src/pulsecore/start-child.c

   1 /***
   2   This file is part of PulseAudio.
   3
   4   Copyright 2007 Lennart Poettering
   5
   6   PulseAudio is free software; you can redistribute it and/or modify
   7   it under the terms of the GNU Lesser General Public License as
   8   published by the Free Software Foundation; either version 2.1 of the
   9   License, or (at your option) any later version.
  10
  11   PulseAudio is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public
  17   License along with PulseAudio; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <errno.h>
  27 #include <stdio.h>
  28 #include <sys/types.h>
  29 #include <dirent.h>
  30 #include <unistd.h>
  31 #include <fcntl.h>
  32 #include <signal.h>
  33
  34 #ifdef HAVE_SYS_PRCTL_H
  35 #include <sys/prctl.h>
  36 #endif
  37 #ifdef HAVE_SYS_RESOURCE_H
  38 #include <sys/resource.h>
  39 #endif
  40
  41 #include <pulsecore/core-util.h>
  42 #include <pulsecore/core-error.h>
  43 #include <pulsecore/pipe.h>
  44
  45 #include "start-child.h"
  46
  47 int pa_start_child_for_read(const char *name, const char *argv1, pid_t *pid) {
  48 #ifdef HAVE_FORK
  49     pid_t child;
  50     int pipe_fds[2] = { -1, -1 };
  51
  52     if (pipe(pipe_fds) < 0) {
  53         pa_log("pipe() failed: %s", pa_cstrerror(errno));
  54         goto fail;
  55     }
  56
  57     if ((child = fork()) == (pid_t) -1) {
  58         pa_log("fork() failed: %s", pa_cstrerror(errno));
  59         goto fail;
  60
  61     } else if (child != 0) {
  62
  63         /* Parent */
  64         pa_assert_se(pa_close(pipe_fds[1]) == 0);
  65
  66         if (pid)
  67             *pid = child;
  68
  69         return pipe_fds[0];
  70     } else {
  71         /* child */
  72
  73         pa_reset_personality();
  74
  75         pa_assert_se(pa_close(pipe_fds[0]) == 0);
  76         pa_assert_se(dup2(pipe_fds[1], STDOUT_FILENO) == STDOUT_FILENO);
  77
  78         if (pipe_fds[1] != STDOUT_FILENO)
  79             pa_assert_se(pa_close(pipe_fds[1]) == 0);
  80
  81         pa_close(STDIN_FILENO);
  82         pa_assert_se(open("/dev/null", O_RDONLY) == STDIN_FILENO);
  83
  84         pa_close(STDERR_FILENO);
  85         pa_assert_se(open("/dev/null", O_WRONLY) == STDERR_FILENO);
  86
  87         pa_close_all(-1);
  88         pa_reset_sigs(-1);
  89         pa_unblock_sigs(-1);
  90         pa_reset_priority();
  91         pa_unset_env_recorded();
  92
  93         /* Make sure our children are not influenced by the
  94          * LD_BIND_NOW we set for ourselves. */
  95         unsetenv("LD_BIND_NOW");
  96
  97 #ifdef PR_SET_PDEATHSIG
  98         /* On Linux we can use PR_SET_PDEATHSIG to have the helper
  99         process killed when the daemon dies abnormally. On non-Linux
 100         machines the client will die as soon as it writes data to
 101         stdout again (SIGPIPE) */
 102
 103         prctl(PR_SET_PDEATHSIG, SIGTERM, 0, 0, 0);
 104 #endif
 105
 106         execl(name, name, argv1, NULL);
 107         _exit(1);
 108     }
 109
 110 fail:
 111     pa_close_pipe(pipe_fds);
 112 #endif /* HAVE_FORK */
 113
 114     return -1;
 115 }