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  • Java XMLRPC request-String

    - by Philip
    Hi, I'm using Apache XML-RPC 3.1.2 to talk to an online-service. They have something special, they need a hash over the whole XML with a secret key for some kind of security, like this: String hash = md5(xmlRequest + secretKey); String requestURL = "http://foo.bar/?authHash=" + hash; So I need the XML-request like this: <?xml version="1.0"?> <methodCall> <methodName>foo.bar</methodName> <params> <param> <value><struct> <member><name>bla</name> <value><int>1</int></value> </member> <member><name>blubb</name> <value><int>2</int></value> </member> </struct></value> </param> </params> </methodCall> But how do I get this String-representation of the XMLRPC-Request with the lib Apache XML-RPC?

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  • Listing directories in Linux from C

    - by nunos
    I am trying to simulate linux command ls using linux api from c. Looking at the code it does make sense, but when I run it I get "stat error: No such file or directory". I have checked that opendir is working ok. I think the problem is in stat, which is returning -1 even though I think it should return 0. What am I missing? Thanks for your help. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <dirent.h> #include <sys/stat.h> #include <errno.h> int main(int argc, char *argv[]) { DIR *dirp; struct dirent *direntp; struct stat stat_buf; char *str; if (argc != 2) { fprintf( stderr, "Usage: %s dir_name\n", argv[0]); exit(1); } if ((dirp = opendir( argv[1])) == NULL) { perror(argv[1]); exit(2); } while ((direntp = readdir( dirp)) != NULL) { if (stat(direntp->d_name, &stat_buf)==-1) { perror("stat ERROR"); exit(3); } if (S_ISREG(stat_buf.st_mode)) str = "regular"; else if (S_ISDIR(stat_buf.st_mode)) str = "directory"; else str = "other"; printf("%-25s - %s\n", direntp->d_name, str); } closedir(dirp); exit(0); }

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  • Signals and Variables in VHDL (order) - Problem

    - by Morano88
    I have a signal and this signal is a bitvector (Z). The length of the bitvector depends on an input n, it is not fixed. In order to find the length, I have to do some computations. Can I define a signal after defining the variables ? It is giving me errors when I do that. It is working fine If I keep the signal before the variables (that what is showing below) .. but I don't want that .. the length of Z depends on the computations of the variables. What is the solution ? library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_ARITH.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity BSD_Full_Comp is Generic (n:integer:=8); Port(X, Y : inout std_logic_vector(n-1 downto 0); FZ : out std_logic_vector(1 downto 0)); end BSD_Full_Comp; architecture struct of BSD_Full_Comp is Component BSD_BitComparator Port ( Ai_1 : inout STD_LOGIC; Ai_0 : inout STD_LOGIC; Bi_1 : inout STD_LOGIC; Bi_0 : inout STD_LOGIC; S1 : out STD_LOGIC; S0 : out STD_LOGIC ); END Component; Signal Z : std_logic_vector(2*n-3 downto 0); begin ass : process Variable length : integer := n; Variable pow : integer :=0 ; Variable ZS : integer :=0; begin while length /= 0 loop length := length/2; pow := pow+1; end loop; length := 2 ** pow; ZS := length - n; wait; end process; end struct;

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  • My Thread Programs Block

    - by user315378
    I wrote a program that worked as a server. Knowing that "accept" was blocking the program. I wanted to launch a thread with this statement to prevent precisely that the program crashes, but this still happens. Can anybody help? Post code Thanks -(IBAction)Connetti{ if(switchConnessione.on){ int port = [fieldPort.text intValue]; labelStatus.text = [[NSString alloc] initWithFormat:@"Il Server è attivo"]; server_len = sizeof(server); server.sin_family = AF_INET; server.sin_port = htons((u_short)port); server.sin_addr.s_addr = INADDR_ANY; sd = socket (AF_INET, SOCK_STREAM, 0); bind(sd, (struct sockaddr*)&server, sizeof(server)); listen(sd, 1); [NSThread detachNewThreadSelector:@selector(startThreadAccept) toTarget:self withObject:nil]; } else { labelStatus.text = [[NSString alloc] initWithFormat:@"Server non attivo"]; switchChat.on = FALSE; switchChat.enabled = FALSE; } } -(void)startThreadAccept{ NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init]; [self performSelectorOnMainThread:@selector(acceptConnection) withObject:nil waitUntilDone:NO]; [pool release]; } -(void)acceptConnection{ new_sd = accept(sd, (struct sockaddr*)&server, &server_len); labelStatus.text = [[NSString alloc] initWithFormat:@"Ho accettato una connessione:%d", new_sd]; switchChat.enabled = TRUE; }

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  • Mixins, variadic templates, and CRTP in C++

    - by Eitan
    Here's the scenario: I'd like to have a host class that can have a variable number of mixins (not too hard with variadic templates--see for example http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.103.144). However, I'd also like the mixins to be parameterized by the host class, so that they can refer to its public types (using the CRTP idiom). The problem arises when trying to mix the too--the correct syntax is unclear to me. For example, the following code fails to compile with g++ 4.4.1: template <template<class> class... Mixins> class Host : public Mixins<Host<Mixins>>... { public: template <class... Args> Host(Args&&... args) : Mixins<Host>(std::forward<Args>(args))... {} }; template <class Host> struct Mix1 {}; template <class Host> struct Mix2 {}; typedef Host<Mix1, Mix2> TopHost; TopHost *th = new TopHost(Mix1<TopHost>(), Mix2<TopHost>()); With the error: tst.cpp: In constructor ‘Host<Mixins>::Host(Args&& ...) [with Args = Mix1<Host<Mix1, Mix2> >, Mix2<Host<Mix1, Mix2> >, Mixins = Mix1, Mix2]’: tst.cpp:33: instantiated from here tst.cpp:18: error: type ‘Mix1<Host<Mix1, Mix2> >’ is not a direct base of ‘Host<Mix1, Mix2>’ tst.cpp:18: error: type ‘Mix2<Host<Mix1, Mix2> >’ is not a direct base of ‘Host<Mix1, Mix2>’ Does anyone have successful experience mixing variadic templates with CRTP?

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  • How to send complex types from PHP SoapClient to ASP.NET SOAP server?

    - by xaguilars
    Hello I'm having problems sending arrays, structs and arrays of structs from PHP to an ASP.NET SOAP server... Anyone have a sollution for this? I've googled for days and any sollution worked for me. Perphaps I'm forgetting something... There are examples of my code: $client = new SoapClient($options); $pCriteria = new stdClass(); $pCriteria->type=1; $pCriteria->capacity=4; //Test 1 (fail): $resp = $client->GetRooms(array("pCriteria"=>$pCriteria)); //Test 2 (fail): $resp = $client->GetRooms(array("pCriteria"=>new SoapVar($pCriteria, SOAP_ENC_OBJECT, "TCriteria", "http://www.w3.org/2001/XMLSchema"))); print_r($resp); I don't know how to code functions that require an array of TCriteria (TCriteria[], TCriteria_Array type) either... i've tried sending the raw array, a SoapVar with SOAP_ENC_ARRAY encoding and TCriteria_Array type, ... but it does not work (the SOAP server becomes unavaiable and needs to be restarted). I've tried creating classes for the complex types too, instead of stdClass, but not working. I don't know where's the problem. The server admins cannot help me and I haven't found any sollution over internet. I'm a bit desperate hehe. Can you help me please? Can you provide samples of code with the three cases (array of simple data, array of struct and struct) ? Thanks!

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  • How can I get bitfields to arrange my bits in the right order?

    - by Jim Hunziker
    To begin with, the application in question is always going to be on the same processor, and the compiler is always gcc, so I'm not concerned about bitfields not being portable. gcc lays out bitfields such that the first listed field corresponds to least significant bit of a byte. So the following structure, with a=0, b=1, c=1, d=1, you get a byte of value e0. struct Bits { unsigned int a:5; unsigned int b:1; unsigned int c:1; unsigned int d:1; } __attribute__((__packed__)); (Actually, this is C++, so I'm talking about g++.) Now let's say I'd like a to be a six bit integer. Now, I can see why this won't work, but I coded the following structure: struct Bits2 { unsigned int a:6; unsigned int b:1; unsigned int c:1; unsigned int d:1; } __attribute__((__packed__)); Setting b, c, and d to 1, and a to 0 results in the following two bytes: c0 01 This isn't what I wanted. I was hoping to see this: e0 00 Is there any way to specify a structure that has three bits in the most significant bits of the first byte and six bits spanning the five least significant bits of the first byte and the most significant bit of the second? Please be aware that I have no control over where these bits are supposed to be laid out: it's a layout of bits that are defined by someone else's interface.

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  • aio_read from file error on OS X

    - by Pyetras
    The following code: #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <aio.h> #include <errno.h> int main (int argc, char const *argv[]) { char name[] = "abc"; int fdes; if ((fdes = open(name, O_RDWR | O_CREAT, 0600 )) < 0) printf("%d, create file", errno); int buffer[] = {0, 1, 2, 3, 4, 5}; if (write(fdes, &buffer, sizeof(buffer)) == 0){ printf("writerr\n"); } struct aiocb aio; int n = 2; while (n--){ aio.aio_reqprio = 0; aio.aio_fildes = fdes; aio.aio_offset = sizeof(int); aio.aio_sigevent.sigev_notify = SIGEV_NONE; int buffer2; aio.aio_buf = &buffer2; aio.aio_nbytes = sizeof(buffer2); if (aio_read(&aio) != 0){ printf("%d, readerr\n", errno); }else{ const struct aiocb *aio_l[] = {&aio}; if (aio_suspend(aio_l, 1, 0) != 0){ printf("%d, suspenderr\n", errno); }else{ printf("%d\n", *(int *)aio.aio_buf); } } } return 0; } Works fine on Linux (Ubuntu 9.10, compiled with -lrt), printing 1 1 But fails on OS X (10.6.6 and 10.6.5, I've tested it on two machines): 1 35, readerr Is this possible that this is due to some library error on OS X, or am I doing something wrong?

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  • Best intro to C++ static metaprogramming?

    - by jwfearn
    Static metaprogramming (aka "template metaprogramming") is a great C++ technique that allows the execution of programs at compile-time. A light bulb went off in my head as soon as I read this canonical metaprogramming example: #include <iostream> using namespace std; template< int n > struct factorial { enum { ret = factorial< n - 1 >::ret * n }; }; template<> struct factorial< 0 > { enum { ret = 1 }; }; int main() { cout << "7! = " << factorial< 7 >::ret << endl; // 5040 return 0; } If one wants to learn more about C++ static metaprogramming, what are the best sources (books, websites, on-line courseware, whatever)?

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  • iPhone static library Clang/LLVM error: non_lazy_symbol_pointers

    - by Bekenn
    After several hours of experimentation, I've managed to reduce the problem to the following example (C++): extern "C" void foo(); struct test { ~test() { } }; void doTest() { test t; // 1 foo(); // 2 } This is being compiled for iOS devices in XCode 4.2, using the provided Clang compiler (Apple LLVM compiler 3.0) and the iOS 5.0 SDK. The project is configured as a Cocoa Touch Static Library, and "Enable Linking With Shared Libraries" is set to No because I'm building an AIR native extension. The function foo is defined in another external library. (In my actual project, this would be any of the C API functions defined by Adobe for use in AIR native extensions.) When attempting to compile this code, I get back the error: FATAL:incompatible feature used: section type non_lazy_symbol_pointers (must specify "-dynamic" to be used) clang: error: assembler command failed with exit code 1 (use -v to see invocation) The error goes away if I comment out either of the lines marked 1 or 2 above, or if I change the build setting "Enable Linking With Shared Libraries" to Yes. (However, if I change the build setting, then I get multiple ld warning: unexpected srelocation type 9 warnings when linking the library into the final project, and the application crashes when running on the device.) The build error also goes away if I remove the destructor from test. So: Is this a bug in Clang? Am I missing some all-important and undocumented build setting? The interaction between an externally-provided function and a struct with a destructor is very peculiar, to say the least.

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  • What is the correct JNA mapping for UniChar on Mac OS X?

    - by Trejkaz
    I have a C struct like this: struct HFSUniStr255 { UInt16 length; UniChar unicode[255]; }; I have mapped this in the expected way: public class HFSUniStr255 extends Structure { public UInt16 length; // UInt16 is just an IntegerType with length 2 for convenience. public /*UniChar*/ char[] unicode = new char[255]; //public /*UniChar*/ byte[] unicode = new byte[255*2]; //public /*UniChar*/ UInt16[] unicode = new UInt16[255]; public HFSUniStr255() { } public HFSUniStr255(Pointer pointer) { super(pointer); } } If I use this version, I get every second character of the string into my char[] ("aits D" for "Macintosh HD".) I am assuming that this is something to do with being on a 64-bit platform and JNA mapping the value to a 32-bit wchar_t but then chopping off the high 16 bits on each wchar_t on copying them back. If I use the byte[] version, I get data which decodes correctly using the UTF-16LE charset. If I use the UInt16[] version, I get the right code point for each character but it is then inconvenient to convert them back into a string. Is there some way I can define my type as char[], and yet have it convert correctly?

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  • Linked List Sorting with Strings In C

    - by user308583
    I have a struct, with a Name and a single Node called nextName It's a Singly Linked list, and my task is to create the list, based on alphabetical order of the strings. So iff i enter Joe Zolt and Arthur i should get my list structured as Joe Than Joe Zolt Than Arthur Joe Zolt I'm having trouble implementing the correct Algorithm, which would put the pointers in the right order. This is What I have as of Now. Temp would be the name the user just entered and is trying to put into the list, namebox is just a copy of my root, being the whole list if(temp != NULL) { struct node* namebox = root; while (namebox!=NULL && (strcmp((namebox)->name,temp->name) <= 0)) { namebox = namebox->nextName; printf("here"); } temp->nextName = namebox; namebox = temp; root = namebox; This Works right now, if i enter names like CCC BBB than AAA I Get Back AAA BBB CCC when i print But if i put AAA BBB CCC , When i print i only get CCC, it cuts the previous off.

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  • Emulating Dynamic Dispatch in C++ based on Template Parameters

    - by Jon Purdy
    This is heavily simplified for the sake of the question. Say I have a hierarchy: struct Base { virtual int precision() const = 0; }; template<int Precision> struct Derived : public Base { typedef Traits<Precision>::Type Type; Derived(Type data) : value(data) {} virtual int precision() const { return Precision; } Type value; }; I want a function like: Base* function(const Base& a, const Base& b); Where the specific type of the result of the function is the same type as whichever of first and second has the greater Precision; something like the following pseudocode: template<class T> T* operation(const T& a, const T& b) { return new T(a.value + b.value); } Base* function(const Base& a, const Base& b) { if (a.precision() > b.precision()) return operation((A&)a, A(b.value)); else if (a.precision() < b.precision()) return operation(B(a.value), (B&)b); else return operation((A&)a, (A&)b); } Where A and B are the specific types of a and b, respectively. I want f to operate independently of how many instantiations of Derived there are. I'd like to avoid a massive table of typeid() comparisons, though RTTI is fine in answers. Any ideas?

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  • Different Linux message queues have the same id?

    - by Halo
    I open a mesage queue in a .c file, and upon success it says the message queue id is 3. While that program is still running, in another terminal I start another program (of another .c file), that creates a new message queue with a different mqd_t. But its id also appears as 3. Is this a problem? server file goes like this: void server(char* req_mq) { struct mq_attr attr; mqd_t mqdes; struct request* msgptr; int n; char *bufptr; int buflen; pid_t apid; //attr.mq_maxmsg = 300; //attr.mq_msgsize = 1024; mqdes = mq_open(req_mq, O_RDWR | O_CREAT, 0666, NULL); if (mqdes == -1) { perror("can not create msg queue\n"); exit(1); } printf("server mq created, mq id = %d\n", (int) mqdes); and the client goes like: void client(char* req_mq, int min, int max, char* dir_path_name, char* outfile) { pid_t pid; /* get the process id */ if ((pid = getpid()) < 0) { perror("unable to get client pid"); } mqd_t mqd, dq; char pfx[50] = DQ_PRFX; char suffix[50]; // sprintf(suffix, "%d", pid); strcat(pfx, suffix); dq = mq_open(pfx, O_RDWR | O_CREAT, 0666, NULL); if (dq == -1) { perror("can not open data queue\n"); exit(1); } printf("data queue created, mq id = %d\n", (int) dq); mqd = mq_open(req_mq, O_RDWR); if (mqd == -1) { perror("can not open msg queue\n"); exit(1); } mqdes and dq seem to share the same id 3.

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  • Compiling and using NTL c++ library for Windows

    - by Martin Lauridsen
    Hi there, I have compiled the NTL inifite precision integer arithmetic library for c++, using Microsoft Visual Studio 2008. I did as explained, on this site, using the Visual Studio interface, rather than from the command prompt. Actually I would rather do it from the command prompt, but I was not sure how to. Anyhow, I got the library compiled, and I now want to compile a program using the library, from the command prompt. The program I am trying to compile, has been tested on a linux system, where I compile it with the following c++ -I/appl/htopopt/Linux_x86_64/NTL-5.4.2/include mpqs.cpp main.cpp -o main -L/appl/htopopt/Linux_x86_64/NTL-5.4.2/lib -lntl -L/appl/htopopt/Linux_x86_64/gmp-4.2.1/lib -lgmp -lm Nevermind the gmp stuff, I dont have that installed on Windows. It is purely an optional thing that will make the NTL run faster. Anyhow, this works fine on linux. Now on Windows I write the following cl /EHsc /I D:\Downloads\WinNTL-5_5_2\include mpqs.cpp main.cpp /link /LIBPATH:"D:\Documents\Visual Studio 2008\Projects\ntl\Debug" But this results in the following errors: mpqs.cpp mpqs.cpp(38) : error C2039: 'find_smooth_vals' : is not a member of 'QS' d:\desktop\qs\mpqs.h(12) : see declaration of 'QS' mpqs.cpp(41) : error C2065: 'M' : undeclared identifier mpqs.cpp(41) : error C2065: 'n' : undeclared identifier mpqs.cpp(42) : error C2065: 'sieve_table' : undeclared identifier mpqs.cpp(42) : error C2228: left of '.size' must have class/struct/union type is ''unknown-type'' mpqs.cpp(43) : error C2065: 'sieve_table' : undeclared identifier mpqs.cpp(44) : error C2065: 'qx_table' : undeclared identifier mpqs.cpp(44) : error C3861: 'test_smoothness': identifier not found mpqs.cpp(45) : error C2065: 'smooth_indices' : undeclared identifier mpqs.cpp(45) : error C2228: left of '.push_back' must have class/struct/union type is ''unknown-type'' main.cpp Generating Code... It is as if, my mpqs.h file is not included into the compilation process? Also I dont understand why it complains about .push_back() for a vector type? Help is much appreciated!

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  • Declare module name of classes for logging

    - by Space_C0wb0y
    I currently am adding some features to our logging-library. One of these is the possibility to declare a module-name for a class that automatically gets preprended to any log-messages writing from within that class. However, if no module-name is provided, nothing is prepended. Currently I am using a trait-class that has a static function that returns the name. template< class T > struct ModuleNameTrait { static std::string Value() { return ""; } }; template< > struct ModuleNameTrait< Foo > { static std::string Value() { return "Foo"; } }; This class can be defined using a helper-macro. The drawback is, that the module-name has to be declared outside of the class. I would like this to be possible within the class. Also, I want to be able to remove all logging-code using a preprocessor directive. I know that using SFINAE one can check if a template argument has a certain member, but since other people, that are not as friendly with templates as I am, will have to maintain the code, I am looking for a much simpler solution. If there is none, I will stick with the traits approach. Thanks in advance!

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  • Free Memory Occupied by Std List, Vector, Map etc

    - by Graviton
    Coming from a C# background, I have only vaguest idea on memory management on C++-- all I know is that I would have to free the memory manually. As a result my C++ code is written in such a way that objects of the type std::vector, std::list, std::map are freely instantiated, used, but not freed. I didn't realize this point until I am almost done with my programs, now my code is consisted of the following kinds of patterns: struct Point_2 { double x; double y; }; struct Point_3 { double x; double y; double z; }; list<list<Point_2>> Computation::ComputationJob(list<Point_3> pts3D, vector<Point_2> vectors) { map<Point_2, double> pt2DMap=ConstructPointMap(pts3D); vector<Point_2> vectorList = ConstructVectors(vectors); list<list<Point_2>> faceList2D=ConstructPoints(vectorList , pt2DMap); return faceList2D; } My question is, must I free every.single.one of the list usage ( in the above example, this means that I would have to free pt2DMap, vectorList and faceList2D)? That would be very tedious! I might just as well rewrite my Computation class so that it is less prone to memory leak. Any idea how to fix this?

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  • Get the signed/unsigned variant of an integer template parameter without explicit traits

    - by Blair Holloway
    I am looking to define a template class whose template parameter will always be an integer type. The class will contain two members, one of type T, and the other as the unsigned variant of type T -- i.e. if T == int, then T_Unsigned == unsigned int. My first instinct was to do this: template <typename T> class Range { typedef unsigned T T_Unsigned; // does not compile public: Range(T min, T_Unsigned range); private: T m_min; T_Unsigned m_range; }; But it doesn't work. I then thought about using partial template specialization, like so: template <typename T> struct UnsignedType {}; // deliberately empty template <> struct UnsignedType<int> { typedef unsigned int Type; }; template <typename T> class Range { typedef UnsignedType<T>::Type T_Unsigned; /* ... */ }; This works, so long as you partially specialize UnsignedType for every integer type. It's a little bit of additional copy-paste work (slash judicious use of macros), but serviceable. However, I'm now curious - is there another way of determining the signed-ness of an integer type, and/or using the unsigned variant of a type, without having to manually define a Traits class per-type? Or is this the only way to do it?

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  • Help understanding linux/tcp.h

    - by Chris
    I'm learning to use raw sockets, and im trying to prase out the tcp header data, but i can't seem to figure out what res1, ece, and cwr are. Through my networking book and google i know what the rest stand for, but can't seem to find anything on those three. Below is the tcphdr struct in my includes area. Ive commented the parts a bit as i was figureing out what they stood for. struct tcphdr { __be16 source; __be16 dest; __be32 seq; __be32 ack_seq; #if defined(__LITTLE_ENDIAN_BITFIELD) _u16 res1:4, doff:4,//tcp header length fin:1,//final syn:1,//synchronization rst:1,//reset psh:1,//push ack:1,//ack urg:1,// urge ece:1, cwr:1; #elif defined(_BIG_ENDIAN_BITFIELD) __u16 doff:4,//tcp header length res1:4, cwr:1, ece:1, urg:1,//urge ack:1,//ack psh:1,//push rst:1,//reset syn:1,//synchronization fin:1;//final #else #error "Adjust your defines" #endif __be16 window; __sum16 check; __be16 urg_ptr; };

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  • Inode to device information

    - by Methos
    I have 3 questions: I want to figure out if a file belongs to a USB device given the file inode. By looking in the latest kernel sources (2.6.33) on LXR, I think one can find that information by following pointers as follows: inode-super_block-block_device-backing_dev_info-device-device_driver(or device_type). However, the kernel that I am working with - 2.6.22.14 - does not have struct device pointer in the backing_dev_info object. So how can I figure out to which device does a file belong to from just the inode? I see that each of the inode, super_block and block_device contain an object of type 'dev_t'. But even after searching a lot, I could not find out how to convert 'dev_t' into struct device *. Is there any way to get that infomation? I tried to print device major and minor numbers using imajor(inode) and iminor(inode). However, for every file - belonging to hdd or usb - it always prints major and minor number as zero. Why would that be happening? I searched online for USB major numbers and I found out that major number for a USB is 180. However, on multiple machines, it showed me the major number associated with the USB dev as 253. $ ls -ltr /dev/usb* crw-rw---- 1 root root 253, 4 2010-04-13 17:20 /dev/usbmon4 crw-rw---- 1 root root 253, 3 2010-04-13 17:20 /dev/usbmon3 crw-rw---- 1 root root 253, 8 2010-04-13 17:20 /dev/usbmon8 crw-rw---- 1 root root 253, 5 2010-04-13 17:20 /dev/usbmon5 crw-rw---- 1 root root 253, 1 2010-04-13 17:20 /dev/usbmon1 crw-rw---- 1 root root 253, 7 2010-04-13 17:20 /dev/usbmon7 Why is that so?

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  • bad_alloc occuring when allocating small structs

    - by SalamiArmi
    A bad_alloc has started showing up in some code which looks perfectly valid to me and has worked very well in the past. The bad alloc only occurs once every 50-3000 iterations of the code, which is also confusing. The code itself is from a singly linked list, simply adding a new element to the queue: template<typename T> struct container { inline container() : next(0) {} container *next; T data; }; void push(const T &data) { container<T> *newQueueMember = new container<T>; //... unrelated to crash } Where T is: struct test { int m[256]; }; Changing the size of the array allocated array to anything but very small values (1-8 ints) still results in a bad_alloc occasionally. A few extra notes about my program: - I used Poco::ThreadPool to thread my program. I've only recently added this functionality, before I had it running with Win32 threads. However, only the main thread ever calls push(). - I am also occasionally getting other crashes which could be related. However, when I try to debug with visual studio 2008, I can't navigate back to the call stack, or the crash happens deep within new(). Thanks in advance.

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  • How `is_base_of` works?

    - by Alexey Malistov
    Why the following code works? typedef char (&yes)[1]; typedef char (&no)[2]; template <typename B, typename D> struct Host { operator B*() const; operator D*(); }; template <typename B, typename D> struct is_base_of { template <typename T> static yes check(D*, T); static no check(B*, int); static const bool value = sizeof(check(Host<B,D>(), int())) == sizeof(yes); }; //Test sample class Base {}; class Derived : private Base {}; //Exspression is true. int test[is_base_of<Base,Derived>::value && !is_base_of<Derived,Base>::value]; Note that B is private base. Note that operator B*() is const. How does this work? Why this works? Why static yes check(D*, T); is better than static yes check(B*, int); ?

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  • How to convert from hex-encoded string to a "human readable" string?

    - by John Jensen
    I'm using the Net-SNMP bindings for python and I'm attempting to grab an ARP cache from a Brocade switch. Here's what my code looks like: #!/usr/bin/env python import netsnmp def get_arp(): oid = netsnmp.VarList(netsnmp.Varbind('ipNetToMediaPhysAddress')) res = netsnmp.snmpwalk(oid, Version=2, DestHost='10.0.1.243', Community='public') return res arp_table = get_arp() print arp_table The SNMP code itself is working fine. Output from snmpwalk looks like this: <snip> IP-MIB::ipNetToMediaPhysAddress.128.10.200.6.158 = STRING: 0:1b:ed:a3:ec:c1 IP-MIB::ipNetToMediaPhysAddress.129.10.200.6.162 = STRING: 0:1b:ed:a4:ac:c1 IP-MIB::ipNetToMediaPhysAddress.130.10.200.6.166 = STRING: 0:1b:ed:38:24:1 IP-MIB::ipNetToMediaPhysAddress.131.10.200.6.170 = STRING: 74:8e:f8:62:84:1 </snip> But my output from the python script yields a tuple of hex-encoded strings that looks like this: ('\x00$8C\x98\xc1', '\x00\x1b\xed;_A', '\x00\x1b\xed\xb4\x8f\x81', '\x00$86\x15\x81', '\x00$8C\x98\x81', '\x00\x1b\xed\x9f\xadA', ...etc) I've spent some time googling and came across the struct module and the .decode("hex") string method, but the .decode("hex") method doesn't seem to work: Python 2.7.3 (default, Apr 10 2013, 06:20:15) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> hexstring = '\x00$8C\x98\xc1' >>> newstring = hexstring.decode("hex") Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.7/encodings/hex_codec.py", line 42, in hex_decode output = binascii.a2b_hex(input) TypeError: Non-hexadecimal digit found >>> And the documentation for struct is a bit over my head.

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  • passing groups of properties from 1 class to another

    - by insanepaul
    I have a group of 13 properties in a class. I created a struct for these properties and passed it to another class. I need to add another 10 groups of these 13 properties. So thats 130 properties in total. What do I do? I could add all 130 properties to the struct. Will this affect performance and readability I could create a list of structs but don't know how to access an item eg. to add to the list: listRowItems.Add(new RowItems(){a=1, b=1, c=1, d=1...}); listRowItems.Add(new RowItems(){a=2, b=2, c=2, d=2...}); How do I access the second group item b? is it Could I use just a dictionary with 130 items Should I use a list of dictionaries (again I don't know how to access a particular item) Should I pass in a class of 130 properties Just for your interest the properties are css parameters used for a composite control. The control displays 13 elements in each row and there are 10 rows and each row is customisable.

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  • Pointer initialization

    - by SoulBeaver
    Sorry if this question has been asked before. On my search through SO I didn't find one that asked what I wanted to know. Basically, when I have this: typedef struct node { int data; node *node; } *head; and do node *newItem = new node; I am under the impression that I am declaring and reserving space, but not defining, a pointer to struct node, is that correct? So when I do newItem->data = 100 and newItem->next = 0 I get confused. newItem = 0would declare what exactly? Both data and next? The object as a whole? I'm especially confused when I use typedef. Which part is the macro? I assume node because that's how I call it, but why do I need it? Finally, what happens when I do: node *temp; temp = new node; temp = head->next; head->next = newItem; newItem->next = temp; I mean, head-next is a pointer pointing to object newItem, so I assume not to newItem.data or next themselves. So how can I use an uninitialized pointer that I described above safely like here? is head now not pointing to an uninitialized pointer?

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