int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence) { int64_t offset1; int64_t pos; int force = whence & AVSEEK_FORCE; whence &= ~AVSEEK_FORCE; if(!s) return AVERROR(EINVAL); pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer)); if (whence != SEEK_CUR && whence != SEEK_SET) return AVERROR(EINVAL); if (whence == SEEK_CUR) { offset1 = pos + (s->buf_ptr - s->buffer); if (offset == 0) return offset1; offset += offset1; } offset1 = offset - 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->is_streamed && !s->write_flag && offset1 >= 0 && (whence != SEEK_END || force)) { while(s->pos < offset && !s->eof_reached) fill_buffer(s); if (s->eof_reached) return AVERROR_EOF; s->buf_ptr = s->buf_end + offset - s->pos; } else { int64_t res = AVERROR(EPIPE); #if CONFIG_MUXERS || CONFIG_NETWORK if (s->write_flag) { flush_buffer(s); s->must_flush = 1; } #endif /* CONFIG_MUXERS || CONFIG_NETWORK */ if (!s->seek || (res = s->seek(s->opaque, offset, SEEK_SET)) < 0) return res; if (!s->write_flag) s->buf_end = s->buffer; s->buf_ptr = s->buffer; s->pos = offset; } s->eof_reached = 0; return offset; }