update: check return values

Nearly all mapper functions can fail and will then return NULL.  Add
checks to all callers.

src/decoder_thread.c

@@ -31,20 +31,25 @@
 static void decodeStart(void)
 {
 	struct song *song = dc.next_song;
+	char buffer[MPD_PATH_MAX];
+	const char *uri;
 	struct decoder decoder;
 	int ret;
 	bool close_instream = true;
 	struct input_stream inStream;
 	struct decoder_plugin *plugin = NULL;
-	char path_max_fs[MPD_PATH_MAX];
 
 	if (song_is_file(song))
-		map_song_fs(song, path_max_fs);
+		uri = map_song_fs(song, buffer);
 	else
-		song_get_url(song, path_max_fs);
+		uri = song_get_url(song, buffer);
+	if (uri == NULL) {
+		dc.error = DECODE_ERROR_FILE;
+		return;
+	}
 
 	dc.current_song = dc.next_song; /* NEED LOCK */
-	if (!input_stream_open(&inStream, path_max_fs)) {
+	if (!input_stream_open(&inStream, uri)) {
 		dc.error = DECODE_ERROR_FILE;
 		return;
 	}
@@ -98,7 +103,7 @@ static void decodeStart(void)
 
 		/* if that fails, try suffix matching the URL: */
 		if (plugin == NULL) {
-			const char *s = getSuffix(path_max_fs);
+			const char *s = getSuffix(uri);
 			next = 0;
 			while ((plugin = decoder_plugin_from_suffix(s, next++))) {
 				if (plugin->stream_decode == NULL)
@@ -129,7 +134,7 @@ static void decodeStart(void)
 		}
 	} else {
 		unsigned int next = 0;
-		const char *s = getSuffix(path_max_fs);
+		const char *s = getSuffix(uri);
 		while ((plugin = decoder_plugin_from_suffix(s, next++))) {
 			if (!plugin->stream_types & INPUT_PLUGIN_STREAM_FILE)
 				continue;
@@ -142,8 +147,7 @@ static void decodeStart(void)
 				input_stream_close(&inStream);
 				close_instream = false;
 				decoder.plugin = plugin;
-				ret = plugin->file_decode(&decoder,
-							  path_max_fs);
+				ret = plugin->file_decode(&decoder, uri);
 				break;
 			} else if (plugin->stream_decode != NULL) {
 				decoder.plugin = plugin;

src/playlist_save.c

@@ -52,5 +52,6 @@ playlist_print_uri(FILE *file, const char *uri)
 	else
 		s = utf8_to_fs_charset(tmp, uri);
 
-	fprintf(file, "%s\n", s);
+	if (s != NULL)
+		fprintf(file, "%s\n", s);
 }

src/song.c

@@ -94,28 +94,31 @@ song_free(struct song *song)
 bool
 song_file_update(struct song *song)
 {
+	char buffer[MPD_PATH_MAX];
+	const char *path_fs;
 	struct decoder_plugin *plugin;
 	unsigned int next = 0;
-	char abs_path[MPD_PATH_MAX];
 	struct stat st;
 
 	assert(song_is_file(song));
 
-	map_song_fs(song, abs_path);
+	path_fs = map_song_fs(song, buffer);
+	if (path_fs == NULL)
+		return false;
 
 	if (song->tag != NULL) {
 		tag_free(song->tag);
 		song->tag = NULL;
 	}
 
-	if (stat(abs_path, &st) < 0 || !S_ISREG(st.st_mode))
+	if (stat(path_fs, &st) < 0 || !S_ISREG(st.st_mode))
 		return false;
 
 	song->mtime = st.st_mtime;
 
 	while (song->tag == NULL &&
-	       (plugin = hasMusicSuffix(abs_path, next++)))
-		song->tag = plugin->tag_dup(abs_path);
+	       (plugin = hasMusicSuffix(path_fs, next++)))
+		song->tag = plugin->tag_dup(path_fs);
 
 	return song->tag != NULL;
 }

src/update.c

@@ -206,9 +206,13 @@ static int
 stat_directory_child(const struct directory *parent, const char *name,
 		     struct stat *st)
 {
-	char path_fs[MPD_PATH_MAX];
+	char buffer[MPD_PATH_MAX];
+	const char *path_fs;
+
+	path_fs = map_directory_child_fs(parent, name, buffer);
+	if (path_fs == NULL)
+		return -1;
 
-	map_directory_child_fs(parent, name, path_fs);
 	return stat(path_fs, st);
 }