Redirecting STDERR and STDOUT in C using library

Hi All,

I want to execute a binary and trap the stdout and stderr . I don't have the code for the binary. I have got the solution for this on the same list which is working fine. Many Thanks to Dave.
Here's the code :
=================================
Main Program:
/*
* Sample program to demonstrate super_popen
*
* by dave madden <dhm@webvision.com>
*/
#include <stdio.h>
#include <errno.h>
#include <sys/select.h>

int
super_popen( FILE **SI_SO_SE, const char *cmd )
{
    int           si[2] = { -1, -1 };
    int           so[2] = { -1, -1 };
    int           se[2] = { -1, -1 };
    pid_t      pid;
    int           e;
    int           fd;

    /*
     * Create 3 pipes to talk to subprocess on stdin/stdout/stderr
     */
    if (pipe( si ) != 0 || pipe( so ) != 0 || pipe( se ) != 0) goto SHUTDOWN;

    if ((pid = fork( )) == -1) goto SHUTDOWN;

    if (pid) {                         /* in parent */
         wait(0);
         close( si[0] );
         close( so[1] );
         close( se[1] );
         SI_SO_SE[0] = fdopen( si[1], "w" );
         SI_SO_SE[1] = fdopen( so[0], "r" );
         SI_SO_SE[2] = fdopen( se[0], "r" );
         
         return 0;                    /* OK! */
    }

    /*
     * This is the child process...we have to fiddle around with the
     * pipe descriptors and then exec the program.
     */

    /*
     * Make sure none of our stdin/stdout/stderr descriptors are
     * on FDs 0, 1, or 2 (if they are, it'll screw things up when
     * we do the dup2()'s)
     */
    if (si[0] < 2 || so[1] < 2 || se[1] < 2) {
         int      free_index = 0;
         int      free_fds[3];
         printf( "have to (Edited by Computer101) with FDs in child\n" );
         for (fd = 3; fd < FD_SETSIZE; fd++) {
              if (fd != si[0] && fd != si[1] && fd != se[1]) {
                   free_fds[free_index++] = fd;
                   if (free_index == 3) break;
              }
         }
         if (dup2( si[0], free_fds[0] ) == -1 ||
              dup2( so[1], free_fds[1] ) == -1 ||
              dup2( se[1], free_fds[2] ) == -1) exit( errno );
         si[0] = free_fds[0];
         so[1] = free_fds[1];
         se[1] = free_fds[2];
    }
         
    /* close all other descriptors...don't want child to have copies */
    for (fd = 0; fd < FD_SETSIZE; fd++)
         if (fd != si[0] && fd != so[1] && fd != se[1]) close( fd );
   
     dup2( si[0], 0 );               /* attach pipes to FD 0, 1, and 2 */
    dup2( so[1], 1 );
    dup2( se[1], 2 );

    close( si[0] );
    close( so[1] );
    close( se[1] );

/*     write( 1, "Hello\n", 6 );
    write( 2, "World\n", 6 );
    exit( 0 );*/

    exit( execl( "/usr/bin/sh", "sh", "-c", cmd, 0 ) ); <=========My binary with arguments works fine

 SHUTDOWN:     /* something went wrong...close the pipes & etc */
    e = errno;
    close( si[0] ); close( si[1] );
    close( so[0] ); close( so[1] );
    close( se[0] ); close( se[1] );
    errno = e;
    return -1;
}

int
main( int argc, char **argv ) <========================Changed to a function in Library and called from my
{                                                                                                     application
    FILE     *child_io[3];

    if (argc != 2) {
         printf( "usage: %s <name-of-program-to-run>\n", argv[0] );
         exit( 1 );
    }

    if (super_popen( child_io, argv[1] ) == 0) {
         char      buf[256];
         
         fprintf( child_io[0], "Message to child\n" );
         fflush( child_io[0] );

         while (fgets( buf, sizeof(buf), child_io[1] ) != 0) { <================= Cannot read This Goes on endlessly
              printf( "Child STDOUT: \"%.*s\"\n", strlen(buf) - 1, buf );                           when function is called from library
         }

         while (fgets( buf, sizeof(buf), child_io[2] ) != 0) { <================= Cannot read This Goes on endlessly
              printf( "Child STDERR: \"%.*s\"\n", strlen(buf) - 1, buf );                            when function is called from library
         }
    } else {
         printf("couldn't run %s: %d (%s)\n", argv[1], errno, strerror(errno));
    }

    exit( 0 );
}





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But my problem is that I want to use all this code in a static library so I converted the main function to a function and made static library using codewarrior .Now when I call this function from my application it does everything finely except that it is not able to read from the File pointers being returned in the parent process in super_popen.
My application is MACOS X application.

(Please see my comments at relevant places in the code)

In the nutshell I cannot read from child_io[1] and child_io[2] when the function is called from the library.

Can somebody please point out what the problem is ?

Thanks in Advance
Deepak Kapila

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This question has been deleted with no points refunded.  01/25/2004 09:32AM PST

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