s->seek(s->opaque, offset, SEEK_SET);
if (s->seek(s->opaque, offset, SEEK_SET) == (offset_t)-EPIPE) return -EPIPE;
offset_t url_fseek(ByteIOContext *s, offset_t offset, int whence){    offset_t offset1;    if (whence != SEEK_CUR && whence != SEEK_SET)        return -EINVAL;    #ifdef CONFIG_ENCODERS    if (s->write_flag) {        if (whence == SEEK_CUR) {            offset1 = s->pos + (s->buf_ptr - s->buffer);            if (offset == 0)                return offset1;            offset += offset1;        }        offset1 = offset - s->pos;        if (!s->must_flush &&             offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {            /* can do the seek inside the buffer */            s->buf_ptr = s->buffer + offset1;        } else {            if (!s->seek)                return -EPIPE;            flush_buffer(s);            s->must_flush = 1;            s->buf_ptr = s->buffer;            s->seek(s->opaque, offset, SEEK_SET);            s->pos = offset;        }    } else #endif //CONFIG_ENCODERS    {        if (whence == SEEK_CUR) {            offset1 = s->pos - (s->buf_end - s->buffer) + (s->buf_ptr - s->buffer);            if (offset == 0)                return offset1;            offset += offset1;        }        offset1 = offset - (s->pos - (s->buf_end - s->buffer));        if (offset1 >= 0 && offset1 <= (s->buf_end - s->buffer)) {            /* can do the seek inside the buffer */            s->buf_ptr = s->buffer + offset1;        } else {            if (!s->seek)                return -EPIPE;            s->buf_ptr = s->buffer;            s->buf_end = s->buffer;            s->seek(s->opaque, offset, SEEK_SET);            s->pos = offset;        }        s->eof_reached = 0;    }    return offset;}