/*
   * JFFS2 -- Journalling Flash File System, Version 2.
   *

   * Copyright © 2001-2007 Red Hat, Inc.

   * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>

   *
   * Created by David Woodhouse <dwmw2@infradead.org>
   *
   * For licensing information, see the file 'LICENCE' in this directory.
   *

   */
  
  #if !defined(__KERNEL__) && !defined(__ECOS)
  #error "The userspace support got too messy and was removed. Update your mkfs.jffs2"
  #endif

  #include <linux/kernel.h>

  #include <linux/zlib.h>
  #include <linux/zutil.h>

  #include "nodelist.h"
  #include "compr.h"

  	/* Plan: call deflate() with avail_in == *sourcelen,
  		avail_out = *dstlen - 12 and flush == Z_FINISH.

  		If it doesn't manage to finish,	call it again with
  		avail_in == 0 and avail_out set to the remaining 12

  		bytes for it to clean up.

  	   Q: Is 12 bytes sufficient?
  	*/
  #define STREAM_END_SPACE 12

  static DEFINE_MUTEX(deflate_mutex);
  static DEFINE_MUTEX(inflate_mutex);

  static z_stream inf_strm, def_strm;
  
  #ifdef __KERNEL__ /* Linux-only */
  #include <linux/vmalloc.h>
  #include <linux/init.h>

  #include <linux/mutex.h>

  
  static int __init alloc_workspaces(void)
  {

  	def_strm.workspace = vmalloc(zlib_deflate_workspacesize(MAX_WBITS,
  							MAX_MEM_LEVEL));

  	if (!def_strm.workspace) {

  		printk(KERN_WARNING "Failed to allocate %d bytes for deflate workspace
  ", zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL));

  		return -ENOMEM;
  	}

  	D1(printk(KERN_DEBUG "Allocated %d bytes for deflate workspace
  ", zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL)));

  	inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
  	if (!inf_strm.workspace) {
  		printk(KERN_WARNING "Failed to allocate %d bytes for inflate workspace
  ", zlib_inflate_workspacesize());
  		vfree(def_strm.workspace);
  		return -ENOMEM;
  	}
  	D1(printk(KERN_DEBUG "Allocated %d bytes for inflate workspace
  ", zlib_inflate_workspacesize()));
  	return 0;
  }
  
  static void free_workspaces(void)
  {
  	vfree(def_strm.workspace);
  	vfree(inf_strm.workspace);
  }
  #else
  #define alloc_workspaces() (0)
  #define free_workspaces() do { } while(0)
  #endif /* __KERNEL__ */

  static int jffs2_zlib_compress(unsigned char *data_in,
  			       unsigned char *cpage_out,

  			       uint32_t *sourcelen, uint32_t *dstlen)

  {
  	int ret;
  
  	if (*dstlen <= STREAM_END_SPACE)
  		return -1;

  	mutex_lock(&deflate_mutex);

  
  	if (Z_OK != zlib_deflateInit(&def_strm, 3)) {
  		printk(KERN_WARNING "deflateInit failed
  ");

  		mutex_unlock(&deflate_mutex);

  		return -1;
  	}
  
  	def_strm.next_in = data_in;
  	def_strm.total_in = 0;

  	def_strm.next_out = cpage_out;
  	def_strm.total_out = 0;
  
  	while (def_strm.total_out < *dstlen - STREAM_END_SPACE && def_strm.total_in < *sourcelen) {
  		def_strm.avail_out = *dstlen - (def_strm.total_out + STREAM_END_SPACE);
  		def_strm.avail_in = min((unsigned)(*sourcelen-def_strm.total_in), def_strm.avail_out);
  		D1(printk(KERN_DEBUG "calling deflate with avail_in %d, avail_out %d
  ",
  			  def_strm.avail_in, def_strm.avail_out));
  		ret = zlib_deflate(&def_strm, Z_PARTIAL_FLUSH);

  		D1(printk(KERN_DEBUG "deflate returned with avail_in %d, avail_out %d, total_in %ld, total_out %ld
  ",

  			  def_strm.avail_in, def_strm.avail_out, def_strm.total_in, def_strm.total_out));
  		if (ret != Z_OK) {
  			D1(printk(KERN_DEBUG "deflate in loop returned %d
  ", ret));
  			zlib_deflateEnd(&def_strm);

  			mutex_unlock(&deflate_mutex);

  			return -1;
  		}
  	}
  	def_strm.avail_out += STREAM_END_SPACE;
  	def_strm.avail_in = 0;
  	ret = zlib_deflate(&def_strm, Z_FINISH);
  	zlib_deflateEnd(&def_strm);
  
  	if (ret != Z_STREAM_END) {
  		D1(printk(KERN_DEBUG "final deflate returned %d
  ", ret));
  		ret = -1;
  		goto out;
  	}
  
  	if (def_strm.total_out >= def_strm.total_in) {
  		D1(printk(KERN_DEBUG "zlib compressed %ld bytes into %ld; failing
  ",
  			  def_strm.total_in, def_strm.total_out));
  		ret = -1;
  		goto out;
  	}
  
  	D1(printk(KERN_DEBUG "zlib compressed %ld bytes into %ld
  ",
  		  def_strm.total_in, def_strm.total_out));
  
  	*dstlen = def_strm.total_out;
  	*sourcelen = def_strm.total_in;
  	ret = 0;
   out:

  	mutex_unlock(&deflate_mutex);

  	return ret;
  }

  static int jffs2_zlib_decompress(unsigned char *data_in,
  				 unsigned char *cpage_out,

  				 uint32_t srclen, uint32_t destlen)

  {
  	int ret;
  	int wbits = MAX_WBITS;

  	mutex_lock(&inflate_mutex);

  
  	inf_strm.next_in = data_in;
  	inf_strm.avail_in = srclen;
  	inf_strm.total_in = 0;

  	inf_strm.next_out = cpage_out;
  	inf_strm.avail_out = destlen;
  	inf_strm.total_out = 0;
  
  	/* If it's deflate, and it's got no preset dictionary, then
  	   we can tell zlib to skip the adler32 check. */
  	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
  	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
  	    !(((data_in[0]<<8) + data_in[1]) % 31)) {
  
  		D2(printk(KERN_DEBUG "inflate skipping adler32
  "));
  		wbits = -((data_in[0] >> 4) + 8);
  		inf_strm.next_in += 2;
  		inf_strm.avail_in -= 2;
  	} else {
  		/* Let this remain D1 for now -- it should never happen */
  		D1(printk(KERN_DEBUG "inflate not skipping adler32
  "));
  	}
  
  
  	if (Z_OK != zlib_inflateInit2(&inf_strm, wbits)) {
  		printk(KERN_WARNING "inflateInit failed
  ");

  		mutex_unlock(&inflate_mutex);

  		return 1;
  	}
  
  	while((ret = zlib_inflate(&inf_strm, Z_FINISH)) == Z_OK)
  		;
  	if (ret != Z_STREAM_END) {
  		printk(KERN_NOTICE "inflate returned %d
  ", ret);
  	}
  	zlib_inflateEnd(&inf_strm);

  	mutex_unlock(&inflate_mutex);

  	return 0;

  }
  
  static struct jffs2_compressor jffs2_zlib_comp = {
      .priority = JFFS2_ZLIB_PRIORITY,
      .name = "zlib",
      .compr = JFFS2_COMPR_ZLIB,
      .compress = &jffs2_zlib_compress,
      .decompress = &jffs2_zlib_decompress,
  #ifdef JFFS2_ZLIB_DISABLED
      .disabled = 1,
  #else
      .disabled = 0,
  #endif
  };
  
  int __init jffs2_zlib_init(void)
  {
      int ret;
  
      ret = alloc_workspaces();
      if (ret)

  	    return ret;

  
      ret = jffs2_register_compressor(&jffs2_zlib_comp);
      if (ret)

  	    free_workspaces();

  
      return ret;
  }
  
  void jffs2_zlib_exit(void)
  {
      jffs2_unregister_compressor(&jffs2_zlib_comp);
      free_workspaces();
  }