/*
* Check a complete in-memory FAT for lost cluster chains
*/
int
checklost(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 && (boot->FSNext >= boot->NumClusters ||
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;
}
int
tryclear(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;
}
int
tryclear(struct bootblock *boot, struct fatEntry *fat, cl_t head, cl_t *truncp)
{
if (ask(0, "Clear chain starting at %u", head)) {
clearchain(boot, fat, head);
return FSFATMOD;
} else if (ask(0, "Truncate")) {
uint32_t len;
cl_t p;
for (p = head, len = 0;
p >= CLUST_FIRST && p < boot->NumClusters;
p = fat[p].next, len++)
continue;
*truncp = CLUST_EOF;
fat[head].length = len;
return FSFATMOD;
} else
return FSERROR;
}
/*
* Check a complete FAT in-memory for crosslinks
*/
int
checkfat(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;
}
