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src/Source/FreeImage/ZLibInterface.cpp  view on Meta::CPAN

    int flags, c;
    DWORD len;

    if (get_byte(stream) != 0x1f || get_byte(stream) != 0x8b)
        return Z_DATA_ERROR;
    if (get_byte(stream) != Z_DEFLATED || ((flags = get_byte(stream)) & 0xE0) != 0)
        return Z_DATA_ERROR;
    for (len = 0; len < 6; len++) (void)get_byte(stream);

    if ((flags & 0x04) != 0) { /* skip the extra field */
        len  =  (DWORD)get_byte(stream);
        len += ((DWORD)get_byte(stream)) << 8;
        /* len is garbage if EOF but the loop below will quit anyway */
        while (len-- != 0 && get_byte(stream) != EOF) ;
    }
    if ((flags & 0x08) != 0) { /* skip the original file name */
        while ((c = get_byte(stream)) != 0 && c != EOF) ;
    }
    if ((flags & 0x10) != 0) {   /* skip the .gz file comment */
        while ((c = get_byte(stream)) != 0 && c != EOF) ;
    }
    if ((flags & 0x02) != 0) {  /* skip the header crc */
        for (len = 0; len < 2; len++) (void)get_byte(stream);
    }
    return Z_OK;
}

DWORD DLL_CALLCONV 
FreeImage_ZLibGUnzip(BYTE *target, DWORD target_size, BYTE *source, DWORD source_size) {
    DWORD src_len  = source_size;
    DWORD dest_len = target_size;
    int   zerr     = Z_DATA_ERROR;

    if (src_len > 0) {
        z_stream stream;
        memset(&stream, 0, sizeof (stream));
        if ((zerr = inflateInit2(&stream, -MAX_WBITS)) == Z_OK) {
            stream.next_in  = source;
            stream.avail_in = source_size;

            stream.next_out  = target;
            stream.avail_out = target_size;

            if ((zerr = checkheader(&stream)) == Z_OK) {
                zerr = inflate (&stream, Z_NO_FLUSH);
                dest_len = target_size - stream.avail_out;

                if (zerr == Z_OK || zerr == Z_STREAM_END)
                    inflateEnd(&stream);
            } 
        }
    }
    if (zerr != Z_OK && zerr != Z_STREAM_END) {
        FreeImage_OutputMessageProc(FIF_UNKNOWN, "Zlib error : %s", zError(zerr));
        return 0;
    }
    return dest_len;
}

/**
Update a running crc from source and return the updated crc, using the ZLib library.
If source is NULL, this function returns the required initial value for the crc.

@param crc Running crc value
@param source Source buffer
@param source_size Size of the source buffer, in bytes
@return Returns the new crc value
*/
DWORD DLL_CALLCONV 
FreeImage_ZLibCRC32(DWORD crc, BYTE *source, DWORD source_size) {

    return crc32(crc, source, source_size);
}