riff, aiff: fixed "limited range" gcc warning

On 32 bit systems with large file support enabled (i.e. "sizeof(off_t)
> sizeof(size_t)") gcc emits a warning because a size_t cast to off_t
can never become negative.

NEWS

@@ -1,6 +1,8 @@
 ver 0.15.5 (2009/??/??)
 * input:
   - curl: don't abort if a packet has only metadata
+* tags:
+  - riff, aiff: fixed "limited range" gcc warning
 * decoder_thread: change the fallback decoder name to "mad"
 
 

src/aiff.c

@@ -84,6 +84,11 @@ aiff_seek_id3(FILE *file)
 			return 0;
 
 		size = GUINT32_FROM_BE(chunk.size);
+		if (size > G_MAXINT32)
+			/* too dangerous, bail out: possible integer
+			   underflow when casting to off_t */
+			return 0;
+
 		if (size % 2 != 0)
 			/* pad byte */
 			++size;
@@ -92,11 +97,6 @@ aiff_seek_id3(FILE *file)
 			/* found it! */
 			return size;
 
-		if ((off_t)size < 0)
-			/* integer underflow after cast to signed
-			   type */
-			return 0;
-
 		ret = fseek(file, size, SEEK_CUR);
 		if (ret != 0)
 			return 0;

src/riff.c

@@ -83,6 +83,11 @@ riff_seek_id3(FILE *file)
 			return 0;
 
 		size = GUINT32_FROM_LE(chunk.size);
+		if (size > G_MAXINT32)
+			/* too dangerous, bail out: possible integer
+			   underflow when casting to off_t */
+			return 0;
+
 		if (size % 2 != 0)
 			/* pad byte */
 			++size;
@@ -91,11 +96,6 @@ riff_seek_id3(FILE *file)
 			/* found it! */
 			return size;
 
-		if ((off_t)size < 0)
-			/* integer underflow after cast to signed
-			   type */
-			return 0;
-
 		ret = fseek(file, size, SEEK_CUR);
 		if (ret != 0)
 			return 0;