/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2015 Toomas Soome <tsoome@me.com>
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <zlib.h>
#include <strings.h>

int gzip_decompress(void *, void *, size_t, size_t, int);
/*
 * Uncompress the buffer 'src' into the buffer 'dst'.  The caller must store
 * the expected decompressed data size externally so it can be passed in.
 * The resulting decompressed size is then returned through dstlen.  This
 * function return Z_OK on success, or another error code on failure.
 */
static int
z_uncompress(void *dst, size_t *dstlen, const void *src, size_t srclen)
{
        z_stream zs;
        int err;

        bzero(&zs, sizeof (zs));
        zs.next_in = (unsigned char *)src;
        zs.avail_in = srclen;
        zs.next_out = dst;
        zs.avail_out = *dstlen;

        /*
         * Call inflateInit2() specifying a window size of DEF_WBITS
         * with the 6th bit set to indicate that the compression format
         * type (zlib or gzip) should be automatically detected.
         */
        if ((err = inflateInit2(&zs, 15 | 0x20)) != Z_OK)
                return (err);

        if ((err = inflate(&zs, Z_FINISH)) != Z_STREAM_END) {
                (void) inflateEnd(&zs);
                return (err == Z_OK ? Z_BUF_ERROR : err);
        }

        *dstlen = zs.total_out;
        return (inflateEnd(&zs));
}

int
gzip_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len,
    int n __unused)
{
        size_t dstlen = d_len;

        if (z_uncompress(d_start, &dstlen, s_start, s_len) != Z_OK)
                return (-1);

        return (0);
}