pull code for starting helper processes out of module-gconf, clean it up, and stick into a new API pa_start_child_for_read()

git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@2046 fefdeb5f-60dc-0310-8127-8f9354f1896f

src/pulsecore/start-child.c

@@ -0,0 +1,162 @@
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2007 Lennart Poettering
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <errno.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h>
+#endif
+#ifdef HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
+
+#include <pulsecore/core-util.h>
+#include <pulsecore/core-error.h>
+
+#include "start-child.h"
+
+int pa_start_child_for_read(const char *name, const char *argv1, pid_t *pid) {
+    pid_t child;
+    int pipe_fds[2] = { -1, -1 };
+
+    if (pipe(pipe_fds) < 0) {
+        pa_log("pipe() failed: %s", pa_cstrerror(errno));
+        goto fail;
+    }
+
+    if ((child = fork()) == (pid_t) -1) {
+        pa_log("fork() failed: %s", pa_cstrerror(errno));
+        goto fail;
+
+    } else if (child != 0) {
+
+        /* Parent */
+        pa_assert_se(pa_close(pipe_fds[1]) == 0);
+
+        if (pid)
+            *pid = child;
+
+        return pipe_fds[0];
+    } else {
+#ifdef __linux__
+        DIR* d;
+#endif
+        int max_fd, i;
+
+        /* child */
+
+        pa_reset_priority();
+
+        pa_assert_se(pa_close(pipe_fds[0]) == 0);
+        pa_assert_se(dup2(pipe_fds[1], 1) == 1);
+
+        if (pipe_fds[1] != 1)
+            pa_assert_se(pa_close(pipe_fds[1]) == 0);
+
+        pa_close(0);
+        pa_assert_se(open("/dev/null", O_RDONLY) == 0);
+
+        pa_close(2);
+        pa_assert_se(open("/dev/null", O_WRONLY) == 2);
+
+#ifdef __linux__
+
+        if ((d = opendir("/proc/self/fd/"))) {
+
+            struct dirent *de;
+
+            while ((de = readdir(d))) {
+                char *e = NULL;
+                int fd;
+
+                if (de->d_name[0] == '.')
+                    continue;
+
+                errno = 0;
+                fd = strtol(de->d_name, &e, 10);
+                pa_assert(errno == 0 && e && *e == 0);
+
+                if (fd >= 3 && dirfd(d) != fd)
+                    pa_close(fd);
+            }
+
+            closedir(d);
+        } else {
+
+#endif
+
+            max_fd = 1024;
+
+#ifdef HAVE_SYS_RESOURCE_H
+            {
+                struct rlimit r;
+                if (getrlimit(RLIMIT_NOFILE, &r) == 0)
+                    max_fd = r.rlim_max;
+            }
+#endif
+
+            for (i = 3; i < max_fd; i++)
+                pa_close(i);
+
+#ifdef __linux__
+        }
+#endif
+
+#ifdef PR_SET_PDEATHSIG
+        /* On Linux we can use PR_SET_PDEATHSIG to have the helper
+        process killed when the daemon dies abnormally. On non-Linux
+        machines the client will die as soon as it writes data to
+        stdout again (SIGPIPE) */
+
+        prctl(PR_SET_PDEATHSIG, SIGTERM, 0, 0, 0);
+#endif
+
+#ifdef SIGPIPE
+        /* Make sure that SIGPIPE kills the child process */
+        signal(SIGPIPE, SIG_DFL);
+#endif
+
+#ifdef SIGTERM
+        /* Make sure that SIGTERM kills the child process */
+        signal(SIGTERM, SIG_DFL);
+#endif
+
+        execl(name, name, argv1, NULL);
+        _exit(1);
+    }
+
+fail:
+    pa_close_pipe(pipe_fds);
+
+    return -1;
+}