static inline int dmg_read_chunk(BlockDriverState *bs, int sector_num)
{
    BDRVDMGState *s = bs->opaque;

    if (!is_sector_in_chunk(s, s->current_chunk, sector_num)) {
        int ret;
        uint32_t chunk = search_chunk(s, sector_num);

        if (chunk >= s->n_chunks) {
            return -1;
        }

        s->current_chunk = s->n_chunks;
        switch (s->types[chunk]) {
        case 0x80000005: { /* zlib compressed */
            /* we need to buffer, because only the chunk as whole can be
             * inflated. */
            ret = bdrv_pread(bs->file, s->offsets[chunk],
                             s->compressed_chunk, s->lengths[chunk]);
            if (ret != s->lengths[chunk]) {
                return -1;
            }

            s->zstream.next_in = s->compressed_chunk;
            s->zstream.avail_in = s->lengths[chunk];
            s->zstream.next_out = s->uncompressed_chunk;
            s->zstream.avail_out = 512 * s->sectorcounts[chunk];
            ret = inflateReset(&s->zstream);
            if (ret != Z_OK) {
                return -1;
            }
            ret = inflate(&s->zstream, Z_FINISH);
            if (ret != Z_STREAM_END ||
                s->zstream.total_out != 512 * s->sectorcounts[chunk]) {
                return -1;
            }
            break; }
        case 1: /* copy */
            ret = bdrv_pread(bs->file, s->offsets[chunk],
                             s->uncompressed_chunk, s->lengths[chunk]);
            if (ret != s->lengths[chunk]) {
                return -1;
            }
            break;
        case 2: /* zero */
            memset(s->uncompressed_chunk, 0, 512 * s->sectorcounts[chunk]);
            break;
        }
        s->current_chunk = chunk;
    }
    return 0;
}
Unknown