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forkexec.c
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forkexec.c
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/*BINFMTC:
* fork/exec helper for pbuilder.
* Copyright (C) 2007-2009 Junichi Uekawa
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdarg.h>
#include "parameter.h"
/*
execvp that does fork.
@return < 0 for failure, exit code for other cases.
*/
int forkexecvp (char *const argv[])
{
int ret;
pid_t pid;
int status;
/* DEBUG: */
{
int i=0;
printf(" forking: ");
while(argv[i])
{
printf("%s ", argv[i]);
i++;
}
printf("\n");
}
fflush(NULL);
switch(pid=fork())
{
case 0:
execvp(argv[0], (char*const*)argv);
perror("execvp");
fprintf(stderr, "Could not execute %s\n", argv[0]);
exit(EXIT_FAILURE);
case -1:
/* error condition in fork(); something is really wrong */
perror("fork");
return -1;
default:
/* parent process, waiting for termination */
if (-1==waitpid(pid, &status, 0))
{
perror("waitpid");
fprintf(stderr, "unexpected waitpid error when waiting for process %i with status %x\n",
pid, status);
return -1;
}
if (!WIFEXITED(status))
{
/* something unexpected */
return -1;
}
ret = WEXITSTATUS(status);
}
return ret;
}
/*
execlp that does fork.
NULL-terminated list of parameters.
cf. execl from FreeBSD sources, and glibc posix/execl.c,
and cygwin exec.cc
@return < 0 for failure, exit code for other cases.
*/
int
forkexeclp (const char *path, const char *arg0, ...)
{
int i, ret;
va_list args;
const char *argv[1024];
pid_t pid;
int status;
va_start(args, arg0);
argv[0] = arg0;
i = 1;
printf(" forking: %s ", argv[0]);/* debug message */
do
{
argv[i] = va_arg(args, const char *);
if (argv[i])
printf("%s ", argv[i]); /* debug message */
if ( i >= 1023 )
{
return -1;
}
}
while (argv[i++] != NULL);
va_end (args);
printf("\n"); /* debug message */
fflush(NULL);
switch(pid=fork())
{
case 0:
execvp(path, (char*const*)argv);
perror("pbuilder: execlp");
fprintf(stderr, "Could not execute %s\n", path);
exit(EXIT_FAILURE);
case -1:
/* error condition in fork(); something is really wrong */
perror("pbuilder: fork");
return -1;
default:
/* parent process, waiting for termination */
if (-1==waitpid(pid, &status, 0))
{
perror("waitpid");
return -1;
}
if (!WIFEXITED(status))
{
/* something unexpected */
return -1;
}
ret = WEXITSTATUS(status);
}
return ret;
}