mirror of https://git.ffmpeg.org/ffmpeg.git
move eob_reached logic into ff_lzw_decode_tail() which simplifies the code, avoids some checks in the innermost loop and also gets rid of the controversal break while hopefully retaining the last byte in a valid bytestream, invalid bytestreams still can have very significant overread
Originally committed as revision 8517 to svn://svn.ffmpeg.org/ffmpeg/trunk
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c59f24e657
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@ -42,7 +42,6 @@ static const uint16_t mask[17] =
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};
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};
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struct LZWState {
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struct LZWState {
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int eob_reached;
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uint8_t *pbuf, *ebuf;
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uint8_t *pbuf, *ebuf;
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int bbits;
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int bbits;
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unsigned int bbuf;
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unsigned int bbuf;
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@ -74,10 +73,6 @@ static int lzw_get_code(struct LZWState * s)
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while (s->bbits < s->cursize) {
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while (s->bbits < s->cursize) {
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if (!s->bs) {
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if (!s->bs) {
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s->bs = *s->pbuf++;
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s->bs = *s->pbuf++;
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if(!s->bs) {
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s->eob_reached = 1;
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break;
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}
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}
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}
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s->bbuf |= (*s->pbuf++) << s->bbits;
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s->bbuf |= (*s->pbuf++) << s->bbits;
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s->bbits += 8;
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s->bbits += 8;
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@ -87,9 +82,6 @@ static int lzw_get_code(struct LZWState * s)
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s->bbuf >>= s->cursize;
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s->bbuf >>= s->cursize;
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} else { // TIFF
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} else { // TIFF
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while (s->bbits < s->cursize) {
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while (s->bbits < s->cursize) {
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if (s->pbuf >= s->ebuf) {
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s->eob_reached = 1;
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}
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s->bbuf = (s->bbuf << 8) | (*s->pbuf++);
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s->bbuf = (s->bbuf << 8) | (*s->pbuf++);
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s->bbits += 8;
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s->bbits += 8;
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}
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}
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@ -107,8 +99,14 @@ uint8_t* ff_lzw_cur_ptr(LZWState *p)
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void ff_lzw_decode_tail(LZWState *p)
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void ff_lzw_decode_tail(LZWState *p)
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{
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{
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struct LZWState *s = (struct LZWState *)p;
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struct LZWState *s = (struct LZWState *)p;
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while(!s->eob_reached)
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lzw_get_code(s);
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if(s->mode == FF_LZW_GIF) {
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while(s->pbuf < s->ebuf && s->bs>0){
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s->pbuf += s->bs;
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s->bs = *s->pbuf++;
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}
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}else
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s->pbuf= s->ebuf;
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}
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}
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void ff_lzw_decode_open(LZWState **p)
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void ff_lzw_decode_open(LZWState **p)
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@ -136,7 +134,6 @@ int ff_lzw_decode_init(LZWState *p, int csize, uint8_t *buf, int buf_size, int m
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if(csize < 1 || csize > LZW_MAXBITS)
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if(csize < 1 || csize > LZW_MAXBITS)
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return -1;
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return -1;
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/* read buffer */
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/* read buffer */
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s->eob_reached = 0;
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s->pbuf = buf;
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s->pbuf = buf;
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s->ebuf = s->pbuf + buf_size;
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s->ebuf = s->pbuf + buf_size;
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s->bbuf = 0;
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s->bbuf = 0;
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