fix bugs with skipping id3v2 tags and long metadata blocks

diff --git a/src/metaflac/main.c b/src/metaflac/main.c
index 2a4b325..b1399be 100644 (file)
--- a/src/metaflac/main.c
+++ b/src/metaflac/main.c
@@ -138,8 +138,45 @@ FLAC__bool list(FILE *f, FLAC__bool verbose)
        FLAC__StreamMetaData metadata;
        unsigned blocknum = 0, byte_offset = 0, i;
 
-       /* read the stream sync code */
-       if(fread(buf, 1, 4, f) < 4 || memcmp(buf, sync_string_, 4)) {
+       /* skip any id3v2 tag */
+       if(fread(buf, 1, 4, f) < 4) {
+               fprintf(stderr, "ERROR: not a FLAC file\n");
+               return false;
+       }
+       if(0 == memcmp(buf, "ID3", 3)) {
+               unsigned tag_length = 0;
+
+               /* skip to the tag length */
+               if(fseek(f, 2, SEEK_CUR) < 0) {
+                       fprintf(stderr, "ERROR: bad ID3v2 tag\n");
+                       return false;
+               }
+
+               /* read the length */
+               for(i = 0; i < 4; i++) {
+                       if(fread(buf, 1, 1, f) < 1 || buf[0] & 0x80) {
+                               fprintf(stderr, "ERROR: bad ID3v2 tag\n");
+                               return false;
+                       }
+                       tag_length <<= 7;
+                       tag_length |= (buf[0] & 0x7f);
+               }
+
+               /* skip the rest of the tag */
+               if(fseek(f, tag_length, SEEK_CUR) < 0) {
+                       fprintf(stderr, "ERROR: bad ID3v2 tag\n");
+                       return false;
+               }
+
+               /* read the stream sync code */
+               if(fread(buf, 1, 4, f) < 4) {
+                       fprintf(stderr, "ERROR: not a FLAC file (no '%s' header)\n", sync_string_);
+                       return false;
+               }
+       }
+
+       /* check the stream sync code */
+       if(memcmp(buf, sync_string_, 4)) {
                fprintf(stderr, "ERROR: not a FLAC file (no '%s' header)\n", sync_string_);
                return false;
        }
@@ -165,6 +202,10 @@ FLAC__bool list(FILE *f, FLAC__bool verbose)
 
                if(metadata.length > sizeof(buf)) {
                        printf("  SKIPPING large block\n");
+                       if(fseek(f, metadata.length, SEEK_CUR) < 0) {
+                               fprintf(stderr, "ERROR: short count skipping metadata block data\n");
+                               return false;
+                       }
                        continue;
                }