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Fixed possible infinite loop in deorphan step

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Normally, the linked-list of directory pairs should terminate at a null
pointer. However, it is possible if the filesystem is corrupted, that
that this linked-list forms a cycle.

This should never happen with littlefs's power resilience, but if it does
we should recover appropriately.

Modified lfs_deorphan to notice if we have a cycle and return
LFS_ERR_CORRUPT in that situation.

Found by kneko715
This commit is contained in:
Christopher Haster
2018-09-19 18:05:39 -05:00
parent 3419284689
commit e5a6938faf
1 changed files with 10 additions and 4 deletions
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14
lfs.c
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@@ -2475,7 +2475,11 @@ int lfs_deorphan(lfs_t *lfs) {
lfs_dir_t cwd = {.d.tail[0] = 0, .d.tail[1] = 1};
// iterate over all directory directory entries
while (!lfs_pairisnull(cwd.d.tail)) {
for (int i = 0; i < lfs->cfg->block_count; i++) {
if (lfs_pairisnull(cwd.d.tail)) {
return 0;
}
int err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
if (err) {
return err;
@@ -2504,7 +2508,7 @@ int lfs_deorphan(lfs_t *lfs) {
return err;
}
break;
return 0;
}
if (!lfs_pairsync(entry.d.u.dir, pdir.d.tail)) {
@@ -2520,7 +2524,7 @@ int lfs_deorphan(lfs_t *lfs) {
return err;
}
break;
return 0;
}
}
@@ -2565,5 +2569,7 @@ int lfs_deorphan(lfs_t *lfs) {
memcpy(&pdir, &cwd, sizeof(pdir));
}
return 0;
// If we reached here, we have more directory pairs than blocks in the
// filesystem... So something must be horribly wrong
return LFS_ERR_CORRUPT;
}