/*****************************************************************************\
 *
 *  zlib.h -- interface of the 'zlib' general purpose compression library
 *  version 1.2.5, April 19th, 2010
 *
 *  Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler
 *
 *  This software is provided 'as-is', without any express or implied
 *  warranty.  In no event will the authors be held liable for any damages
 *  arising from the use of this software.
 *
 *  Permission is granted to anyone to use this software for any purpose,
 *  including commercial applications, and to alter it and redistribute it
 *  freely, subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you must not
 *     claim that you wrote the original software. If you use this software
 *     in a product, an acknowledgment in the product documentation would be
 *     appreciated but is not required.
 *  2. Altered source versions must be plainly marked as such, and must not be
 *     misrepresented as being the original software.
 *  3. This notice may not be removed or altered from any source distribution.
 *
 *  Jean-loup Gailly
 *  Mark Adler
\*****************************************************************************/


#include <sys/kmem.h>
#include <sys/zmod.h>
#include <spl-debug.h>
#include <libkern/zlib.h>

#ifdef DEBUG_SUBSYSTEM
#undef DEBUG_SUBSYSTEM
#endif

#define DEBUG_SUBSYSTEM SS_ZLIB

static spl_kmem_cache_t *zlib_workspace_cache;

/*
 * A kmem_cache is used for the zlib workspaces to avoid having to vmalloc
 * and vfree for every call.  Using a kmem_cache also has the advantage
 * that improves the odds that the memory used will be local to this cpu.
 * To further improve things it might be wise to create a dedicated per-cpu
 * workspace for use.  This would take some additional care because we then
 * must disable preemption around the critical section, and verify that
 * zlib_deflate* and zlib_inflate* never internally call schedule().
 */
static void *
zlib_workspace_alloc(int flags)
{
	return kmem_cache_alloc(zlib_workspace_cache, flags & ~(__GFP_FS));
}

static void
zlib_workspace_free(void *workspace)
{
	kmem_cache_free(zlib_workspace_cache, workspace);
}

/*
 * Compresses the source buffer into the destination buffer. The level
 * parameter has the same meaning as in deflateInit.  sourceLen is the byte
 * length of the source buffer. Upon entry, destLen is the total size of the
 * destination buffer, which must be at least 0.1% larger than sourceLen plus
 * 12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
 *
 * compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
 * memory, Z_BUF_ERROR if there was not enough room in the output buffer,
 * Z_STREAM_ERROR if the level parameter is invalid.
 */
int
z_compress_level(void *dest, size_t *destLen, const void *source,
                 size_t sourceLen, int level)
{
	z_stream stream;
	int err;

	stream.next_in = (Byte *)source;
	stream.avail_in = (uInt)sourceLen;
	stream.next_out = dest;
	stream.avail_out = (uInt)*destLen;

	if ((size_t)stream.avail_out != *destLen)
		return Z_BUF_ERROR;

	stream.workspace = zlib_workspace_alloc(KM_SLEEP);
	if (!stream.workspace)
		return Z_MEM_ERROR;

	err = zlib_deflateInit(&stream, level);
	if (err != Z_OK) {
		zlib_workspace_free(stream.workspace);
		return err;
	}

	err = zlib_deflate(&stream, Z_FINISH);
	if (err != Z_STREAM_END) {
		zlib_deflateEnd(&stream);
		zlib_workspace_free(stream.workspace);
		return err == Z_OK ? Z_BUF_ERROR : err;
	}
	*destLen = stream.total_out;

	err = zlib_deflateEnd(&stream);
	zlib_workspace_free(stream.workspace);

	return err;
}
EXPORT_SYMBOL(z_compress_level);

/*
 * Decompresses the source buffer into the destination buffer.  sourceLen is
 * the byte length of the source buffer. Upon entry, destLen is the total
 * size of the destination buffer, which must be large enough to hold the
 * entire uncompressed data. (The size of the uncompressed data must have
 * been saved previously by the compressor and transmitted to the decompressor
 * by some mechanism outside the scope of this compression library.)
 * Upon exit, destLen is the actual size of the compressed buffer.
 * This function can be used to decompress a whole file at once if the
 * input file is mmap'ed.
 *
 * uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
 * enough memory, Z_BUF_ERROR if there was not enough room in the output
 * buffer, or Z_DATA_ERROR if the input data was corrupted.
 */
int
z_uncompress(void *dest, size_t *destLen, const void *source, size_t sourceLen)
{
	z_stream stream;
	int err;

	stream.next_in = (Byte *)source;
	stream.avail_in = (uInt)sourceLen;
	stream.next_out = dest;
	stream.avail_out = (uInt)*destLen;

	if ((size_t)stream.avail_out != *destLen)
		return Z_BUF_ERROR;

	stream.workspace = zlib_workspace_alloc(KM_SLEEP);
	if (!stream.workspace)
		return Z_MEM_ERROR;

	err = zlib_inflateInit(&stream);
	if (err != Z_OK) {
		zlib_workspace_free(stream.workspace);
		return err;
	}

	err = zlib_inflate(&stream, Z_FINISH);
	if (err != Z_STREAM_END) {
		zlib_inflateEnd(&stream);
		zlib_workspace_free(stream.workspace);

		if (err == Z_NEED_DICT ||
		   (err == Z_BUF_ERROR && stream.avail_in == 0))
			return Z_DATA_ERROR;

		return err;
	}
	*destLen = stream.total_out;

	err = zlib_inflateEnd(&stream);
	zlib_workspace_free(stream.workspace);

	return err;
}
EXPORT_SYMBOL(z_uncompress);

int
spl_zlib_init(void)
{
	int size;
        SENTRY;

	size = MAX(spl_zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
	    zlib_inflate_workspacesize());

	zlib_workspace_cache = kmem_cache_create(
	    "spl_zlib_workspace_cache",
	    size, 0, NULL, NULL, NULL, NULL, NULL,
	    KMC_VMEM | KMC_NOEMERGENCY);
        if (!zlib_workspace_cache)
		SRETURN(1);

        SRETURN(0);
}

void
spl_zlib_fini(void)
{
        SENTRY;
	kmem_cache_destroy(zlib_workspace_cache);
        zlib_workspace_cache = NULL;
        SEXIT;
}
