[FFmpeg-devel] [RFC] seek when streamed

[Baptiste Coudurier]

Hi

I noticed a weird behaviour (bug ?) when seeking is requested when file
is streamed:

in url_fseek:
    } else if(s->is_streamed && !s->write_flag &&
         offset1 >= 0 && offset1 < (s->buf_end - s->buffer) + (1<<16)){
        while(s->pos < offset && !s->eof_reached)
            fill_buffer(s);
        s->buf_ptr = s->buf_end + offset - s->pos;

if eof_is_reached then s->pos might be < offset, therefore buf_ptr might
be > buf_end. Next get_buffer will memcpy negative size:

int get_buffer(ByteIOContext *s, unsigned char *buf, int size)
{
    int len, size1;

    size1 = size;
    while (size > 0) {
        len = s->buf_end - s->buf_ptr;
        if (len > size)
            len = size;
        if (len == 0) {
	   [...]
	} else {
	    memcpy(buf, s->buf_ptr, len);
            buf += len;
	[...]

Note that url_fseek clear eof_reached.

That will only happen when reading a streamed file.
Im submitting the attached patch, but Im not sure what the correct
behaviour should be. Any suggestion welcome.

--
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
SMARTJOG S.A.                                    http://www.smartjog.com
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
Phone: +33 1 49966312
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