/*
   * 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 <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);
  		vfree(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];
  	int window_bits, mem_level;
  	size_t workspacesize;
  	int ret;
  
  	ret = nla_parse(tb, ZLIB_COMP_MAX, params, len, NULL);
  	if (ret)
  		return ret;
  
  	zlib_comp_exit(ctx);
  
  	window_bits = tb[ZLIB_COMP_WINDOWBITS]
  					? nla_get_u32(tb[ZLIB_COMP_WINDOWBITS])
  					: MAX_WBITS;
  	mem_level = tb[ZLIB_COMP_MEMLEVEL]
  					? nla_get_u32(tb[ZLIB_COMP_MEMLEVEL])
  					: DEF_MEM_LEVEL;
  
  	workspacesize = zlib_deflate_workspacesize(window_bits, mem_level);
  	stream->workspace = vzalloc(workspacesize);
  	if (!stream->workspace)
  		return -ENOMEM;
  
  	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,
  				window_bits,
  				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
  ", 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
  ");
  		return -EAGAIN;
  
  	default:
  		pr_debug("zlib_deflate failed %d
  ", ret);
  		return -EINVAL;
  	}
  
  	ret = req->avail_out - stream->avail_out;
  	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)
  ",
  		 stream->avail_in, stream->avail_out,
  		 req->avail_in - stream->avail_in, ret);
  	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 ret;
  }
  
  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
  ", 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
  ", ret);
  		return -EINVAL;
  	}
  
  	ret = req->avail_out - stream->avail_out;
  	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)
  ",
  		 stream->avail_in, stream->avail_out,
  		 req->avail_in - stream->avail_in, ret);
  	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 ret;
  }
  
  
  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 = vzalloc(zlib_inflate_workspacesize());
  	if (!stream->workspace)
  		return -ENOMEM;
  
  	ret = zlib_inflateInit2(stream, ctx->decomp_windowBits);
  	if (ret != Z_OK) {
  		vfree(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
  ", 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
  ");
  		return -EAGAIN;
  
  	default:
  		pr_debug("zlib_inflate failed %d
  ", ret);
  		return -EINVAL;
  	}
  
  	ret = req->avail_out - stream->avail_out;
  	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)
  ",
  		 stream->avail_in, stream->avail_out,
  		 req->avail_in - stream->avail_in, ret);
  	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 ret;
  }
  
  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
  ", 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
  ", ret);
  		return -EINVAL;
  	}
  
  	ret = req->avail_out - stream->avail_out;
  	pr_debug("avail_in %u, avail_out %u (consumed %u, produced %u)
  ",
  		 stream->avail_in, stream->avail_out,
  		 req->avail_in - stream->avail_in, ret);
  	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 ret;
  }
  
  
  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");