Several bugfixes during exit found by valgrind

First, make sure we call finishPlaylist() before
closeMp3Directory() since the latter will free non-SONG_TYPE_URL
songs in playlist, which causes an invalid read when we try to
look for SONG_TYPE_URL songs to free in finishPlaylist.

Secondly, make sure our children have all exited before freeing
the playerData.  If we do not, slowly-delivered signals can
trigger a race condition in the signal handlers of the decode
and player processes which rely on getPlayerData.  To avoid
waitpid-ing too long (or at all), move the freePlayerData() call
farther down in main() (this won't affect anything else)
to give the OS a better chance to deliver signals and finish running
sig handlers for terminated children.

git-svn-id: https://svn.musicpd.org/mpd/trunk@4640 09075e82-0dd4-0310-85a5-a0d7c8717e4f

src/main.c

@@ -477,14 +477,13 @@ int main(int argc, char *argv[])
 	playerKill();
 	freeAllInterfaces();
 	closeAllListenSockets();
+	finishPlaylist();
 
 	start = clock();
 	closeMp3Directory();
 	DEBUG("closeMp3Directory took %f seconds\n", 
 	      ((float)(clock()-start))/CLOCKS_PER_SEC);
 
-	finishPlaylist();
-	freePlayerData();
 	finishNormalization();
 	finishAudioDriver();
 	finishAudioConfig();
@@ -495,6 +494,7 @@ int main(int argc, char *argv[])
 	finishInputPlugins();
 	cleanUpPidFile();
 	finishConf();
+	freePlayerData();
 
 	close_log_files();
 	return EXIT_SUCCESS;

src/player.c

@@ -124,8 +124,8 @@ int playerInit(void)
 
 		closeAllListenSockets();
 		freeAllInterfaces();
-		closeMp3Directory();
 		finishPlaylist();
+		closeMp3Directory();
 		finishPermissions();
 		finishCommands();
 		finishVolume();

src/playerData.c

@@ -21,6 +21,7 @@
 #include "log.h"
 
 #include <sys/types.h>
+#include <sys/wait.h>
 #include <sys/ipc.h>
 #include <sys/shm.h>
 #include <stdio.h>
@@ -164,5 +165,9 @@ PlayerData *getPlayerData(void)
 
 void freePlayerData(void)
 {
+	/* We don't want to release this memory until we know our player and
+	 * decoder have exited.  Otherwise, their signal handlers will want to
+	 * access playerData_pd and we need to keep it available for them */
+	waitpid(-1, NULL, 0);
 	shmdt(playerData_pd);
 }