/* * JFFS2 -- Journalling Flash File System, Version 2. * * Copyright (C) 2001-2003 Red Hat, Inc. * Created by Arjan van de Ven <arjanv@redhat.com> * * Copyright (C) 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>, *                    University of Szeged, Hungary * * For licensing information, see the file 'LICENCE' in this directory. * * $Id: compr.c,v 1.42 2004/08/07 21:56:08 dwmw2 Exp $ * */#include "compr.h"static spinlock_t jffs2_compressor_list_lock = SPIN_LOCK_UNLOCKED;/* Available compressors are on this list */static LIST_HEAD(jffs2_compressor_list);/* Actual compression mode */static int jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;void jffs2_set_compression_mode(int mode) {        jffs2_compression_mode = mode;}int jffs2_get_compression_mode(void){        return jffs2_compression_mode;}/* Statistics for blocks stored without compression */static uint32_t none_stat_compr_blocks=0,none_stat_decompr_blocks=0,none_stat_compr_size=0;/* jffs2_compress: * @data: Pointer to uncompressed data * @cdata: 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 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;        switch (jffs2_compression_mode) {        case JFFS2_COMPR_MODE_NONE:                break;        case JFFS2_COMPR_MODE_PRIORITY:                output_buf = kmalloc(*cdatalen,GFP_KERNEL);                if (!output_buf) {                        printk(KERN_WARNING "JFFS2: No memory for compressor allocation. Compression failed.\n");                        goto out;                }                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;                        this->usecount++;                        spin_unlock(&jffs2_compressor_list_lock);                        *datalen  = orig_slen;                        *cdatalen = orig_dlen;                        compr_ret = this->compress(data_in, output_buf, datalen, cdatalen, NULL);                        spin_lock(&jffs2_compressor_list_lock);                        this->usecount--;                        if (!compr_ret) {                                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);                break;        case JFFS2_COMPR_MODE_SIZE:                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_dlen)&&(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_dlen,GFP_KERNEL);                                spin_lock(&jffs2_compressor_list_lock);                                if (!tmp_buf) {                                        printk(KERN_WARNING "JFFS2: No memory for compressor allocation. (%d bytes)\n",orig_dlen);                                        continue;                                }                                else {                                        this->compr_buf = tmp_buf;                                        this->compr_buf_size = orig_dlen;                                }                        }                        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, NULL);                        spin_lock(&jffs2_compressor_list_lock);                        this->usecount--;                        if (!compr_ret) {                                if ((!best_dlen)||(best_dlen>*cdatalen)) {                                        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;                }                spin_unlock(&jffs2_compressor_list_lock);                break;        default:                printk(KERN_ERR "JFFS2: unknow compression mode.\n");        } out:        if (ret == JFFS2_COMPR_NONE) {	        *cpage_out = data_in;	        *datalen = *cdatalen;                none_stat_compr_blocks++;                none_stat_compr_size += *datalen;        }        else {                *cpage_out = output_buf;        }	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, NULL);                                spin_lock(&jffs2_compressor_list_lock);                                if (ret) {                                        printk(KERN_WARNING "Decompressor \"%s\" returned %d\n", this->name, ret);                                }                                else {                                        this->stat_decompr_blocks++;                                }                                this->usecount--;                                spin_unlock(&jffs2_compressor_list_lock);                                return ret;                        }                }		printk(KERN_WARNING "JFFS2 compression type 0x%02x not available.\n", 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) {                printk(KERN_WARNING "NULL compressor name at registering JFFS2 compressor. Failed.\n");                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;        D1(printk(KERN_DEBUG "Registering JFFS2 compressor \"%s\"\n", comp->name));        spin_lock(&jffs2_compressor_list_lock);