Add FLAC__stream_decoder_get_link_lengths (#793)

Author: ktmf01

include/FLAC/stream_decoder.h

@@ -1112,6 +1112,43 @@ FLAC_API FLAC__bool FLAC__stream_decoder_get_decode_position(const FLAC__StreamD
  */
 FLAC_API const void *FLAC__stream_decoder_get_client_data(FLAC__StreamDecoder *decoder);
 
+#define FLAC__STREAM_DECODER_GET_LINK_LENGTHS_INVALID -1
+#define FLAC__STREAM_DECODER_GET_LINK_LENGTHS_NOT_INDEXED -2
+#define FLAC__STREAM_DECODER_GET_LINK_LENGTHS_MEMORY_ALLOCATION_ERROR -3
+
+/** Get the link lengths in samples in a chained stream
+ *
+ *  After either processing the whole file or using
+ *  FLAC__stream_decoder_find_total_samples, this function
+ *  returns an array with link lengths in samples. If it fails,
+ *  it returns a negative number as error code, currently either
+ *  FLAC__STREAM_DECODER_GET_LINK_LENGTHS_INVALID if the current
+ *  decoder is not in a valid state or not processing a chained
+ *  stream, FLAC__STREAM_DECODER_GET_LINK_LENGTHS_NOT_INDEXED if
+ *  the stream hasn't been indexed yet, and
+ *  FLAC__STREAM_DECODER_GET_LINK_LENGTHS_MEMORY_ALLOCATION_ERROR
+ *  if allocating memory failed.
+ *
+ *  If the function succeeds, the return value is the number of
+ *  links. The link_lengths parameter is a FLAC__uint64 pointer
+ *  which is allocated by the call, and must be freed by the user.
+ *  If a null pointer is passed, the function only returns the
+ *  number of links, not their lengths. The length of the returned
+ *  array is equal to the number of links and thus to the return
+ *  value of the function.
+ *
+ * \param  decoder   A decoder instance to query.
+ * \param  link_lengths  Address at which to return the link lengths
+ *                       array.
+ * \assert
+ *    \code decoder != NULL \endcode
+ * \retval int32_t
+ *    \c the number of links if successful, zero or a negative
+ *    number if unsuccessful
+ */
+
+FLAC_API int32_t FLAC__stream_decoder_get_link_lengths(FLAC__StreamDecoder *decoder, FLAC__uint64 **link_lengths);
+
 /** Initialize the decoder instance to decode native FLAC streams.
  *
  *  This flavor of initialization sets up the decoder to decode from a

oss-fuzz/seek.cc

@@ -34,6 +34,10 @@
 #include "FLAC/stream_decoder.h"
 #include "common.h"
 
+#if MSAN == 1
+extern "C" void __msan_check_mem_is_initialized(const volatile void *x, size_t size);
+#endif
+
 int write_abort_check_counter = -1;
 int written_uncompressed_bytes = 0;
 int errors_received_counter = 0;
@@ -226,6 +230,26 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 						decoder_valid = false;
 				}
 				break;
+			case 13:
+				int32_t retval;
+				FLAC__uint64 *link_lengths;
+				FPRINTF_DEBUG_ONLY(stderr,"get_link_lengths\n");
+				retval = FLAC__stream_decoder_get_link_lengths(decoder, &link_lengths);
+				if(retval == FLAC__STREAM_DECODER_GET_LINK_LENGTHS_MEMORY_ALLOCATION_ERROR) {
+					decoder_valid = false;
+				}
+				if(retval > 0) {
+					for(int32_t j = 0; j < retval; j++) {
+#if MSAN == 1
+						 __msan_check_mem_is_initialized(&link_lengths[j],sizeof(link_lengths[j]));
+#else
+						;
+#endif
+					}
+					free(link_lengths);
+				}
+				break;
+			/* case 14 is already used above */
 		}
 		if(!decoder_valid) {
 			/* Try again if possible */

src/libFLAC/ogg_decoder_aspect.c

@@ -696,6 +696,10 @@ FLAC__OggDecoderAspectReadStatus FLAC__ogg_decoder_aspect_skip_link(FLAC__OggDec
 			else if(aspect->end_of_stream) {
 				if(aspect->beginning_of_link && !aspect->bos_flag_seen) {
 					/* We were looking for the next link, but found end of stream instead */
+					if(aspect->current_linknumber == 0)
+						return FLAC__OGG_DECODER_ASPECT_READ_STATUS_LOST_SYNC;
+					aspect->current_linknumber--;
+					aspect->linkdetails[aspect->current_linknumber].is_last = true;
 					return FLAC__OGG_DECODER_ASPECT_READ_STATUS_END_OF_STREAM;
 				}
 				else if(did_a_seek) {

src/libFLAC/stream_decoder.c

@@ -1471,6 +1471,43 @@ FLAC_API FLAC__uint64 FLAC__stream_decoder_find_total_samples(FLAC__StreamDecode
 	return 0;
 }
 
+FLAC_API int32_t FLAC__stream_decoder_get_link_lengths(FLAC__StreamDecoder *decoder, FLAC__uint64 **link_lengths)
+{
+	/* If we don't have Ogg, this is (for now) useless, fail */
+#if FLAC__HAS_OGG
+	uint32_t i;
+
+	/* Check whether we're decoding chaines ogg, and decoder is somewhat valid */
+	if(!decoder->private_->is_ogg ||
+	   !FLAC__stream_decoder_get_decode_chained_stream(decoder) ||
+	   decoder->protected_->state == FLAC__STREAM_DECODER_ABORTED ||
+	   decoder->protected_->state == FLAC__STREAM_DECODER_MEMORY_ALLOCATION_ERROR ||
+	   decoder->protected_->state == FLAC__STREAM_DECODER_UNINITIALIZED)
+		return FLAC__STREAM_DECODER_GET_LINK_LENGTHS_INVALID;
+
+	/* Check whether link details are known. If not, fail */
+	if(decoder->protected_->ogg_decoder_aspect.number_of_links_indexed == 0 ||
+	   !decoder->protected_->ogg_decoder_aspect.linkdetails[decoder->protected_->ogg_decoder_aspect.number_of_links_indexed - 1].is_last)
+		return FLAC__STREAM_DECODER_GET_LINK_LENGTHS_NOT_INDEXED;
+
+	if(link_lengths != NULL) {
+		*link_lengths = safe_malloc_mul_2op_p(sizeof(FLAC__uint64), decoder->protected_->ogg_decoder_aspect.number_of_links_indexed);
+		if(*link_lengths == NULL)
+			return FLAC__STREAM_DECODER_GET_LINK_LENGTHS_MEMORY_ALLOCATION_ERROR;
+
+		for(i = 0; i < decoder->protected_->ogg_decoder_aspect.number_of_links_indexed; i++)
+			(*link_lengths)[i] = decoder->protected_->ogg_decoder_aspect.linkdetails[i].samples;
+	}
+
+	return decoder->protected_->ogg_decoder_aspect.number_of_links_indexed;
+#else
+	(void)decoder;
+	(void)link_lengths;
+	return FLAC__STREAM_DECODER_GET_LINK_LENGTHS_INVALID;
+#endif
+}
+
+
 /***********************************************************************
  *
  * Protected class methods

src/test_libFLAC/decoders.c

@@ -560,6 +560,17 @@ static FLAC__bool test_stream_decoder(Layer layer, FLAC__bool is_ogg, FLAC__bool
 		return die_s_(0, decoder);
 	printf("OK\n");
 
+	printf("testing FLAC__stream_decoder_get_link_lengths()... ");
+	if(is_chained_ogg) {
+		if(FLAC__stream_decoder_get_link_lengths(decoder, NULL) != FLAC__STREAM_DECODER_GET_LINK_LENGTHS_NOT_INDEXED)
+			return die_s_("returned incorrectly", decoder);
+	}
+	else{ /* not chained ogg */
+		if(FLAC__stream_decoder_get_link_lengths(decoder, NULL) != FLAC__STREAM_DECODER_GET_LINK_LENGTHS_INVALID)
+			return die_s_("returned incorrectly", decoder);
+	}
+	printf("OK\n");
+
 	printf("testing FLAC__stream_decoder_find_total_samples... ");
 	total_samples = FLAC__stream_decoder_find_total_samples(decoder);
 	printf("Number of samples returned is %" PRIu64 "... ",total_samples);
@@ -569,6 +580,22 @@ static FLAC__bool test_stream_decoder(Layer layer, FLAC__bool is_ogg, FLAC__bool
 		return die_s_("returned wrong number of samples", decoder);
 	printf("OK\n");
 
+	if(is_chained_ogg) {
+		printf("testing FLAC__stream_decoder_get_link_lengths()... ");
+		if(layer == LAYER_STREAM) {
+			if(FLAC__stream_decoder_get_link_lengths(decoder, NULL) != FLAC__STREAM_DECODER_GET_LINK_LENGTHS_NOT_INDEXED)
+				return die_s_("returned incorrectly", decoder);
+		}
+		else {
+			int32_t retval = FLAC__stream_decoder_get_link_lengths(decoder, NULL);
+			printf("Number of links returned is %d\n",retval);
+			if(retval != 2)
+				return die_s_("returned incorrectly", decoder);
+
+		}
+		printf("OK\n");
+	}
+
 	if(layer < LAYER_FILE) /* for LAYER_FILE, FLAC__stream_decoder_finish() closes the file */
 		fclose(decoder_client_data.file);
 
@@ -722,6 +749,20 @@ static FLAC__bool test_stream_decoder(Layer layer, FLAC__bool is_ogg, FLAC__bool
 		}
 		printf("returned state = %u (%s)... OK\n", state, FLAC__StreamDecoderStateString[state]);
 
+		printf("testing FLAC__stream_decoder_get_link_lengths()... ");
+		{
+			FLAC__uint64 *link_lengths;
+			int32_t retval = FLAC__stream_decoder_get_link_lengths(decoder, &link_lengths);
+			printf("Number of links returned is %d\n",retval);
+			printf("Number of samples is %" PRIu64 " and %" PRIu64 "\n",link_lengths[0],link_lengths[1]);
+			if(retval != 2)
+				return die_s_("returned incorrectly", decoder);
+			free(link_lengths);
+
+		}
+		printf("OK\n");
+
+
 		printf("testing FLAC__stream_decoder_reset()... ");
 		if(!FLAC__stream_decoder_reset(decoder)) {
 			state = FLAC__stream_decoder_get_state(decoder);