spawn.c

   1 /*
   2  * Copyright 2005 Timo Hirvonen
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  17  * 02111-1307, USA.
  18  */
  19
  20 #include "spawn.h"
  21 #include "file.h"
  22
  23 #include <sys/types.h>
  24 #include <sys/wait.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <fcntl.h>
  28 #include <errno.h>
  29
  30 int spawn(char *argv[], int *status)
  31 {
  32         pid_t pid;
  33         int err_pipe[2];
  34
  35         if (pipe(err_pipe) == -1)
  36                 return -1;
  37
  38         pid = fork();
  39         if (pid == -1) {
  40                 /* error */
  41                 return -1;
  42         } else if (pid == 0) {
  43                 /* child */
  44                 int dev_null, err, i;
  45
  46                 close(err_pipe[0]);
  47                 fcntl(err_pipe[1], F_SETFD, FD_CLOEXEC);
  48
  49                 /* redirect stdout and stderr to /dev/null if possible */
  50                 dev_null = open("/dev/null", O_WRONLY);
  51                 if (dev_null != -1) {
  52                         dup2(dev_null, 1);
  53                         dup2(dev_null, 2);
  54                 }
  55
  56                 /* not interactive, close stdin */
  57                 close(0);
  58
  59                 /* close unused fds */
  60                 for (i = 3; i < 30; i++)
  61                         close(i);
  62
  63                 execvp(argv[0], argv);
  64
  65                 /* error */
  66                 err = errno;
  67                 write_all(err_pipe[1], &err, sizeof(int));
  68                 exit(1);
  69         } else {
  70                 /* parent */
  71                 int rc, errno_save, child_errno;
  72
  73                 close(err_pipe[1]);
  74                 rc = read_all(err_pipe[0], &child_errno, sizeof(int));
  75                 errno_save = errno;
  76                 close(err_pipe[0]);
  77
  78                 waitpid(pid, status, 0);
  79
  80                 if (rc == -1) {
  81                         errno = errno_save;
  82                         return -1;
  83                 }
  84                 if (rc == sizeof(int)) {
  85                         errno = child_errno;
  86                         return -1;
  87                 }
  88                 if (rc != 0) {
  89                         errno = EMSGSIZE;
  90                         return -1;
  91                 }
  92                 return 0;
  93         }
  94 }