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

   * Copyright © 2001-2007 Red Hat, Inc.

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

   * Copyright © 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>,

   *		    University of Szeged, Hungary

   *

   * Created by Arjan van de Ven <arjan@infradead.org>
   *

   * For licensing information, see the file 'LICENCE' in this directory.
   *

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include "compr.h"
  
  static DEFINE_SPINLOCK(jffs2_compressor_list_lock);
  
  /* Available compressors are on this list */
  static LIST_HEAD(jffs2_compressor_list);
  
  /* Actual compression mode */
  static int jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;
  
  /* Statistics for blocks stored without compression */
  static uint32_t none_stat_compr_blocks=0,none_stat_decompr_blocks=0,none_stat_compr_size=0;

  
  /*
   * Return 1 to use this compression
   */
  static int jffs2_is_best_compression(struct jffs2_compressor *this,
  		struct jffs2_compressor *best, uint32_t size, uint32_t bestsize)
  {
  	switch (jffs2_compression_mode) {
  	case JFFS2_COMPR_MODE_SIZE:
  		if (bestsize > size)
  			return 1;
  		return 0;
  	case JFFS2_COMPR_MODE_FAVOURLZO:
  		if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > size))
  			return 1;
  		if ((best->compr != JFFS2_COMPR_LZO) && (bestsize > size))
  			return 1;
  		if ((this->compr == JFFS2_COMPR_LZO) && (bestsize > (size * FAVOUR_LZO_PERCENT / 100)))
  			return 1;
  		if ((bestsize * FAVOUR_LZO_PERCENT / 100) > size)
  			return 1;
  
  		return 0;
  	}
  	/* Shouldn't happen */
  	return 0;
  }

  /*
   * jffs2_selected_compress:
   * @compr: Explicit compression type to use (ie, JFFS2_COMPR_ZLIB).
   *	If 0, just take the first available compression mode.
   * @data_in: Pointer to uncompressed data
   * @cpage_out: Pointer to returned pointer to buffer for compressed data
   * @datalen: On entry, holds the amount of data available for compression.
   *	On exit, expected to hold the amount of data actually compressed.
   * @cdatalen: On entry, holds the amount of space available for compressed
   *	data. On exit, expected to hold the actual size of the compressed
   *	data.
   *
   * Returns: the compression type used.  Zero is used to show that the data
   * could not be compressed; probably because we couldn't find the requested
   * compression mode.
   */
  static int jffs2_selected_compress(u8 compr, unsigned char *data_in,
  		unsigned char **cpage_out, u32 *datalen, u32 *cdatalen)
  {
  	struct jffs2_compressor *this;
  	int err, ret = JFFS2_COMPR_NONE;
  	uint32_t orig_slen, orig_dlen;
  	char *output_buf;
  
  	output_buf = kmalloc(*cdatalen, GFP_KERNEL);
  	if (!output_buf) {

  		pr_warn("No memory for compressor allocation. Compression failed.
  ");

  		return ret;
  	}
  	orig_slen = *datalen;
  	orig_dlen = *cdatalen;
  	spin_lock(&jffs2_compressor_list_lock);
  	list_for_each_entry(this, &jffs2_compressor_list, list) {
  		/* Skip decompress-only and disabled modules */
  		if (!this->compress || this->disabled)
  			continue;
  
  		/* Skip if not the desired compression type */
  		if (compr && (compr != this->compr))
  			continue;
  
  		/*
  		 * Either compression type was unspecified, or we found our
  		 * compressor; either way, we're good to go.
  		 */
  		this->usecount++;
  		spin_unlock(&jffs2_compressor_list_lock);
  
  		*datalen  = orig_slen;
  		*cdatalen = orig_dlen;
  		err = this->compress(data_in, output_buf, datalen, cdatalen);
  
  		spin_lock(&jffs2_compressor_list_lock);
  		this->usecount--;
  		if (!err) {
  			/* Success */
  			ret = this->compr;
  			this->stat_compr_blocks++;
  			this->stat_compr_orig_size += *datalen;
  			this->stat_compr_new_size += *cdatalen;
  			break;
  		}
  	}
  	spin_unlock(&jffs2_compressor_list_lock);
  	if (ret == JFFS2_COMPR_NONE)
  		kfree(output_buf);
  	else
  		*cpage_out = output_buf;
  
  	return ret;
  }

  /* jffs2_compress:

   * @data_in: Pointer to uncompressed data
   * @cpage_out: Pointer to returned pointer to buffer for compressed data

   * @datalen: On entry, holds the amount of data available for compression.
   *	On exit, expected to hold the amount of data actually compressed.
   * @cdatalen: On entry, holds the amount of space available for compressed
   *	data. On exit, expected to hold the actual size of the compressed
   *	data.
   *
   * Returns: Lower byte to be stored with data indicating compression type used.

   * Zero is used to show that the data could not be compressed - the

   * compressed version was actually larger than the original.
   * Upper byte will be used later. (soon)
   *
   * If the cdata buffer isn't large enough to hold all the uncompressed data,

   * jffs2_compress should compress as much as will fit, and should set

   * *datalen accordingly to show the amount of data which were compressed.
   */
  uint16_t jffs2_compress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,

  			unsigned char *data_in, unsigned char **cpage_out,
  			uint32_t *datalen, uint32_t *cdatalen)

  {
  	int ret = JFFS2_COMPR_NONE;

  	int mode, compr_ret;

  	struct jffs2_compressor *this, *best=NULL;
  	unsigned char *output_buf = NULL, *tmp_buf;
  	uint32_t orig_slen, orig_dlen;
  	uint32_t best_slen=0, best_dlen=0;

  	if (c->mount_opts.override_compr)
  		mode = c->mount_opts.compr;
  	else
  		mode = jffs2_compression_mode;
  
  	switch (mode) {

  	case JFFS2_COMPR_MODE_NONE:
  		break;
  	case JFFS2_COMPR_MODE_PRIORITY:

  		ret = jffs2_selected_compress(0, data_in, cpage_out, datalen,
  				cdatalen);

  		break;
  	case JFFS2_COMPR_MODE_SIZE:

  	case JFFS2_COMPR_MODE_FAVOURLZO:

  		orig_slen = *datalen;
  		orig_dlen = *cdatalen;
  		spin_lock(&jffs2_compressor_list_lock);
  		list_for_each_entry(this, &jffs2_compressor_list, list) {
  			/* Skip decompress-only backwards-compatibility and disabled modules */
  			if ((!this->compress)||(this->disabled))
  				continue;
  			/* Allocating memory for output buffer if necessary */

  			if ((this->compr_buf_size < orig_slen) && (this->compr_buf)) {

  				spin_unlock(&jffs2_compressor_list_lock);
  				kfree(this->compr_buf);
  				spin_lock(&jffs2_compressor_list_lock);
  				this->compr_buf_size=0;
  				this->compr_buf=NULL;
  			}
  			if (!this->compr_buf) {
  				spin_unlock(&jffs2_compressor_list_lock);

  				tmp_buf = kmalloc(orig_slen, GFP_KERNEL);

  				spin_lock(&jffs2_compressor_list_lock);
  				if (!tmp_buf) {

  					pr_warn("No memory for compressor allocation. (%d bytes)
  ",

  						orig_slen);

  					continue;
  				}
  				else {
  					this->compr_buf = tmp_buf;

  					this->compr_buf_size = orig_slen;

  				}
  			}
  			this->usecount++;
  			spin_unlock(&jffs2_compressor_list_lock);
  			*datalen  = orig_slen;
  			*cdatalen = orig_dlen;

  			compr_ret = this->compress(data_in, this->compr_buf, datalen, cdatalen);

  			spin_lock(&jffs2_compressor_list_lock);
  			this->usecount--;
  			if (!compr_ret) {

  				if (((!best_dlen) || jffs2_is_best_compression(this, best, *cdatalen, best_dlen))
  						&& (*cdatalen < *datalen)) {

  					best_dlen = *cdatalen;
  					best_slen = *datalen;
  					best = this;
  				}
  			}
  		}
  		if (best_dlen) {
  			*cdatalen = best_dlen;
  			*datalen  = best_slen;
  			output_buf = best->compr_buf;
  			best->compr_buf = NULL;
  			best->compr_buf_size = 0;
  			best->stat_compr_blocks++;
  			best->stat_compr_orig_size += best_slen;
  			best->stat_compr_new_size  += best_dlen;
  			ret = best->compr;

  			*cpage_out = output_buf;

  		}
  		spin_unlock(&jffs2_compressor_list_lock);
  		break;

  	case JFFS2_COMPR_MODE_FORCELZO:
  		ret = jffs2_selected_compress(JFFS2_COMPR_LZO, data_in,
  				cpage_out, datalen, cdatalen);
  		break;
  	case JFFS2_COMPR_MODE_FORCEZLIB:
  		ret = jffs2_selected_compress(JFFS2_COMPR_ZLIB, data_in,
  				cpage_out, datalen, cdatalen);
  		break;

  	default:

  		pr_err("unknown compression mode
  ");

  	}

  	if (ret == JFFS2_COMPR_NONE) {
  		*cpage_out = data_in;
  		*datalen = *cdatalen;
  		none_stat_compr_blocks++;
  		none_stat_compr_size += *datalen;
  	}

  	return ret;
  }
  
  int jffs2_decompress(struct jffs2_sb_info *c, struct jffs2_inode_info *f,

  		     uint16_t comprtype, unsigned char *cdata_in,

  		     unsigned char *data_out, uint32_t cdatalen, uint32_t datalen)
  {

  	struct jffs2_compressor *this;
  	int ret;

  
  	/* Older code had a bug where it would write non-zero 'usercompr'
  	   fields. Deal with it. */
  	if ((comprtype & 0xff) <= JFFS2_COMPR_ZLIB)
  		comprtype &= 0xff;
  
  	switch (comprtype & 0xff) {
  	case JFFS2_COMPR_NONE:
  		/* This should be special-cased elsewhere, but we might as well deal with it */
  		memcpy(data_out, cdata_in, datalen);

  		none_stat_decompr_blocks++;

  		break;
  	case JFFS2_COMPR_ZERO:
  		memset(data_out, 0, datalen);
  		break;
  	default:

  		spin_lock(&jffs2_compressor_list_lock);
  		list_for_each_entry(this, &jffs2_compressor_list, list) {
  			if (comprtype == this->compr) {
  				this->usecount++;
  				spin_unlock(&jffs2_compressor_list_lock);

  				ret = this->decompress(cdata_in, data_out, cdatalen, datalen);

  				spin_lock(&jffs2_compressor_list_lock);
  				if (ret) {

  					pr_warn("Decompressor \"%s\" returned %d
  ",
  						this->name, ret);

  				}
  				else {
  					this->stat_decompr_blocks++;
  				}
  				this->usecount--;
  				spin_unlock(&jffs2_compressor_list_lock);
  				return ret;
  			}
  		}

  		pr_warn("compression type 0x%02x not available
  ", comprtype);

  		spin_unlock(&jffs2_compressor_list_lock);

  		return -EIO;
  	}
  	return 0;
  }
  
  int jffs2_register_compressor(struct jffs2_compressor *comp)
  {

  	struct jffs2_compressor *this;

  	if (!comp->name) {

  		pr_warn("NULL compressor name at registering JFFS2 compressor. Failed.
  ");

  		return -1;
  	}
  	comp->compr_buf_size=0;
  	comp->compr_buf=NULL;
  	comp->usecount=0;
  	comp->stat_compr_orig_size=0;
  	comp->stat_compr_new_size=0;
  	comp->stat_compr_blocks=0;
  	comp->stat_decompr_blocks=0;

  	jffs2_dbg(1, "Registering JFFS2 compressor \"%s\"
  ", comp->name);

  	spin_lock(&jffs2_compressor_list_lock);

  	list_for_each_entry(this, &jffs2_compressor_list, list) {
  		if (this->priority < comp->priority) {
  			list_add(&comp->list, this->list.prev);
  			goto out;
  		}
  	}
  	list_add_tail(&comp->list, &jffs2_compressor_list);

  out:

  	D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
  		printk(KERN_DEBUG "Compressor \"%s\", prio %d
  ", this->name, this->priority);
  	})

  	spin_unlock(&jffs2_compressor_list_lock);

  	return 0;

  }
  
  int jffs2_unregister_compressor(struct jffs2_compressor *comp)
  {

  	D2(struct jffs2_compressor *this);

  	jffs2_dbg(1, "Unregistering JFFS2 compressor \"%s\"
  ", comp->name);

  	spin_lock(&jffs2_compressor_list_lock);

  	if (comp->usecount) {
  		spin_unlock(&jffs2_compressor_list_lock);

  		pr_warn("Compressor module is in use. Unregister failed.
  ");

  		return -1;
  	}
  	list_del(&comp->list);

  	D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
  		printk(KERN_DEBUG "Compressor \"%s\", prio %d
  ", this->name, this->priority);
  	})
  	spin_unlock(&jffs2_compressor_list_lock);
  	return 0;

  }

  void jffs2_free_comprbuf(unsigned char *comprbuf, unsigned char *orig)
  {

  	if (orig != comprbuf)
  		kfree(comprbuf);

  }

  int __init jffs2_compressors_init(void)

  {
  /* Registering compressors */
  #ifdef CONFIG_JFFS2_ZLIB

  	jffs2_zlib_init();

  #endif
  #ifdef CONFIG_JFFS2_RTIME

  	jffs2_rtime_init();

  #endif
  #ifdef CONFIG_JFFS2_RUBIN

  	jffs2_rubinmips_init();
  	jffs2_dynrubin_init();

  #endif

  #ifdef CONFIG_JFFS2_LZO
  	jffs2_lzo_init();
  #endif

  /* Setting default compression mode */
  #ifdef CONFIG_JFFS2_CMODE_NONE

  	jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;

  	jffs2_dbg(1, "default compression mode: none
  ");

  #else
  #ifdef CONFIG_JFFS2_CMODE_SIZE

  	jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;

  	jffs2_dbg(1, "default compression mode: size
  ");

  #else

  #ifdef CONFIG_JFFS2_CMODE_FAVOURLZO
  	jffs2_compression_mode = JFFS2_COMPR_MODE_FAVOURLZO;

  	jffs2_dbg(1, "default compression mode: favourlzo
  ");

  #else

  	jffs2_dbg(1, "default compression mode: priority
  ");

  #endif
  #endif

  #endif

  	return 0;

  }

  int jffs2_compressors_exit(void)

  {
  /* Unregistering compressors */

  #ifdef CONFIG_JFFS2_LZO
  	jffs2_lzo_exit();
  #endif

  #ifdef CONFIG_JFFS2_RUBIN

  	jffs2_dynrubin_exit();
  	jffs2_rubinmips_exit();

  #endif
  #ifdef CONFIG_JFFS2_RTIME

  	jffs2_rtime_exit();

  #endif
  #ifdef CONFIG_JFFS2_ZLIB

  	jffs2_zlib_exit();

  #endif

  	return 0;

  }