fixup for 5c87b6864

Duplicate test_relocation.toml into a variant with removeall.

README.md

@@ -192,7 +192,7 @@ More details on how littlefs works can be found in [DESIGN.md](DESIGN.md) and
 ## Testing
 
 The littlefs comes with a test suite designed to run on a PC using the
-[emulated block device](bd/lfs_testbd.h) found in the `bd` directory.
+[emulated block device](emubd/lfs_emubd.h) found in the emubd directory.
 The tests assume a Linux environment and can be started with make:
 
 ``` bash

lfs.c

@@ -3190,7 +3190,106 @@ static int lfs_rawstat(lfs_t *lfs, const char *path, struct lfs_info *info) {
 }
 
 #ifndef LFS_READONLY
-static int lfs_rawremove(lfs_t *lfs, const char *path) {
+typedef int (*lfs_dir_prep_helper_t)(lfs_t *, struct lfs_mlist *, lfs_gstate_t *);
+
+static int lfs_dir_prep_remove_nonempty_folders(lfs_t *lfs, struct lfs_mlist *dir,
+        lfs_gstate_t *tmp_gstate)
+{
+    lfs_gstate_t split_gstate;
+    uint16_t id = 0;
+
+    // Walk tags stored in this directory and check for any directory
+    // tags.  Removal of directories with a directory in them can lead
+    // to additional orphans in the filesystem, so we return
+    // LFS_ERR_NOTEMPTY in this case.  Otherwise, leave the loaded
+    // directory for the tail end of the directory split to leave a proper
+    // view of the filesystem after removal.
+    while (true) {
+        if (dir->m.count == id) {
+            if (!dir->m.split) {
+                // We have iterated through the folder to the last
+                // tag.
+                break;
+            }
+
+            // Before we fetch the next block, update our fetched gstate xor
+            lfs_dir_getgstate(lfs, &dir->m, &split_gstate);
+            lfs_gstate_xor(tmp_gstate, &split_gstate);
+
+            int err = lfs_dir_fetch(lfs, &dir->m, dir->m.tail);
+            if (err) {
+                return err;
+            }
+
+            id = 0;
+        }
+
+        lfs_stag_t tag = lfs_dir_get(lfs, &dir->m, LFS_MKTAG(0x780, 0x3ff, 0),
+                LFS_MKTAG(LFS_TYPE_NAME, id, 0), NULL);
+
+        if (tag < 0) {
+            return tag;
+        }
+
+        if (lfs_tag_type3(tag) == LFS_TYPE_DIR) {
+            return LFS_ERR_NOTEMPTY;
+        }
+
+        id += 1;
+    }
+
+    return 0;
+}
+
+static int lfs_dir_prep_removal(lfs_t *lfs, struct lfs_mlist *dir,
+        lfs_mdir_t *newcwd, uint16_t newid, lfs_block_t *pair,
+        lfs_gstate_t *tmp_gstate, lfs_dir_prep_helper_t helper)
+{
+    lfs_stag_t res = lfs_dir_get(lfs, newcwd, LFS_MKTAG(0x700, 0x3ff, 0),
+            LFS_MKTAG(LFS_TYPE_STRUCT, newid, 8), pair);
+    if (res < 0) {
+        return (int)res;
+    }
+    lfs_pair_fromle32(pair);
+
+    memset(tmp_gstate, 0, sizeof(*tmp_gstate));
+
+    int err = lfs_dir_fetch(lfs, &dir->m, pair);
+    if (err) {
+        return err;
+    }
+
+    if (dir->m.count > 0 || dir->m.split) {
+        // Normal POSIX behavior wouldn't allow a non-empty
+        // folder to be removed/renamed into in this manner
+        if (NULL == helper) {
+            return LFS_ERR_NOTEMPTY;
+        }
+
+        err = helper(lfs, dir, tmp_gstate);
+        if (err) {
+            return err;
+        }
+    }
+
+    // mark fs as orphaned
+    err = lfs_fs_preporphans(lfs, +1);
+    if (err) {
+        return err;
+    }
+
+    // I know it's crazy but yes, dir can be changed by our parent's
+    // commit (if predecessor is child)
+    dir->type = 0;
+    dir->id = 0;
+    lfs->mlist = dir;
+
+    return 0;
+}
+#endif
+
+#ifndef LFS_READONLY
+static int lfs_rawremove(lfs_t *lfs, const char *path, lfs_dir_prep_helper_t helper) {
     // deorphan if we haven't yet, needed at most once after poweron
     int err = lfs_fs_forceconsistency(lfs);
     if (err) {
@@ -3204,37 +3303,16 @@ static int lfs_rawremove(lfs_t *lfs, const char *path) {
     }
 
     struct lfs_mlist dir;
+    lfs_block_t pair[2];
+    lfs_gstate_t tmp_gstate;
     dir.next = lfs->mlist;
     if (lfs_tag_type3(tag) == LFS_TYPE_DIR) {
-        // must be empty before removal
+        // must be empty before removal to prevent orphans
-        lfs_block_t pair[2];
+        err = lfs_dir_prep_removal(lfs, &dir, &cwd, lfs_tag_id(tag),
-        lfs_stag_t res = lfs_dir_get(lfs, &cwd, LFS_MKTAG(0x700, 0x3ff, 0),
+                pair, &tmp_gstate, helper);
-                LFS_MKTAG(LFS_TYPE_STRUCT, lfs_tag_id(tag), 8), pair);
+        if (err < 0) {
-        if (res < 0) {
-            return (int)res;
-        }
-        lfs_pair_fromle32(pair);
-
-        err = lfs_dir_fetch(lfs, &dir.m, pair);
-        if (err) {
             return err;
         }
-
-        if (dir.m.count > 0 || dir.m.split) {
-            return LFS_ERR_NOTEMPTY;
-        }
-
-        // mark fs as orphaned
-        err = lfs_fs_preporphans(lfs, +1);
-        if (err) {
-            return err;
-        }
-
-        // I know it's crazy but yes, dir can be changed by our parent's
-        // commit (if predecessor is child)
-        dir.type = 0;
-        dir.id = 0;
-        lfs->mlist = &dir;
     }
 
     // delete the entry
@@ -3253,11 +3331,15 @@ static int lfs_rawremove(lfs_t *lfs, const char *path) {
             return err;
         }
 
-        err = lfs_fs_pred(lfs, dir.m.pair, &cwd);
+        err = lfs_fs_pred(lfs, pair, &cwd);
         if (err) {
             return err;
         }
 
+        // Merge in gstate from first block splits within the directory;
+        // lfs_dir_drop will pick up the last gstate entry.
+        lfs_gstate_xor(&lfs->gdelta, &tmp_gstate);
+
         err = lfs_dir_drop(lfs, &cwd, &dir.m);
         if (err) {
             return err;
@@ -3269,7 +3351,8 @@ static int lfs_rawremove(lfs_t *lfs, const char *path) {
 #endif
 
 #ifndef LFS_READONLY
-static int lfs_rawrename(lfs_t *lfs, const char *oldpath, const char *newpath) {
+static int lfs_rawrename(lfs_t *lfs, const char *oldpath,
+        const char *newpath, lfs_dir_prep_helper_t helper) {
     // deorphan if we haven't yet, needed at most once after poweron
     int err = lfs_fs_forceconsistency(lfs);
     if (err) {
@@ -3297,6 +3380,8 @@ static int lfs_rawrename(lfs_t *lfs, const char *oldpath, const char *newpath) {
     uint16_t newoldid = lfs_tag_id(oldtag);
 
     struct lfs_mlist prevdir;
+    lfs_block_t dir_pair[2];
+    lfs_gstate_t tmp_gstate;
     prevdir.next = lfs->mlist;
     if (prevtag == LFS_ERR_NOENT) {
         // check that name fits
@@ -3317,36 +3402,12 @@ static int lfs_rawrename(lfs_t *lfs, const char *oldpath, const char *newpath) {
         // we're renaming to ourselves??
         return 0;
     } else if (lfs_tag_type3(prevtag) == LFS_TYPE_DIR) {
-        // must be empty before removal
+        // must be empty before removal to prevent orphans
-        lfs_block_t prevpair[2];
+        err = lfs_dir_prep_removal(lfs, &prevdir, &newcwd, newid,
-        lfs_stag_t res = lfs_dir_get(lfs, &newcwd, LFS_MKTAG(0x700, 0x3ff, 0),
+                dir_pair, &tmp_gstate, helper);
-                LFS_MKTAG(LFS_TYPE_STRUCT, newid, 8), prevpair);
-        if (res < 0) {
-            return (int)res;
-        }
-        lfs_pair_fromle32(prevpair);
-
-        // must be empty before removal
-        err = lfs_dir_fetch(lfs, &prevdir.m, prevpair);
         if (err) {
             return err;
         }
-
-        if (prevdir.m.count > 0 || prevdir.m.split) {
-            return LFS_ERR_NOTEMPTY;
-        }
-
-        // mark fs as orphaned
-        err = lfs_fs_preporphans(lfs, +1);
-        if (err) {
-            return err;
-        }
-
-        // I know it's crazy but yes, dir can be changed by our parent's
-        // commit (if predecessor is child)
-        prevdir.type = 0;
-        prevdir.id = 0;
-        lfs->mlist = &prevdir;
     }
 
     if (!samepair) {
@@ -3388,11 +3449,15 @@ static int lfs_rawrename(lfs_t *lfs, const char *oldpath, const char *newpath) {
             return err;
         }
 
-        err = lfs_fs_pred(lfs, prevdir.m.pair, &newcwd);
+        err = lfs_fs_pred(lfs, dir_pair, &newcwd);
         if (err) {
             return err;
         }
 
+        // Merge in gstate from first split blocks in the directory;
+        // lfs_dir_drop will pick up the other gstate entries.
+        lfs_gstate_xor(&lfs->gdelta, &tmp_gstate);
+
         err = lfs_dir_drop(lfs, &newcwd, &prevdir.m);
         if (err) {
             return err;
@@ -4994,7 +5059,7 @@ int lfs_remove(lfs_t *lfs, const char *path) {
     }
     LFS_TRACE("lfs_remove(%p, \"%s\")", (void*)lfs, path);
 
-    err = lfs_rawremove(lfs, path);
+    err = lfs_rawremove(lfs, path, NULL);
 
     LFS_TRACE("lfs_remove -> %d", err);
     LFS_UNLOCK(lfs->cfg);
@@ -5002,6 +5067,24 @@ int lfs_remove(lfs_t *lfs, const char *path) {
 }
 #endif
 
+#ifndef LFS_READONLY
+int lfs_removeall(lfs_t *lfs, const char *path) {
+    int err = LFS_LOCK(lfs->cfg);
+    if (err) {
+        return err;
+    }
+    LFS_TRACE("lfs_removeall(%p, \"%s\")", (void*)lfs, path);
+
+    // Note: We pass in a helper pointer here so that this extra
+    //       logic can be dropped if it is never referenced
+    err = lfs_rawremove(lfs, path, lfs_dir_prep_remove_nonempty_folders);
+
+    LFS_TRACE("lfs_removeall -> %d", err);
+    LFS_UNLOCK(lfs->cfg);
+    return err;
+}
+#endif
+
 #ifndef LFS_READONLY
 int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
     int err = LFS_LOCK(lfs->cfg);
@@ -5010,7 +5093,25 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
     }
     LFS_TRACE("lfs_rename(%p, \"%s\", \"%s\")", (void*)lfs, oldpath, newpath);
 
-    err = lfs_rawrename(lfs, oldpath, newpath);
+    err = lfs_rawrename(lfs, oldpath, newpath, NULL);
+
+    LFS_TRACE("lfs_rename -> %d", err);
+    LFS_UNLOCK(lfs->cfg);
+    return err;
+}
+#endif
+
+#ifndef LFS_READONLY
+int lfs_rename_with_removeall(lfs_t *lfs, const char *oldpath, const char *newpath) {
+    int err = LFS_LOCK(lfs->cfg);
+    if (err) {
+        return err;
+    }
+    LFS_TRACE("lfs_rename(%p, \"%s\", \"%s\")", (void*)lfs, oldpath, newpath);
+
+    // Note: We pass in a helper pointer here so that this extra
+    //       logic can be dropped if it is never referenced
+    err = lfs_rawrename(lfs, oldpath, newpath, lfs_dir_prep_remove_nonempty_folders);
 
     LFS_TRACE("lfs_rename -> %d", err);
     LFS_UNLOCK(lfs->cfg);

lfs.h

@@ -458,6 +458,17 @@ int lfs_unmount(lfs_t *lfs);
 int lfs_remove(lfs_t *lfs, const char *path);
 #endif
 
+#ifndef LFS_READONLY
+// Removes a file or directory
+//
+// If removing a directory, the directory must not have
+// any directories but it may contain files.  This is
+// non-POSIX behavior, and thus is a different call
+// than lfs_remove(...)
+// Returns a negative error code on failure.
+int lfs_removeall(lfs_t *lfs, const char *path);
+#endif
+
 #ifndef LFS_READONLY
 // Rename or move a file or directory
 //
@@ -468,6 +479,19 @@ int lfs_remove(lfs_t *lfs, const char *path);
 int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath);
 #endif
 
+#ifndef LFS_READONLY
+// Rename or move a file or directory
+//
+// If the destination exists, it must match the source in type.
+// If the destination is a directory, it may not contain
+// any directories but it may contain files.  This is
+// non-POSIX behavior, and thus is a different call
+// than lfs_rename(...)
+//
+// Returns a negative error code on failure.
+int lfs_rename_with_removeall(lfs_t *lfs, const char *oldpath, const char *newpath);
+#endif
+
 // Find info about a file or directory
 //
 // Fills out the info structure, based on the specified file or directory.

scripts/test.py

@@ -292,8 +292,6 @@ class TestCase:
                     if e.errno == errno.EIO:
                         break
                     raise
-                if not line:
-                    break;
                 stdout.append(line)
                 if args.get('verbose'):
                     sys.stdout.write(line)
@@ -689,8 +687,6 @@ def main(**args):
             if e.errno == errno.EIO:
                 break
             raise
-        if not line:
-            break;
         stdout.append(line)
         if args.get('verbose'):
             sys.stdout.write(line)

tests/test_relocations_with_removeall.toml

@@ -0,0 +1,305 @@
+# specific corner cases worth explicitly testing for
+[[case]] # dangling split dir test
+define.ITERATIONS = 20
+define.COUNT = 10
+define.LFS_BLOCK_CYCLES = [8, 1]
+code = '''
+    lfs_format(&lfs, &cfg) => 0;
+    // fill up filesystem so only ~16 blocks are left
+    lfs_mount(&lfs, &cfg) => 0;
+    lfs_file_open(&lfs, &file, "padding", LFS_O_CREAT | LFS_O_WRONLY) => 0;
+    memset(buffer, 0, 512);
+    while (LFS_BLOCK_COUNT - lfs_fs_size(&lfs) > 16) {
+        lfs_file_write(&lfs, &file, buffer, 512) => 512;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    // make a child dir to use in bounded space
+    lfs_mkdir(&lfs, "child") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, &cfg) => 0;
+    for (int j = 0; j < ITERATIONS; j++) {
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_CREAT | LFS_O_WRONLY) => 0;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+
+        lfs_dir_open(&lfs, &dir, "child") => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+        lfs_dir_close(&lfs, &dir) => 0;
+
+        if (j == ITERATIONS-1) {
+            break;
+        }
+
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_removeall(&lfs, path) => 0;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, &cfg) => 0;
+    lfs_dir_open(&lfs, &dir, "child") => 0;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    for (int i = 0; i < COUNT; i++) {
+        sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        strcmp(info.name, path) => 0;
+    }
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+    lfs_dir_close(&lfs, &dir) => 0;
+    for (int i = 0; i < COUNT; i++) {
+        sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+        lfs_removeall(&lfs, path) => 0;
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[[case]] # outdated head test
+define.ITERATIONS = 20
+define.COUNT = 10
+define.LFS_BLOCK_CYCLES = [8, 1]
+code = '''
+    lfs_format(&lfs, &cfg) => 0;
+    // fill up filesystem so only ~16 blocks are left
+    lfs_mount(&lfs, &cfg) => 0;
+    lfs_file_open(&lfs, &file, "padding", LFS_O_CREAT | LFS_O_WRONLY) => 0;
+    memset(buffer, 0, 512);
+    while (LFS_BLOCK_COUNT - lfs_fs_size(&lfs) > 16) {
+        lfs_file_write(&lfs, &file, buffer, 512) => 512;
+    }
+    lfs_file_close(&lfs, &file) => 0;
+    // make a child dir to use in bounded space
+    lfs_mkdir(&lfs, "child") => 0;
+    lfs_unmount(&lfs) => 0;
+
+    lfs_mount(&lfs, &cfg) => 0;
+    for (int j = 0; j < ITERATIONS; j++) {
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_CREAT | LFS_O_WRONLY) => 0;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+
+        lfs_dir_open(&lfs, &dir, "child") => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+            info.size => 0;
+
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_WRONLY) => 0;
+            lfs_file_write(&lfs, &file, "hi", 2) => 2;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+
+        lfs_dir_rewind(&lfs, &dir) => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+            info.size => 2;
+
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_file_open(&lfs, &file, path, LFS_O_WRONLY) => 0;
+            lfs_file_write(&lfs, &file, "hi", 2) => 2;
+            lfs_file_close(&lfs, &file) => 0;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+
+        lfs_dir_rewind(&lfs, &dir) => 0;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "test%03d_loooooooooooooooooong_name", i);
+            lfs_dir_read(&lfs, &dir, &info) => 1;
+            strcmp(info.name, path) => 0;
+            info.size => 2;
+        }
+        lfs_dir_read(&lfs, &dir, &info) => 0;
+        lfs_dir_close(&lfs, &dir) => 0;
+
+        for (int i = 0; i < COUNT; i++) {
+            sprintf(path, "child/test%03d_loooooooooooooooooong_name", i);
+            lfs_removeall(&lfs, path) => 0;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[[case]] # reentrant testing for relocations, this is the same as the
+         # orphan testing, except here we also set block_cycles so that
+         # almost every tree operation needs a relocation
+reentrant = true
+# TODO fix this case, caused by non-DAG trees
+if = '!(DEPTH == 3 && LFS_CACHE_SIZE != 64)'
+define = [
+    {FILES=6,  DEPTH=1, CYCLES=20, LFS_BLOCK_CYCLES=1},
+    {FILES=26, DEPTH=1, CYCLES=20, LFS_BLOCK_CYCLES=1},
+    {FILES=3,  DEPTH=3, CYCLES=20, LFS_BLOCK_CYCLES=1},
+]
+code = '''
+    err = lfs_mount(&lfs, &cfg);
+    if (err) {
+        lfs_format(&lfs, &cfg) => 0;
+        lfs_mount(&lfs, &cfg) => 0;
+    }
+
+    srand(1);
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (int i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (int d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[rand() % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        int res = lfs_stat(&lfs, full_path, &info);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (int d = 0; d < DEPTH; d++) {
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (int d = 0; d < DEPTH; d++) {
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            // is valid dir?
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // try to delete path in reverse order, ignore if dir is not empty
+            for (int d = DEPTH-1; d >= 0; d--) {
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_removeall(&lfs, path);
+                assert(!err || err == LFS_ERR_NOTEMPTY);
+            }
+
+            lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''
+
+[[case]] # reentrant testing for relocations, but now with random renames!
+reentrant = true
+# TODO fix this case, caused by non-DAG trees
+if = '!(DEPTH == 3 && LFS_CACHE_SIZE != 64)'
+define = [
+    {FILES=6,  DEPTH=1, CYCLES=20, LFS_BLOCK_CYCLES=1},
+    {FILES=26, DEPTH=1, CYCLES=20, LFS_BLOCK_CYCLES=1},
+    {FILES=3,  DEPTH=3, CYCLES=20, LFS_BLOCK_CYCLES=1},
+]
+code = '''
+    err = lfs_mount(&lfs, &cfg);
+    if (err) {
+        lfs_format(&lfs, &cfg) => 0;
+        lfs_mount(&lfs, &cfg) => 0;
+    }
+
+    srand(1);
+    const char alpha[] = "abcdefghijklmnopqrstuvwxyz";
+    for (int i = 0; i < CYCLES; i++) {
+        // create random path
+        char full_path[256];
+        for (int d = 0; d < DEPTH; d++) {
+            sprintf(&full_path[2*d], "/%c", alpha[rand() % FILES]);
+        }
+
+        // if it does not exist, we create it, else we destroy
+        int res = lfs_stat(&lfs, full_path, &info);
+        assert(!res || res == LFS_ERR_NOENT);
+        if (res == LFS_ERR_NOENT) {
+            // create each directory in turn, ignore if dir already exists
+            for (int d = 0; d < DEPTH; d++) {
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                err = lfs_mkdir(&lfs, path);
+                assert(!err || err == LFS_ERR_EXIST);
+            }
+
+            for (int d = 0; d < DEPTH; d++) {
+                strcpy(path, full_path);
+                path[2*d+2] = '\0';
+                lfs_stat(&lfs, path, &info) => 0;
+                assert(strcmp(info.name, &path[2*d+1]) == 0);
+                assert(info.type == LFS_TYPE_DIR);
+            }
+        } else {
+            assert(strcmp(info.name, &full_path[2*(DEPTH-1)+1]) == 0);
+            assert(info.type == LFS_TYPE_DIR);
+
+            // create new random path
+            char new_path[256];
+            for (int d = 0; d < DEPTH; d++) {
+                sprintf(&new_path[2*d], "/%c", alpha[rand() % FILES]);
+            }
+
+            // if new path does not exist, rename, otherwise destroy
+            res = lfs_stat(&lfs, new_path, &info);
+            assert(!res || res == LFS_ERR_NOENT);
+            if (res == LFS_ERR_NOENT) {
+                // stop once some dir is renamed
+                for (int d = 0; d < DEPTH; d++) {
+                    strcpy(&path[2*d], &full_path[2*d]);
+                    path[2*d+2] = '\0';
+                    strcpy(&path[128+2*d], &new_path[2*d]);
+                    path[128+2*d+2] = '\0';
+                    err = lfs_rename(&lfs, path, path+128);
+                    assert(!err || err == LFS_ERR_NOTEMPTY);
+                    if (!err) {
+                        strcpy(path, path+128);
+                    }
+                }
+
+                for (int d = 0; d < DEPTH; d++) {
+                    strcpy(path, new_path);
+                    path[2*d+2] = '\0';
+                    lfs_stat(&lfs, path, &info) => 0;
+                    assert(strcmp(info.name, &path[2*d+1]) == 0);
+                    assert(info.type == LFS_TYPE_DIR);
+                }
+                
+                lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+            } else {
+                // try to delete path in reverse order,
+                // ignore if dir is not empty
+                for (int d = DEPTH-1; d >= 0; d--) {
+                    strcpy(path, full_path);
+                    path[2*d+2] = '\0';
+                    err = lfs_removeall(&lfs, path);
+                    assert(!err || err == LFS_ERR_NOTEMPTY);
+                }
+
+                lfs_stat(&lfs, full_path, &info) => LFS_ERR_NOENT;
+            }
+        }
+    }
+    lfs_unmount(&lfs) => 0;
+'''