From 224177c389556fffc6aa37dacd39930c03028549 Mon Sep 17 00:00:00 2001
From: Josh Coalson <jcoalson@users.sourceforce.net>
Date: Tue, 10 Jul 2007 02:08:51 +0000
Subject: [PATCH] fix bug where invalid seek tables could cause some seeks to
 fail

---
 doc/html/changelog.html      |  9 ++------
 src/libFLAC/stream_decoder.c | 40 ++++++++++++++++++++++++++++--------
 2 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/doc/html/changelog.html b/doc/html/changelog.html
index ba4a5eba..637759d0 100644
--- a/doc/html/changelog.html
+++ b/doc/html/changelog.html
@@ -80,7 +80,7 @@
 				flac:
 				<ul>
 					<li>Added runtime detection of SSE OS support for most operating systems.</li>
-					<li>Added a new undocumented option <span class="argument">--ignore-chunk-sizes</span> for ignoring the size of the 'data' chunk (WAVE) or 'SSND' chunk(AIFF).  Can be used to encode files with bogus data sizes.  Use with caution, all subsequent data is treated as audio, so the data/SSND chunk must be the last or the following data/tags will be treated as audio and encoded.</li>
+					<li>Added a new undocumented option <span class="argument">--ignore-chunk-sizes</span> for ignoring the size of the 'data' chunk (WAVE) or 'SSND' chunk (AIFF).  Can be used to encode files with bogus data sizes (e.g. with WAV files piped from foobar2000 to flac.exe as an external encoder).  <b>Use with caution</b>: all subsequent data is treated as audio, so the data/SSND chunk must be the last or the following data/tags will be treated as audio and encoded.</li>
 				</ul>
 			</li>
 			<li>
@@ -105,17 +105,12 @@
 				libraries:
 				<ul>
 					<li>Added runtime detection of SSE OS support for most operating systems.</li>
+					<li>Fixed bug where invalid seek tables could cause some seeks to fail.</li>
 				</ul>
 			</li>
 			<li>
 				Interface changes (see also the <a href="http://flac.sourceforge.net/api/group__porting__1__1__4__to__1__2__0.html">porting guide</a> for specific instructions on porting to FLAC 1.2.0):
 				<ul>
-					<li>
-						all libraries;
-						<ul>
-							<li>(none)</li>
-						</ul>
-					</li>
 					<li>
 						libFLAC:
 						<ul>
diff --git a/src/libFLAC/stream_decoder.c b/src/libFLAC/stream_decoder.c
index 4223ed39..6be647fd 100644
--- a/src/libFLAC/stream_decoder.c
+++ b/src/libFLAC/stream_decoder.c
@@ -3007,33 +3007,55 @@ FLAC__bool seek_to_absolute_sample_(FLAC__StreamDecoder *decoder, FLAC__uint64 s
 	upper_bound = stream_length;
 	upper_bound_sample = total_samples > 0 ? total_samples : target_sample /*estimate it*/;
 
-	/*@@@@@@ add step to validate seek table before using?  encoding to pipe leaves some flac files with incomplete seektables which screw us up */
-	/*@@@@@@ ignore seekpoints where frame_samples = 0 or if point is >= total_samples and total_samples is known (or just alter seek_table in read_metadata_seektable_()) */
-
 	/*
 	 * Now we refine the bounds if we have a seektable with
 	 * suitable points.  Note that according to the spec they
 	 * must be ordered by ascending sample number.
+	 *
+	 * Note: to protect against invalid seek tables we will ignore points
+	 * that have frame_samples==0 or sample_number>=total_samples
 	 */
 	if(seek_table) {
+		FLAC__uint64 new_lower_bound = lower_bound;
+		FLAC__uint64 new_upper_bound = upper_bound;
+		FLAC__uint64 new_lower_bound_sample = lower_bound_sample;
+		FLAC__uint64 new_upper_bound_sample = upper_bound_sample;
+
 		/* find the closest seek point <= target_sample, if it exists */
 		for(i = (int)seek_table->num_points - 1; i >= 0; i--) {
-			if(seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && seek_table->points[i].sample_number <= target_sample)
+			if(
+				seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER &&
+				seek_table->points[i].frame_samples > 0 && /* defense against bad seekpoints */
+				(total_samples <= 0 || seek_table->points[i].sample_number < total_samples) && /* defense against bad seekpoints */
+				seek_table->points[i].sample_number <= target_sample
+			)
 				break;
 		}
 		if(i >= 0) { /* i.e. we found a suitable seek point... */
-			lower_bound = first_frame_offset + seek_table->points[i].stream_offset;
-			lower_bound_sample = seek_table->points[i].sample_number;
+			new_lower_bound = first_frame_offset + seek_table->points[i].stream_offset;
+			new_lower_bound_sample = seek_table->points[i].sample_number;
 		}
 
 		/* find the closest seek point > target_sample, if it exists */
 		for(i = 0; i < (int)seek_table->num_points; i++) {
-			if(seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && seek_table->points[i].sample_number > target_sample)
+			if(
+				seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER &&
+				seek_table->points[i].frame_samples > 0 && /* defense against bad seekpoints */
+				(total_samples <= 0 || seek_table->points[i].sample_number < total_samples) && /* defense against bad seekpoints */
+				seek_table->points[i].sample_number > target_sample
+			)
 				break;
 		}
 		if(i < (int)seek_table->num_points) { /* i.e. we found a suitable seek point... */
-			upper_bound = first_frame_offset + seek_table->points[i].stream_offset;
-			upper_bound_sample = seek_table->points[i].sample_number;
+			new_upper_bound = first_frame_offset + seek_table->points[i].stream_offset;
+			new_upper_bound_sample = seek_table->points[i].sample_number;
+		}
+		/* final protection against unsorted seek tables; keep original values if bogus */
+		if(new_upper_bound >= new_lower_bound) {
+			lower_bound = new_lower_bound;
+			upper_bound = new_upper_bound;
+			lower_bound_sample = new_lower_bound_sample;
+			upper_bound_sample = new_upper_bound_sample;
 		}
 	}