code.delx.au - pulseaudio/blob - src/pulsecore/start-child.c

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of PulseAudio.
   5
   6   Copyright 2007 Lennart Poettering
   7
   8   PulseAudio is free software; you can redistribute it and/or modify
   9   it under the terms of the GNU Lesser General Public License as
  10   published by the Free Software Foundation; either version 2.1 of the
  11   License, or (at your option) any later version.
  12
  13   PulseAudio is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public
  19   License along with PulseAudio; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  21   USA.
  22 ***/
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include <errno.h>
  29 #include <stdio.h>
  30 #include <sys/types.h>
  31 #include <dirent.h>
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34 #include <signal.h>
  35
  36 #ifdef HAVE_SYS_PRCTL_H
  37 #include <sys/prctl.h>
  38 #endif
  39 #ifdef HAVE_SYS_RESOURCE_H
  40 #include <sys/resource.h>
  41 #endif
  42
  43 #include <pulsecore/core-util.h>
  44 #include <pulsecore/core-error.h>
  45
  46 #include "start-child.h"
  47
  48 int pa_start_child_for_read(const char *name, const char *argv1, pid_t *pid) {
  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 #ifdef __linux__
  72         DIR* d;
  73 #endif
  74         int max_fd, i;
  75
  76         /* child */
  77
  78         pa_reset_priority();
  79
  80         pa_assert_se(pa_close(pipe_fds[0]) == 0);
  81         pa_assert_se(dup2(pipe_fds[1], 1) == 1);
  82
  83         if (pipe_fds[1] != 1)
  84             pa_assert_se(pa_close(pipe_fds[1]) == 0);
  85
  86         pa_close(0);
  87         pa_assert_se(open("/dev/null", O_RDONLY) == 0);
  88
  89         pa_close(2);
  90         pa_assert_se(open("/dev/null", O_WRONLY) == 2);
  91
  92 #ifdef __linux__
  93
  94         if ((d = opendir("/proc/self/fd/"))) {
  95
  96             struct dirent *de;
  97
  98             while ((de = readdir(d))) {
  99                 char *e = NULL;
 100                 int fd;
 101
 102                 if (de->d_name[0] == '.')
 103                     continue;
 104
 105                 errno = 0;
 106                 fd = strtol(de->d_name, &e, 10);
 107                 pa_assert(errno == 0 && e && *e == 0);
 108
 109                 if (fd >= 3 && dirfd(d) != fd)
 110                     pa_close(fd);
 111             }
 112
 113             closedir(d);
 114         } else {
 115
 116 #endif
 117
 118             max_fd = 1024;
 119
 120 #ifdef HAVE_SYS_RESOURCE_H
 121             {
 122                 struct rlimit r;
 123                 if (getrlimit(RLIMIT_NOFILE, &r) == 0)
 124                     max_fd = r.rlim_max;
 125             }
 126 #endif
 127
 128             for (i = 3; i < max_fd; i++)
 129                 pa_close(i);
 130
 131 #ifdef __linux__
 132         }
 133 #endif
 134
 135 #ifdef PR_SET_PDEATHSIG
 136         /* On Linux we can use PR_SET_PDEATHSIG to have the helper
 137         process killed when the daemon dies abnormally. On non-Linux
 138         machines the client will die as soon as it writes data to
 139         stdout again (SIGPIPE) */
 140
 141         prctl(PR_SET_PDEATHSIG, SIGTERM, 0, 0, 0);
 142 #endif
 143
 144 #ifdef SIGPIPE
 145         /* Make sure that SIGPIPE kills the child process */
 146         signal(SIGPIPE, SIG_DFL);
 147 #endif
 148
 149 #ifdef SIGTERM
 150         /* Make sure that SIGTERM kills the child process */
 151         signal(SIGTERM, SIG_DFL);
 152 #endif
 153
 154         execl(name, name, argv1, NULL);
 155         _exit(1);
 156     }
 157
 158 fail:
 159     pa_close_pipe(pipe_fds);
 160
 161     return -1;
 162 }