[PATCH] [main] Write the pid of plymouthd to a file

[Scott James Remnant]

Add a --pid-file option to plymouthd that will cause the daemon's
pid to be written to the named file.  Useful to avoid grovelling
through ps output to find it again.

Author: Alberto Milone <alberto.milone at canonical.com>
Signed-off-by: Scott James Remnant <scott at ubuntu.com>
---
 src/libply/ply-utils.c |   25 ++++++++++++++++++++++++-
 src/libply/ply-utils.h |    4 +++-
 src/main.c             |   19 ++++++++++++++++++-
 3 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/src/libply/ply-utils.c b/src/libply/ply-utils.c
index b26773c..4b40e67 100644
--- a/src/libply/ply-utils.c
+++ b/src/libply/ply-utils.c
@@ -794,7 +794,7 @@ ply_show_new_kernel_messages (bool should_show)
 }
 
 ply_daemon_handle_t *
-ply_create_daemon (void)
+ply_create_daemon (const char *pid_file)
 {
   pid_t pid;
   int sender_fd, receiver_fd;
@@ -820,6 +820,22 @@ ply_create_daemon (void)
           _exit (1);
         }
 
+      if ((byte == 0) && (pid_file != NULL))
+        {
+	  FILE *pidf;
+
+	  pidf = fopen (pid_file, "w");
+	  if (!pidf)
+	    {
+	      ply_error ("could not write pid file %s: %m", pid_file);
+	    }
+	  else
+	    {
+	      fprintf (pidf, "%d\n", pid);
+	      fclose (pidf);
+	    }
+	}
+
       _exit ((int) byte);
     }
   close (receiver_fd);
@@ -853,6 +869,13 @@ ply_detach_daemon (ply_daemon_handle_t *handle,
   return true;
 }
 
+void
+ply_remove_pid_file (const char *pid_file)
+{
+  if (ply_file_exists (pid_file))
+    unlink (pid_file);
+}
+
 
 /*                    UTF-8 encoding
 00000000-01111111 	00-7F 	US-ASCII (single byte)
diff --git a/src/libply/ply-utils.h b/src/libply/ply-utils.h
index 5e41f84..16f37ad 100644
--- a/src/libply/ply-utils.h
+++ b/src/libply/ply-utils.h
@@ -98,10 +98,12 @@ bool ply_create_file_link (const char *source,
                            const char *destination);
 void ply_show_new_kernel_messages (bool should_show);
 
-ply_daemon_handle_t *ply_create_daemon (void);
+ply_daemon_handle_t *ply_create_daemon (const char *pid_file);
 bool ply_detach_daemon (ply_daemon_handle_t *handle,
                         int                  exit_code);
 
+void ply_remove_pid_file (const char *pid_file);
+
 int ply_utf8_character_get_size (const char   *string,
                                  size_t        n);
 int ply_utf8_string_get_length (const char   *string,
diff --git a/src/main.c b/src/main.c
index af956ee..9dbd293 100644
--- a/src/main.c
+++ b/src/main.c
@@ -134,6 +134,7 @@ static void on_error_message (ply_buffer_t *debug_buffer,
                               size_t        number_of_bytes);
 static ply_buffer_t *debug_buffer;
 static char *debug_buffer_path = NULL;
+static char *pid_file = NULL;
 static void check_for_consoles (state_t    *state,
                                 const char *default_tty,
                                 bool        should_add_displays);
@@ -688,6 +689,13 @@ quit_program (state_t *state)
   ply_trace ("exiting event loop");
   ply_event_loop_exit (state->loop, 0);
 
+  if (pid_file != NULL)
+    {
+      ply_remove_pid_file (pid_file);
+      free (pid_file);
+      pid_file = NULL;
+    }
+
 #ifdef PLY_ENABLE_GDM_TRANSITION
   if (state->should_retain_splash)
     {
@@ -1515,6 +1523,13 @@ on_crash (int signum)
         pause ();
       }
 
+    if (pid_file != NULL)
+      {
+	ply_remove_pid_file (pid_file);
+	free (pid_file);
+	pid_file = NULL;
+      }
+
     signal (signum, SIG_DFL);
     raise(signum);
 }
@@ -1543,6 +1558,7 @@ main (int    argc,
                                   "debug", "Output debugging information", PLY_COMMAND_OPTION_TYPE_FLAG,
                                   "debug-file", "File to output debugging information to", PLY_COMMAND_OPTION_TYPE_STRING,
                                   "mode", "Mode is one of: boot, shutdown", PLY_COMMAND_OPTION_TYPE_STRING,
+				  "pid-file", "Write the pid of the daemon to a file", PLY_COMMAND_OPTION_TYPE_STRING,
                                   NULL);
 
   if (!ply_command_parser_parse_arguments (state.command_parser, state.loop, argv, argc))
@@ -1564,6 +1580,7 @@ main (int    argc,
                                   "no-daemon", &no_daemon,
                                   "debug", &debug,
                                   "debug-file", &debug_buffer_path,
+				  "pid-file", &pid_file,
                                   NULL);
 
   if (should_help)
@@ -1605,7 +1622,7 @@ main (int    argc,
 
   if (! no_daemon)
     {
-      daemon_handle = ply_create_daemon ();
+      daemon_handle = ply_create_daemon (pid_file);
 
       if (daemon_handle == NULL)
         {
-- 
1.6.3.3