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Merge pull request #1013 from wdfk-prog/feature_2.9.3

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Write the detect cycles function as a function to optimize code
This commit is contained in:
Christopher Haster
2024-12-06 13:44:37 -06:00
committed by GitHub
parent b78afe2518 a2c2e49e6b
commit bd01a4c0ee
1 changed files with 56 additions and 54 deletions
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110
lfs.c
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@@ -4396,6 +4396,30 @@ cleanup:
}
#endif
struct lfs_tortoise_t {
lfs_block_t pair[2];
lfs_size_t i;
lfs_size_t period;
};
static int lfs_tortoise_detectcycles(
const lfs_mdir_t *dir, struct lfs_tortoise_t *tortoise) {
// detect cycles with Brent's algorithm
if (lfs_pair_issync(dir->tail, tortoise->pair)) {
LFS_WARN("Cycle detected in tail list");
return LFS_ERR_CORRUPT;
}
if (tortoise->i == tortoise->period) {
tortoise->pair[0] = dir->tail[0];
tortoise->pair[1] = dir->tail[1];
tortoise->i = 0;
tortoise->period *= 2;
}
tortoise->i += 1;
return LFS_ERR_OK;
}
static int lfs_mount_(lfs_t *lfs, const struct lfs_config *cfg) {
int err = lfs_init(lfs, cfg);
if (err) {
@@ -4404,23 +4428,16 @@ static int lfs_mount_(lfs_t *lfs, const struct lfs_config *cfg) {
// scan directory blocks for superblock and any global updates
lfs_mdir_t dir = {.tail = {0, 1}};
lfs_block_t tortoise[2] = {LFS_BLOCK_NULL, LFS_BLOCK_NULL};
lfs_size_t tortoise_i = 1;
lfs_size_t tortoise_period = 1;
struct lfs_tortoise_t tortoise = {
.pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL},
.i = 1,
.period = 1,
};
while (!lfs_pair_isnull(dir.tail)) {
// detect cycles with Brent's algorithm
if (lfs_pair_issync(dir.tail, tortoise)) {
LFS_WARN("Cycle detected in tail list");
err = LFS_ERR_CORRUPT;
err = lfs_tortoise_detectcycles(&dir, &tortoise);
if (err < 0) {
goto cleanup;
}
if (tortoise_i == tortoise_period) {
tortoise[0] = dir.tail[0];
tortoise[1] = dir.tail[1];
tortoise_i = 0;
tortoise_period *= 2;
}
tortoise_i += 1;
// fetch next block in tail list
lfs_stag_t tag = lfs_dir_fetchmatch(lfs, &dir, dir.tail,
@@ -4633,22 +4650,17 @@ int lfs_fs_traverse_(lfs_t *lfs,
}
#endif
lfs_block_t tortoise[2] = {LFS_BLOCK_NULL, LFS_BLOCK_NULL};
lfs_size_t tortoise_i = 1;
lfs_size_t tortoise_period = 1;
struct lfs_tortoise_t tortoise = {
.pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL},
.i = 1,
.period = 1,
};
int err = LFS_ERR_OK;
while (!lfs_pair_isnull(dir.tail)) {
// detect cycles with Brent's algorithm
if (lfs_pair_issync(dir.tail, tortoise)) {
LFS_WARN("Cycle detected in tail list");
err = lfs_tortoise_detectcycles(&dir, &tortoise);
if (err < 0) {
return LFS_ERR_CORRUPT;
}
if (tortoise_i == tortoise_period) {
tortoise[0] = dir.tail[0];
tortoise[1] = dir.tail[1];
tortoise_i = 0;
tortoise_period *= 2;
}
tortoise_i += 1;
for (int i = 0; i < 2; i++) {
int err = cb(data, dir.tail[i]);
@@ -4727,22 +4739,17 @@ static int lfs_fs_pred(lfs_t *lfs,
// iterate over all directory directory entries
pdir->tail[0] = 0;
pdir->tail[1] = 1;
lfs_block_t tortoise[2] = {LFS_BLOCK_NULL, LFS_BLOCK_NULL};
lfs_size_t tortoise_i = 1;
lfs_size_t tortoise_period = 1;
struct lfs_tortoise_t tortoise = {
.pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL},
.i = 1,
.period = 1,
};
int err = LFS_ERR_OK;
while (!lfs_pair_isnull(pdir->tail)) {
// detect cycles with Brent's algorithm
if (lfs_pair_issync(pdir->tail, tortoise)) {
LFS_WARN("Cycle detected in tail list");
err = lfs_tortoise_detectcycles(pdir, &tortoise);
if (err < 0) {
return LFS_ERR_CORRUPT;
}
if (tortoise_i == tortoise_period) {
tortoise[0] = pdir->tail[0];
tortoise[1] = pdir->tail[1];
tortoise_i = 0;
tortoise_period *= 2;
}
tortoise_i += 1;
if (lfs_pair_cmp(pdir->tail, pair) == 0) {
return 0;
@@ -4792,22 +4799,17 @@ static lfs_stag_t lfs_fs_parent(lfs_t *lfs, const lfs_block_t pair[2],
// use fetchmatch with callback to find pairs
parent->tail[0] = 0;
parent->tail[1] = 1;
lfs_block_t tortoise[2] = {LFS_BLOCK_NULL, LFS_BLOCK_NULL};
lfs_size_t tortoise_i = 1;
lfs_size_t tortoise_period = 1;
struct lfs_tortoise_t tortoise = {
.pair = {LFS_BLOCK_NULL, LFS_BLOCK_NULL},
.i = 1,
.period = 1,
};
int err = LFS_ERR_OK;
while (!lfs_pair_isnull(parent->tail)) {
// detect cycles with Brent's algorithm
if (lfs_pair_issync(parent->tail, tortoise)) {
LFS_WARN("Cycle detected in tail list");
return LFS_ERR_CORRUPT;
err = lfs_tortoise_detectcycles(parent, &tortoise);
if (err < 0) {
return err;
}
if (tortoise_i == tortoise_period) {
tortoise[0] = parent->tail[0];
tortoise[1] = parent->tail[1];
tortoise_i = 0;
tortoise_period *= 2;
}
tortoise_i += 1;
lfs_stag_t tag = lfs_dir_fetchmatch(lfs, parent, parent->tail,
LFS_MKTAG(0x7ff, 0, 0x3ff),