2003-04-06 Havoc Pennington <hp@pobox.com>

	* dbus/dbus-sysdeps.c (_dbus_become_daemon): write the pidfile
	here in the parent process, so we can return an error if it
	fails. Also, move some of the code into the child so the parent
	is less hosed if we fail midway through.

	* bus/bus.c (bus_context_new): move pidfile detection further up
	in the function, before we start overwriting sockets and such.

	* bus/messagebus.in: adjust this a bit, not sure if it will work.

	* configure.in: add --with-system-pid-file and --with-system-socket

2003-04-06  Colin Walters  <walters@verbum.org>

	* configure.in (DBUS_SYSTEM_PID_FILE): New variable.

	* bus/system.conf.in: Declare a pidfile.

	* bus/bus.c (bus_context_new): Test for an existing pid file, and
	create one (if appropriate).

	* bus/config-parser.c (enum ElementType) [ELEMENT_PIDFILE]: New.
	(struct BusConfigParser) [pidfile]: New.
	(element_type_to_name, merge_included, start_busconfig_child)
	(bus_config_parser_end_element, bus_config_parser_content): Handle it.
	(bus_config_parser_unref): Free it.
	(bus_config_parser_get_pidfile): New function.

	* bus/config-parser.h (_dbus_write_pid_file): Prototype.

	* dbus/dbus-errors.h (DBUS_ERROR_PIDFILE_EXISTS): New error.

	* dbus/dbus-sysdeps.c (_dbus_write_pid_file): New function.

	* dbus/dbus-sysdeps.h: Prototype it.

3 files changed, 113 insertions, 34 deletions

diff --git a/dbus/Makefile.am b/dbus/Makefile.am
index 2065e75e..7d5ed501 100644
--- a/dbus/Makefile.am
+++ b/dbus/Makefile.am
@@ -1,6 +1,6 @@
 
 INCLUDES=-I$(top_srcdir) $(DBUS_CLIENT_CFLAGS) -DDBUS_COMPILATION		\
-	-DDBUS_SYSTEM_BUS_PATH=\""@EXPANDED_LOCALSTATEDIR@/@DBUS_SYSTEM_SOCKET@"\"
+	-DDBUS_SYSTEM_BUS_PATH=\""@DBUS_SYSTEM_SOCKET@"\"
 
 dbusincludedir=$(includedir)/dbus-1.0/dbus
 
diff --git a/dbus/dbus-sysdeps.c b/dbus/dbus-sysdeps.c
index 7a389956..df921b17 100644
--- a/dbus/dbus-sysdeps.c
+++ b/dbus/dbus-sysdeps.c
@@ -1700,6 +1700,15 @@ _dbus_string_append_our_uid (DBusString *str)
   return _dbus_string_append_int (str, getuid ());
 }
 
+/**
+ * Gets our process ID
+ * @returns process ID
+ */
+unsigned long
+_dbus_getpid (void)
+{
+  return getpid ();
+}
 
 _DBUS_DEFINE_GLOBAL_LOCK (atomic);
 
@@ -2930,17 +2939,17 @@ _dbus_print_backtrace (void)
 /**
  * Does the chdir, fork, setsid, etc. to become a daemon process.
  *
+ * @param pidfile #NULL, or pidfile to create
  * @param error return location for errors
  * @returns #FALSE on failure
  */
 dbus_bool_t
-_dbus_become_daemon (DBusError *error)
+_dbus_become_daemon (const DBusString *pidfile,
+                     DBusError        *error)
 {
   const char *s;
+  pid_t child_pid;
 
-  /* This is so we don't prevent unmounting of devices. We divert
-   * all messages to syslog
-   */
   if (chdir ("/") < 0)
     {
       dbus_set_error (error, DBUS_ERROR_FAILED,
@@ -2948,29 +2957,7 @@ _dbus_become_daemon (DBusError *error)
       return FALSE;
     }
 
-  s = _dbus_getenv ("DBUS_DEBUG_OUTPUT");
-  if (s == NULL || *s == '\0')
-    {
-      int dev_null_fd;
-
-      /* silently ignore failures here, if someone
-       * doesn't have /dev/null we may as well try
-       * to continue anyhow
-       */
-
-      dev_null_fd = open ("/dev/null", O_RDWR);
-      if (dev_null_fd >= 0)
-        {
-         dup2 (dev_null_fd, 0);
-         dup2 (dev_null_fd, 1);
-         dup2 (dev_null_fd, 2);
-       }
-    }
-
-  /* Get a predictable umask */
-  umask (022);
-
-  switch (fork ())
+  switch ((child_pid = fork ()))
     {
     case -1:
       dbus_set_error (error, _dbus_error_from_errno (errno),
@@ -2978,10 +2965,41 @@ _dbus_become_daemon (DBusError *error)
       return FALSE;
       break;
 
-    case 0:      
+    case 0:
+      s = _dbus_getenv ("DBUS_DEBUG_OUTPUT");
+      if (s == NULL || *s == '\0')
+        {
+          int dev_null_fd;
+
+          /* silently ignore failures here, if someone
+           * doesn't have /dev/null we may as well try
+           * to continue anyhow
+           */
+
+          dev_null_fd = open ("/dev/null", O_RDWR);
+          if (dev_null_fd >= 0)
+            {
+              dup2 (dev_null_fd, 0);
+              dup2 (dev_null_fd, 1);
+              dup2 (dev_null_fd, 2);
+            }
+        }
+
+      /* Get a predictable umask */
+      umask (022);
       break;
 
     default:
+      if (pidfile)
+        {
+          if (!_dbus_write_pid_file (pidfile,
+                                     child_pid,
+                                     error))
+            {
+              kill (child_pid, SIGTERM);
+              return FALSE;
+            }
+        }
       _exit (0);
       break;
     }
@@ -2993,6 +3011,62 @@ _dbus_become_daemon (DBusError *error)
 }
 
 /**
+ * Creates a file containing the process ID.
+ *
+ * @param filename the filename to write to
+ * @param pid our process ID
+ * @param error return location for errors
+ * @returns #FALSE on failure
+ */
+dbus_bool_t
+_dbus_write_pid_file (const DBusString *filename,
+                      unsigned long     pid,
+		      DBusError        *error)
+{
+  const char *cfilename;
+  int fd;
+  FILE *f;
+
+  cfilename = _dbus_string_get_const_data (filename);
+  
+  fd = open (cfilename, O_WRONLY|O_CREAT|O_EXCL|O_BINARY, 0644);
+  
+  if (fd < 0)
+    {
+      dbus_set_error (error, _dbus_error_from_errno (errno),
+                      "Failed to open \"%s\": %s", cfilename,
+                      _dbus_strerror (errno));
+      return FALSE;
+    }
+
+  if ((f = fdopen (fd, "w")) == NULL)
+    {
+      dbus_set_error (error, _dbus_error_from_errno (errno),
+                      "Failed to fdopen fd %d: %s", fd, _dbus_strerror (errno));
+      close (fd);
+      return FALSE;
+    }
+  
+  if (fprintf (f, "%lu\n", pid) < 0)
+    {
+      dbus_set_error (error, _dbus_error_from_errno (errno),
+                      "Failed to write to \"%s\": %s", cfilename,
+                      _dbus_strerror (errno));
+      return FALSE;
+    }
+
+  if (fclose (f) == EOF)
+    {
+      dbus_set_error (error, _dbus_error_from_errno (errno),
+                      "Failed to close \"%s\": %s", cfilename,
+                      _dbus_strerror (errno));
+      return FALSE;
+    }
+  
+  return TRUE;
+}
+
+/**
  * Changes the user and group the bus is running as.
  *
  * @param uid the new user ID
diff --git a/dbus/dbus-sysdeps.h b/dbus/dbus-sysdeps.h
index 933e2775..0a4a34dd 100644
--- a/dbus/dbus-sysdeps.h
+++ b/dbus/dbus-sysdeps.h
@@ -119,6 +119,8 @@ dbus_bool_t _dbus_get_groups   (unsigned long      uid,
                                 unsigned long    **group_ids,
                                 int               *n_group_ids);
 
+unsigned long _dbus_getpid (void);
+
 typedef int dbus_atomic_t;
 
 dbus_atomic_t _dbus_atomic_inc (dbus_atomic_t *atomic);
@@ -216,11 +218,14 @@ dbus_bool_t _dbus_close            (int               fd,
 
 void        _dbus_print_backtrace  (void);
 
-dbus_bool_t _dbus_become_daemon    (DBusError *error);
-
-dbus_bool_t _dbus_change_identity  (unsigned long  uid,
-                                    unsigned long  gid,
-                                    DBusError     *error);
+dbus_bool_t _dbus_become_daemon   (const DBusString *pidfile,
+                                   DBusError        *error);
+dbus_bool_t _dbus_write_pid_file  (const DBusString *filename,
+                                   unsigned long     pid,
+                                   DBusError        *error);
+dbus_bool_t _dbus_change_identity (unsigned long     uid,
+                                   unsigned long     gid,
+                                   DBusError        *error);
 
 typedef void (* DBusSignalHandler) (int sig);