Write the detect cycles function as a function to optimize code

lfs.c

@@ -4396,6 +4396,32 @@ static int lfs_format_(lfs_t *lfs, const struct lfs_config *cfg) {
 }
 #endif
 
+struct lfs_tortoise_t
+{
+ lfs_block_t pair[2];
+ lfs_size_t i;
+ lfs_size_t period;
+};
+
+static int lfs_detect_cycles(lfs_mdir_t *dir, struct lfs_tortoise_t *tortoise)
+{
+ int err = LFS_ERR_OK;
+ // 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 err;
+}
+
 static int lfs_mount_(lfs_t *lfs, const struct lfs_config *cfg) {
  int err = lfs_init(lfs, cfg);
  if (err) {
@@ -4404,23 +4430,16 @@ 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_detect_cycles(&dir, &tortoise);
+ if (err == LFS_ERR_CORRUPT) {
  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 +4652,16 @@ 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,
+ };
+
  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");
+ if (lfs_detect_cycles(&dir, &tortoise) == LFS_ERR_CORRUPT) {
  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 +4740,15 @@ 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,
+ };
  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");
+ if (lfs_detect_cycles(pdir, &tortoise) == LFS_ERR_CORRUPT) {
  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 +4798,15 @@ 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,
+ };
  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");
+ if (lfs_detect_cycles(parent, &tortoise) == LFS_ERR_CORRUPT) {
  return LFS_ERR_CORRUPT;
  }
- 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),