tag_handler: handle arbitrary name/value pairs

The new method pair() receives an arbitrary name/value pair.  Support
for this is being added to a few decoder plugins.

src/decoder/ffmpeg_metadata.c

@@ -50,6 +50,21 @@ ffmpeg_copy_metadata(enum tag_type type,
 				       type, mt->value);
 }
 
+#if LIBAVUTIL_VERSION_INT >= AV_VERSION_INT(51,5,0)
+
+static void
+ffmpeg_scan_pairs(AVDictionary *dict,
+		  const struct tag_handler *handler, void *handler_ctx)
+{
+	AVDictionaryEntry *i = NULL;
+
+	while ((i = av_dict_get(dict, "", i, AV_DICT_IGNORE_SUFFIX)) != NULL)
+		tag_handler_invoke_pair(handler, handler_ctx,
+					i->key, i->value);
+}
+
+#endif
+
 void
 ffmpeg_scan_dictionary(AVDictionary *dict,
 		       const struct tag_handler *handler, void *handler_ctx)
@@ -62,4 +77,9 @@ ffmpeg_scan_dictionary(AVDictionary *dict,
 	     i->name != NULL; ++i)
 		ffmpeg_copy_metadata(i->type, dict, i->name,
 				     handler, handler_ctx);
+
+#if LIBAVUTIL_VERSION_INT >= AV_VERSION_INT(51,5,0)
+	if (handler->pair != NULL)
+		ffmpeg_scan_pairs(dict, handler, handler_ctx);
+#endif
 }

src/decoder/flac_metadata.c

@@ -196,6 +196,19 @@ flac_scan_comment(const char *char_tnum,
 		  const FLAC__StreamMetadata_VorbisComment_Entry *entry,
 		  const struct tag_handler *handler, void *handler_ctx)
 {
+	if (handler->pair != NULL) {
+		char *name = g_strdup((const char*)entry->entry);
+		char *value = strchr(name, '=');
+
+		if (value != NULL && value > name) {
+			*value++ = 0;
+			tag_handler_invoke_pair(handler, handler_ctx,
+						name, value);
+		}
+
+		g_free(name);
+	}
+
 	for (const struct tag_table *i = flac_tags; i->name != NULL; ++i)
 		if (flac_copy_comment(entry, i->name, i->type, char_tnum,
 				      handler, handler_ctx))

src/decoder/mp4ff_decoder_plugin.c

@@ -414,6 +414,8 @@ mp4ff_scan_stream(struct input_stream *is,
 
 		mp4ff_meta_get_by_index(mp4fh, i, &item, &value);
 
+		tag_handler_invoke_pair(handler, handler_ctx, item, value);
+
 		enum tag_type type = mp4ff_tag_name_parse(item);
 		if (type != TAG_NUM_OF_ITEM_TYPES)
 			tag_handler_invoke_tag(handler, handler_ctx,

src/decoder/vorbis_comments.c

@@ -106,6 +106,19 @@ static void
 vorbis_scan_comment(const char *comment,
 		    const struct tag_handler *handler, void *handler_ctx)
 {
+	if (handler->pair != NULL) {
+		char *name = g_strdup((const char*)comment);
+		char *value = strchr(name, '=');
+
+		if (value != NULL && value > name) {
+			*value++ = 0;
+			tag_handler_invoke_pair(handler, handler_ctx,
+						name, value);
+		}
+
+		g_free(name);
+	}
+
 	for (const struct tag_table *i = vorbis_tags; i->name != NULL; ++i)
 		if (vorbis_copy_comment(comment, i->name, i->type,
 					handler, handler_ctx))

src/decoder/wavpack_decoder_plugin.c

@@ -286,6 +286,19 @@ wavpack_scan_tag_item(WavpackContext *wpc, const char *name,
 
 }
 
+static void
+wavpack_scan_pair(WavpackContext *wpc, const char *name,
+		  const struct tag_handler *handler, void *handler_ctx)
+{
+	char buffer[1024];
+	int len = WavpackGetTagItem(wpc, name, buffer, sizeof(buffer));
+	if (len <= 0 || (unsigned)len >= sizeof(buffer))
+		return;
+
+	tag_handler_invoke_pair(handler, handler_ctx, name, buffer);
+
+}
+
 /*
  * Reads metainfo from the specified file.
  */
@@ -313,6 +326,20 @@ wavpack_scan_file(const char *fname,
 		wavpack_scan_tag_item(wpc, i->name, i->type,
 				      handler, handler_ctx);
 
+	if (handler->pair != NULL) {
+		char name[64];
+
+		for (int i = 0, n = WavpackGetNumTagItems(wpc);
+		     i < n; ++i) {
+			int len = WavpackGetTagItemIndexed(wpc, i, name,
+							   sizeof(name));
+			if (len <= 0 || (unsigned)len >= sizeof(name))
+				continue;
+
+			wavpack_scan_pair(wpc, name, handler, handler_ctx);
+		}
+	}
+
 	WavpackCloseFile(wpc);
 
 	return true;

src/tag_ape.c

@@ -49,6 +49,8 @@ tag_ape_import_item(unsigned long flags,
 	if ((flags & (0x3 << 1)) != 0)
 		return;
 
+	tag_handler_invoke_pair(handler, handler_ctx, key, value);
+
 	enum tag_type type = tag_ape_name_parse(key);
 	if (type == TAG_NUM_OF_ITEM_TYPES)
 		return;

src/tag_handler.h

@@ -43,6 +43,12 @@ struct tag_handler {
 	 * invalid after returning
 	 */
 	void (*tag)(enum tag_type type, const char *value, void *ctx);
+
+	/**
+	 * A name-value pair has been read.  It is the codec specific
+	 * representation of tags.
+	 */
+	void (*pair)(const char *key, const char *value, void *ctx);
 };
 
 static inline void
@@ -67,6 +73,18 @@ tag_handler_invoke_tag(const struct tag_handler *handler, void *ctx,
 		handler->tag(type, value, ctx);
 }
 
+static inline void
+tag_handler_invoke_pair(const struct tag_handler *handler, void *ctx,
+			const char *name, const char *value)
+{
+	assert(handler != NULL);
+	assert(name != NULL);
+	assert(value != NULL);
+
+	if (handler->pair != NULL)
+		handler->pair(name, value, ctx);
+}
+
 /**
  * This #tag_handler implementation adds tag values to a #tag object
  * (casted from the context pointer).

src/tag_id3.c

@@ -282,18 +282,21 @@ tag_id3_import_musicbrainz(struct id3_tag *id3_tag,
 		if (name == NULL)
 			continue;
 
-		type = tag_id3_parse_txxx_name((const char*)name);
-		free(name);
-
-		if (type == TAG_NUM_OF_ITEM_TYPES)
-			continue;
-
 		value = tag_id3_getstring(frame, 2);
 		if (value == NULL)
 			continue;
 
-		tag_handler_invoke_tag(handler, handler_ctx,
+		tag_handler_invoke_pair(handler, handler_ctx,
-				       type, (const char*)value);
+					(const char *)name,
+					(const char *)value);
+
+		type = tag_id3_parse_txxx_name((const char*)name);
+		free(name);
+
+		if (type != TAG_NUM_OF_ITEM_TYPES)
+			tag_handler_invoke_tag(handler, handler_ctx,
+					       type, (const char*)value);
+
 		free(value);
 	}
 }

test/read_tags.c

@@ -145,13 +145,20 @@ print_duration(unsigned seconds, G_GNUC_UNUSED void *ctx)
 static void
 print_tag(enum tag_type type, const char *value, G_GNUC_UNUSED void *ctx)
 {
-	g_print("%s=%s\n", tag_item_names[type], value);
+	g_print("[%s]=%s\n", tag_item_names[type], value);
 	empty = false;
 }
 
+static void
+print_pair(const char *name, const char *value, G_GNUC_UNUSED void *ctx)
+{
+	g_print("\"%s\"=%s\n", name, value);
+}
+
 static const struct tag_handler print_handler = {
 	.duration = print_duration,
 	.tag = print_tag,
+	.pair = print_pair,
 };
 
 int main(int argc, char **argv)