prompt(void) { printf("%s", PROMPT); } void syntax_error(void) { printf("msh syntax error\n"); } void free_mem(Command_Info *cmd_info) { int i; for (i = 0; cmd_info->arg[i] != NULL; i++) free(cmd_info->arg[i]); free(cmd_info->arg); free(cmd_info->infile); free(cmd_info->outfile); } int main(int argc, char* argv[]) { char cmd_line[MAX_COMMAND_LENGTH]; Command_Info cmd_info; //char* history[MAX_HISTORY_NUMBER]; while (true) { type_prompt(); get_cmd(cmd_line); if ( parse_cmd(cmd_line, &cmd_info) == -1) { syntax_error(); continue; } if (!strcmp(cmd_line, "")) continue; if (!strcmp(cmd_info.arg[0], "exit")) exit(0); pid_t pid = exec_simple(&cmd_info); waitpid(pid, NULL, 0); free_mem(&cmd_info); } return 0; }

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• Unknown error in Producer/Consumer program, believe it to be an infinite loop.

  - by ray2k

  Hello, I am writing a program that is solving the producer/consumer problem, specifically the bounded-buffer version(i believe they mean the same thing). The producer will be generating x number of random numbers, where x is a command line parameter to my program. At the current moment, I believe my program is entering an infinite loop, but I'm not sure why it is occurring. I believe I am executing the semaphores correctly. You compile it like this: gcc -o prodcon prodcon.cpp -lpthread -lrt Then to run, ./prodcon 100(the number of randum nums to produce) This is my code. typedef int buffer_item; #include <stdlib.h> #include <stdio.h> #include <pthread.h> #include <semaphore.h> #include <unistd.h> #define BUFF_SIZE 10 #define RAND_DIVISOR 100000000 #define TRUE 1 //two threads void *Producer(void *param); void *Consumer(void *param); int insert_item(buffer_item item); int remove_item(buffer_item *item); int returnRandom(); //the global semaphores sem_t empty, full, mutex; //the buffer buffer_item buf[BUFF_SIZE]; //buffer counter int counter; //number of random numbers to produce int numRand; int main(int argc, char** argv) { /* thread ids and attributes */ pthread_t pid, cid; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM); numRand = atoi(argv[1]); sem_init(&empty,0,BUFF_SIZE); sem_init(&full,0,0); sem_init(&mutex,0,0); printf("main started\n"); pthread_create(&pid, &attr, Producer, NULL); pthread_create(&cid, &attr, Consumer, NULL); printf("main gets here"); pthread_join(pid, NULL); pthread_join(cid, NULL); printf("main done\n"); return 0; } //generates a randum number between 1 and 100 int returnRandom() { int num; srand(time(NULL)); num = rand() % 100 + 1; return num; } //begin producing items void *Producer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { //sleep for a random period of time int rNum = rand() / RAND_DIVISOR; sleep(rNum); //generate a random number item = returnRandom(); //acquire the empty lock sem_wait(&empty); //acquire the mutex lock sem_wait(&mutex); if(insert_item(item)) { fprintf(stderr, " Producer report error condition\n"); } else { printf("producer produced %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal full */ sem_post(&full); } return NULL; } /* Consumer Thread */ void *Consumer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { /* sleep for a random period of time */ int rNum = rand() / RAND_DIVISOR; sleep(rNum); /* aquire the full lock */ sem_wait(&full); /* aquire the mutex lock */ sem_wait(&mutex); if(remove_item(&item)) { fprintf(stderr, "Consumer report error condition\n"); } else { printf("consumer consumed %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal empty */ sem_post(&empty); } return NULL; } /* Add an item to the buffer */ int insert_item(buffer_item item) { /* When the buffer is not full add the item and increment the counter*/ if(counter < BUFF_SIZE) { buf[counter] = item; counter++; return 0; } else { /* Error the buffer is full */ return -1; } } /* Remove an item from the buffer */ int remove_item(buffer_item *item) { /* When the buffer is not empty remove the item and decrement the counter */ if(counter > 0) { *item = buf[(counter-1)]; counter--; return 0; } else { /* Error buffer empty */ return -1; } }

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• a program similar to ls with some modifications

  - by Bond

  Hi, here is a simple puzzle I wanted to discuss. A C program to take directory name as command line argument and print last 3 directories and 3 files in all subdirectories without using api 'system' inside it. suppose directory bond0 contains bond1, di2, bond3, bond4, bond5 and my_file1, my_file2, my_file3, my_file4, my_file5, my_file6 and bond1 contains bond6 my_file7 my_file8 my_file9 my_file10 program should output - bond3, bond4, bond5, my_file4, my_file5, my_file6, bond6, my_file8, my_file9, my_file10 My code for the above problem is here #include<dirent.h> #include<unistd.h> #include<string.h> #include<sys/stat.h> #include<stdlib.h> #include<stdio.h> char *directs[20], *files[20]; int i = 0; int j = 0; int count = 0; void printdir(char *); int count_dirs(char *); int count_files(char *); int main() { char startdir[20]; printf("Scanning user directories\n"); scanf("%s", startdir); printdir(startdir); } void printdir(char *dir) { printf("printdir called %d directory is %s\n", ++count, dir); DIR *dp = opendir(dir); int nDirs, nFiles, nD, nF; nDirs = 0; nFiles = 0; nD = 0; nF = 0; if (dp) { struct dirent *entry = 0; struct stat statBuf; nDirs = count_dirs(dir); nFiles = count_files(dir); printf("The no of subdirectories in %s is %d \n", dir, nDirs); printf("The no of files in %s is %d \n", dir, nFiles); while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { } if (S_ISDIR(statBuf.st_mode)) { nD++; if ((nDirs - nD) < 3) { printf("The directory is %s\n",entry->d_name); } } else { nF++; if ((nFiles - nF) < 3) { printf("The files are %s\n", entry->d_name); } //if } //else free(filepath); } //if(filepath) } //while while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } printf("In second while loop *entry=%s\n",entry->d_name); char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { } if (S_ISDIR(statBuf.st_mode)) { printdir(entry->d_name); } } //else free(filepath); } //2nd while closedir(dp); } else { fprintf(stderr, "Error, cannot open directory %s\n", dir); } } //printdir int count_dirs(char *dir) { DIR *dp = opendir(dir); int nD; nD = 0; if (dp) { struct dirent *entry = 0; struct stat statBuf; while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { fprintf(stderr, "File Not found? %s\n", filepath); } if (S_ISDIR(statBuf.st_mode)) { nD++; } else { continue; } free(filepath); } } closedir(dp); } else { fprintf(stderr, "Error, cannot open directory %s\n", dir); } return nD; } int count_files(char *dir) { DIR *dp = opendir(dir); int nF; nF = 0; if (dp) { struct dirent *entry = 0; struct stat statBuf; while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { fprintf(stderr, "File Not found? %s\n", filepath); } if (S_ISDIR(statBuf.st_mode)) { continue; } else { nF++; } free(filepath); } } closedir(dp); } else { fprintf(stderr, "Error, cannot open file %s\n", dir); } return nF; } The above code I wrote is a bit not functioning correctly can some one help me to understand the error which is coming.So that I improve it further.There seems to be some small glitch which is not clear to me right now.

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• Qt C++ signals and slots did not fire

  - by Xegara

  I have programmed Qt a couple of times already and I really like the signals and slots feature. But now, I guess I'm having a problem when a signal is emitted from one thread, the corresponding slot from another thread is not fired. The connection was made in the main program. This is also my first time to use Qt for ROS which uses CMake. The signal fired by the QThread triggered their corresponding slots but the emitted signal of my class UserInput did not trigger the slot in tflistener where it supposed to. I have tried everything I can. Any help? The code is provided below. Main.cpp #include <QCoreApplication> #include <QThread> #include "userinput.h" #include "tfcompleter.h" int main(int argc, char** argv) { QCoreApplication app(argc, argv); QThread *thread1 = new QThread(); QThread *thread2 = new QThread(); UserInput *input1 = new UserInput(); TfCompleter *completer = new TfCompleter(); QObject::connect(input1, SIGNAL(togglePause2()), completer, SLOT(toggle())); QObject::connect(thread1, SIGNAL(started()), completer, SLOT(startCounting())); QObject::connect(thread2, SIGNAL(started()), input1, SLOT(start())); completer->moveToThread(thread1); input1->moveToThread(thread2); thread1->start(); thread2->start(); app.exec(); return 0; } What I want to do is.. There are two seperate threads. One thread is for the user input. When the user enters [space], the thread emits a signal to toggle the boolean member field of the other thread. The other thread 's task is to just continue its process if the user wants it to run, otherwise, the user does not want it to run. I wanted to grant the user to toggle the processing anytime that he wants, that's why I decided to bring them into seperate threads. The following codes are the tflistener and userinput. tfcompleter.h #ifndef TFCOMPLETER_H #define TFCOMPLETER_H #include <QObject> #include <QtCore> class TfCompleter : public QObject { Q_OBJECT private: bool isCount; public Q_SLOTS: void toggle(); void startCounting(); }; #endif tflistener.cpp #include "tfcompleter.h" #include <iostream> void TfCompleter::startCounting() { static uint i = 0; while(true) { if(isCount) std::cout << i++ << std::endl; } } void TfCompleter::toggle() { // isCount = ~isCount; std::cout << "isCount " << std::endl; } UserInput.h #ifndef USERINPUT_H #define USERINPUT_H #include <QObject> #include <QtCore> class UserInput : public QObject { Q_OBJECT public Q_SLOTS: void start(); // Waits for the keypress from the user and emits the corresponding signal. public: Q_SIGNALS: void togglePause2(); }; #endif UserInput.cpp #include "userinput.h" #include <iostream> #include <cstdio> // Implementation of getch #include <termios.h> #include <unistd.h> /* reads from keypress, doesn't echo */ int getch(void) { struct termios oldattr, newattr; int ch; tcgetattr( STDIN_FILENO, &oldattr ); newattr = oldattr; newattr.c_lflag &= ~( ICANON | ECHO ); tcsetattr( STDIN_FILENO, TCSANOW, &newattr ); ch = getchar(); tcsetattr( STDIN_FILENO, TCSANOW, &oldattr ); return ch; } void UserInput::start() { char c = 0; while (true) { c = getch(); if (c == ' ') { Q_EMIT togglePause2(); std::cout << "SPACE" << std::endl; } c = 0; } } Here is the CMakeLists.txt. I just placed it here also since I don't know maybe the CMake has also a factor here. CMakeLists.txt ############################################################################## # CMake ############################################################################## cmake_minimum_required(VERSION 2.4.6) ############################################################################## # Ros Initialisation ############################################################################## include($ENV{ROS_ROOT}/core/rosbuild/rosbuild.cmake) rosbuild_init() set(CMAKE_AUTOMOC ON) #set the default path for built executables to the "bin" directory set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin) #set the default path for built libraries to the "lib" directory set(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/lib) # Set the build type. Options are: # Coverage : w/ debug symbols, w/o optimization, w/ code-coverage # Debug : w/ debug symbols, w/o optimization # Release : w/o debug symbols, w/ optimization # RelWithDebInfo : w/ debug symbols, w/ optimization # MinSizeRel : w/o debug symbols, w/ optimization, stripped binaries #set(ROS_BUILD_TYPE Debug) ############################################################################## # Qt Environment ############################################################################## # Could use this, but qt-ros would need an updated deb, instead we'll move to catkin # rosbuild_include(qt_build qt-ros) rosbuild_find_ros_package(qt_build) include(${qt_build_PACKAGE_PATH}/qt-ros.cmake) rosbuild_prepare_qt4(QtCore) # Add the appropriate components to the component list here ADD_DEFINITIONS(-DQT_NO_KEYWORDS) ############################################################################## # Sections ############################################################################## #file(GLOB QT_FORMS RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} ui/*.ui) #file(GLOB QT_RESOURCES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} resources/*.qrc) file(GLOB_RECURSE QT_MOC RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} FOLLOW_SYMLINKS include/rgbdslam_client/*.hpp) #QT4_ADD_RESOURCES(QT_RESOURCES_CPP ${QT_RESOURCES}) #QT4_WRAP_UI(QT_FORMS_HPP ${QT_FORMS}) QT4_WRAP_CPP(QT_MOC_HPP ${QT_MOC}) ############################################################################## # Sources ############################################################################## file(GLOB_RECURSE QT_SOURCES RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} FOLLOW_SYMLINKS src/*.cpp) ############################################################################## # Binaries ############################################################################## rosbuild_add_executable(rgbdslam_client ${QT_SOURCES} ${QT_MOC_HPP}) #rosbuild_add_executable(rgbdslam_client ${QT_SOURCES} ${QT_RESOURCES_CPP} ${QT_FORMS_HPP} ${QT_MOC_HPP}) target_link_libraries(rgbdslam_client ${QT_LIBRARIES})

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• timer_getoverrun() doesn't behave as expected when using sleep()

  - by dlp

  Here is a program that uses a POSIX per-process timer alongside the sleep subroutine. The signal used by the timer has been set to SIGUSR1 rather than SIGALRM, since SIGALRM may be used internally by sleep, but it still doesn't seem to work. I have run the program using the command line timer-overruns -d 1 -n 10000000 (1 cs interval) so, in theory, we should expect 100 overruns between calls to sigwaitinfo. However, timer_getoverrun returns 0. I have also tried a version using a time-consuming for loop to introduce the delay. In this case, overruns are recorded. Does anyone know why this happens? I am running a 3.4 Linux kernel. Program source /* * timer-overruns.c */ #include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <signal.h> #include <time.h> // Signal to be used for timer expirations #define TIMER_SIGNAL SIGUSR1 int main(int argc, char **argv) { int opt; int d = 0; int r = 0; // Repeat indefinitely struct itimerspec its; its.it_interval.tv_sec = 0; its.it_interval.tv_nsec = 0; // Parse arguments while ((opt = getopt(argc, argv, "d:r:s:n:")) != -1) { switch (opt) { case 'd': // Delay before calling sigwaitinfo() d = atoi(optarg); break; case 'r': // Number of times to call sigwaitinfo() r = atoi(optarg); break; case 's': // Timer interval (seconds) its.it_interval.tv_sec = its.it_value.tv_sec = atoi(optarg); break; case 'n': // Timer interval (nanoseconds) its.it_interval.tv_nsec = its.it_value.tv_nsec = atoi(optarg); break; default: /* '?' */ fprintf(stderr, "Usage: %s [-d signal_accept_delay] [-r repetitions] [-s interval_seconds] [-n interval_nanoseconds]\n", argv[0]); exit(EXIT_FAILURE); } } // Check sanity of command line arguments short e = 0; if (d < 0) { fprintf(stderr, "Delay (-d) cannot be negative!\n"); e++; } if (r < 0) { fprintf(stderr, "Number of repetitions (-r) cannot be negative!\n"); e++; } if (its.it_interval.tv_sec < 0) { fprintf(stderr, "Interval seconds value (-s) cannot be negative!\n"); e++; } if (its.it_interval.tv_nsec < 0) { fprintf(stderr, "Interval nanoseconds value (-n) cannot be negative!\n"); e++; } if (its.it_interval.tv_nsec > 999999999) { fprintf(stderr, "Interval nanoseconds value (-n) must be < 1 second.\n"); e++; } if (e > 0) exit(EXIT_FAILURE); // Set default values if not specified if (its.it_interval.tv_sec == 0 && its.it_interval.tv_nsec == 0) { its.it_interval.tv_sec = its.it_value.tv_sec = 1; its.it_value.tv_nsec = 0; } printf("Running with timer delay %d.%09d seconds\n", (int) its.it_interval.tv_sec, (int) its.it_interval.tv_nsec); // Will be waiting for signals synchronously, so block the one in use. sigset_t sigset; sigemptyset(&sigset); sigaddset(&sigset, TIMER_SIGNAL); sigprocmask(SIG_BLOCK, &sigset, NULL ); // Create and arm the timer struct sigevent sev; timer_t timer; sev.sigev_notify = SIGEV_SIGNAL; sev.sigev_signo = TIMER_SIGNAL; sev.sigev_value.sival_ptr = timer; timer_create(CLOCK_REALTIME, &sev, &timer); timer_settime(timer, TIMER_ABSTIME, &its, NULL ); // Signal handling loop int overruns; siginfo_t si; // Make the loop infinite if r = 0 if (r == 0) r = -1; while (r != 0) { // Sleeping should cause overruns if (d > 0) sleep(d); sigwaitinfo(&sigset, &si); // Check that the signal is from the timer if (si.si_code != SI_TIMER) continue; overruns = timer_getoverrun(timer); if (overruns > 0) { printf("Timer overrun occurred for %d expirations.\n", overruns); } // Decrement r if not repeating indefinitely if (r > 0) r--; } return EXIT_SUCCESS; }

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• Auto not being recognised by the compiler, what would be the best replacement?

  - by user1719605

  So I have wrote a program that uses auto however the compiler doesn't seem to recognize it, probably it is an earlier compiler. I was wondering for my code, with are suitable variables to fix my code so that I do not need to use the auto keyword? I'm thinking a pointer to a string? or a string iterator, though I am not sure. #include <cstdlib> #include <string> #include <iostream> #include <unistd.h> #include <algorithm> using namespace std; int main(int argc, char* argv[]) { enum MODE { WHOLE, PREFIX, SUFFIX, ANYWHERE, EMBEDDED } mode = WHOLE; bool reverse_match = false; int c; while ((c = getopt(argc, argv, ":wpsaev")) != -1) { switch (c) { case 'w': // pattern matches whole word mode = WHOLE; break; case 'p': // pattern matches prefix mode = PREFIX; break; case 'a': // pattern matches anywhere mode = ANYWHERE; break; case 's': // pattern matches suffix mode = SUFFIX; break; case 'e': // pattern matches anywhere mode = EMBEDDED; break; case 'v': // reverse sense of match reverse_match = true; break; } } argc -= optind; argv += optind; string pattern = argv[0]; string word; int matches = 0; while (cin >> word) { switch (mode) { case WHOLE: if (reverse_match) { if (pattern != word) { matches += 1; cout << word << endl; } } else if (pattern == word) { matches += 1; cout << word << endl; } break; case PREFIX: if (pattern.size() <= word.size()) { auto res = mismatch(pattern.begin(), pattern.end(), word.begin()); if (reverse_match) { if (res.first != word.end()) { matches += 1; cout << word << endl; } } else if (res.first == word.end()) { matches += 1; cout << word << endl; } } break; case ANYWHERE: if (reverse_match) { if (!word.find(pattern) != string::npos) { matches += 1; cout << word << endl; } } else if (word.find(pattern) != string::npos) { matches += 1; cout << word << endl; } break; case SUFFIX: if (pattern.size() <= word.size()) { auto res = mismatch(pattern.rbegin(), pattern.rend(), word.rbegin()); if (reverse_match) { if (res.first != word.rend()) { matches = +1; cout << word << endl; } } else if (res.first == word.rend()) { matches = +1; cout << word << endl; } } break; case EMBEDDED: if (reverse_match) { if (!pattern.find(word) != string::npos) { matches += 1; cout << word << endl;} } else if (pattern.find(word) != string::npos) { matches += 1; cout << word << endl; } break; } } return (matches == 0) ? 1 : 0; } Thanks in advance!

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• Nagging As A Strategy For Better Linking: -z guidance

  - by user9154181

  The link-editor (ld) in Solaris 11 has a new feature that we call guidance that is intended to help you build better objects. The basic idea behind guidance is that if (and only if) you request it, the link-editor will issue messages suggesting better options and other changes you might make to your ld command to get better results. You can choose to take the advice, or you can disable specific types of guidance while acting on others. In some ways, this works like an experienced friend leaning over your shoulder and giving you advice — you're free to take it or leave it as you see fit, but you get nudged to do a better job than you might have otherwise. We use guidance to build the core Solaris OS, and it has proven to be useful, both in improving our objects, and in making sure that regressions don't creep back in later. In this article, I'm going to describe the evolution in thinking and design that led to the implementation of the -z guidance option, as well as give a brief description of how it works. The guidance feature issues non-fatal warnings. However, experience shows that once developers get used to ignoring warnings, it is inevitable that real problems will be lost in the noise and ignored or missed. This is why we have a zero tolerance policy against build noise in the core Solaris OS. In order to get maximum benefit from -z guidance while maintaining this policy, I added the -z fatal-warnings option at the same time. Much of the material presented here is adapted from the arc case: PSARC 2010/312 Link-editor guidance The History Of Unfortunate Link-Editor Defaults The Solaris link-editor is one of the oldest Unix commands. It stands to reason that this would be true — in order to write an operating system, you need the ability to compile and link code. The original link-editor (ld) had defaults that made sense at the time. As new features were needed, command line option switches were added to let the user use them, while maintaining backward compatibility for those who didn't. Backward compatibility is always a concern in system design, but is particularly important in the case of the tool chain (compilers, linker, and related tools), since it is a basic building block for the entire system. Over the years, applications have grown in size and complexity. Important concepts like dynamic linking that didn't exist in the original Unix system were invented. Object file formats changed. In the case of System V Release 4 Unix derivatives like Solaris, the ELF (Extensible Linking Format) was adopted. Since then, the ELF system has evolved to provide tools needed to manage today's larger and more complex environments. Features such as lazy loading, and direct bindings have been added. In an ideal world, many of these options would be defaults, with rarely used options that allow the user to turn them off. However, the reality is exactly the reverse: For backward compatibility, these features are all options that must be explicitly turned on by the user. This has led to a situation in which most applications do not take advantage of the many improvements that have been made in linking over the last 20 years. If their code seems to link and run without issue, what motivation does a developer have to read a complex manpage, absorb the information provided, choose the features that matter for their application, and apply them? Experience shows that only the most motivated and diligent programmers will make that effort. We know that most programs would be improved if we could just get you to use the various whizzy features that we provide, but the defaults conspire against us. We have long wanted to do something to make it easier for our users to use the linkers more effectively. There have been many conversations over the years regarding this issue, and how to address it. They always break down along the following lines: Change ld Defaults Since the world would be a better place the newer ld features were the defaults, why not change things to make it so? This idea is simple, elegant, and impossible. Doing so would break a large number of existing applications, including those of ISVs, big customers, and a plethora of existing open source packages. In each case, the owner of that code may choose to follow our lead and fix their code, or they may view it as an invitation to reconsider their commitment to our platform. Backward compatibility, and our installed base of working software, is one of our greatest assets, and not something to be lightly put at risk. Breaking backward compatibility at this level of the system is likely to do more harm than good. But, it sure is tempting. New Link-Editor One might create a new linker command, not called 'ld', leaving the old command as it is. The new one could use the same code as ld, but would offer only modern options, with the proper defaults for features such as direct binding. The resulting link-editor would be a pleasure to use. However, the approach is doomed to niche status. There is a vast pile of exiting code in the world built around the existing ld command, that reaches back to the 1970's. ld use is embedded in large and unknown numbers of makefiles, and is used by name by compilers that execute it. A Unix link-editor that is not named ld will not find a majority audience no matter how good it might be. Finally, a new linker command will eventually cease to be new, and will accumulate its own burden of backward compatibility issues. An Option To Make ld Do The Right Things Automatically This line of reasoning is best summarized by a CR filed in 2005, entitled 6239804 make it easier for ld(1) to do what's best The idea is to have a '-z best' option that unchains ld from its backward compatibility commitment, and allows it to turn on the "best" set of features, as determined by the authors of ld. The specific set of features enabled by -z best would be subject to change over time, as requirements change. This idea is more realistic than the other two, but was never implemented because it has some important issues that we could never answer to our satisfaction: The -z best proposal assumes that the user can turn it on, and trust it to select good options without the user needing to be aware of the options being applied. This is a fallacy. Features such as direct bindings require the user to do some analysis to ensure that the resulting program will still operate properly. A user who is willing to do the work to verify that what -z best does will be OK for their application is capable of turning on those features directly, and therefore gains little added benefit from -z best. The intent is that when a user opts into -z best, that they understand that z best is subject to sometimes incompatible evolution. Experience teaches us that this won't work. People will use this feature, the meaning of -z best will change, code that used to build will fail, and then there will be complaints and demands to retract the change. When (not if) this occurs, we will of course defend our actions, and point at the disclaimer. We'll win some of those debates, and lose others. Ultimately, we'll end up with -z best2 (-z better), or other compromises, and our goal of simplifying the world will have failed. The -z best idea rolls up a set of features that may or may not be related to each other into a unit that must be taken wholesale, or not at all. It could be that only a subset of what it does is compatible with a given application, in which case the user is expected to abandon -z best and instead set the options that apply to their application directly. In doing so, they lose one of the benefits of -z best, that if you use it, future versions of ld may choose a different set of options, and automatically improve the object through the act of rebuilding it. I drew two conclusions from the above history: For a link-editor, backward compatibility is vital. If a given command line linked your application 10 years ago, you have every reason to expect that it will link today, assuming that the libraries you're linking against are still available and compatible with their previous interfaces. For an application of any size or complexity, there is no substitute for the work involved in examining the code and determining which linker options apply and which do not. These options are largely orthogonal to each other, and it can be reasonable not to use any or all of them, depending on the situation, even in modern applications. It is a mistake to tie them together. The idea for -z guidance came from consideration of these points. By decoupling the advice from the act of taking the advice, we can retain the good aspects of -z best while avoiding its pitfalls: -z guidance gives advice, but the decision to take that advice remains with the user who must evaluate its merit and make a decision to take it or not. As such, we are free to change the specific guidance given in future releases of ld, without breaking existing applications. The only fallout from this will be some new warnings in the build output, which can be ignored or dealt with at the user's convenience. It does not couple the various features given into a single "take it or leave it" option, meaning that there will never be a need to offer "-zguidance2", or other such variants as things change over time. Guidance has the potential to be our final word on this subject. The user is given the flexibility to disable specific categories of guidance without losing the benefit of others, including those that might be added to future versions of the system. Although -z fatal-warnings stands on its own as a useful feature, it is of particular interest in combination with -z guidance. Used together, the guidance turns from advice to hard requirement: The user must either make the suggested change, or explicitly reject the advice by specifying a guidance exception token, in order to get a build. This is valuable in environments with high coding standards. ld Command Line Options The guidance effort resulted in new link-editor options for guidance and for turning warnings into fatal errors. Before I reproduce that text here, I'd like to highlight the strategic decisions embedded in the guidance feature: In order to get guidance, you have to opt in. We hope you will opt in, and believe you'll get better objects if you do, but our default mode of operation will continue as it always has, with full backward compatibility, and without judgement. Guidance suggestions always offers specific advice, and not vague generalizations. You can disable some guidance without turning off the entire feature. When you get guidance warnings, you can choose to take the advice, or you can specify a keyword to disable guidance for just that category. This allows you to get guidance for things that are useful to you, without being bothered about things that you've already considered and dismissed. As the world changes, we will add new guidance to steer you in the right direction. All such new guidance will come with a keyword that let's you turn it off. In order to facilitate building your code on different versions of Solaris, we quietly ignore any guidance keywords we don't recognize, assuming that they are intended for newer versions of the link-editor. If you want to see what guidance tokens ld does and does not recognize on your system, you can use the ld debugging feature as follows: % ld -Dargs -z guidance=foo,nodefs debug: debug: Solaris Linkers: 5.11-1.2275 debug: debug: arg[1] option=-D: option-argument: args debug: arg[2] option=-z: option-argument: guidance=foo,nodefs debug: warning: unrecognized -z guidance item: foo The -z fatal-warning option is straightforward, and generally useful in environments with strict coding standards. Note that the GNU ld already had this feature, and we accept their option names as synonyms: -z fatal-warnings | nofatal-warnings --fatal-warnings | --no-fatal-warnings The -z fatal-warnings and the --fatal-warnings option cause the link-editor to treat warnings as fatal errors. The -z nofatal-warnings and the --no-fatal-warnings option cause the link-editor to treat warnings as non-fatal. This is the default behavior. The -z guidance option is defined as follows: -z guidance[=item1,item2,...] Provide guidance messages to suggest ld options that can improve the quality of the resulting object, or which are otherwise considered to be beneficial. The specific guidance offered is subject to change over time as the system evolves. Obsolete guidance offered by older versions of ld may be dropped in new versions. Similarly, new guidance may be added to new versions of ld. Guidance therefore always represents current best practices. It is possible to enable guidance, while preventing specific guidance messages, by providing a list of item tokens, representing the class of guidance to be suppressed. In this way, unwanted advice can be suppressed without losing the benefit of other guidance. Unrecognized item tokens are quietly ignored by ld, allowing a given ld command line to be executed on a variety of older or newer versions of Solaris. The guidance offered by the current version of ld, and the item tokens used to disable these messages, are as follows. Specify Required Dependencies Dynamic executables and shared objects should explicitly define all of the dependencies they require. Guidance recommends the use of the -z defs option, should any symbol references remain unsatisfied when building dynamic objects. This guidance can be disabled with -z guidance=nodefs. Do Not Specify Non-Required Dependencies Dynamic executables and shared objects should not define any dependencies that do not satisfy the symbol references made by the dynamic object. Guidance recommends that unused dependencies be removed. This guidance can be disabled with -z guidance=nounused. Lazy Loading Dependencies should be identified for lazy loading. Guidance recommends the use of the -z lazyload option should any dependency be processed before either a -z lazyload or -z nolazyload option is encountered. This guidance can be disabled with -z guidance=nolazyload. Direct Bindings Dependencies should be referenced with direct bindings. Guidance recommends the use of the -B direct, or -z direct options should any dependency be processed before either of these options, or the -z nodirect option is encountered. This guidance can be disabled with -z guidance=nodirect. Pure Text Segment Dynamic objects should not contain relocations to non-writable, allocable sections. Guidance recommends compiling objects with Position Independent Code (PIC) should any relocations against the text segment remain, and neither the -z textwarn or -z textoff options are encountered. This guidance can be disabled with -z guidance=notext. Mapfile Syntax All mapfiles should use the version 2 mapfile syntax. Guidance recommends the use of the version 2 syntax should any mapfiles be encountered that use the version 1 syntax. This guidance can be disabled with -z guidance=nomapfile. Library Search Path Inappropriate dependencies that are encountered by ld are quietly ignored. For example, a 32-bit dependency that is encountered when generating a 64-bit object is ignored. These dependencies can result from incorrect search path settings, such as supplying an incorrect -L option. Although benign, this dependency processing is wasteful, and might hide a build problem that should be solved. Guidance recommends the removal of any inappropriate dependencies. This guidance can be disabled with -z guidance=nolibpath. In addition, -z guidance=noall can be used to entirely disable the guidance feature. See Chapter 7, Link-Editor Quick Reference, in the Linker and Libraries Guide for more information on guidance and advice for building better objects. Example The following example demonstrates how the guidance feature is intended to work. We will build a shared object that has a variety of shortcomings: Does not specify all it's dependencies Specifies dependencies it does not use Does not use direct bindings Uses a version 1 mapfile Contains relocations to the readonly allocable text (not PIC) This scenario is sadly very common — many shared objects have one or more of these issues. % cat hello.c #include <stdio.h> #include <unistd.h> void hello(void) { printf("hello user %d\n", getpid()); } % cat mapfile.v1 # This version 1 mapfile will trigger a guidance message % cc hello.c -o hello.so -G -M mapfile.v1 -lelf As you can see, the operation completes without error, resulting in a usable object. However, turning on guidance reveals a number of things that could be better: % cc hello.c -o hello.so -G -M mapfile.v1 -lelf -zguidance ld: guidance: version 2 mapfile syntax recommended: mapfile.v1 ld: guidance: -z lazyload option recommended before first dependency ld: guidance: -B direct or -z direct option recommended before first dependency Undefined first referenced symbol in file getpid hello.o (symbol belongs to implicit dependency /lib/libc.so.1) printf hello.o (symbol belongs to implicit dependency /lib/libc.so.1) ld: warning: symbol referencing errors ld: guidance: -z defs option recommended for shared objects ld: guidance: removal of unused dependency recommended: libelf.so.1 warning: Text relocation remains referenced against symbol offset in file .rodata1 (section) 0xa hello.o getpid 0x4 hello.o printf 0xf hello.o ld: guidance: position independent (PIC) code recommended for shared objects ld: guidance: see ld(1) -z guidance for more information Given the explicit advice in the above guidance messages, it is relatively easy to modify the example to do the right things: % cat mapfile.v2 # This version 2 mapfile will not trigger a guidance message $mapfile_version 2 % cc hello.c -o hello.so -Kpic -G -Bdirect -M mapfile.v2 -lc -zguidance There are situations in which the guidance does not fit the object being built. For instance, you want to build an object without direct bindings: % cc -Kpic hello.c -o hello.so -G -M mapfile.v2 -lc -zguidance ld: guidance: -B direct or -z direct option recommended before first dependency ld: guidance: see ld(1) -z guidance for more information It is easy to disable that specific guidance warning without losing the overall benefit from allowing the remainder of the guidance feature to operate: % cc -Kpic hello.c -o hello.so -G -M mapfile.v2 -lc -zguidance=nodirect Conclusions The linking guidelines enforced by the ld guidance feature correspond rather directly to our standards for building the core Solaris OS. I'm sure that comes as no surprise. It only makes sense that we would want to build our own product as well as we know how. Solaris is usually the first significant test for any new linker feature. We now enable guidance by default for all builds, and the effect has been very positive. Guidance helps us find suboptimal objects more quickly. Programmers get concrete advice for what to change instead of vague generalities. Even in the cases where we override the guidance, the makefile rules to do so serve as documentation of the fact. Deciding to use guidance is likely to cause some up front work for most code, as it forces you to consider using new features such as direct bindings. Such investigation is worthwhile, but does not come for free. However, the guidance suggestions offer a structured and straightforward way to tackle modernizing your objects, and once that work is done, for keeping them that way. The investment is often worth it, and will replay you in terms of better performance and fewer problems. I hope that you find guidance to be as useful as we have.

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• Why does fprintf start printing out of order or not at all?

  - by Steve Melvin

  This code should take an integer, create pipes, spawn two children, wait until they are dead, and start all over again. However, around the third time around the loop I lose my prompt to enter a number and it no longer prints the number I've entered. Any ideas? #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #define WRITE 1 #define READ 0 int main (int argc, const char * argv[]) { //Pipe file-descriptor array unsigned int isChildA = 0; int pipeA[2]; int pipeB[2]; int num = 0; while(1){ fprintf(stderr,"Enter an integer: "); scanf("%i", &num); if(num == 0){ fprintf(stderr,"You entered zero, exiting...\n"); exit(0); } //Open Pipes if(pipe(pipeA) < 0){ fprintf(stderr,"Could not create pipe A.\n"); exit(1); } if(pipe(pipeB) < 0){ fprintf(stderr,"Could not create pipe B.\n"); exit(1); } fprintf(stderr,"Value read: %i \n", num); fprintf(stderr,"Parent PID: %i\n", getpid()); pid_t procID = fork(); switch (procID) { case -1: fprintf(stderr,"Fork error, quitting...\n"); exit(1); break; case 0: isChildA = 1; break; default: procID = fork(); if (procID<0) { fprintf(stderr,"Fork error, quitting...\n"); exit(1); } else if(procID == 0){ isChildA = 0; } else { write(pipeA[WRITE], &num, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); pid_t pid; while (pid = waitpid(-1, NULL, 0)) { if (errno == ECHILD) { break; } } } break; } if (procID == 0) { //We're a child, do kid-stuff. ssize_t bytesRead = 0; int response; while (1) { while (bytesRead == 0) { bytesRead = read((isChildA?pipeA[READ]:pipeB[READ]), &response, sizeof(int)); } if (response < 2) { //Kill other child and self fprintf(stderr, "Terminating PROCID: %i\n", getpid()); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); return 0; } else if(!(response%2)){ //Even response/=2; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } else { //Odd response*=3; response++; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } } } } return 0; } This is the output I am getting... bash-3.00$ ./proj2 Enter an integer: 101 Value read: 101 Parent PID: 9379 PROCID: 9380, VALUE: 304 PROCID: 9381, VALUE: 152 PROCID: 9380, VALUE: 76 PROCID: 9381, VALUE: 38 PROCID: 9380, VALUE: 19 PROCID: 9381, VALUE: 58 PROCID: 9380, VALUE: 29 PROCID: 9381, VALUE: 88 PROCID: 9380, VALUE: 44 PROCID: 9381, VALUE: 22 PROCID: 9380, VALUE: 11 PROCID: 9381, VALUE: 34 PROCID: 9380, VALUE: 17 PROCID: 9381, VALUE: 52 PROCID: 9380, VALUE: 26 PROCID: 9381, VALUE: 13 PROCID: 9380, VALUE: 40 PROCID: 9381, VALUE: 20 PROCID: 9380, VALUE: 10 PROCID: 9381, VALUE: 5 PROCID: 9380, VALUE: 16 PROCID: 9381, VALUE: 8 PROCID: 9380, VALUE: 4 PROCID: 9381, VALUE: 2 PROCID: 9380, VALUE: 1 Terminating PROCID: 9381 Terminating PROCID: 9380 Enter an integer: 102 Value read: 102 Parent PID: 9379 PROCID: 9386, VALUE: 51 PROCID: 9387, VALUE: 154 PROCID: 9386, VALUE: 77 PROCID: 9387, VALUE: 232 PROCID: 9386, VALUE: 116 PROCID: 9387, VALUE: 58 PROCID: 9386, VALUE: 29 PROCID: 9387, VALUE: 88 PROCID: 9386, VALUE: 44 PROCID: 9387, VALUE: 22 PROCID: 9386, VALUE: 11 PROCID: 9387, VALUE: 34 PROCID: 9386, VALUE: 17 PROCID: 9387, VALUE: 52 PROCID: 9386, VALUE: 26 PROCID: 9387, VALUE: 13 PROCID: 9386, VALUE: 40 PROCID: 9387, VALUE: 20 PROCID: 9386, VALUE: 10 PROCID: 9387, VALUE: 5 PROCID: 9386, VALUE: 16 PROCID: 9387, VALUE: 8 PROCID: 9386, VALUE: 4 PROCID: 9387, VALUE: 2 PROCID: 9386, VALUE: 1 Terminating PROCID: 9387 Terminating PROCID: 9386 Enter an integer: 104 Value read: 104 Parent PID: 9379 Enter an integer: PROCID: 9388, VALUE: 52 PROCID: 9389, VALUE: 26 PROCID: 9388, VALUE: 13 PROCID: 9389, VALUE: 40 PROCID: 9388, VALUE: 20 PROCID: 9389, VALUE: 10 PROCID: 9388, VALUE: 5 PROCID: 9389, VALUE: 16 PROCID: 9388, VALUE: 8 PROCID: 9389, VALUE: 4 PROCID: 9388, VALUE: 2 PROCID: 9389, VALUE: 1 Terminating PROCID: 9388 Terminating PROCID: 9389 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9395, VALUE: 316 PROCID: 9396, VALUE: 158 PROCID: 9395, VALUE: 79 PROCID: 9396, VALUE: 238 PROCID: 9395, VALUE: 119 PROCID: 9396, VALUE: 358 PROCID: 9395, VALUE: 179 PROCID: 9396, VALUE: 538 PROCID: 9395, VALUE: 269 PROCID: 9396, VALUE: 808 PROCID: 9395, VALUE: 404 PROCID: 9396, VALUE: 202 PROCID: 9395, VALUE: 101 PROCID: 9396, VALUE: 304 PROCID: 9395, VALUE: 152 PROCID: 9396, VALUE: 76 PROCID: 9395, VALUE: 38 PROCID: 9396, VALUE: 19 PROCID: 9395, VALUE: 58 PROCID: 9396, VALUE: 29 PROCID: 9395, VALUE: 88 PROCID: 9396, VALUE: 44 PROCID: 9395, VALUE: 22 PROCID: 9396, VALUE: 11 PROCID: 9395, VALUE: 34 PROCID: 9396, VALUE: 17 PROCID: 9395, VALUE: 52 PROCID: 9396, VALUE: 26 PROCID: 9395, VALUE: 13 PROCID: 9396, VALUE: 40 PROCID: 9395, VALUE: 20 PROCID: 9396, VALUE: 10 PROCID: 9395, VALUE: 5 PROCID: 9396, VALUE: 16 PROCID: 9395, VALUE: 8 PROCID: 9396, VALUE: 4 PROCID: 9395, VALUE: 2 PROCID: 9396, VALUE: 1 Terminating PROCID: 9395 Terminating PROCID: 9396 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9397, VALUE: 316 PROCID: 9398, VALUE: 158 PROCID: 9397, VALUE: 79 PROCID: 9398, VALUE: 238 PROCID: 9397, VALUE: 119 PROCID: 9398, VALUE: 358 PROCID: 9397, VALUE: 179 PROCID: 9398, VALUE: 538 PROCID: 9397, VALUE: 269 PROCID: 9398, VALUE: 808 PROCID: 9397, VALUE: 404 PROCID: 9398, VALUE: 202 PROCID: 9397, VALUE: 101 PROCID: 9398, VALUE: 304 PROCID: 9397, VALUE: 152 PROCID: 9398, VALUE: 76 PROCID: 9397, VALUE: 38 PROCID: 9398, VALUE: 19 PROCID: 9397, VALUE: 58 PROCID: 9398, VALUE: 29 PROCID: 9397, VALUE: 88 PROCID: 9398, VALUE: 44 PROCID: 9397, VALUE: 22 PROCID: 9398, VALUE: 11 PROCID: 9397, VALUE: 34 PROCID: 9398, VALUE: 17 PROCID: 9397, VALUE: 52 PROCID: 9398, VALUE: 26 PROCID: 9397, VALUE: 13 PROCID: 9398, VALUE: 40 PROCID: 9397, VALUE: 20 PROCID: 9398, VALUE: 10 PROCID: 9397, VALUE: 5 PROCID: 9398, VALUE: 16 PROCID: 9397, VALUE: 8 PROCID: 9398, VALUE: 4 PROCID: 9397, VALUE: 2 PROCID: 9398, VALUE: 1 Terminating PROCID: 9397 Terminating PROCID: 9398 106 Value read: 106 Parent PID: 9379 Enter an integer: PROCID: 9399, VALUE: 53 PROCID: 9400, VALUE: 160 PROCID: 9399, VALUE: 80 PROCID: 9400, VALUE: 40 PROCID: 9399, VALUE: 20 PROCID: 9400, VALUE: 10 PROCID: 9399, VALUE: 5 PROCID: 9400, VALUE: 16 PROCID: 9399, VALUE: 8 PROCID: 9400, VALUE: 4 PROCID: 9399, VALUE: 2 PROCID: 9400, VALUE: 1 Terminating PROCID: 9399 Terminating PROCID: 9400 ^C Another thing that's strange, when ran from within XCode it behaves normally. However, when ran from bash on Solaris or OSX it acts up.

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• Char error C langauge

  - by Nadeem tabbaa

  i have a project for a course, i did almost everything but i have this error i dont know who to solve it... the project about doing our own shell some of them we have to write our code, others we will use the fork method.. this is the code, #include <sys/wait.h> #include <dirent.h> #include <limits.h> #include <errno.h> #include <stdlib.h> #include <string.h> #include<stdio.h> #include<fcntl.h> #include<unistd.h> #include<sys/stat.h> #include<sys/types.h> int main(int argc, char **argv) { pid_t pid; char str[21], *arg[10]; int x,status,number; system("clear"); while(1) { printf("Rshell>" ); fgets(str,21,stdin); x = 0; arg[x] = strtok(str, " \n\t"); while(arg[x]) arg[++x] = strtok(NULL, " \n\t"); if(NULL!=arg[0]) { if(strcasecmp(arg[0],"cat")==0) //done { int f=0,n; char l[1]; struct stat s; if(x!=2) { printf("Mismatch argument\n"); } /*if(access(arg[1],F_OK)) { printf("File Exist"); exit(1); } if(stat(arg[1],&s)<0) { printf("Stat ERROR"); exit(1); } if(S_ISREG(s.st_mode)<0) { printf("Not a Regular FILE"); exit(1); } if(geteuid()==s.st_uid) if(s.st_mode & S_IRUSR) f=1; else if(getegid()==s.st_gid) if(s.st_mode & S_IRGRP) f=1; else if(s.st_mode & S_IROTH) f=1; if(!f) { printf("Permission denied"); exit(1); }*/ f=open(arg[1],O_RDONLY); while((n=read(f,l,1))>0) write(1,l,n); } else if(strcasecmp(arg[0],"rm")==0) //done { if( unlink( arg[1] ) != 0 ) perror( "Error deleting file" ); else puts( "File successfully deleted" ); } else if(strcasecmp(arg[0],"rmdir")==0) //done { if( remove( arg[1] ) != 0 ) perror( "Error deleting Directory" ); else puts( "Directory successfully deleted" ); } else if(strcasecmp(arg[0],"ls")==0) //done { DIR *dir; struct dirent *dirent; char *where = NULL; //printf("x== %i\n",x); //printf("x== %s\n",arg[1]); //printf("x== %i\n",get_current_dir_name()); if (x == 1) where = get_current_dir_name(); else where = arg[1]; if (NULL == (dir = opendir(where))) { fprintf(stderr,"%d (%s) opendir %s failed\n", errno, strerror(errno), where); return 2; } while (NULL != (dirent = readdir(dir))) { printf("%s\n", dirent->d_name); } closedir(dir); } else if(strcasecmp(arg[0],"cp")==0) //not yet for Raed { FILE *from, *to; char ch; if(argc!=3) { printf("Usage: copy <source> <destination>\n"); exit(1); } /* open source file */ if((from = fopen(argv[1], "rb"))==NULL) { printf("Cannot open source file.\n"); exit(1); } /* open destination file */ if((to = fopen(argv[2], "wb"))==NULL) { printf("Cannot open destination file.\n"); exit(1); } /* copy the file */ while(!feof(from)) { ch = fgetc(from); if(ferror(from)) { printf("Error reading source file.\n"); exit(1); } if(!feof(from)) fputc(ch, to); if(ferror(to)) { printf("Error writing destination file.\n"); exit(1); } } if(fclose(from)==EOF) { printf("Error closing source file.\n"); exit(1); } if(fclose(to)==EOF) { printf("Error closing destination file.\n"); exit(1); } } else if(strcasecmp(arg[0],"mv")==0)//done { if( rename(arg[1],arg[2]) != 0 ) perror( "Error moving file" ); else puts( "File successfully moved" ); } else if(strcasecmp(arg[0],"hi")==0)//done { printf("hello\n"); } else if(strcasecmp(arg[0],"exit")==0) // done { return 0; } else if(strcasecmp(arg[0],"sleep")==0) // done { if(x==1) printf("plz enter the # seconds to sleep\n"); else sleep(atoi(arg[1])); } else if(strcmp(arg[0],"history")==0) // not done { FILE *infile; //char fname[40]; char line[100]; int lcount; ///* Read in the filename */ //printf("Enter the name of a ascii file: "); //fgets(History.txt, sizeof(fname), stdin); /* Open the file. If NULL is returned there was an error */ if((infile = fopen("History.txt", "r")) == NULL) { printf("Error Opening File.\n"); exit(1); } while( fgets(line, sizeof(line), infile) != NULL ) { /* Get each line from the infile */ lcount++; /* print the line number and data */ printf("Line %d: %s", lcount, line); } fclose(infile); /* Close the file */ writeHistory(arg); //write to txt file every new executed command //read from the file once the history command been called //if a command called not for the first time then just replace it to the end of the file } else if(strncmp(arg[0],"@",1)==0) // not done { //scripting files // read from the file command by command and executing them } else if(strcmp(arg[0],"type")==0) //not done { //if(x==1) //printf("plz enter the argument\n"); //else //type((arg[1])); } else { pid = fork( ); if (pid == 0) { execlp(arg[0], arg[0], arg[1], arg[2], NULL); printf ("EXEC Failed\n"); } else { wait(&status); if(strcmp(arg[0],"clear")!=0) { printf("status %04X\n",status); if(WIFEXITED(status)) printf("Normal termination, exit code %d\n", WEXITSTATUS(status)); else printf("Abnormal termination\n"); } } } } } } void writeHistory(char *arg[]) { FILE *file; file = fopen("History.txt","a+"); /* apend file (add text to a file or create a file if it does not exist.*/ int i =0; while(strcasecmp(arg[0],NULL)==0) { fprintf(file,"%s ",arg[i]); /*writes*/ } fprintf(file,"\n"); /*new line*/ fclose(file); /*done!*/ getchar(); /* pause and wait for key */ //return 0; } the thing is when i compile the code, this what it gives me /home/ugics/st255375/ICS431Labs/Project/Rshell.c: At top level: /home/ugics/st255375/ICS431Labs/Project/Rshell.c:264: warning: conflicting types for ‘writeHistory’ /home/ugics/st255375/ICS431Labs/Project/Rshell.c:217: note: previous implicit declaration of ‘writeHistory’ was here can any one help me??? thanks

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• Suggestions for duplicate file finder algorithm (using C)

  - by Andrei Ciobanu

  Hello, I wanted to write a program that test if two files are duplicates (have exactly the same content). First I test if the files have the same sizes, and if they have i start to compare their contents. My first idea, was to "split" the files into fixed size blocks, then start a thread for every block, fseek to startup character of every block and continue the comparisons in parallel. When a comparison from a thread fails, the other working threads are canceled, and the program exits out of the thread spawning loop. The code looks like this: dupf.h #ifndef __NM__DUPF__H__ #define __NM__DUPF__H__ #define NUM_THREADS 15 #define BLOCK_SIZE 8192 /* Thread argument structure */ struct thread_arg_s { const char *name_f1; /* First file name */ const char *name_f2; /* Second file name */ int cursor; /* Where to seek in the file */ }; typedef struct thread_arg_s thread_arg; /** * 'arg' is of type thread_arg. * Checks if the specified file blocks are * duplicates. */ void *check_block_dup(void *arg); /** * Checks if two files are duplicates */ int check_dup(const char *name_f1, const char *name_f2); /** * Returns a valid pointer to a file. * If the file (given by the path/name 'fname') cannot be opened * in 'mode', the program is interrupted an error message is shown. **/ FILE *safe_fopen(const char *name, const char *mode); #endif dupf.c #include <errno.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include "dupf.h" FILE *safe_fopen(const char *fname, const char *mode) { FILE *f = NULL; f = fopen(fname, mode); if (f == NULL) { char emsg[255]; sprintf(emsg, "FOPEN() %s\t", fname); perror(emsg); exit(-1); } return (f); } void *check_block_dup(void *arg) { const char *name_f1 = NULL, *name_f2 = NULL; /* File names */ FILE *f1 = NULL, *f2 = NULL; /* Streams */ int cursor = 0; /* Reading cursor */ char buff_f1[BLOCK_SIZE], buff_f2[BLOCK_SIZE]; /* Character buffers */ int rchars_1, rchars_2; /* Readed characters */ /* Initializing variables from 'arg' */ name_f1 = ((thread_arg*)arg)->name_f1; name_f2 = ((thread_arg*)arg)->name_f2; cursor = ((thread_arg*)arg)->cursor; /* Opening files */ f1 = safe_fopen(name_f1, "r"); f2 = safe_fopen(name_f2, "r"); /* Setup cursor in files */ fseek(f1, cursor, SEEK_SET); fseek(f2, cursor, SEEK_SET); /* Initialize buffers */ rchars_1 = fread(buff_f1, 1, BLOCK_SIZE, f1); rchars_2 = fread(buff_f2, 1, BLOCK_SIZE, f2); if (rchars_1 != rchars_2) { /* fread failed to read the same portion. * program cannot continue */ perror("ERROR WHEN READING BLOCK"); exit(-1); } while (rchars_1-->0) { if (buff_f1[rchars_1] != buff_f2[rchars_1]) { /* Different characters */ fclose(f1); fclose(f2); pthread_exit("notdup"); } } /* Close streams */ fclose(f1); fclose(f2); pthread_exit("dup"); } int check_dup(const char *name_f1, const char *name_f2) { int num_blocks = 0; /* Number of 'blocks' to check */ int num_tsp = 0; /* Number of threads spawns */ int tsp_iter = 0; /* Iterator for threads spawns */ pthread_t *tsp_threads = NULL; thread_arg *tsp_threads_args = NULL; int tsp_threads_iter = 0; int thread_c_res = 0; /* Thread creation result */ int thread_j_res = 0; /* Thread join res */ int loop_res = 0; /* Function result */ int cursor; struct stat buf_f1; struct stat buf_f2; if (name_f1 == NULL || name_f2 == NULL) { /* Invalid input parameters */ perror("INVALID FNAMES\t"); return (-1); } if (stat(name_f1, &buf_f1) != 0 || stat(name_f2, &buf_f2) != 0) { /* Stat fails */ char emsg[255]; sprintf(emsg, "STAT() ERROR: %s %s\t", name_f1, name_f2); perror(emsg); return (-1); } if (buf_f1.st_size != buf_f2.st_size) { /* File have different sizes */ return (1); } /* Files have the same size, function exec. is continued */ num_blocks = (buf_f1.st_size / BLOCK_SIZE) + 1; num_tsp = (num_blocks / NUM_THREADS) + 1; cursor = 0; for (tsp_iter = 0; tsp_iter < num_tsp; tsp_iter++) { loop_res = 0; /* Create threads array for this spawn */ tsp_threads = malloc(NUM_THREADS * sizeof(*tsp_threads)); if (tsp_threads == NULL) { perror("TSP_THREADS ALLOC FAILURE\t"); return (-1); } /* Create arguments for every thread in the current spawn */ tsp_threads_args = malloc(NUM_THREADS * sizeof(*tsp_threads_args)); if (tsp_threads_args == NULL) { perror("TSP THREADS ARGS ALLOCA FAILURE\t"); return (-1); } /* Initialize arguments and create threads */ for (tsp_threads_iter = 0; tsp_threads_iter < NUM_THREADS; tsp_threads_iter++) { if (cursor >= buf_f1.st_size) { break; } tsp_threads_args[tsp_threads_iter].name_f1 = name_f1; tsp_threads_args[tsp_threads_iter].name_f2 = name_f2; tsp_threads_args[tsp_threads_iter].cursor = cursor; thread_c_res = pthread_create( &tsp_threads[tsp_threads_iter], NULL, check_block_dup, (void*)&tsp_threads_args[tsp_threads_iter]); if (thread_c_res != 0) { perror("THREAD CREATION FAILURE"); return (-1); } cursor+=BLOCK_SIZE; } /* Join last threads and get their status */ while (tsp_threads_iter-->0) { void *thread_res = NULL; thread_j_res = pthread_join(tsp_threads[tsp_threads_iter], &thread_res); if (thread_j_res != 0) { perror("THREAD JOIN FAILURE"); return (-1); } if (strcmp((char*)thread_res, "notdup")==0) { loop_res++; /* Closing other threads and exiting by condition * from loop. */ while (tsp_threads_iter-->0) { pthread_cancel(tsp_threads[tsp_threads_iter]); } } } free(tsp_threads); free(tsp_threads_args); if (loop_res > 0) { break; } } return (loop_res > 0) ? 1 : 0; } The function works fine (at least for what I've tested). Still, some guys from #C (freenode) suggested that the solution is overly complicated, and it may perform poorly because of parallel reading on hddisk. What I want to know: Is the threaded approach flawed by default ? Is fseek() so slow ? Is there a way to somehow map the files to memory and then compare them ?

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• How to know if the client has terminated in sockets

  - by shadyabhi

  Suppose, I have a connected socket after writing this code.. if ((sd = accept(socket_d, (struct sockaddr *)&client_addr, &alen)) < 0) { perror("accept failed\n"); exit(1); } How can I know at the server side that client has exited. My whole program actually does the following.. Accepts a connection from client Starts a new thread that reads messages from that particular client and then broadcast this message to all the connected clients. If you want to see the whole code... In this whole code. I am also struggling with one more problem that whenever I kill a client with Ctrl+C, my server terminates abruptly.. It would be nice if anyone could suggest what the problem is.. #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <signal.h> #include <errno.h> #include <pthread.h> /*CONSTANTS*/ #define DEFAULT_PORT 10000 #define LISTEN_QUEUE_LIMIT 6 #define TOTAL_CLIENTS 10 #define CHAR_BUFFER 256 /*GLOBAL VARIABLE*/ int current_client = 0; int connected_clients[TOTAL_CLIENTS]; extern int errno; void *client_handler(void * socket_d); int main(int argc, char *argv[]) { struct sockaddr_in server_addr;/* structure to hold server's address*/ int socket_d; /* listening socket descriptor */ int port; /* protocol port number */ int option_value; /* needed for setsockopt */ pthread_t tid[TOTAL_CLIENTS]; port = (argc > 1)?atoi(argv[1]):DEFAULT_PORT; /* Socket Server address structure */ memset((char *)&server_addr, 0, sizeof(server_addr)); server_addr.sin_family = AF_INET; /* set family to Internet */ server_addr.sin_addr.s_addr = INADDR_ANY; /* set the local IP address */ server_addr.sin_port = htons((u_short)port); /* Set port */ /* Create socket */ if ( (socket_d = socket(PF_INET, SOCK_STREAM, 0)) < 0) { fprintf(stderr, "socket creation failed\n"); exit(1); } /* Make listening socket's port reusable */ if (setsockopt(socket_d, SOL_SOCKET, SO_REUSEADDR, (char *)&option_value, sizeof(option_value)) < 0) { fprintf(stderr, "setsockopt failure\n"); exit(1); } /* Bind a local address to the socket */ if (bind(socket_d, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) { fprintf(stderr, "bind failed\n"); exit(1); } /* Specify size of request queue */ if (listen(socket_d, LISTEN_QUEUE_LIMIT) < 0) { fprintf(stderr, "listen failed\n"); exit(1); } memset(connected_clients,0,sizeof(int)*TOTAL_CLIENTS); for (;;) { struct sockaddr_in client_addr; /* structure to hold client's address*/ int alen = sizeof(client_addr); /* length of address */ int sd; /* connected socket descriptor */ if ((sd = accept(socket_d, (struct sockaddr *)&client_addr, &alen)) < 0) { perror("accept failed\n"); exit(1); } else printf("\n I got a connection from (%s , %d)\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port)); if (pthread_create(&tid[current_client],NULL,(void *)client_handler,(void *)sd) != 0) { perror("pthread_create error"); continue; } connected_clients[current_client]=sd; current_client++; /*Incrementing Client number*/ } return 0; } void *client_handler(void *connected_socket) { int sd; sd = (int)connected_socket; for ( ; ; ) { ssize_t n; char buffer[CHAR_BUFFER]; for ( ; ; ) { if (n = read(sd, buffer, sizeof(char)*CHAR_BUFFER) == -1) { perror("Error reading from client"); pthread_exit(1); } int i=0; for (i=0;i<current_client;i++) { if (write(connected_clients[i],buffer,sizeof(char)*CHAR_BUFFER) == -1) perror("Error sending messages to a client while multicasting"); } } } } My client side is this (Maye be irrelevant while answering my question) #include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <stdlib.h> void error(char *msg) { perror(msg); exit(0); } void *listen_for_message(void * fd) { int sockfd = (int)fd; int n; char buffer[256]; bzero(buffer,256); printf("YOUR MESSAGE: "); fflush(stdout); while (1) { n = read(sockfd,buffer,256); if (n < 0) error("ERROR reading from socket"); if (n == 0) pthread_exit(1); printf("\nMESSAGE BROADCAST: %sYOUR MESSAGE: ",buffer); fflush(stdout); } } int main(int argc, char *argv[]) { int sockfd, portno, n; struct sockaddr_in serv_addr; struct hostent *server; pthread_t read_message; char buffer[256]; if (argc < 3) { fprintf(stderr,"usage %s hostname port\n", argv[0]); exit(0); } portno = atoi(argv[2]); sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) error("ERROR opening socket"); server = gethostbyname(argv[1]); if (server == NULL) { fprintf(stderr,"ERROR, no such host\n"); exit(0); } bzero((char *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length); serv_addr.sin_port = htons(portno); if (connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0) error("ERROR connecting"); bzero(buffer,256); if (pthread_create(&read_message,NULL,(void *)listen_for_message,(void *)sockfd) !=0 ) { perror("error creating thread"); } while (1) { fgets(buffer,255,stdin); n = write(sockfd,buffer,256); if (n < 0) error("ERROR writing to socket"); bzero(buffer,256); } return 0; }

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• Reading a child process's /proc/pid/mem file from the parent

  - by Amittai Aviram

  In the program below, I am trying to cause the following to happen: Process A assigns a value to a stack variable a. Process A (parent) creates process B (child) with PID child_pid. Process B calls function func1, passing a pointer to a. Process B changes the value of variable a through the pointer. Process B opens its /proc/self/mem file, seeks to the page containing a, and prints the new value of a. Process A (at the same time) opens /proc/child_pid/mem, seeks to the right page, and prints the new value of a. The problem is that, in step 6, the parent only sees the old value of a in /proc/child_pid/mem, while the child can indeed see the new value in its /proc/self/mem. Why is this the case? Is there any way that I can get the parent to to see the child's changes to its address space through the /proc filesystem? #include <fcntl.h> #include <stdbool.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <unistd.h> #define PAGE_SIZE 0x1000 #define LOG_PAGE_SIZE 0xc #define PAGE_ROUND_DOWN(v) ((v) & (~(PAGE_SIZE - 1))) #define PAGE_ROUND_UP(v) (((v) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1))) #define OFFSET_IN_PAGE(v) ((v) & (PAGE_SIZE - 1)) # if defined ARCH && ARCH == 32 #define BP "ebp" #define SP "esp" #else #define BP "rbp" #define SP "rsp" #endif typedef struct arg_t { int a; } arg_t; void func1(void * data) { arg_t * arg_ptr = (arg_t *)data; printf("func1: old value: %d\n", arg_ptr->a); arg_ptr->a = 53; printf("func1: address: %p\n", &arg_ptr->a); printf("func1: new value: %d\n", arg_ptr->a); } void expore_proc_mem(void (*fn)(void *), void * data) { off_t frame_pointer, stack_start; char buffer[PAGE_SIZE]; const char * path = "/proc/self/mem"; int child_pid, status; int parent_to_child[2]; int child_to_parent[2]; arg_t * arg_ptr; off_t child_offset; asm volatile ("mov %%"BP", %0" : "=m" (frame_pointer)); stack_start = PAGE_ROUND_DOWN(frame_pointer); printf("Stack_start: %lx\n", (unsigned long)stack_start); arg_ptr = (arg_t *)data; child_offset = OFFSET_IN_PAGE((off_t)&arg_ptr->a); printf("Address of arg_ptr->a: %p\n", &arg_ptr->a); pipe(parent_to_child); pipe(child_to_parent); bool msg; int child_mem_fd; char child_path[0x20]; child_pid = fork(); if (child_pid == -1) { perror("fork"); exit(EXIT_FAILURE); } if (!child_pid) { close(child_to_parent[0]); close(parent_to_child[1]); printf("CHILD (pid %d, parent pid %d).\n", getpid(), getppid()); fn(data); msg = true; write(child_to_parent[1], &msg, 1); child_mem_fd = open("/proc/self/mem", O_RDONLY); if (child_mem_fd == -1) { perror("open (child)"); exit(EXIT_FAILURE); } printf("CHILD: child_mem_fd: %d\n", child_mem_fd); if (lseek(child_mem_fd, stack_start, SEEK_SET) == (off_t)-1) { perror("lseek"); exit(EXIT_FAILURE); } if (read(child_mem_fd, buffer, sizeof(buffer)) != sizeof(buffer)) { perror("read"); exit(EXIT_FAILURE); } printf("CHILD: new value %d\n", *(int *)(buffer + child_offset)); read(parent_to_child[0], &msg, 1); exit(EXIT_SUCCESS); } else { printf("PARENT (pid %d, child pid %d)\n", getpid(), child_pid); printf("PARENT: child_offset: %lx\n", child_offset); read(child_to_parent[0], &msg, 1); printf("PARENT: message from child: %d\n", msg); snprintf(child_path, 0x20, "/proc/%d/mem", child_pid); printf("PARENT: child_path: %s\n", child_path); child_mem_fd = open(path, O_RDONLY); if (child_mem_fd == -1) { perror("open (child)"); exit(EXIT_FAILURE); } printf("PARENT: child_mem_fd: %d\n", child_mem_fd); if (lseek(child_mem_fd, stack_start, SEEK_SET) == (off_t)-1) { perror("lseek"); exit(EXIT_FAILURE); } if (read(child_mem_fd, buffer, sizeof(buffer)) != sizeof(buffer)) { perror("read"); exit(EXIT_FAILURE); } printf("PARENT: new value %d\n", *(int *)(buffer + child_offset)); close(child_mem_fd); printf("ENDING CHILD PROCESS.\n"); write(parent_to_child[1], &msg, 1); if (waitpid(child_pid, &status, 0) == -1) { perror("waitpid"); exit(EXIT_FAILURE); } } } int main(void) { arg_t arg; arg.a = 42; printf("In main: address of arg.a: %p\n", &arg.a); explore_proc_mem(&func1, &arg.a); return EXIT_SUCCESS; } This program produces the output below. Notice that the value of a (boldfaced) differs between parent's and child's reading of the /proc/child_pid/mem file. In main: address of arg.a: 0x7ffffe1964f0 Stack_start: 7ffffe196000 Address of arg_ptr-a: 0x7ffffe1964f0 PARENT (pid 20376, child pid 20377) PARENT: child_offset: 4f0 CHILD (pid 20377, parent pid 20376). func1: old value: 42 func1: address: 0x7ffffe1964f0 func1: new value: 53 PARENT: message from child: 1 CHILD: child_mem_fd: 4 PARENT: child_path: /proc/20377/mem CHILD: new value 53 PARENT: child_mem_fd: 7 PARENT: new value 42 ENDING CHILD PROCESS.

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