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  • Unable to capture standard output of process using Boost.Process

    - by Chris Kaminski
    Currently am using Boost.Process from the Boost sandbox, and am having issues getting it to capture my standard output properly; wondering if someone can give me a second pair of eyeballs into what I might be doing wrong. I'm trying to take thumbnails out of RAW camera images using DCRAW (latest version), and capture them for conversion to QT QImage's. The process launch function: namespace bf = ::boost::filesystem; namespace bp = ::boost::process; QImage DCRawInterface::convertRawImage(string path) { // commandline: dcraw -e -c <srcfile> -> piped to stdout. if ( bf::exists( path ) ) { std::string exec = "bin\\dcraw.exe"; std::vector<std::string> args; args.push_back("-v"); args.push_back("-c"); args.push_back("-e"); args.push_back(path); bp::context ctx; ctx.stdout_behavior = bp::capture_stream(); bp::child c = bp::launch(exec, args, ctx); bp::pistream &is = c.get_stdout(); ofstream output("C:\\temp\\testcfk.jpg"); streamcopy(is, output); } return (NULL); } inline void streamcopy(std::istream& input, std::ostream& out) { char buffer[4096]; int i = 0; while (!input.eof() ) { memset(buffer, 0, sizeof(buffer)); int bytes = input.readsome(buffer, sizeof buffer); out.write(buffer, bytes); i++; } } Invoking the converter: DCRawInterface DcRaw; DcRaw.convertRawImage("test/CFK_2439.NEF"); The goal is to simply verify that I can copy the input stream to an output file. Currently, if I comment out the following line: args.push_back("-c"); then the thumbnail is written by DCRAW to the source directory with a name of CFK_2439.thumb.jpg, which proves to me that the process is getting invoked with the right arguments. What's not happening is connecting to the output pipe properly. FWIW: I'm performing this test on Windows XP under Eclipse 3.5/Latest MingW (GCC 4.4).

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  • File I/O OS handling

    - by Albinoswordfish
    This isn't a direct coding question but more of a OS handling mechanism. I was reading somebody's previous question regarding C# and file handling. Apparently C# was throwing an exception regarding a file being locked when trying to access this. So my question is, does C# use an internal lock to handle file I/O between processes, or does the OS use some type of mutual exclusion for file I/O? From what I learned about operating systems, well at least unix, is that the OS doesn't implement any type of mutual exclusion for processes trying to access the same file.

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  • High PageIOLatch_SH Waits with High Drive Idle times

    - by Marty Trenouth
    We are experiencing high volume of PageIOLatch_SH waits on our database (row counts in the Billions). However it seems that our drive Idle time Percentage hovers around 50-60 percent. CPU usage is nill. The Database Tuning Advisor gives no suggestions for optimization. The query plan (actual) from the single stored procedure used on the database puts the majority of the expense on index seek (yeah I know these should be optimial) operations. Anyone have suggestions of how to increase throughput?

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  • image scaling with C

    - by sa125
    Hi - I'm trying to read an image file and scale it by multiplying each byte by a scale its pixel levels by some absolute factor. I'm not sure I'm doing it right, though - void scale_file(char *infile, char *outfile, float scale) { // open files for reading FILE *infile_p = fopen(infile, 'r'); FILE *outfile_p = fopen(outfile, 'w'); // init data holders char *data; char *scaled_data; // read each byte, scale and write back while ( fread(&data, 1, 1, infile_p) != EOF ) { *scaled_data = (*data) * scale; fwrite(&scaled_data, 1, 1, outfile); } // close files fclose(infile_p); fclose(outfile_p); } What gets me is how to do each byte multiplication (scale is 0-1.0 float) - I'm pretty sure I'm either reading it wrong or missing something big. Also, data is assumed to be unsigned (0-255). Please don't judge my poor code :) thanks

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  • Displaying Image On SmallBASIC

    - by Nathan Campos
    I want to display a image using SmallBASIC. For this I've started by searching on the references, then I found a reference for IMAGE, that is like this: IMAGE #handle, index, x, y [,sx,sy [,w,h]] Then I found another to open files(OPEN): OPEN file [FOR {INPUT|OUTPUT|APPEND}] AS #fileN But I want to know some things: What image types this function can display? There is any real example to use IMAGE?

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  • Using fgets to read strings from file in C

    - by Ivan
    I am trying to read strings from a file that has each string on a new line but I think it reads a newline character once instead of a string and I don't know why. If I'm going about reading strings the wrong way please correct me. i=0; F1 = fopen("alg.txt", "r"); F2 = fopen("tul.txt", "w"); if(!feof(F1)) { do{ //start scanning file fgets(inimene[i].Enimi, 20, F1); fgets(inimene[i].Pnimi, 20, F1); fgets(inimene[i].Kood, 12, F1); printf("i=%d\nEnimi=%s\nPnimi=%s\nKaad=%s",i,inimene[i].Enimi,inimene[i].Pnimi,inimene[i].Kood); i++;} while(!feof(F1));}; /*finish getting structs*/ The printf is there to let me see what was read into what and here is the result i=0 Enimi=peter Pnimi=pupkin Kood=223456iatb i=1 Enimi= Pnimi=masha Kaad=gubkina i=2 Enimi=234567iasb Pnimi=sasha Kood=dudkina As you can see after the first struct is read there is a blank(a newline?) onct and then everything is shifted. I suppose I could read a dummy string to absorb that extra blank and then nothing would be shifted, but that doesn't help me understand the problem and avoid in the future.

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  • Why are my attempts to open a file using open for writing failing? Ada 95

    - by mat_geek
    When I attempt to open a file to write to I get an Ada.IO_Exceptions.Name_Error. The procedure call is Ada.Text_IO.Open The file name is "C:\CC_TEST_LOG.TXT". This file does not exist. This is on Windows XP on an NTFS partition. The user has permissions to create and write to the directory. The filename is well under the WIN32 max path length. name_2 : String := "C:\CC_TEST_LOG.TXT" if name_2'last > name_2'first then begin Ada.Text_IO.Open(file, Ada.Text_IO.Out_File, name_2); Ada.Text_IO.Put_Line( "CC_Test_Utils: LogFile: ERROR: Open, File " & name_2); return; exception when The_Error : others => Ada.Text_IO.Put_Line( "CC_Test_Utils: LogFile: ERROR: Open Failed; " & Ada.Exceptions.Exception_Name(The_Error) & ", File " & name_2); end; end if;

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  • fstream - correct error checking after output

    - by Truncheon
    What's the correct way to check for a general error when sending data to an fstream? I have the following code, which seems a bit overkill. int Saver::output() { save_file_handle.open(file_name.c_str()); if (save_file_handle.is_open()) { save_file_handle << save_str.c_str(); if (save_file_handle.bad()) { x_message("Error - failed to save file"); return 0; } save_file_handle.close(); if (save_file_handle.bad()) { x_message("Error - failed to save file"); return 0; } return 1; } else { x_message("Error - couldn't open save file"); return 0; } }

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  • 'Programming by Coincidence' Excercise: Java File Writer

    - by Tapas
    I just read the article Programming by Coincidence. At the end of the page there are excercises. A few code fragments that are cases of "programming by coincidence". But I cant figure out the error in this piece: This code comes from a general-purpose Java tracing suite. The function writes a string to a log file. It passes its unit test, but fails when one of the Web developers uses it. What coincidence does it rely on? public static void debug(String s) throws IOException { FileWriter fw = new FileWriter("debug.log", true); fw.write(s); fw.flush(); fw.close(); } What is wrong about this?

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  • Writing to a file in Python inserts null bytes

    - by Javier Badia
    I'm writing a todo list program. It keeps a file with a thing to do per line, and lets the user add or delete items. The problem is that for some reason, I end up with a lot of zero bytes at the start of the file, even though the item is correctly deleted. I'll show you a couple of screenshots to make sure I'm making myself clear. This is the file in Notepad++ before running the program: This is the file after deleting item 3 (counting from 1): This is the relevant code. The actual program is bigger, but running just this part triggers the error. import os TODO_FILE = r"E:\javi\code\Python\todo-list\src\todo.txt" def del_elems(f, delete): """Takes an open file and either a number or a list of numbers, and deletes the lines corresponding to those numbers (counting from 1).""" if isinstance(delete, int): delete = [delete] lines = f.readlines() f.truncate(0) counter = 1 for line in lines: if counter not in delete: f.write(line) counter += 1 f = open(TODO_FILE, "r+") del_elems(f, 3) f.close() Could you please point out where's the mistake?

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  • Javascript - why do I sometimes fail to read file content with GDownloadUrl?

    - by Daj pan spokój
    Hi everybody. I try to read some file with google's GDownloadUrl and it works only from time to time. failure means fileRows == "blah blah" success means fileRows == (real file content) I've noticed, however, that when I cease (with Firebug) the execution on line 3 for a couple of seconds, it succeeds more often. Maybe it is some kind of threading bug, then? Do You guys have any tip or idea? 1 var fileContent = "blah blah"; 2 availabilityFile = "input/available/" + date + ".csv"; 3 GDownloadUrl(availabilityFile, function(fileData) { 4 fileContent = fileData; 5 }); 6 fileRows = fileContent.split("\n");

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  • Reading from a file, atoi() returns zero only on first element

    - by Nazgulled
    Hi, I don't understand why atoi() is working for every entry but the first one. I have the following code to parse a simple .csv file: void ioReadSampleDataUsers(SocialNetwork *social, char *file) { FILE *fp = fopen(file, "r"); if(!fp) { perror("fopen"); exit(EXIT_FAILURE); } char line[BUFSIZ], *word, *buffer, name[30], address[35]; int ssn = 0, arg; while(fgets(line, BUFSIZ, fp)) { line[strlen(line) - 2] = '\0'; buffer = line; arg = 1; do { word = strsep(&buffer, ";"); if(word) { switch(arg) { case 1: printf("[%s] - (%d)\n", word, atoi(word)); ssn = atoi(word); break; case 2: strcpy(name, word); break; case 3: strcpy(address, word); break; } arg++; } } while(word); userInsert(social, name, address, ssn); } fclose(fp); } And the .csv sample file is this: 900011000;Jon Yang;3761 N. 14th St 900011001;Eugene Huang;2243 W St. 900011002;Ruben Torres;5844 Linden Land 900011003;Christy Zhu;1825 Village Pl. 900011004;Elizabeth Johnson;7553 Harness Circle But this is the output: [900011000] - (0) [900011001] - (900011001) [900011002] - (900011002) [900011003] - (900011003) [900011004] - (900011004) What am I doing wrong?

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  • read a file with both text and binary information in .Net

    - by Yin Zhu
    I need to read binary PGM image files. Its format: P5 # comments nrows ncolumns max-value binary values start at this line. (totally nrows*ncolumns bytes/unsigned char) I know how to do it in C or C++ using FILE handler by reading several lines first and read the binary block. But don't know how to do it in .Net.

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  • Reading a file from a jar, or anywhere on the classpath?

    - by Stefan Kendall
    I'm trying to build an application that builds a resource file into a jar, but I'd like to have the project runnable within eclipse. I have a basic maven 2 structure for my project, and I'm unsure how to read in the file such that it's found and used when run from the JAR or from within eclipse. Thought? Structure: src/main/java src/main/resources/file.txt Current reading method: getClass().getResourceAsStream("/file.txt") Is there reading method that will pick up src/main/resources/*, as well as the root level of the JAR (where resources are deployed)?

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  • What is the root directory OR how do I set the directory in DotNetZip

    - by Chris
    where does DotNetZip get it's root directory for saving. All the save examples don't show the directory. My goal is to recurse a folder and subfolders. In each folder I want to zip all the files into one zip and delete the source files. private void CopyFolder(string srcPath, string dstPath) { if (!Directory.Exists(dstPath)) Directory.CreateDirectory(dstPath); string[] files = Directory.GetFiles(srcPath); string msg; string zipFileName; using (ZipFile z = new ZipFile(Path.Combine(srcPath,String.Format("Archive{0:yyyyMMdd}.zip", DateTime.Now)))) { z.ReadProgress += new EventHandler<ReadProgressEventArgs>(z_ReadProgress); foreach (string file in files) { FileInfo fi = new FileInfo(file); AddLog(String.Format("Adding {0}", file)); z.AddFile(file); } //z.Save(Path.Combine(srcPath, String.Format("Archive{0:yyyyMMdd}.zip", DateTime.Now))); z.Save(); if (deleteSource) { foreach (string file in files) { File.Delete(file); } } zipFileName = z.Name; } if (!compressOnly) File.Copy(Path.Combine(srcPath,zipFileName), Path.Combine(dstPath, Path.GetFileName(zipFileName))); string[] folders = Directory.GetDirectories(sourcePath); foreach (string folder in folders) { string name = Path.GetFileName(folder); string dest = Path.Combine(dstPath, name); Console.WriteLine(ln); log.Add(ln); msg = String.Format("{3}{4}Start Copy: {0}{4}Directory: {1}{4}To: {2}", DateTime.Now.ToString("G"), name, dest, ln, Environment.NewLine); AddLog(msg); if (recurseFolders) CopyFolder(folder, dest); msg = String.Format("Copied Directory: {0}{4}To: {1}\nAt: {2}{3}", folder, dest, DateTime.Now.ToString("G"), Environment.NewLine); AddLog(msg); } }

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  • Modify Executing Jar file

    - by pinkynobrain
    Hello Stack Overflow friends. I have a simple problem which i fear doesnt have a simple solution and i need advice as to how to proceed. I am developing a java application packaged as and executable JAR but it requires to modify some of its JAR file contents during execution. At this stage i hit a problem because some OS lock the file preventing writes to it. It is essential that the user sees an updated version of the jar file by the time the application exits allthough i can be pretty flexible as to how to achieve this. A clean and efficient solution is obviously prefereable but portability is the only hard requirement. The following are three approaches i can see to solving the problem, feel free to comment on them or suggest others. Tell Java to unlock the JAR file for writing(this doesnt seem possible but it would be the easyest solution) Copy the executable class files to a tempory file on application startup, use a class loader to load these files and unload the ones from the initial JAR file.(Not had much experience with the classloaders but hopefully the JVM would then be smart enough to realize that the original JAR is nolonger in use and so unlock it) Put a Second executable JAR File inside the First, on startup extract the inner jar to e temporaryfile, invoke a new java process and pass it the location of the Outer JAR, first process exits, second process modifys the Outer jar unincumbered.(This will work but im not sure there is a platform independant way of one java app invoking another) I know this is a weird question but any help would be appreciated.

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  • Is it possible for competing file access to cause deadlock in Java?

    - by BlairHippo
    I'm chasing a production bug that's intermittent enough to be a real bastich to diagnose properly but frequent enough to be a legitimate nuisance for our customers. While I'm waiting for it to happen again on a machine set to spam the logfile with trace output, I'm trying to come up with a theory on what it could be. Is there any way for competing file read/writes to create what amounts to a deadlock condition? For instance, let's say I have Thread A that occasionally writes to config.xml, and Thread B that occasionally reads from it. Is there a set of circumstances that would cause Thread B to prevent Thread A from proceeding? My thanks in advance to anybody who helps with this theoretical fishing expedition. Edit: To answer Pyrolistical's questions: the code isn't using Filelock, and is running on a WinXP machine.

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  • Persist changes in C

    - by Mohit Deshpande
    I am developing a database-like application that stores a a structure containing: struct Dictionary { char *key; char *value; struct Dictionary *next; }; As you can see, I am using a linked list to store information. But the problem begins when the user exits out of the program. I want the information to be stored somewhere. So I was thinking of storing the linked list in a permanent or temporary file using fopen, then, when the user starts the program, retrieve the linked list. Here is the method that prints the linked list to the console: void PrintList() { int count = 0; struct Dictionary *current; current = head; if (current == NULL) { printf("\nThe list is empty!"); return; } printf(" Key \t Value\n"); printf(" ======== \t ========\n"); while (current != NULL) { count++; printf("%d. %s \t %s\n", count, current->key, current->value); current = current->next; } } So I am thinking of modifying this method to print the information through fprintf instead of printf and then the program would just get the infomation from the file. Could someone help me on how I can read and write to this file? What kind of file should it be, temporary or regular? How should I format the file (like I was thinking of just having the key first, then the value, then a newline character)?

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  • Elegant way to take basename of directory in Python?

    - by user248237
    I have several scripts that take as input a directory name, and my program creates files in those directories. Sometimes I want to take the basename of a directory given to the program and use it to make various files in the directory. For example, # directory name given by user via command-line output_dir = "..." # obtained by OptParser, for example my_filename = output_dir + '/' + os.path.basename(output_dir) + '.my_program_output' # write stuff to my_filename The problem is that if the user gives a directory name with a trailing slash, then os.path.basename will return the empty string, which is not what I want. What is the most elegant way to deal with these slash/trailing slash issues in python? I know I can manually check for the slash at the end of output_dir and remove it if it's there, but there seems like there should be a better way. Is there? Also, is it OK to manually add '/' characters? E.g. output_dir + '/' os.path.basename() or is there a more generic way to build up paths? Thanks.

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  • Exception when ASP.NET attempts to delete network file.

    - by Jordan Terrell
    Greetings - I've got an ASP.NET application that is trying to delete a file on a network share. The ASP.NET application's worker process is running under a domain account (confirmed this by looking in TaskManager and by using ShowContexts2.aspx¹). I've been assured by the network admins that the process account is a member of a group that has Modify permissions to the directory that contains the file I'm trying to delete. However, it is unable to do so, and instead I get an exception (changed the file path to all x's): System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. --- System.UnauthorizedAccessException: Access to the path '\xxxxxxx\xxxxxxx\xxxxxxx\xxxxxx.xxx' is denied. Any ideas on how to diagnose/fix this issue? Thanks - Jordan ¹ http://www.leastprivilege.com/ShowContextsNET20Version.aspx

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