src/fat.c - platform/external/dosfstools - Git at Google

 /* fat.c - Read/write access to the FAT

    Copyright (C) 1993 Werner Almesberger <werner.almesberger@lrc.di.epfl.ch>
    Copyright (C) 1998 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.

    On Debian systems, the complete text of the GNU General Public License
    can be found in /usr/share/common-licenses/GPL-3 file.
 */

 /* FAT32, VFAT, Atari format support, and various fixes additions May 1998
  * by Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> */


 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>

 #include "common.h"
 #include "dosfsck.h"
 #include "io.h"
 #include "check.h"
 #include "fat.h"


 static void get_fat(FAT_ENTRY *entry,void *fat,unsigned long cluster,DOS_FS *fs)
 {
     unsigned char *ptr;

     switch(fs->fat_bits) {
       case 12:
 	ptr = &((unsigned char *) fat)[cluster*3/2];
 	entry->value = 0xfff & (cluster & 1 ? (ptr[0] >> 4) | (ptr[1] << 4) :
 	  (ptr[0] | ptr[1] << 8));
 	break;
       case 16:
 	entry->value = CF_LE_W(((unsigned short *) fat)[cluster]);
 	break;
       case 32:
 	/* According to M$, the high 4 bits of a FAT32 entry are reserved and
 	 * are not part of the cluster number. So we cut them off. */
 	{
 	    unsigned long e = CF_LE_L(((unsigned int *) fat)[cluster]);
 	    entry->value = e & 0xfffffff;
 	    entry->reserved = e >> 28;
 	}
 	break;
       default:
 	die("Bad FAT entry size: %d bits.",fs->fat_bits);
     }
     entry->owner = NULL;
 }


 void read_fat(DOS_FS *fs)
 {
     int eff_size;
     unsigned long i;
     void *first,*second = NULL;
     int first_ok,second_ok;

     eff_size = ((fs->clusters+2ULL)*fs->fat_bits+7)/8ULL;
     first = alloc(eff_size);
     fs_read(fs->fat_start,eff_size,first);
     if (fs->nfats > 1) {
 	second = alloc(eff_size);
 	fs_read(fs->fat_start+fs->fat_size,eff_size,second);
     }
     if (second && memcmp(first,second,eff_size) != 0) {
 	FAT_ENTRY first_media, second_media;
 	get_fat(&first_media,first,0,fs);
 	get_fat(&second_media,second,0,fs);
 	first_ok = (first_media.value & FAT_EXTD(fs)) == FAT_EXTD(fs);
 	second_ok = (second_media.value & FAT_EXTD(fs)) == FAT_EXTD(fs);
 	if (first_ok && !second_ok) {
 	    printf("FATs differ - using first FAT.\n");
 	    fs_write(fs->fat_start+fs->fat_size,eff_size,first);
 	}
 	if (!first_ok && second_ok) {
 	    printf("FATs differ - using second FAT.\n");
 	    fs_write(fs->fat_start,eff_size,second);
 	    memcpy(first,second,eff_size);
 	}
 	if (first_ok && second_ok) {
 	    if (interactive) {
 		printf("FATs differ but appear to be intact. Use which FAT ?\n"
 		  "1) Use first FAT\n2) Use second FAT\n");
 		if (get_key("12","?") == '1') {
 		    fs_write(fs->fat_start+fs->fat_size,eff_size,first);
 		} else {
 		    fs_write(fs->fat_start,eff_size,second);
 		    memcpy(first,second,eff_size);
 		}
 	    }
 	    else {
 		printf("FATs differ but appear to be intact. Using first "
 		  "FAT.\n");
 		fs_write(fs->fat_start+fs->fat_size,eff_size,first);
 	    }
 	}
 	if (!first_ok && !second_ok) {
 	    printf("Both FATs appear to be corrupt. Giving up.\n");
 	    exit(1);
 	}
     }
     if (second) {
           free(second);
     }
     fs->fat = qalloc(&mem_queue,sizeof(FAT_ENTRY)*(fs->clusters+2ULL));
     for (i = 2; i < fs->clusters+2; i++) get_fat(&fs->fat[i],first,i,fs);
     for (i = 2; i < fs->clusters+2; i++)
 	if (fs->fat[i].value >= fs->clusters+2 &&
 	    (fs->fat[i].value < FAT_MIN_BAD(fs))) {
 	    printf("Cluster %ld out of range (%ld > %ld). Setting to EOF.\n",
 		   i-2,fs->fat[i].value,fs->clusters+2-1);
 	    set_fat(fs,i,-1);
 	}
     free(first);
 }


 void set_fat(DOS_FS *fs,unsigned long cluster,unsigned long new)
 {
     unsigned char data[4];
     int size;
     loff_t offs;

     if ((long)new == -1)
 	new = FAT_EOF(fs);
     else if ((long)new == -2)
 	new = FAT_BAD(fs);
     switch( fs->fat_bits ) {
       case 12:
 	offs = fs->fat_start+cluster*3/2;
 	if (cluster & 1) {
 	    data[0] = ((new & 0xf) << 4) | (fs->fat[cluster-1].value >> 8);
 	    data[1] = new >> 4;
 	}
 	else {
 	    data[0] = new & 0xff;
 	    data[1] = (new >> 8) | (cluster == fs->clusters-1 ? 0 :
 	      (0xff & fs->fat[cluster+1].value) << 4);
 	}
 	size = 2;
 	break;
       case 16:
 	offs = fs->fat_start+cluster*2;
 	*(unsigned short *) data = CT_LE_W(new);
 	size = 2;
 	break;
       case 32:
 	offs = fs->fat_start+cluster*4;
 	/* According to M$, the high 4 bits of a FAT32 entry are reserved and
 	 * are not part of the cluster number. So we never touch them. */
 	*(unsigned long *) data = CT_LE_L( (new & 0xfffffff) |
 					   (fs->fat[cluster].reserved << 28) );
 	size = 4;
 	break;
       default:
 	die("Bad FAT entry size: %d bits.",fs->fat_bits);
     }
     fs->fat[cluster].value = new;
     fs_write(offs,size,&data);
     fs_write(offs+fs->fat_size,size,&data);
 }


 int bad_cluster(DOS_FS *fs,unsigned long cluster)
 {
     return FAT_IS_BAD(fs,fs->fat[cluster].value);
 }


 unsigned long next_cluster(DOS_FS *fs,unsigned long cluster)
 {
     unsigned long value;

     value = fs->fat[cluster].value;
     if (FAT_IS_BAD(fs,value))
 	die("Internal error: next_cluster on bad cluster");
     return FAT_IS_EOF(fs,value) ? -1 : value;
 }


 loff_t cluster_start(DOS_FS *fs,unsigned long cluster)
 {
     return fs->data_start+((loff_t)cluster-2)*(unsigned long long)fs->cluster_size;
 }


 void set_owner(DOS_FS *fs,unsigned long cluster,DOS_FILE *owner)
 {
     if (owner && fs->fat[cluster].owner)
 	die("Internal error: attempt to change file owner");
     fs->fat[cluster].owner = owner;
 }


 DOS_FILE *get_owner(DOS_FS *fs,unsigned long cluster)
 {
     return fs->fat[cluster].owner;
 }


 void fix_bad(DOS_FS *fs)
 {
     unsigned long i;

     if (verbose)
 	printf("Checking for bad clusters.\n");
     for (i = 2; i < fs->clusters+2; i++)
 	if (!get_owner(fs,i) && !FAT_IS_BAD(fs,fs->fat[i].value))
 	    if (!fs_test(cluster_start(fs,i),fs->cluster_size)) {
 		printf("Cluster %lu is unreadable.\n",i);
 		set_fat(fs,i,-2);
 	    }
 }


 void reclaim_free(DOS_FS *fs)
 {
     int reclaimed;
     unsigned long i;

     if (verbose)
 	printf("Checking for unused clusters.\n");
     reclaimed = 0;
     for (i = 2; i < fs->clusters+2; i++)
 	if (!get_owner(fs,i) && fs->fat[i].value &&
 	    !FAT_IS_BAD(fs,fs->fat[i].value)) {
 	    set_fat(fs,i,0);
 	    reclaimed++;
 	}
     if (reclaimed)
 	printf("Reclaimed %d unused cluster%s (%llu bytes).\n",reclaimed,
 	  reclaimed == 1 ?  "" : "s",(unsigned long long)reclaimed*fs->cluster_size);
 }


 static void tag_free(DOS_FS *fs,DOS_FILE *ptr)
 {
     DOS_FILE *owner;
     int prev;
     unsigned long i,walk;

     for (i = 2; i < fs->clusters+2; i++)
 	if (fs->fat[i].value && !FAT_IS_BAD(fs,fs->fat[i].value) &&
 	    !get_owner(fs,i) && !fs->fat[i].prev) {
 	    prev = 0;
 	    for (walk = i; walk > 0 && walk != -1;
 		 walk = next_cluster(fs,walk)) {
 		if (!(owner = get_owner(fs,walk))) set_owner(fs,walk,ptr);
 		else if (owner != ptr)
 		        die("Internal error: free chain collides with file");
 		    else {
 			set_fat(fs,prev,-1);
 			break;
 		    }
 		prev = walk;
 	    }
 	}
 }


 void reclaim_file(DOS_FS *fs)
 {
     DOS_FILE dummy;
     int reclaimed,files,changed;
     unsigned long i,next,walk;

     if (verbose)
 	printf("Reclaiming unconnected clusters.\n");
     for (i = 2; i < fs->clusters+2; i++) fs->fat[i].prev = 0;
     for (i = 2; i < fs->clusters+2; i++) {
 	next = fs->fat[i].value;
 	if (!get_owner(fs,i) && next && next < fs->clusters+2) {
 	    if (get_owner(fs,next) || !fs->fat[next].value ||
 		FAT_IS_BAD(fs,fs->fat[next].value)) set_fat(fs,i,-1);
 	    else fs->fat[next].prev++;
 	}
     }
     do {
 	tag_free(fs,&dummy);
 	changed = 0;
 	for (i = 2; i < fs->clusters+2; i++)
 	    if (fs->fat[i].value && !FAT_IS_BAD(fs,fs->fat[i].value) &&
 		!get_owner(fs, i)) {
 		if (!fs->fat[fs->fat[i].value].prev--)
 		    die("Internal error: prev going below zero");
 		set_fat(fs,i,-1);
 		changed = 1;
 		printf("Broke cycle at cluster %lu in free chain.\n",i);
 		break;
 	    }
     }
     while (changed);
     files = reclaimed = 0;
     for (i = 2; i < fs->clusters+2; i++)
 	if (get_owner(fs,i) == &dummy && !fs->fat[i].prev) {
 	    DIR_ENT de;
 	    loff_t offset;
 	    files++;
 	    offset = alloc_rootdir_entry(fs,&de,"FSCK%04dREC");
 	    de.start = CT_LE_W(i&0xffff);
 	    if (fs->fat_bits == 32)
 		de.starthi = CT_LE_W(i>>16);
 	    for (walk = i; walk > 0 && walk != -1;
 		 walk = next_cluster(fs,walk)) {
 		de.size = CT_LE_L(CF_LE_L(de.size)+fs->cluster_size);
 		reclaimed++;
 	    }
 	    fs_write(offset,sizeof(DIR_ENT),&de);
 	}
     if (reclaimed)
 	printf("Reclaimed %d unused cluster%s (%llu bytes) in %d chain%s.\n",
 	  reclaimed,reclaimed == 1 ? "" : "s",(unsigned long long)reclaimed*fs->cluster_size,files,
 	  files == 1 ? "" : "s");
 }


 unsigned long update_free(DOS_FS *fs)
 {
     unsigned long i;
     unsigned long free = 0;
     int do_set = 0;

     for (i = 2; i < fs->clusters+2; i++)
 	if (!get_owner(fs,i) && !FAT_IS_BAD(fs,fs->fat[i].value))
 	    ++free;

     if (!fs->fsinfo_start)
 	return free;

     if (verbose)
 	printf("Checking free cluster summary.\n");
     if (fs->free_clusters >= 0) {
 	if (free != fs->free_clusters) {
 	    printf( "Free cluster summary wrong (%ld vs. really %ld)\n",
 		    fs->free_clusters,free);
 	    if (interactive)
 		printf( "1) Correct\n2) Don't correct\n" );
 	    else printf( "  Auto-correcting.\n" );
 	    if (!interactive || get_key("12","?") == '1')
 		do_set = 1;
 	}
     }
     else {
 	printf( "Free cluster summary uninitialized (should be %ld)\n", free );
 	if (interactive)
 	    printf( "1) Set it\n2) Leave it uninitialized\n" );
 	else printf( "  Auto-setting.\n" );
 	if (!interactive || get_key("12","?") == '1')
 	    do_set = 1;
     }

     if (do_set) {
 	fs->free_clusters = free;
 	free = CT_LE_L(free);
 	fs_write(fs->fsinfo_start+offsetof(struct info_sector,free_clusters),
 		 sizeof(free),&free);
     }

     return free;
 }

 /* Local Variables: */
 /* tab-width: 8     */
 /* End:             */
	/* fat.c - Read/write access to the FAT

	Copyright (C) 1993 Werner Almesberger <werner.almesberger@lrc.di.epfl.ch>
	Copyright (C) 1998 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program. If not, see <http://www.gnu.org/licenses/>.

	On Debian systems, the complete text of the GNU General Public License
	can be found in /usr/share/common-licenses/GPL-3 file.
	*/

	/* FAT32, VFAT, Atari format support, and various fixes additions May 1998
	* by Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> */


	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>

	#include "common.h"
	#include "dosfsck.h"
	#include "io.h"
	#include "check.h"
	#include "fat.h"


	static void get_fat(FAT_ENTRY entry,void fat,unsigned long cluster,DOS_FS *fs)
	{
	unsigned char *ptr;

	switch(fs->fat_bits) {
	case 12:
	ptr = &((unsigned char ) fat)[cluster3/2];
	entry->value = 0xfff & (cluster & 1 ? (ptr[0] >> 4) \| (ptr[1] << 4) :
	(ptr[0] \| ptr[1] << 8));
	break;
	case 16:
	entry->value = CF_LE_W(((unsigned short *) fat)[cluster]);
	break;
	case 32:
	/* According to M$, the high 4 bits of a FAT32 entry are reserved and
	* are not part of the cluster number. So we cut them off. */
	{
	unsigned long e = CF_LE_L(((unsigned int *) fat)[cluster]);
	entry->value = e & 0xfffffff;
	entry->reserved = e >> 28;
	}
	break;
	default:
	die("Bad FAT entry size: %d bits.",fs->fat_bits);
	}
	entry->owner = NULL;
	}


	void read_fat(DOS_FS *fs)
	{
	int eff_size;
	unsigned long i;
	void first,second = NULL;
	int first_ok,second_ok;

	eff_size = ((fs->clusters+2ULL)*fs->fat_bits+7)/8ULL;
	first = alloc(eff_size);
	fs_read(fs->fat_start,eff_size,first);
	if (fs->nfats > 1) {
	second = alloc(eff_size);
	fs_read(fs->fat_start+fs->fat_size,eff_size,second);
	}
	if (second && memcmp(first,second,eff_size) != 0) {
	FAT_ENTRY first_media, second_media;
	get_fat(&first_media,first,0,fs);
	get_fat(&second_media,second,0,fs);
	first_ok = (first_media.value & FAT_EXTD(fs)) == FAT_EXTD(fs);
	second_ok = (second_media.value & FAT_EXTD(fs)) == FAT_EXTD(fs);
	if (first_ok && !second_ok) {
	printf("FATs differ - using first FAT.\n");
	fs_write(fs->fat_start+fs->fat_size,eff_size,first);
	}
	if (!first_ok && second_ok) {
	printf("FATs differ - using second FAT.\n");
	fs_write(fs->fat_start,eff_size,second);
	memcpy(first,second,eff_size);
	}
	if (first_ok && second_ok) {
	if (interactive) {
	printf("FATs differ but appear to be intact. Use which FAT ?\n"
	"1) Use first FAT\n2) Use second FAT\n");
	if (get_key("12","?") == '1') {
	fs_write(fs->fat_start+fs->fat_size,eff_size,first);
	} else {
	fs_write(fs->fat_start,eff_size,second);
	memcpy(first,second,eff_size);
	}
	}
	else {
	printf("FATs differ but appear to be intact. Using first "
	"FAT.\n");
	fs_write(fs->fat_start+fs->fat_size,eff_size,first);
	}
	}
	if (!first_ok && !second_ok) {
	printf("Both FATs appear to be corrupt. Giving up.\n");
	exit(1);
	}
	}
	if (second) {
	free(second);
	}
	fs->fat = qalloc(&mem_queue,sizeof(FAT_ENTRY)*(fs->clusters+2ULL));
	for (i = 2; i < fs->clusters+2; i++) get_fat(&fs->fat[i],first,i,fs);
	for (i = 2; i < fs->clusters+2; i++)
	if (fs->fat[i].value >= fs->clusters+2 &&
	(fs->fat[i].value < FAT_MIN_BAD(fs))) {
	printf("Cluster %ld out of range (%ld > %ld). Setting to EOF.\n",
	i-2,fs->fat[i].value,fs->clusters+2-1);
	set_fat(fs,i,-1);
	}
	free(first);
	}


	void set_fat(DOS_FS *fs,unsigned long cluster,unsigned long new)
	{
	unsigned char data[4];
	int size;
	loff_t offs;

	if ((long)new == -1)
	new = FAT_EOF(fs);
	else if ((long)new == -2)
	new = FAT_BAD(fs);
	switch( fs->fat_bits ) {
	case 12:
	offs = fs->fat_start+cluster*3/2;
	if (cluster & 1) {
	data[0] = ((new & 0xf) << 4) \| (fs->fat[cluster-1].value >> 8);
	data[1] = new >> 4;
	}
	else {
	data[0] = new & 0xff;
	data[1] = (new >> 8) \| (cluster == fs->clusters-1 ? 0 :
	(0xff & fs->fat[cluster+1].value) << 4);
	}
	size = 2;
	break;
	case 16:
	offs = fs->fat_start+cluster*2;
	(unsigned short ) data = CT_LE_W(new);
	size = 2;
	break;
	case 32:
	offs = fs->fat_start+cluster*4;
	/* According to M$, the high 4 bits of a FAT32 entry are reserved and
	* are not part of the cluster number. So we never touch them. */
	(unsigned long ) data = CT_LE_L( (new & 0xfffffff) \|
	(fs->fat[cluster].reserved << 28) );
	size = 4;
	break;
	default:
	die("Bad FAT entry size: %d bits.",fs->fat_bits);
	}
	fs->fat[cluster].value = new;
	fs_write(offs,size,&data);
	fs_write(offs+fs->fat_size,size,&data);
	}


	int bad_cluster(DOS_FS *fs,unsigned long cluster)
	{
	return FAT_IS_BAD(fs,fs->fat[cluster].value);
	}


	unsigned long next_cluster(DOS_FS *fs,unsigned long cluster)
	{
	unsigned long value;

	value = fs->fat[cluster].value;
	if (FAT_IS_BAD(fs,value))
	die("Internal error: next_cluster on bad cluster");
	return FAT_IS_EOF(fs,value) ? -1 : value;
	}


	loff_t cluster_start(DOS_FS *fs,unsigned long cluster)
	{
	return fs->data_start+((loff_t)cluster-2)*(unsigned long long)fs->cluster_size;
	}


	void set_owner(DOS_FS fs,unsigned long cluster,DOS_FILE owner)
	{
	if (owner && fs->fat[cluster].owner)
	die("Internal error: attempt to change file owner");
	fs->fat[cluster].owner = owner;
	}


	DOS_FILE get_owner(DOS_FS fs,unsigned long cluster)
	{
	return fs->fat[cluster].owner;
	}


	void fix_bad(DOS_FS *fs)
	{
	unsigned long i;

	if (verbose)
	printf("Checking for bad clusters.\n");
	for (i = 2; i < fs->clusters+2; i++)
	if (!get_owner(fs,i) && !FAT_IS_BAD(fs,fs->fat[i].value))
	if (!fs_test(cluster_start(fs,i),fs->cluster_size)) {
	printf("Cluster %lu is unreadable.\n",i);
	set_fat(fs,i,-2);
	}
	}


	void reclaim_free(DOS_FS *fs)
	{
	int reclaimed;
	unsigned long i;

	if (verbose)
	printf("Checking for unused clusters.\n");
	reclaimed = 0;
	for (i = 2; i < fs->clusters+2; i++)
	if (!get_owner(fs,i) && fs->fat[i].value &&
	!FAT_IS_BAD(fs,fs->fat[i].value)) {
	set_fat(fs,i,0);
	reclaimed++;
	}
	if (reclaimed)
	printf("Reclaimed %d unused cluster%s (%llu bytes).\n",reclaimed,
	reclaimed == 1 ? "" : "s",(unsigned long long)reclaimed*fs->cluster_size);
	}


	static void tag_free(DOS_FS fs,DOS_FILE ptr)
	{
	DOS_FILE *owner;
	int prev;
	unsigned long i,walk;

	for (i = 2; i < fs->clusters+2; i++)
	if (fs->fat[i].value && !FAT_IS_BAD(fs,fs->fat[i].value) &&
	!get_owner(fs,i) && !fs->fat[i].prev) {
	prev = 0;
	for (walk = i; walk > 0 && walk != -1;
	walk = next_cluster(fs,walk)) {
	if (!(owner = get_owner(fs,walk))) set_owner(fs,walk,ptr);
	else if (owner != ptr)
	die("Internal error: free chain collides with file");
	else {
	set_fat(fs,prev,-1);
	break;
	}
	prev = walk;
	}
	}
	}


	void reclaim_file(DOS_FS *fs)
	{
	DOS_FILE dummy;
	int reclaimed,files,changed;
	unsigned long i,next,walk;

	if (verbose)
	printf("Reclaiming unconnected clusters.\n");
	for (i = 2; i < fs->clusters+2; i++) fs->fat[i].prev = 0;
	for (i = 2; i < fs->clusters+2; i++) {
	next = fs->fat[i].value;
	if (!get_owner(fs,i) && next && next < fs->clusters+2) {
	if (get_owner(fs,next) \|\| !fs->fat[next].value \|\|
	FAT_IS_BAD(fs,fs->fat[next].value)) set_fat(fs,i,-1);
	else fs->fat[next].prev++;
	}
	}
	do {
	tag_free(fs,&dummy);
	changed = 0;
	for (i = 2; i < fs->clusters+2; i++)
	if (fs->fat[i].value && !FAT_IS_BAD(fs,fs->fat[i].value) &&
	!get_owner(fs, i)) {
	if (!fs->fat[fs->fat[i].value].prev--)
	die("Internal error: prev going below zero");
	set_fat(fs,i,-1);
	changed = 1;
	printf("Broke cycle at cluster %lu in free chain.\n",i);
	break;
	}
	}
	while (changed);
	files = reclaimed = 0;
	for (i = 2; i < fs->clusters+2; i++)
	if (get_owner(fs,i) == &dummy && !fs->fat[i].prev) {
	DIR_ENT de;
	loff_t offset;
	files++;
	offset = alloc_rootdir_entry(fs,&de,"FSCK%04dREC");
	de.start = CT_LE_W(i&0xffff);
	if (fs->fat_bits == 32)
	de.starthi = CT_LE_W(i>>16);
	for (walk = i; walk > 0 && walk != -1;
	walk = next_cluster(fs,walk)) {
	de.size = CT_LE_L(CF_LE_L(de.size)+fs->cluster_size);
	reclaimed++;
	}
	fs_write(offset,sizeof(DIR_ENT),&de);
	}
	if (reclaimed)
	printf("Reclaimed %d unused cluster%s (%llu bytes) in %d chain%s.\n",
	reclaimed,reclaimed == 1 ? "" : "s",(unsigned long long)reclaimed*fs->cluster_size,files,
	files == 1 ? "" : "s");
	}


	unsigned long update_free(DOS_FS *fs)
	{
	unsigned long i;
	unsigned long free = 0;
	int do_set = 0;

	for (i = 2; i < fs->clusters+2; i++)
	if (!get_owner(fs,i) && !FAT_IS_BAD(fs,fs->fat[i].value))
	++free;

	if (!fs->fsinfo_start)
	return free;

	if (verbose)
	printf("Checking free cluster summary.\n");
	if (fs->free_clusters >= 0) {
	if (free != fs->free_clusters) {
	printf( "Free cluster summary wrong (%ld vs. really %ld)\n",
	fs->free_clusters,free);
	if (interactive)
	printf( "1) Correct\n2) Don't correct\n" );
	else printf( " Auto-correcting.\n" );
	if (!interactive \|\| get_key("12","?") == '1')
	do_set = 1;
	}
	}
	else {
	printf( "Free cluster summary uninitialized (should be %ld)\n", free );
	if (interactive)
	printf( "1) Set it\n2) Leave it uninitialized\n" );
	else printf( " Auto-setting.\n" );
	if (!interactive \|\| get_key("12","?") == '1')
	do_set = 1;
	}

	if (do_set) {
	fs->free_clusters = free;
	free = CT_LE_L(free);
	fs_write(fs->fsinfo_start+offsetof(struct info_sector,free_clusters),
	sizeof(free),&free);
	}

	return free;
	}

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	/* End: */