/* SPDX-License-Identifier: BSD-2-Clause */
/* Minimal DEFLATE decompressor for EROFS FreeBSD */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <contrib/zlib/zlib.h>

#include "internal.h"

int
z_erofs_load_deflate_config(struct erofs_mount *em, const void *data,
    size_t size)
{
	const struct z_erofs_deflate_cfgs *deflate;

	if (size < sizeof(*deflate))
		return (EINVAL);
	deflate = data;
	if (deflate->windowbits < 8 || deflate->windowbits > 15)
		return (EOPNOTSUPP);
	em->deflate_windowbits = deflate->windowbits;
	return (0);
}

int
deflate_decompress(void *src, size_t srclen, void *dst, size_t dstlen, int n,
    bool partial)
{
	z_stream strm;
	uInt in_before, out_before;
	int endret, ret;

	if (n < 8 || n > MAX_WBITS || srclen > (size_t)(uInt)-1 ||
	    dstlen > (size_t)(uInt)-1 || dstlen == 0)
		return (-1);

	bzero(&strm, sizeof(strm));
	strm.next_in = src;
	strm.avail_in = srclen;
	strm.next_out = dst;
	strm.avail_out = dstlen;

	ret = inflateInit2(&strm, -n);
	if (ret != Z_OK)
		return (-1);

	ret = Z_OK;
	while (strm.avail_out != 0) {
		in_before = strm.avail_in;
		out_before = strm.avail_out;
		ret = inflate(&strm, Z_SYNC_FLUSH);
		if (ret == Z_STREAM_END)
			break;
		if (ret != Z_OK ||
		    (strm.avail_in == in_before && strm.avail_out == out_before))
			break;
	}
	endret = inflateEnd(&strm);
	if (endret != Z_OK || strm.avail_out != 0)
		return (-1);
	if (partial)
		return (ret == Z_OK || ret == Z_STREAM_END ? 0 : -1);
	if (ret != Z_STREAM_END || strm.avail_in != 0)
		return (-1);

	return (0);
}