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[help-gengetopt] Re: Gengetopt V 2.20 String Parser/Multiple Parsers pro

From: Lorenzo Bettini
Subject: [help-gengetopt] Re: Gengetopt V 2.20 String Parser/Multiple Parsers problems with blank spaces around numerics and order of the arguments.
Date: Wed, 01 Aug 2007 16:11:54 +0200
User-agent: Mozilla-Thunderbird (X11/20070622)

Nikolay Yevik wrote:

Would be much obliged if anybody could help me with the following problems I see with gengetopt 2.20 (latest)
as well as previous versions (tried down to 2.17) using string parser.

OS: Linux (tested Open SUSE Linux 10.2 and Mandriva 2006 and 2007 (0x86 and 0x86_64) )

Gengetopt V 2.20 (latest) compiled with GCC 4.1.x.

I wrote a client that must take arguments from both CLI as well as from a file.

When parameters are passed on CLI everything works fine (using cmdline_parser() function).

For example:

./client –v –c 0x1234 –print

When using cmdline_parser_string() to read flags from a file line by line I start seeing strange behavior:

   1. Parser becomes very picky about white/ blank spaces at the end or
      beginning of each line and especially around numeric values.

   2. Parser becomes picky about the order of arguments/flags. Whereas
      for CLI parser it did not matter in what order I passed the flags,
      it matters for the string parser.

I traced the first problem down to the generated cmdline_parser_internal() function that has the following code for each and every numeric option/argument passed to the command:

if (!(stop_char && *stop_char == '\0')) {

fprintf(stderr, "%s: invalid numeric value: %s\n", argv[0], optarg);

            goto failure;


If for every numeric command argument I comment out this generated code in the cmdline.c file generated by gengetopt from my .ggo file I circumvent at least the first problem.

However, this is a rather crude hack and I’d like to understand the root cause of this problem is.

Is this a bug?

I am still trying to find a behavior pattern for the second problem. That is, - why some order of parameters work and the other don’t and why the order should matter at all.

For one thing it appears that it does not like the long options to be the first.

I am attaching a test case illustrating the problem.

The client can take commands from both command line as well as a file or just from a file.


./client –c 0x1234 –f testfile.txt


./client –f testfile.txt

Any help will be greatly appreciated.

Hi Nikolay

I think the problem is actually in the client.c code: when you read a line from the file with fgets you also get the \n at the end, thus when you get to the line

-c 0xFFDD

strtol tries to convert to a number this string 0xFFDD\n which is not a valid number.

I could also clean the \n in the generated parser code, but I think it would not be right, since the string parser expects a valid command line (i.e., without the terminating \n newline char). However, concerning this point I'd like to hear from other people on the list.

If you modify your client code as in the attached file, you won't have this problem; the modified part is as follows (notice that I also avoid empty strings, just to be safe):

>                 /* avoid empty strings */
>                 if (!strlen(commandLine)) continue;
>                 /* make sure to remove the \n char */
>                 if (commandLine[strlen(commandLine)-1] == '\n')
>                   commandLine[strlen(commandLine)-1] = '\0';

as for the other problem, i.e., the order of arguments, could you please provide an example of this problem? I didn't experience this, but I'm pretty sure it was due to the above \n issue.

I hope to hear from you soon!


Lorenzo Bettini, PhD in Computer Science, DSI, Univ. di Firenze
ICQ# lbetto, 16080134     (GNU/Linux User # 158233)
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <limits.h>
#include <time.h>
#include <signal.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "cmdline.h"

int main(int argc, char *argv[]) 
    char * iam = "client main()";
    struct sigaction newAction, oldAction;
    struct gengetopt_args_info args, argsFile;
    char commandLine[LINE_MAX];
    FILE *commandFile = NULL;;
    int counter = 0;
    // Call CLI parser.
    if (cmdline_parser (argc, argv, &args) != 0) {
        fprintf(stderr, "%s: Bad args - exit!", iam);
        syslog(LOG_ERR, "%s: Bad args - exit!", iam);
        exit(EXIT_FAILURE) ;

    if (args.command_given) {
        fprintf (stdout, "Everything is fine!\n");              
    if (args.sleep_given) usleep(args.sleep_arg * 1000);
    if (args.file_given) { // Reading commands from file
        if ((commandFile = fopen(args.file_arg, "r")) == NULL) {
            syslog(LOG_ERR, "%s: Cannot open file %s - exit!\n", 
                   iam, args.file_arg);
            fprintf(stderr, "%s: Cannot open file %s - exit!\n", 
                             iam, args.file_arg);
            exit (EXIT_FAILURE);
        while (counter != args.times2run_arg) {
            if (args.times2run_arg != -1) counter ++;   
            fseek(commandFile, 0, SEEK_SET);
            while(!feof(commandFile)) {
                if(fgets(commandLine, LINE_MAX, commandFile) == NULL)
                if(commandLine[0] == '#') continue;
                /* avoid empty strings */
                if (!strlen(commandLine)) continue;

                /* make sure to remove the \n char */
                if (commandLine[strlen(commandLine)-1] == '\n')
                  commandLine[strlen(commandLine)-1] = '\0';

                                          &argsFile, argv[0])) != 0) {
                    fprintf(stderr, "%s: Bad args - exit!", iam);
                    syslog(LOG_ERR, "%s: Bad args - exit!", iam);
                    exit(EXIT_FAILURE) ;
                if(argsFile.command_given) {
                  fprintf(stdout, "Everything is fine here as well!\n");
    // Finalizing...
    cmdline_parser_free (&args);
    exit (EXIT_SUCCESS);                     
} // End main().

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