Changeset 266

Timestamp:

04/15/07 23:40:45 (18 years ago)

Author:

r2d

Message:

Improved decoder robustness against corrupted files

Location:

libmpc/branches/r2d/libmpcdec

Files:

• internal.h (modified) (2 diffs)
• mpc_demux.c (modified) (7 diffs)

libmpc/branches/r2d/libmpcdec/internal.h

@@ -62 +62 @@
         unsigned int count; /// unread bits in current byte
 };
-
-#define DEMUX_BUFFER_SIZE 65536
+        
+#define MAX_FRAME_SIZE 4352
+#define DEMUX_BUFFER_SIZE (65536 - MAX_FRAME_SIZE) // need some space as sand box
 
 struct mpc_demux_t {
@@ -71 +72 @@
 
         // buffer
-        mpc_uint8_t buffer[DEMUX_BUFFER_SIZE];
+        mpc_uint8_t buffer[DEMUX_BUFFER_SIZE + MAX_FRAME_SIZE];
         mpc_size_t bytes_total;
         mpc_bits_reader bits_reader;

libmpc/branches/r2d/libmpcdec/mpc_demux.c

@@ -50 +50 @@
 void  streaminfo_gain(mpc_streaminfo* si, const mpc_bits_reader * r_in);
 
-#define MAX_FRAME_SIZE 4352
 
 enum {
@@ -300 +299 @@
                 mpc_demux_fill(d, 11, 0); // max header block size
                 size = mpc_bits_get_block(&d->bits_reader, &b);
+                // FIXME : stop scan if invalid key
                 while( memcmp(b.key, "AP", 2) != 0 ){ // scan all blocks until audio
                         mpc_demux_fill(d, 11 + (mpc_uint32_t) b.size, 0);
@@ -317 +317 @@
                 }
                 d->bits_reader.buff -= size;
+                if (d->si.stream_version == 0) // si no initialized !!!
+                        return MPC_STATUS_INVALIDSV;
         } else
                 return MPC_STATUS_INVALIDSV;
@@ -335 +337 @@
                         p_tmp->d = mpc_decoder_init(&p_tmp->si);
                 } else {
+                        if (p_tmp->seek_table)
+                                free(p_tmp->seek_table);
                         free(p_tmp);
                         p_tmp = 0;
@@ -357 +361 @@
 void mpc_demux_decode(mpc_demux * d, mpc_frame_info * i)
 {
+        mpc_bits_reader r;
         if (d->si.stream_version >= 8) {
-                mpc_bits_reader r;
                 i->is_key_frame = MPC_FALSE;
 
@@ -389 +393 @@
                 d->block_bits -= ((d->bits_reader.buff - r.buff) << 3) + r.count - d->bits_reader.count;
                 d->block_frames--;
-                if (d->block_bits < 0) i->bits = -1;
+                if (d->block_bits < 0 || (d->block_frames == 0 && d->block_bits > 7)) {
+                        // an error occured, stop decoding
+                        // FIXME : return an error code.
+                        i->bits = -1; // we pretend it's end of file
+                }
         } else {
-                mpc_bits_reader r;
                 if (d->d->decoded_samples == (d->seek_table_size << d->seek_pwr) * MPC_FRAME_LENGTH) {
                         d->seek_table[d->seek_table_size] = (mpc_uint32_t) mpc_demux_pos(d);
@@ -397 +404 @@
                 }
                 mpc_demux_fill(d, MAX_FRAME_SIZE, MPC_BUFFER_FULL | MPC_BUFFER_SWAP);
-                mpc_bits_read(&d->bits_reader, 20); // read frame size
+                d->block_bits = (mpc_int_t) mpc_bits_read(&d->bits_reader, 20); // read frame size
                 r = d->bits_reader;
                 mpc_decoder_decode_frame(d->d, &d->bits_reader, i);
+                if (d->block_bits != ((d->bits_reader.buff - r.buff) << 3) + r.count - d->bits_reader.count) {
+                        // an error occured, stop decoding
+                        // FIXME : return an error code.
+                        i->bits = -1; // we pretend it's end of file
+                }
+        }
+        if (d->buffer + d->bytes_total < d->bits_reader.buff + ((8 - d->bits_reader.count) >> 3)) {
+                // we're reading outside the buffer bytes, this is an error !
+                // FIXME : return an error code.
+                i->bits = -1; // we pretend it's end of file
         }
 }