decoder_list: pass previous plugin pointer to lookup functions

Remove the static integer hack, that's not thread safe and sucks.

4 files changed, 40 insertions, 19 deletions

diff --git a/src/decoder_list.c b/src/decoder_list.c
index 837c5ca7b..53c882161 100644
--- a/src/decoder_list.c
+++ b/src/decoder_list.c
@@ -107,23 +107,38 @@ enum {
 /** which plugins have been initialized successfully? */
 static bool decoder_plugins_enabled[num_decoder_plugins];
 
-const struct decoder_plugin *
-decoder_plugin_from_suffix(const char *suffix, unsigned int next)
+static unsigned
+decoder_plugin_index(const struct decoder_plugin *plugin)
 {
-	static unsigned i = num_decoder_plugins;
+	unsigned i = 0;
+
+	while (decoder_plugins[i] != plugin)
+		++i;
+
+	return i;
+}
+
+static unsigned
+decoder_plugin_next_index(const struct decoder_plugin *plugin)
+{
+	return plugin == 0
+		? 0 /* start with first plugin */
+		: decoder_plugin_index(plugin) + 1;
+}
 
+const struct decoder_plugin *
+decoder_plugin_from_suffix(const char *suffix,
+			   const struct decoder_plugin *plugin)
+{
 	if (suffix == NULL)
 		return NULL;
 
-	if (!next)
-		i = 0;
-	for (; decoder_plugins[i] != NULL; ++i) {
-		const struct decoder_plugin *plugin = decoder_plugins[i];
+	for (unsigned i = decoder_plugin_next_index(plugin);
+	     decoder_plugins[i] != NULL; ++i) {
+		plugin = decoder_plugins[i];
 		if (decoder_plugins_enabled[i] &&
-		    decoder_plugin_supports_suffix(plugin, suffix)) {
-			++i;
+		    decoder_plugin_supports_suffix(plugin, suffix))
 			return plugin;
-		}
 	}
 
 	return NULL;
diff --git a/src/decoder_list.h b/src/decoder_list.h
index 23788189c..3b3cfd040 100644
--- a/src/decoder_list.h
+++ b/src/decoder_list.h
@@ -26,8 +26,16 @@ struct decoder_plugin;
 
 /* interface for using plugins */
 
+/**
+ * Find the next enabled decoder plugin which supports the specified suffix.
+ *
+ * @param suffix the file name suffix
+ * @param plugin the previous plugin, or NULL to find the first plugin
+ * @return a plugin, or NULL if none matches
+ */
 const struct decoder_plugin *
-decoder_plugin_from_suffix(const char *suffix, unsigned int next);
+decoder_plugin_from_suffix(const char *suffix,
+			   const struct decoder_plugin *plugin);
 
 const struct decoder_plugin *
 decoder_plugin_from_mime_type(const char *mimeType, unsigned int next);
diff --git a/src/decoder_thread.c b/src/decoder_thread.c
index e39c7f98e..1e850a037 100644
--- a/src/decoder_thread.c
+++ b/src/decoder_thread.c
@@ -118,13 +118,12 @@ decoder_run_stream_suffix(struct decoder *decoder, struct input_stream *is,
 			  const char *uri)
 {
 	const char *suffix = uri_get_suffix(uri);
-	const struct decoder_plugin *plugin;
-	unsigned int next = 0;
+	const struct decoder_plugin *plugin = NULL;
 
 	if (suffix == NULL)
 		return false;
 
-	while ((plugin = decoder_plugin_from_suffix(suffix, next++)))
+	while ((plugin = decoder_plugin_from_suffix(suffix, plugin)) != NULL)
 		if (plugin->stream_decode != NULL &&
 		    decoder_stream_decode(plugin, decoder, is))
 			return true;
@@ -212,15 +211,14 @@ static bool
 decoder_run_file(struct decoder *decoder, const char *path_fs)
 {
 	const char *suffix = uri_get_suffix(path_fs);
-	const struct decoder_plugin *plugin;
-	unsigned int next = 0;
+	const struct decoder_plugin *plugin = NULL;
 
 	if (suffix == NULL)
 		return false;
 
 	decoder_unlock(decoder->dc);
 
-	while ((plugin = decoder_plugin_from_suffix(suffix, next++))) {
+	while ((plugin = decoder_plugin_from_suffix(suffix, plugin)) != NULL) {
 		if (plugin->file_decode != NULL) {
 			decoder_lock(decoder->dc);
 
diff --git a/src/song_update.c b/src/song_update.c
index cfef5861f..2239f9aa6 100644
--- a/src/song_update.c
+++ b/src/song_update.c
@@ -107,7 +107,7 @@ song_file_update(struct song *song)
 	if (suffix == NULL)
 		return false;
 
-	plugin = decoder_plugin_from_suffix(suffix, false);
+	plugin = decoder_plugin_from_suffix(suffix, NULL);
 	if (plugin == NULL)
 		return false;
 
@@ -132,7 +132,7 @@ song_file_update(struct song *song)
 		if (song->tag != NULL)
 			break;
 
-		plugin = decoder_plugin_from_suffix(suffix, true);
+		plugin = decoder_plugin_from_suffix(suffix, plugin);
 	} while (plugin != NULL);
 
 	if (song->tag != NULL && tag_is_empty(song->tag))