/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>,
 *                    University of Szeged, Hungary
 *
 * For licensing information, see the file 'LICENCE' in this directory
 * in the jffs2 directory.
 *
 * $Id: compr.c,v 1.7 2005/02/17 14:55:06 hvr Exp $
 *
 */

#include "compr.h"
#include <string.h>
#include <stdlib.h>
#include <linux/jffs2.h>

extern int page_size;

/* LIST IMPLEMENTATION (from linux/list.h) */

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name) \
        struct list_head name = LIST_HEAD_INIT(name)

static inline void __list_add(struct list_head *new,
                              struct list_head *prev,
                              struct list_head *next)
{
        next->prev = new;
        new->next = next;
        new->prev = prev;
        prev->next = new;
}

static inline void list_add(struct list_head *new, struct list_head *head)
{
        __list_add(new, head, head->next);
}

static inline void list_add_tail(struct list_head *new, struct list_head *head)
{
        __list_add(new, head->prev, head);
}

static inline void __list_del(struct list_head *prev, struct list_head *next)
{
        next->prev = prev;
        prev->next = next;
}

static inline void list_del(struct list_head *entry)
{
        __list_del(entry->prev, entry->next);
        entry->next = (void *) 0;
        entry->prev = (void *) 0;
}

#define list_entry(ptr, type, member) \
        ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

#define list_for_each_entry(pos, head, member)                          \
        for (pos = list_entry((head)->next, typeof(*pos), member);      \
             &pos->member != (head);                                    \
             pos = list_entry(pos->member.next, typeof(*pos), member))


/* 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;

/* Compression test stuffs */

static int jffs2_compression_check = 0;

static unsigned char *jffs2_compression_check_buf = NULL;

void jffs2_compression_check_set(int yesno)
{
        jffs2_compression_check = yesno;
}

int jffs2_compression_check_get(void)
{
        return jffs2_compression_check;
}

static int jffs2_error_cnt = 0;

int jffs2_compression_check_errorcnt_get(void)
{
        return jffs2_error_cnt;
}

#define JFFS2_BUFFER_FILL 0x55

/* Called before compression (if compression_check is setted) to prepare 
   the buffer for buffer overflow test */
static void jffs2_decompression_test_prepare(unsigned char *buf, int size)
{
        memset(buf,JFFS2_BUFFER_FILL,size+1);
}

/* Called after compression (if compression_check is setted) to test the result */
static void jffs2_decompression_test(struct jffs2_compressor *compr,
                                     unsigned char *data_in, unsigned char *output_buf,
                                     uint32_t cdatalen, uint32_t datalen, uint32_t buf_size)
{
        uint32_t i;

        /* buffer overflow test */
        for (i=buf_size;i>cdatalen;i--) {
                if (output_buf[i]!=JFFS2_BUFFER_FILL) {
                        fprintf(stderr,"COMPR_ERROR: buffer overflow at %s. "
                                    "(bs=%d csize=%d b[%d]=%d)\n", compr->name, 
                                    buf_size, cdatalen, i, (int)(output_buf[i]));
                        jffs2_error_cnt++;
                        return;
                }
        }
        /* allocing temporary buffer for decompression */
        if (!jffs2_compression_check_buf) {
                jffs2_compression_check_buf = malloc(page_size);
                if (!jffs2_compression_check_buf) {
                        fprintf(stderr,"No memory for buffer allocation. Compression check disabled.\n");
                        jffs2_compression_check = 0;
                        return;
                }
        }
        /* decompressing */
        if (!compr->decompress) {
                fprintf(stderr,"JFFS2 compression check: there is no decompress function at %s.\n", compr->name);
                jffs2_error_cnt++;
                return;
        }
        if (compr->decompress(output_buf,jffs2_compression_check_buf,cdatalen,datalen,NULL)) {
                fprintf(stderr,"JFFS2 compression check: decompression failed at %s.\n", compr->name);
                jffs2_error_cnt++;
        }
        /* validate decompression */
        else {
                for (i=0;i<datalen;i++) {
                        if (data_in[i]!=jffs2_compression_check_buf[i]) {
                                fprintf(stderr,"JFFS2 compression check: data mismatch at %s (pos %d).\n", compr->name, i);
                                jffs2_error_cnt++;
                                break;
                        }
                }                
        }
}

/* 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( 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:
                orig_slen = *datalen;
                orig_dlen = *cdatalen;
                output_buf = malloc(orig_dlen+jffs2_compression_check);
                if (!output_buf) {
                        fprintf(stderr,"mkfs.jffs2: No memory for compressor allocation. Compression failed.\n");
                        goto out;
                }
                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++;

                        if (jffs2_compression_check) /*preparing output buffer for testing buffer overflow */
                                jffs2_decompression_test_prepare(output_buf, orig_dlen);

                        *datalen  = orig_slen;
                        *cdatalen = orig_dlen;
                        compr_ret = this->compress(data_in, output_buf, datalen, cdatalen, NULL);
                        this->usecount--;
                        if (!compr_ret) {
                                ret = this->compr;
                                this->stat_compr_blocks++;
                                this->stat_compr_orig_size += *datalen;
                                this->stat_compr_new_size  += *cdatalen;
                                if (jffs2_compression_check)
                                        jffs2_decompression_test(this, data_in, output_buf, *cdatalen, *datalen, orig_dlen);
                                break;
                        }
                }
                if (ret == JFFS2_COMPR_NONE) free(output_buf);
                break;
        case JFFS2_COMPR_MODE_SIZE:
                orig_slen = *datalen;
                orig_dlen = *cdatalen;
                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+jffs2_compression_check)&&(this->compr_buf)) {
                                free(this->compr_buf);
                                this->compr_buf_size=0;
                                this->compr_buf=NULL;
                        }
                        if (!this->compr_buf) {
                                tmp_buf = malloc(orig_dlen+jffs2_compression_check);
                                if (!tmp_buf) {
                                        fprintf(stderr,"mkfs.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++;
                        if (jffs2_compression_check) /*preparing output buffer for testing buffer overflow */
                                jffs2_decompression_test_prepare(this->compr_buf,this->compr_buf_size);
                        *datalen  = orig_slen;
                        *cdatalen = orig_dlen;
                        compr_ret = this->compress(data_in, this->compr_buf, datalen, cdatalen, NULL);
                        this->usecount--;
                        if (!compr_ret) {
                                if (jffs2_compression_check)
                                    jffs2_decompression_test(this, data_in, this->compr_buf, *cdatalen, *datalen, this->compr_buf_size);
                                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;
                }
                break;
        default:
                fprintf(stderr,"mkfs.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_register_compressor(struct jffs2_compressor *comp)
{
        struct jffs2_compressor *this;

        if (!comp->name) {
                fprintf(stderr,"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;

        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:
        return 0;
}

int jffs2_unregister_compressor(struct jffs2_compressor *comp)
{

        if (comp->usecount) {
                fprintf(stderr,"mkfs.jffs2: Compressor modul is in use. Unregister failed.\n");
                return -1;
        }
        list_del(&comp->list);

        return 0;
}

#define JFFS2_STAT_BUF_SIZE 16000

char *jffs2_list_compressors(void)
{
        struct jffs2_compressor *this;
        char *buf, *act_buf;

        act_buf = buf = malloc(JFFS2_STAT_BUF_SIZE);
        list_for_each_entry(this, &jffs2_compressor_list, list) {
                act_buf += sprintf(act_buf, "%10s priority:%d ", this->name, this->priority);
                if ((this->disabled)||(!this->compress))
                        act_buf += sprintf(act_buf,"disabled");
                else
                        act_buf += sprintf(act_buf,"enabled");
                act_buf += sprintf(act_buf,"\n");
        }
        return buf;
}

char *jffs2_stats(void)
{
        struct jffs2_compressor *this;
        char *buf, *act_buf;

        act_buf = buf = malloc(JFFS2_STAT_BUF_SIZE);

        act_buf += sprintf(act_buf,"Compression mode: ");
        switch (jffs2_compression_mode) {
        case JFFS2_COMPR_MODE_NONE:
                act_buf += sprintf(act_buf,"none");
                break;
        case JFFS2_COMPR_MODE_PRIORITY:
                act_buf += sprintf(act_buf,"priority");
                break;
        case JFFS2_COMPR_MODE_SIZE:
                act_buf += sprintf(act_buf,"size");
                break;
        default:
                act_buf += sprintf(act_buf,"unkown");
                break;
        }
        act_buf += sprintf(act_buf,"\nCompressors:\n");
        act_buf += sprintf(act_buf,"%10s             ","none");
        act_buf += sprintf(act_buf,"compr: %d blocks (%d)  decompr: %d blocks\n", none_stat_compr_blocks, 
                           none_stat_compr_size, none_stat_decompr_blocks);
        list_for_each_entry(this, &jffs2_compressor_list, list) {
                act_buf += sprintf(act_buf,"%10s (prio:%d) ",this->name,this->priority);
                if ((this->disabled)||(!this->compress))
                        act_buf += sprintf(act_buf,"- ");
                else
                        act_buf += sprintf(act_buf,"+ ");
                act_buf += sprintf(act_buf,"compr: %d blocks (%d/%d)  decompr: %d blocks ", this->stat_compr_blocks, 
                                   this->stat_compr_new_size, this->stat_compr_orig_size, 
                                   this->stat_decompr_blocks);
                act_buf += sprintf(act_buf,"\n");
        }
        return buf;
}

int jffs2_set_compression_mode_name(const char *name) 
{
        if (!strcmp("none",name)) {
                jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
                return 0;
        }
        if (!strcmp("priority",name)) {
                jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;
                return 0;
        }
        if (!strcmp("size",name)) {
                jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
                return 0;
        }
        return 1;
}

static int jffs2_compressor_Xable(const char *name, int disabled)
{
        struct jffs2_compressor *this;
        list_for_each_entry(this, &jffs2_compressor_list, list) {
                if (!strcmp(this->name, name)) {
                        this->disabled = disabled;
                        return 0;
                }
        }
        return 1;
}

int jffs2_enable_compressor_name(const char *name)
{
        return jffs2_compressor_Xable(name, 0);
}

int jffs2_disable_compressor_name(const char *name)
{
        return jffs2_compressor_Xable(name, 1);
}

int jffs2_set_compressor_priority(const char *name, int priority)
{
        struct jffs2_compressor *this,*comp;
        list_for_each_entry(this, &jffs2_compressor_list, list) {
                if (!strcmp(this->name, name)) {
                        this->priority = priority;
                        comp = this;
                        goto reinsert;
                }
        }
        fprintf(stderr,"mkfs.jffs2: compressor %s not found.\n",name);
        return 1;
reinsert:
        /* list is sorted in the order of priority, so if
           we change it we have to reinsert it into the
           good place */
        list_del(&comp->list);
        list_for_each_entry(this, &jffs2_compressor_list, list) {
                if (this->priority < comp->priority) {
                        list_add(&comp->list, this->list.prev);
                        return 0;
                }
        }
        list_add_tail(&comp->list, &jffs2_compressor_list);
        return 0;
}


int jffs2_compressors_init(void)
{
#ifdef CONFIG_JFFS2_ZLIB
        jffs2_zlib_init();
#endif
#ifdef CONFIG_JFFS2_RTIME
        jffs2_rtime_init();
#endif
#ifdef CONFIG_JFFS2_LZARI
        jffs2_lzari_init();
#endif
#ifdef CONFIG_JFFS2_LZO
        jffs2_lzo_init();
#endif
        return 0;
}

int jffs2_compressors_exit(void)
{
#ifdef CONFIG_JFFS2_LZO
        jffs2_lzo_exit();
#endif
#ifdef CONFIG_JFFS2_LZARI
        jffs2_lzari_exit();
#endif
#ifdef CONFIG_JFFS2_RTIME
        jffs2_rtime_exit();
#endif
#ifdef CONFIG_JFFS2_ZLIB
        jffs2_zlib_exit();
#endif
        return 0;
}
