/*
 * Cryptographic API.
 *
 * Zlib algorithm
 *
 * Copyright 2008 Sony Corporation
 *
 * Based on deflate.c, which is
 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * FIXME: deflate transforms will require up to a total of about 436k of kernel
 * memory on i386 (390k for compression, the rest for decompression), as the
 * current zlib kernel code uses a worst case pre-allocation system by default.
 * This needs to be fixed so that the amount of memory required is properly
 * related to the winbits and memlevel parameters.
 */

#define pr_fmt(fmt)	"%s: " fmt, __func__

#include <linux/init.h>
#include <linux/module.h>
#include <linux/zlib.h>
#include <linux/vmalloc.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/net.h>
#include <linux/slab.h>

#include <crypto/internal/compress.h>

#include <net/netlink.h>


struct zlib_ctx {
	struct z_stream_s comp_stream;
	struct z_stream_s decomp_stream;
	int decomp_windowBits;
};


static void zlib_comp_exit(struct zlib_ctx *ctx)
{
	struct z_stream_s *stream = &ctx->comp_stream;

	if (stream->workspace) {
		zlib_deflateEnd(stream);
		vfree(stream->workspace);
		stream->workspace = NULL;
	}
}

static void zlib_decomp_exit(struct zlib_ctx *ctx)
{
	struct z_stream_s *stream = &ctx->decomp_stream;

	if (stream->workspace) {
		zlib_inflateEnd(stream);
		kfree(stream->workspace);
		stream->workspace = NULL;
	}
}

static int zlib_init(struct crypto_tfm *tfm)
{
	return 0;
}

static void zlib_exit(struct crypto_tfm *tfm)
{
	struct zlib_ctx *ctx = crypto_tfm_ctx(tfm);

	zlib_comp_exit(ctx);
	zlib_decomp_exit(ctx);
}


static int zlib_compress_setup(struct crypto_pcomp *tfm, void *params,
			       unsigned int len)
{
	struct zlib_ctx *ctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &ctx->comp_stream;
	struct nlattr *tb[ZLIB_COMP_MAX + 1];
	size_t workspacesize;
	int ret;

	ret = nla_parse(tb, ZLIB_COMP_MAX, params, len, NULL);
	if (ret)
		return ret;

	zlib_comp_exit(ctx);

	workspacesize = zlib_deflate_workspacesize();
	stream->workspace = vmalloc(workspacesize);
	if (!stream->workspace)
		return -ENOMEM;

	memset(stream->workspace, 0, workspacesize);
	ret = zlib_deflateInit2(stream,
				tb[ZLIB_COMP_LEVEL]
					? nla_get_u32(tb[ZLIB_COMP_LEVEL])
					: Z_DEFAULT_COMPRESSION,
				tb[ZLIB_COMP_METHOD]
					? nla_get_u32(tb[ZLIB_COMP_METHOD])
					: Z_DEFLATED,
				tb[ZLIB_COMP_WINDOWBITS]
					? nla_get_u32(tb[ZLIB_COMP_WINDOWBITS])
					: MAX_WBITS,
				tb[ZLIB_COMP_MEMLEVEL]
					? nla_get_u32(tb[ZLIB_COMP_MEMLEVEL])
					: DEF_MEM_LEVEL,
				tb[ZLIB_COMP_STRATEGY]
					? nla_get_u32(tb[ZLIB_COMP_STRATEGY])
					: Z_DEFAULT_STRATEGY);
	if (ret != Z_OK) {
		vfree(stream->workspace);
		stream->workspace = NULL;
		return -EINVAL;
	}

	return 0;
}

static int zlib_compress_init(struct crypto_pcomp *tfm)
{
	int ret;
	struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &dctx->comp_stream;

	ret = zlib_deflateReset(stream);
	if (ret != Z_OK)
		return -EINVAL;

	return 0;
}

static int zlib_compress_update(struct crypto_pcomp *tfm,
				struct comp_request *req)
{
	int ret;
	struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &dctx->comp_stream;

	pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
	stream->next_in = req->next_in;
	stream->avail_in = req->avail_in;
	stream->next_out = req->next_out;
	stream->avail_out = req->avail_out;

	ret = zlib_deflate(stream, Z_NO_FLUSH);
	switch (ret) {
	case Z_OK:
		break;

	case Z_BUF_ERROR:
		pr_debug("zlib_deflate could not make progress\n");
		return -EAGAIN;

	default:
		pr_debug("zlib_deflate failed %d\n", ret);
		return -EINVAL;
	}

	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
		 stream->avail_in, stream->avail_out,
		 req->avail_in - stream->avail_in,
		 req->avail_out - stream->avail_out);
	req->next_in = stream->next_in;
	req->avail_in = stream->avail_in;
	req->next_out = stream->next_out;
	req->avail_out = stream->avail_out;
	return 0;
}

static int zlib_compress_final(struct crypto_pcomp *tfm,
			       struct comp_request *req)
{
	int ret;
	struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &dctx->comp_stream;

	pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
	stream->next_in = req->next_in;
	stream->avail_in = req->avail_in;
	stream->next_out = req->next_out;
	stream->avail_out = req->avail_out;

	ret = zlib_deflate(stream, Z_FINISH);
	if (ret != Z_STREAM_END) {
		pr_debug("zlib_deflate failed %d\n", ret);
		return -EINVAL;
	}

	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
		 stream->avail_in, stream->avail_out,
		 req->avail_in - stream->avail_in,
		 req->avail_out - stream->avail_out);
	req->next_in = stream->next_in;
	req->avail_in = stream->avail_in;
	req->next_out = stream->next_out;
	req->avail_out = stream->avail_out;
	return 0;
}


static int zlib_decompress_setup(struct crypto_pcomp *tfm, void *params,
				 unsigned int len)
{
	struct zlib_ctx *ctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &ctx->decomp_stream;
	struct nlattr *tb[ZLIB_DECOMP_MAX + 1];
	int ret = 0;

	ret = nla_parse(tb, ZLIB_DECOMP_MAX, params, len, NULL);
	if (ret)
		return ret;

	zlib_decomp_exit(ctx);

	ctx->decomp_windowBits = tb[ZLIB_DECOMP_WINDOWBITS]
				 ? nla_get_u32(tb[ZLIB_DECOMP_WINDOWBITS])
				 : DEF_WBITS;

	stream->workspace = kzalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
	if (!stream->workspace)
		return -ENOMEM;

	ret = zlib_inflateInit2(stream, ctx->decomp_windowBits);
	if (ret != Z_OK) {
		kfree(stream->workspace);
		stream->workspace = NULL;
		return -EINVAL;
	}

	return 0;
}

static int zlib_decompress_init(struct crypto_pcomp *tfm)
{
	int ret;
	struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &dctx->decomp_stream;

	ret = zlib_inflateReset(stream);
	if (ret != Z_OK)
		return -EINVAL;

	return 0;
}

static int zlib_decompress_update(struct crypto_pcomp *tfm,
				  struct comp_request *req)
{
	int ret;
	struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &dctx->decomp_stream;

	pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
	stream->next_in = req->next_in;
	stream->avail_in = req->avail_in;
	stream->next_out = req->next_out;
	stream->avail_out = req->avail_out;

	ret = zlib_inflate(stream, Z_SYNC_FLUSH);
	switch (ret) {
	case Z_OK:
	case Z_STREAM_END:
		break;

	case Z_BUF_ERROR:
		pr_debug("zlib_inflate could not make progress\n");
		return -EAGAIN;

	default:
		pr_debug("zlib_inflate failed %d\n", ret);
		return -EINVAL;
	}

	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
		 stream->avail_in, stream->avail_out,
		 req->avail_in - stream->avail_in,
		 req->avail_out - stream->avail_out);
	req->next_in = stream->next_in;
	req->avail_in = stream->avail_in;
	req->next_out = stream->next_out;
	req->avail_out = stream->avail_out;
	return 0;
}

static int zlib_decompress_final(struct crypto_pcomp *tfm,
				 struct comp_request *req)
{
	int ret;
	struct zlib_ctx *dctx = crypto_tfm_ctx(crypto_pcomp_tfm(tfm));
	struct z_stream_s *stream = &dctx->decomp_stream;

	pr_debug("avail_in %u, avail_out %u\n", req->avail_in, req->avail_out);
	stream->next_in = req->next_in;
	stream->avail_in = req->avail_in;
	stream->next_out = req->next_out;
	stream->avail_out = req->avail_out;

	if (dctx->decomp_windowBits < 0) {
		ret = zlib_inflate(stream, Z_SYNC_FLUSH);
		/*
		 * Work around a bug in zlib, which sometimes wants to taste an
		 * extra byte when being used in the (undocumented) raw deflate
		 * mode. (From USAGI).
		 */
		if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
			const void *saved_next_in = stream->next_in;
			u8 zerostuff = 0;

			stream->next_in = &zerostuff;
			stream->avail_in = 1;
			ret = zlib_inflate(stream, Z_FINISH);
			stream->next_in = saved_next_in;
			stream->avail_in = 0;
		}
	} else
		ret = zlib_inflate(stream, Z_FINISH);
	if (ret != Z_STREAM_END) {
		pr_debug("zlib_inflate failed %d\n", ret);
		return -EINVAL;
	}

	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)\n",
		 stream->avail_in, stream->avail_out,
		 req->avail_in - stream->avail_in,
		 req->avail_out - stream->avail_out);
	req->next_in = stream->next_in;
	req->avail_in = stream->avail_in;
	req->next_out = stream->next_out;
	req->avail_out = stream->avail_out;
	return 0;
}


static struct pcomp_alg zlib_alg = {
	.compress_setup		= zlib_compress_setup,
	.compress_init		= zlib_compress_init,
	.compress_update	= zlib_compress_update,
	.compress_final		= zlib_compress_final,
	.decompress_setup	= zlib_decompress_setup,
	.decompress_init	= zlib_decompress_init,
	.decompress_update	= zlib_decompress_update,
	.decompress_final	= zlib_decompress_final,

	.base			= {
		.cra_name	= "zlib",
		.cra_flags	= CRYPTO_ALG_TYPE_PCOMPRESS,
		.cra_ctxsize	= sizeof(struct zlib_ctx),
		.cra_module	= THIS_MODULE,
		.cra_init	= zlib_init,
		.cra_exit	= zlib_exit,
	}
};

static int __init zlib_mod_init(void)
{
	return crypto_register_pcomp(&zlib_alg);
}

static void __exit zlib_mod_fini(void)
{
	crypto_unregister_pcomp(&zlib_alg);
}

module_init(zlib_mod_init);
module_exit(zlib_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Zlib Compression Algorithm");
MODULE_AUTHOR("Sony Corporation");