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-rw-r--r--sbin/fsck_msdosfs/fat.c659
1 files changed, 659 insertions, 0 deletions
diff --git a/sbin/fsck_msdosfs/fat.c b/sbin/fsck_msdosfs/fat.c
new file mode 100644
index 000000000000..ff21f41f93bf
--- /dev/null
+++ b/sbin/fsck_msdosfs/fat.c
@@ -0,0 +1,659 @@
+/*
+ * Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
+ * Copyright (c) 1995 Martin Husemann
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by Martin Husemann
+ * and Wolfgang Solfrank.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+#include <sys/cdefs.h>
+#ifndef lint
+__RCSID("$NetBSD: fat.c,v 1.12 2000/10/10 20:24:52 is Exp $");
+static const char rcsid[] =
+ "$FreeBSD$";
+#endif /* not lint */
+
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "ext.h"
+#include "fsutil.h"
+
+static int checkclnum __P((struct bootblock *, int, cl_t, cl_t *));
+static int clustdiffer __P((cl_t, cl_t *, cl_t *, int));
+static int tryclear __P((struct bootblock *, struct fatEntry *, cl_t, cl_t *));
+static int _readfat __P((int, struct bootblock *, int, u_char **));
+
+/*
+ * Check a cluster number for valid value
+ */
+static int
+checkclnum(boot, fat, cl, next)
+ struct bootblock *boot;
+ int fat;
+ cl_t cl;
+ cl_t *next;
+{
+ if (*next >= (CLUST_RSRVD&boot->ClustMask))
+ *next |= ~boot->ClustMask;
+ if (*next == CLUST_FREE) {
+ boot->NumFree++;
+ return FSOK;
+ }
+ if (*next == CLUST_BAD) {
+ boot->NumBad++;
+ return FSOK;
+ }
+ if (*next < CLUST_FIRST
+ || (*next >= boot->NumClusters && *next < CLUST_EOFS)) {
+ pwarn("Cluster %u in FAT %d continues with %s cluster number %u\n",
+ cl, fat,
+ *next < CLUST_RSRVD ? "out of range" : "reserved",
+ *next&boot->ClustMask);
+ if (ask(0, "Truncate")) {
+ *next = CLUST_EOF;
+ return FSFATMOD;
+ }
+ return FSERROR;
+ }
+ return FSOK;
+}
+
+/*
+ * Read a FAT from disk. Returns 1 if successful, 0 otherwise.
+ */
+static int
+_readfat(fs, boot, no, buffer)
+ int fs;
+ struct bootblock *boot;
+ int no;
+ u_char **buffer;
+{
+ off_t off;
+
+ *buffer = malloc(boot->FATsecs * boot->BytesPerSec);
+ if (*buffer == NULL) {
+ perror("No space for FAT");
+ return 0;
+ }
+
+ off = boot->ResSectors + no * boot->FATsecs;
+ off *= boot->BytesPerSec;
+
+ if (lseek(fs, off, SEEK_SET) != off) {
+ perror("Unable to read FAT");
+ goto err;
+ }
+
+ if (read(fs, *buffer, boot->FATsecs * boot->BytesPerSec)
+ != boot->FATsecs * boot->BytesPerSec) {
+ perror("Unable to read FAT");
+ goto err;
+ }
+
+ return 1;
+
+ err:
+ free(*buffer);
+ return 0;
+}
+
+/*
+ * Read a FAT and decode it into internal format
+ */
+int
+readfat(fs, boot, no, fp)
+ int fs;
+ struct bootblock *boot;
+ int no;
+ struct fatEntry **fp;
+{
+ struct fatEntry *fat;
+ u_char *buffer, *p;
+ cl_t cl;
+ int ret = FSOK;
+
+ boot->NumFree = boot->NumBad = 0;
+
+ if (!_readfat(fs, boot, no, &buffer))
+ return FSFATAL;
+
+ fat = calloc(boot->NumClusters, sizeof(struct fatEntry));
+ if (fat == NULL) {
+ perror("No space for FAT");
+ free(buffer);
+ return FSFATAL;
+ }
+
+ if (buffer[0] != boot->Media
+ || buffer[1] != 0xff || buffer[2] != 0xff
+ || (boot->ClustMask == CLUST16_MASK && buffer[3] != 0xff)
+ || (boot->ClustMask == CLUST32_MASK
+ && ((buffer[3]&0x0f) != 0x0f
+ || buffer[4] != 0xff || buffer[5] != 0xff
+ || buffer[6] != 0xff || (buffer[7]&0x0f) != 0x0f))) {
+
+ /* Windows 95 OSR2 (and possibly any later) changes
+ * the FAT signature to 0xXXffff7f for FAT16 and to
+ * 0xXXffff0fffffff07 for FAT32 upon boot, to know that the
+ * filesystem is dirty if it doesn't reboot cleanly.
+ * Check this special condition before errorring out.
+ */
+ if (buffer[0] == boot->Media && buffer[1] == 0xff
+ && buffer[2] == 0xff
+ && ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
+ || (boot->ClustMask == CLUST32_MASK
+ && buffer[3] == 0x0f && buffer[4] == 0xff
+ && buffer[5] == 0xff && buffer[6] == 0xff
+ && buffer[7] == 0x07)))
+ ret |= FSDIRTY;
+ else {
+ /* just some odd byte sequence in FAT */
+
+ switch (boot->ClustMask) {
+ case CLUST32_MASK:
+ pwarn("%s (%02x%02x%02x%02x%02x%02x%02x%02x)\n",
+ "FAT starts with odd byte sequence",
+ buffer[0], buffer[1], buffer[2], buffer[3],
+ buffer[4], buffer[5], buffer[6], buffer[7]);
+ break;
+ case CLUST16_MASK:
+ pwarn("%s (%02x%02x%02x%02x)\n",
+ "FAT starts with odd byte sequence",
+ buffer[0], buffer[1], buffer[2], buffer[3]);
+ break;
+ default:
+ pwarn("%s (%02x%02x%02x)\n",
+ "FAT starts with odd byte sequence",
+ buffer[0], buffer[1], buffer[2]);
+ break;
+ }
+
+
+ if (ask(1, "Correct"))
+ ret |= FSFIXFAT;
+ }
+ }
+ switch (boot->ClustMask) {
+ case CLUST32_MASK:
+ p = buffer + 8;
+ break;
+ case CLUST16_MASK:
+ p = buffer + 4;
+ break;
+ default:
+ p = buffer + 3;
+ break;
+ }
+ for (cl = CLUST_FIRST; cl < boot->NumClusters;) {
+ switch (boot->ClustMask) {
+ case CLUST32_MASK:
+ fat[cl].next = p[0] + (p[1] << 8)
+ + (p[2] << 16) + (p[3] << 24);
+ fat[cl].next &= boot->ClustMask;
+ ret |= checkclnum(boot, no, cl, &fat[cl].next);
+ cl++;
+ p += 4;
+ break;
+ case CLUST16_MASK:
+ fat[cl].next = p[0] + (p[1] << 8);
+ ret |= checkclnum(boot, no, cl, &fat[cl].next);
+ cl++;
+ p += 2;
+ break;
+ default:
+ fat[cl].next = (p[0] + (p[1] << 8)) & 0x0fff;
+ ret |= checkclnum(boot, no, cl, &fat[cl].next);
+ cl++;
+ if (cl >= boot->NumClusters)
+ break;
+ fat[cl].next = ((p[1] >> 4) + (p[2] << 4)) & 0x0fff;
+ ret |= checkclnum(boot, no, cl, &fat[cl].next);
+ cl++;
+ p += 3;
+ break;
+ }
+ }
+
+ free(buffer);
+ *fp = fat;
+ return ret;
+}
+
+/*
+ * Get type of reserved cluster
+ */
+char *
+rsrvdcltype(cl)
+ cl_t cl;
+{
+ if (cl == CLUST_FREE)
+ return "free";
+ if (cl < CLUST_BAD)
+ return "reserved";
+ if (cl > CLUST_BAD)
+ return "as EOF";
+ return "bad";
+}
+
+static int
+clustdiffer(cl, cp1, cp2, fatnum)
+ cl_t cl;
+ cl_t *cp1;
+ cl_t *cp2;
+ int fatnum;
+{
+ if (*cp1 == CLUST_FREE || *cp1 >= CLUST_RSRVD) {
+ if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
+ if ((*cp1 != CLUST_FREE && *cp1 < CLUST_BAD
+ && *cp2 != CLUST_FREE && *cp2 < CLUST_BAD)
+ || (*cp1 > CLUST_BAD && *cp2 > CLUST_BAD)) {
+ pwarn("Cluster %u is marked %s with different indicators, ",
+ cl, rsrvdcltype(*cp1));
+ if (ask(1, "fix")) {
+ *cp2 = *cp1;
+ return FSFATMOD;
+ }
+ return FSFATAL;
+ }
+ pwarn("Cluster %u is marked %s in FAT 0, %s in FAT %d\n",
+ cl, rsrvdcltype(*cp1), rsrvdcltype(*cp2), fatnum);
+ if (ask(0, "use FAT 0's entry")) {
+ *cp2 = *cp1;
+ return FSFATMOD;
+ }
+ if (ask(0, "use FAT %d's entry", fatnum)) {
+ *cp1 = *cp2;
+ return FSFATMOD;
+ }
+ return FSFATAL;
+ }
+ pwarn("Cluster %u is marked %s in FAT 0, but continues with cluster %u in FAT %d\n",
+ cl, rsrvdcltype(*cp1), *cp2, fatnum);
+ if (ask(0, "Use continuation from FAT %d", fatnum)) {
+ *cp1 = *cp2;
+ return FSFATMOD;
+ }
+ if (ask(0, "Use mark from FAT 0")) {
+ *cp2 = *cp1;
+ return FSFATMOD;
+ }
+ return FSFATAL;
+ }
+ if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
+ pwarn("Cluster %u continues with cluster %u in FAT 0, but is marked %s in FAT %d\n",
+ cl, *cp1, rsrvdcltype(*cp2), fatnum);
+ if (ask(0, "Use continuation from FAT 0")) {
+ *cp2 = *cp1;
+ return FSFATMOD;
+ }
+ if (ask(0, "Use mark from FAT %d", fatnum)) {
+ *cp1 = *cp2;
+ return FSFATMOD;
+ }
+ return FSERROR;
+ }
+ pwarn("Cluster %u continues with cluster %u in FAT 0, but with cluster %u in FAT %d\n",
+ cl, *cp1, *cp2, fatnum);
+ if (ask(0, "Use continuation from FAT 0")) {
+ *cp2 = *cp1;
+ return FSFATMOD;
+ }
+ if (ask(0, "Use continuation from FAT %d", fatnum)) {
+ *cp1 = *cp2;
+ return FSFATMOD;
+ }
+ return FSERROR;
+}
+
+/*
+ * Compare two FAT copies in memory. Resolve any conflicts and merge them
+ * into the first one.
+ */
+int
+comparefat(boot, first, second, fatnum)
+ struct bootblock *boot;
+ struct fatEntry *first;
+ struct fatEntry *second;
+ int fatnum;
+{
+ cl_t cl;
+ int ret = FSOK;
+
+ for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++)
+ if (first[cl].next != second[cl].next)
+ ret |= clustdiffer(cl, &first[cl].next, &second[cl].next, fatnum);
+ return ret;
+}
+
+void
+clearchain(boot, fat, head)
+ struct bootblock *boot;
+ struct fatEntry *fat;
+ cl_t head;
+{
+ cl_t p, q;
+
+ for (p = head; p >= CLUST_FIRST && p < boot->NumClusters; p = q) {
+ if (fat[p].head != head)
+ break;
+ q = fat[p].next;
+ fat[p].next = fat[p].head = CLUST_FREE;
+ fat[p].length = 0;
+ }
+}
+
+int
+tryclear(boot, fat, head, trunc)
+ struct bootblock *boot;
+ struct fatEntry *fat;
+ cl_t head;
+ cl_t *trunc;
+{
+ if (ask(0, "Clear chain starting at %u", head)) {
+ clearchain(boot, fat, head);
+ return FSFATMOD;
+ } else if (ask(0, "Truncate")) {
+ *trunc = CLUST_EOF;
+ return FSFATMOD;
+ } else
+ return FSERROR;
+}
+
+/*
+ * Check a complete FAT in-memory for crosslinks
+ */
+int
+checkfat(boot, fat)
+ struct bootblock *boot;
+ struct fatEntry *fat;
+{
+ cl_t head, p, h, n;
+ u_int len;
+ int ret = 0;
+ int conf;
+
+ /*
+ * pass 1: figure out the cluster chains.
+ */
+ for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
+ /* find next untravelled chain */
+ if (fat[head].head != 0 /* cluster already belongs to some chain */
+ || fat[head].next == CLUST_FREE
+ || fat[head].next == CLUST_BAD)
+ continue; /* skip it. */
+
+ /* follow the chain and mark all clusters on the way */
+ for (len = 0, p = head;
+ p >= CLUST_FIRST && p < boot->NumClusters;
+ p = fat[p].next) {
+ fat[p].head = head;
+ len++;
+ }
+
+ /* the head record gets the length */
+ fat[head].length = fat[head].next == CLUST_FREE ? 0 : len;
+ }
+
+ /*
+ * pass 2: check for crosslinked chains (we couldn't do this in pass 1 because
+ * we didn't know the real start of the chain then - would have treated partial
+ * chains as interlinked with their main chain)
+ */
+ for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
+ /* find next untravelled chain */
+ if (fat[head].head != head)
+ continue;
+
+ /* follow the chain to its end (hopefully) */
+ for (p = head;
+ (n = fat[p].next) >= CLUST_FIRST && n < boot->NumClusters;
+ p = n)
+ if (fat[n].head != head)
+ break;
+ if (n >= CLUST_EOFS)
+ continue;
+
+ if (n == CLUST_FREE || n >= CLUST_RSRVD) {
+ pwarn("Cluster chain starting at %u ends with cluster marked %s\n",
+ head, rsrvdcltype(n));
+ ret |= tryclear(boot, fat, head, &fat[p].next);
+ continue;
+ }
+ if (n < CLUST_FIRST || n >= boot->NumClusters) {
+ pwarn("Cluster chain starting at %u ends with cluster out of range (%u)\n",
+ head, n);
+ ret |= tryclear(boot, fat, head, &fat[p].next);
+ continue;
+ }
+ pwarn("Cluster chains starting at %u and %u are linked at cluster %u\n",
+ head, fat[n].head, n);
+ conf = tryclear(boot, fat, head, &fat[p].next);
+ if (ask(0, "Clear chain starting at %u", h = fat[n].head)) {
+ if (conf == FSERROR) {
+ /*
+ * Transfer the common chain to the one not cleared above.
+ */
+ for (p = n;
+ p >= CLUST_FIRST && p < boot->NumClusters;
+ p = fat[p].next) {
+ if (h != fat[p].head) {
+ /*
+ * Have to reexamine this chain.
+ */
+ head--;
+ break;
+ }
+ fat[p].head = head;
+ }
+ }
+ clearchain(boot, fat, h);
+ conf |= FSFATMOD;
+ }
+ ret |= conf;
+ }
+
+ return ret;
+}
+
+/*
+ * Write out FATs encoding them from the internal format
+ */
+int
+writefat(fs, boot, fat, correct_fat)
+ int fs;
+ struct bootblock *boot;
+ struct fatEntry *fat;
+ int correct_fat;
+{
+ u_char *buffer, *p;
+ cl_t cl;
+ int i;
+ u_int32_t fatsz;
+ off_t off;
+ int ret = FSOK;
+
+ buffer = malloc(fatsz = boot->FATsecs * boot->BytesPerSec);
+ if (buffer == NULL) {
+ perror("No space for FAT");
+ return FSFATAL;
+ }
+ memset(buffer, 0, fatsz);
+ boot->NumFree = 0;
+ p = buffer;
+ if (correct_fat) {
+ *p++ = (u_char)boot->Media;
+ *p++ = 0xff;
+ *p++ = 0xff;
+ switch (boot->ClustMask) {
+ case CLUST16_MASK:
+ *p++ = 0xff;
+ break;
+ case CLUST32_MASK:
+ *p++ = 0x0f;
+ *p++ = 0xff;
+ *p++ = 0xff;
+ *p++ = 0xff;
+ *p++ = 0x0f;
+ break;
+ }
+ } else {
+ /* use same FAT signature as the old FAT has */
+ int count;
+ u_char *old_fat;
+
+ switch (boot->ClustMask) {
+ case CLUST32_MASK:
+ count = 8;
+ break;
+ case CLUST16_MASK:
+ count = 4;
+ break;
+ default:
+ count = 3;
+ break;
+ }
+
+ if (!_readfat(fs, boot, boot->ValidFat >= 0 ? boot->ValidFat :0,
+ &old_fat)) {
+ free(buffer);
+ return FSFATAL;
+ }
+
+ memcpy(p, old_fat, count);
+ free(old_fat);
+ p += count;
+ }
+
+ for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++) {
+ switch (boot->ClustMask) {
+ case CLUST32_MASK:
+ if (fat[cl].next == CLUST_FREE)
+ boot->NumFree++;
+ *p++ = (u_char)fat[cl].next;
+ *p++ = (u_char)(fat[cl].next >> 8);
+ *p++ = (u_char)(fat[cl].next >> 16);
+ *p &= 0xf0;
+ *p++ |= (fat[cl].next >> 24)&0x0f;
+ break;
+ case CLUST16_MASK:
+ if (fat[cl].next == CLUST_FREE)
+ boot->NumFree++;
+ *p++ = (u_char)fat[cl].next;
+ *p++ = (u_char)(fat[cl].next >> 8);
+ break;
+ default:
+ if (fat[cl].next == CLUST_FREE)
+ boot->NumFree++;
+ if (cl + 1 < boot->NumClusters
+ && fat[cl + 1].next == CLUST_FREE)
+ boot->NumFree++;
+ *p++ = (u_char)fat[cl].next;
+ *p++ = (u_char)((fat[cl].next >> 8) & 0xf)
+ |(u_char)(fat[cl+1].next << 4);
+ *p++ = (u_char)(fat[++cl].next >> 4);
+ break;
+ }
+ }
+ for (i = 0; i < boot->FATs; i++) {
+ off = boot->ResSectors + i * boot->FATsecs;
+ off *= boot->BytesPerSec;
+ if (lseek(fs, off, SEEK_SET) != off
+ || write(fs, buffer, fatsz) != fatsz) {
+ perror("Unable to write FAT");
+ ret = FSFATAL; /* Return immediately? XXX */
+ }
+ }
+ free(buffer);
+ return ret;
+}
+
+/*
+ * Check a complete in-memory FAT for lost cluster chains
+ */
+int
+checklost(dosfs, boot, fat)
+ int dosfs;
+ struct bootblock *boot;
+ struct fatEntry *fat;
+{
+ cl_t head;
+ int mod = FSOK;
+ int ret;
+
+ for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
+ /* find next untravelled chain */
+ if (fat[head].head != head
+ || fat[head].next == CLUST_FREE
+ || (fat[head].next >= CLUST_RSRVD
+ && fat[head].next < CLUST_EOFS)
+ || (fat[head].flags & FAT_USED))
+ continue;
+
+ pwarn("Lost cluster chain at cluster %u\n%d Cluster(s) lost\n",
+ head, fat[head].length);
+ mod |= ret = reconnect(dosfs, boot, fat, head);
+ if (mod & FSFATAL)
+ break;
+ if (ret == FSERROR && ask(0, "Clear")) {
+ clearchain(boot, fat, head);
+ mod |= FSFATMOD;
+ }
+ }
+ finishlf();
+
+ if (boot->FSInfo) {
+ ret = 0;
+ if (boot->FSFree != boot->NumFree) {
+ pwarn("Free space in FSInfo block (%d) not correct (%d)\n",
+ boot->FSFree, boot->NumFree);
+ if (ask(1, "fix")) {
+ boot->FSFree = boot->NumFree;
+ ret = 1;
+ }
+ }
+ if (boot->NumFree && fat[boot->FSNext].next != CLUST_FREE) {
+ pwarn("Next free cluster in FSInfo block (%u) not free\n",
+ boot->FSNext);
+ if (ask(1, "fix"))
+ for (head = CLUST_FIRST; head < boot->NumClusters; head++)
+ if (fat[head].next == CLUST_FREE) {
+ boot->FSNext = head;
+ ret = 1;
+ break;
+ }
+ }
+ if (ret)
+ mod |= writefsinfo(dosfs, boot);
+ }
+
+ return mod;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-26 16:00:45 +0000