flac: always allocate tag object

Free the tag object when it turns out to be empty.  This simplifies
several functions and APIs.

src/decoder/_flac_common.c

@@ -99,10 +99,9 @@ static const char *VORBIS_COMMENT_TRACK_KEY = "tracknumber";
 static const char *VORBIS_COMMENT_DISC_KEY = "discnumber";
 
 static bool
-flac_copy_vorbis_comment(const
-			 FLAC__StreamMetadata_VorbisComment_Entry * entry,
-			 enum tag_type type,
-			 struct tag ** tag)
+flac_copy_vorbis_comment(struct tag *tag,
+			 const FLAC__StreamMetadata_VorbisComment_Entry *entry,
+			 enum tag_type type)
 {
 	const char *str;
 	size_t slen;
@@ -123,10 +122,7 @@ flac_copy_vorbis_comment(const
 
 	if ((vlen > 0) && (0 == strncasecmp(str, (char *)entry->entry, slen))
 	    && (*(entry->entry + slen) == '=')) {
-		if (!*tag)
-			*tag = tag_new();
-
-		tag_add_item_n(*tag, type,
+		tag_add_item_n(tag, type,
 			       (char *)(entry->entry + slen + 1), vlen);
 
 		return true;
@@ -135,9 +131,9 @@ flac_copy_vorbis_comment(const
 	return false;
 }
 
-struct tag *
-flac_vorbis_comments_to_tag(const FLAC__StreamMetadata * block,
-			    struct tag * tag)
+void
+flac_vorbis_comments_to_tag(struct tag *tag,
+			    const FLAC__StreamMetadata *block)
 {
 	unsigned int i, j;
 	FLAC__StreamMetadata_VorbisComment_Entry *comments;
@@ -146,13 +142,11 @@ flac_vorbis_comments_to_tag(const FLAC__StreamMetadata * block,
 
 	for (i = block->data.vorbis_comment.num_comments; i != 0; --i) {
 		for (j = TAG_NUM_OF_ITEM_TYPES; j--;) {
-			if (flac_copy_vorbis_comment(comments, j, &tag))
+			if (flac_copy_vorbis_comment(tag, comments, j))
 				break;
 		}
 		comments++;
 	}
-
-	return tag;
 }
 
 void flac_metadata_common_cb(const FLAC__StreamMetadata * block,

src/decoder/_flac_common.h

@@ -166,9 +166,9 @@ void flac_error_common_cb(const char *plugin,
 			  FLAC__StreamDecoderErrorStatus status,
 			  struct flac_data *data);
 
-struct tag *
-flac_vorbis_comments_to_tag(const FLAC__StreamMetadata * block,
-			    struct tag *tag);
+void
+flac_vorbis_comments_to_tag(struct tag *tag,
+			    const FLAC__StreamMetadata *block);
 
 FLAC__StreamDecoderWriteStatus
 flac_common_write(struct flac_data *data, const FLAC__Frame * frame,

src/decoder/flac_plugin.c

@@ -225,7 +225,7 @@ flac_write_cb(const flac_decoder *dec, const FLAC__Frame *frame,
 static struct tag *
 flac_tag_load(const char *file)
 {
-	struct tag *ret = NULL;
+	struct tag *tag;
 	FLAC__Metadata_SimpleIterator *it;
 	FLAC__StreamMetadata *block = NULL;
 
@@ -252,27 +252,31 @@ flac_tag_load(const char *file)
 		g_debug("Reading '%s' metadata gave the following error: %s\n",
 			file, err);
 		FLAC__metadata_simple_iterator_delete(it);
-		return ret;
+		return NULL;
 	}
 
+	tag = tag_new();
 	do {
 		block = FLAC__metadata_simple_iterator_get_block(it);
 		if (!block)
 			break;
 		if (block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT) {
-			flac_vorbis_comments_to_tag(block, ret);
+			flac_vorbis_comments_to_tag(tag, block);
 		} else if (block->type == FLAC__METADATA_TYPE_STREAMINFO) {
-			if (!ret)
-				ret = tag_new();
-			ret->time = ((float)block->data.stream_info.
-				     total_samples) /
+			tag->time = ((float)block->data.stream_info.total_samples) /
 			    block->data.stream_info.sample_rate + 0.5;
 		}
 		FLAC__metadata_object_delete(block);
 	} while (FLAC__metadata_simple_iterator_next(it));
 
 	FLAC__metadata_simple_iterator_delete(it);
-	return ret;
+
+	if (!tag_is_defined(tag)) {
+		tag_free(tag);
+		tag = NULL;
+	}
+
+	return tag;
 }
 
 static struct tag *
@@ -419,20 +423,26 @@ oggflac_tag_dup(const char *file)
 		goto out;
 	it = FLAC__metadata_iterator_new();
 	FLAC__metadata_iterator_init(it, chain);
+
+	ret = tag_new();
 	do {
 		if (!(block = FLAC__metadata_iterator_get_block(it)))
 			break;
 		if (block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT) {
-			ret = flac_vorbis_comments_to_tag(block, ret);
+			flac_vorbis_comments_to_tag(ret, block);
 		} else if (block->type == FLAC__METADATA_TYPE_STREAMINFO) {
-			if (!ret)
-				ret = tag_new();
 			ret->time = ((float)block->data.stream_info.
 				     total_samples) /
 			    block->data.stream_info.sample_rate + 0.5;
 		}
 	} while (FLAC__metadata_iterator_next(it));
 	FLAC__metadata_iterator_delete(it);
+
+	if (!tag_is_defined(ret)) {
+		tag_free(ret);
+		ret = NULL;
+	}
+
 out:
 	FLAC__metadata_chain_delete(chain);
 	return ret;

src/decoder/oggflac_plugin.c

@@ -24,6 +24,7 @@
 
 #include <glib.h>
 #include <OggFLAC/seekable_stream_decoder.h>
+#include <assert.h>
 #include <unistd.h>
 
 static void oggflac_cleanup(struct flac_data *data,
@@ -168,16 +169,16 @@ static void of_metadata_dup_cb(G_GNUC_UNUSED const OggFLAC__SeekableStreamDecode
 {
 	struct flac_data *data = (struct flac_data *) vdata;
 
+	assert(data->tag != NULL);
+
 	switch (block->type) {
 	case FLAC__METADATA_TYPE_STREAMINFO:
-		if (!data->tag)
-			data->tag = tag_new();
 		data->tag->time = ((float)block->data.stream_info.
 				   total_samples) /
 		    block->data.stream_info.sample_rate + 0.5;
 		return;
 	case FLAC__METADATA_TYPE_VORBIS_COMMENT:
-		flac_vorbis_comments_to_tag(block, data->tag);
+		flac_vorbis_comments_to_tag(data->tag, block);
 	default:
 		break;
 	}
@@ -271,6 +272,8 @@ oggflac_tag_dup(const char *file)
 
 	flac_data_init(&data, NULL, &input_stream);
 
+	data.tag = tag_new();
+
 	/* errors here won't matter,
 	 * data.tag will be set or unset, that's all we care about */
 	decoder = full_decoder_init_and_read_metadata(&data, 1);
@@ -278,6 +281,11 @@ oggflac_tag_dup(const char *file)
 	oggflac_cleanup(&data, decoder);
 	input_stream_close(&input_stream);
 
+	if (!tag_is_defined(data.tag)) {
+		tag_free(data.tag);
+		data.tag = NULL;
+	}
+
 	return data.tag;
 }