Generated v2 prefixes

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
       github.event.workflow_run.head_sha == github.sha}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           ref: ${{github.event.workflow_run.head_sha}}
           # need workflow access since we push branches
@@ -30,26 +30,29 @@ jobs:
           fetch-depth: 0
 
       # try to get results from tests
-      - uses: dawidd6/action-download-artifact@v2
+      - uses: actions/download-artifact@v4
         continue-on-error: true
         with:
-          workflow: ${{github.event.workflow_run.name}}
+          github-token: ${{secrets.GITHUB_TOKEN}}
-          run_id: ${{github.event.workflow_run.id}}
+          run-id: ${{github.event.workflow_run.id}}
-          name: sizes
+          pattern: '{sizes,sizes-*}'
+          merge-multiple: true
           path: sizes
-      - uses: dawidd6/action-download-artifact@v2
+      - uses: actions/download-artifact@v4
         continue-on-error: true
         with:
-          workflow: ${{github.event.workflow_run.name}}
+          github-token: ${{secrets.GITHUB_TOKEN}}
-          run_id: ${{github.event.workflow_run.id}}
+          run-id: ${{github.event.workflow_run.id}}
-          name: cov
+          pattern: '{cov,cov-*}'
+          merge-multiple: true
           path: cov
-      - uses: dawidd6/action-download-artifact@v2
+      - uses: actions/download-artifact@v4
         continue-on-error: true
         with:
-          workflow: ${{github.event.workflow_run.name}}
+          github-token: ${{secrets.GITHUB_TOKEN}}
-          run_id: ${{github.event.workflow_run.id}}
+          run-id: ${{github.event.workflow_run.id}}
-          name: bench
+          pattern: '{bench,bench-*}'
+          merge-multiple: true
           path: bench
 
       - name: find-version

.github/workflows/status.yml

@@ -13,12 +13,13 @@ jobs:
   status:
     runs-on: ubuntu-latest
     steps:
-      - uses: dawidd6/action-download-artifact@v2
+      - uses: actions/download-artifact@v4
         continue-on-error: true
         with:
-          workflow: ${{github.event.workflow_run.name}}
+          github-token: ${{secrets.GITHUB_TOKEN}}
-          run_id: ${{github.event.workflow_run.id}}
+          run-id: ${{github.event.workflow_run.id}}
-          name: status
+          pattern: '{status,status-*}'
+          merge-multiple: true
           path: status
       - name: update-status
         continue-on-error: true
@@ -67,12 +68,13 @@ jobs:
 
     steps:
       # generated comment?
-      - uses: dawidd6/action-download-artifact@v2
+      - uses: actions/download-artifact@v4
         continue-on-error: true
         with:
-          workflow: ${{github.event.workflow_run.name}}
+          github-token: ${{secrets.GITHUB_TOKEN}}
-          run_id: ${{github.event.workflow_run.id}}
+          run-id: ${{github.event.workflow_run.id}}
-          name: comment
+          pattern: '{comment,comment-*}'
+          merge-multiple: true
           path: comment
       - name: update-comment
         continue-on-error: true

.github/workflows/test.yml

@@ -21,7 +21,7 @@ jobs:
         arch: [x86_64, thumb, mips, powerpc]
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -235,9 +235,9 @@ jobs:
 
       # create size statuses
       - name: upload-sizes
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
-          name: sizes
+          name: sizes-${{matrix.arch}}
           path: sizes
       - name: status-sizes
         run: |
@@ -273,16 +273,16 @@ jobs:
             }' | tee status/$(basename $f .csv).json
           done
       - name: upload-status-sizes
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
-          name: status
+          name: status-sizes-${{matrix.arch}}
           path: status
           retention-days: 1
 
       # create cov statuses
       - name: upload-cov
         if: ${{matrix.arch == 'x86_64'}}
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: cov
           path: cov
@@ -317,11 +317,11 @@ jobs:
               target_step: env.STEP,
             }' | tee status/$(basename $f .csv)-$s.json
           done
-      - name: upload-status-sizes
+      - name: upload-status-cov
         if: ${{matrix.arch == 'x86_64'}}
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
-          name: status
+          name: status-cov
           path: status
           retention-days: 1
 
@@ -336,7 +336,7 @@ jobs:
         pls: [1, 2]
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -361,7 +361,7 @@ jobs:
   test-no-intrinsics:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -378,7 +378,7 @@ jobs:
   test-multiversion:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -395,7 +395,7 @@ jobs:
   test-lfs22_0:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -414,7 +414,7 @@ jobs:
   test-valgrind:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -436,7 +436,7 @@ jobs:
   test-clang:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -459,7 +459,7 @@ jobs:
   bench:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -491,7 +491,7 @@ jobs:
 
       # create bench statuses
       - name: upload-bench
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: bench
           path: bench
@@ -525,9 +525,9 @@ jobs:
             }' | tee status/$(basename $f .csv)-$s.json
           done
       - name: upload-status-bench
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
-          name: status
+          name: status-bench
           path: status
           retention-days: 1
 
@@ -535,10 +535,10 @@ jobs:
   test-compat:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         if: ${{github.event_name == 'pull_request'}}
       # checkout the current pr target into lfs2p
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         if: ${{github.event_name == 'pull_request'}}
         with:
           ref: ${{github.event.pull_request.base.ref}}
@@ -572,7 +572,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{!endsWith(github.ref, '-prefix')}}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -582,7 +582,7 @@ jobs:
           gcc --version
           python3 --version
           fusermount -V
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           repository: littlefs-project/littlefs-fuse
           ref: v2
@@ -622,7 +622,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{!endsWith(github.ref, '-prefix')}}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: install
         run: |
           # need a few things
@@ -632,12 +632,12 @@ jobs:
           gcc --version
           python3 --version
           fusermount -V
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           repository: littlefs-project/littlefs-fuse
           ref: v2
           path: v2
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           repository: littlefs-project/littlefs-fuse
           ref: v1
@@ -694,7 +694,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: [test, bench]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         if: ${{github.event_name == 'pull_request'}}
       - name: install
         if: ${{github.event_name == 'pull_request'}}
@@ -704,23 +704,26 @@ jobs:
           pip3 install toml
           gcc --version
           python3 --version
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
         if: ${{github.event_name == 'pull_request'}}
         continue-on-error: true
         with:
-          name: sizes
+          pattern: '{sizes,sizes-*}'
+          merge-multiple: true
           path: sizes
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
         if: ${{github.event_name == 'pull_request'}}
         continue-on-error: true
         with:
-          name: cov
+          pattern: '{cov,cov-*}'
+          merge-multiple: true
           path: cov
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
         if: ${{github.event_name == 'pull_request'}}
         continue-on-error: true
         with:
-          name: bench
+          pattern: '{bench,bench-*}'
+          merge-multiple: true
           path: bench
 
       # try to find results from tests
@@ -862,7 +865,7 @@ jobs:
             body: $comment,
           }' | tee comment/comment.json
       - name: upload-comment
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: comment
           path: comment

README.md

@@ -251,6 +251,12 @@ License Identifiers that are here available: http://spdx.org/licenses/
   filesystem over USB. Allows mounting littlefs on a host PC without additional
   drivers.
 
+- [ramcrc32bd] - An example block device using littlefs's 32-bit CRC for
+  error-correction.
+
+- [ramrsbd] - An example block device using Reed-Solomon codes for
+  error-correction.
+
 - [Mbed OS] - The easiest way to get started with littlefs is to jump into Mbed
   which already has block device drivers for most forms of embedded storage.
   littlefs is available in Mbed OS as the [LittleFileSystem] class.
@@ -281,6 +287,8 @@ License Identifiers that are here available: http://spdx.org/licenses/
 [mklfs]: https://github.com/whitecatboard/Lua-RTOS-ESP32/tree/master/components/mklfs/src
 [mklittlefs]: https://github.com/earlephilhower/mklittlefs
 [pico-littlefs-usb]: https://github.com/oyama/pico-littlefs-usb
+[ramcrc32bd]: https://github.com/geky/ramcrc32bd
+[ramrsbd]: https://github.com/geky/ramrsbd
 [Mbed OS]: https://github.com/armmbed/mbed-os
 [LittleFileSystem]: https://os.mbed.com/docs/mbed-os/latest/apis/littlefilesystem.html
 [SPIFFS]: https://github.com/pellepl/spiffs

lfs2.c

@@ -282,6 +282,21 @@ static int lfs2_bd_erase(lfs2_t *lfs2, lfs2_block_t block) {
 
 
 /// Small type-level utilities ///
+
+// some operations on paths
+static inline lfs2_size_t lfs2_path_namelen(const char *path) {
+    return strcspn(path, "/");
+}
+
+static inline bool lfs2_path_islast(const char *path) {
+    lfs2_size_t namelen = lfs2_path_namelen(path);
+    return path[namelen + strspn(path + namelen, "/")] == '\0';
+}
+
+static inline bool lfs2_path_isdir(const char *path) {
+    return path[lfs2_path_namelen(path)] != '\0';
+}
+
 // operations on block pairs
 static inline void lfs2_pair_swap(lfs2_block_t pair[2]) {
     lfs2_block_t t = pair[0];
@@ -1461,32 +1476,46 @@ static int lfs2_dir_find_match(void *data,
     return LFS2_CMP_EQ;
 }
 
+// lfs2_dir_find tries to set path and id even if file is not found
+//
+// returns:
+// - 0                  if file is found
+// - LFS2_ERR_NOENT      if file or parent is not found
+// - LFS2_ERR_NOTDIR     if parent is not a dir
 static lfs2_stag_t lfs2_dir_find(lfs2_t *lfs2, lfs2_mdir_t *dir,
         const char **path, uint16_t *id) {
     // we reduce path to a single name if we can find it
     const char *name = *path;
-    if (id) {
-        *id = 0x3ff;
-    }
 
     // default to root dir
     lfs2_stag_t tag = LFS2_MKTAG(LFS2_TYPE_DIR, 0x3ff, 0);
     dir->tail[0] = lfs2->root[0];
     dir->tail[1] = lfs2->root[1];
 
+    // empty paths are not allowed
+    if (*name == '\0') {
+        return LFS2_ERR_INVAL;
+    }
+
     while (true) {
 nextname:
-        // skip slashes
+        // skip slashes if we're a directory
-        name += strspn(name, "/");
+        if (lfs2_tag_type3(tag) == LFS2_TYPE_DIR) {
+            name += strspn(name, "/");
+        }
         lfs2_size_t namelen = strcspn(name, "/");
 
-        // skip '.' and root '..'
+        // skip '.'
-        if ((namelen == 1 && memcmp(name, ".", 1) == 0) ||
+        if (namelen == 1 && memcmp(name, ".", 1) == 0) {
-            (namelen == 2 && memcmp(name, "..", 2) == 0)) {
             name += namelen;
             goto nextname;
         }
 
+        // error on unmatched '..', trying to go above root?
+        if (namelen == 2 && memcmp(name, "..", 2) == 0) {
+            return LFS2_ERR_INVAL;
+        }
+
         // skip if matched by '..' in name
         const char *suffix = name + namelen;
         lfs2_size_t sufflen;
@@ -1498,7 +1527,9 @@ nextname:
                 break;
             }
 
-            if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
+            if (sufflen == 1 && memcmp(suffix, ".", 1) == 0) {
+                // noop
+            } else if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
                 depth -= 1;
                 if (depth == 0) {
                     name = suffix + sufflen;
@@ -1512,14 +1543,14 @@ nextname:
         }
 
         // found path
-        if (name[0] == '\0') {
+        if (*name == '\0') {
             return tag;
         }
 
         // update what we've found so far
         *path = name;
 
-        // only continue if we hit a directory
+        // only continue if we're a directory
         if (lfs2_tag_type3(tag) != LFS2_TYPE_DIR) {
             return LFS2_ERR_NOTDIR;
         }
@@ -1539,8 +1570,7 @@ nextname:
             tag = lfs2_dir_fetchmatch(lfs2, dir, dir->tail,
                     LFS2_MKTAG(0x780, 0, 0),
                     LFS2_MKTAG(LFS2_TYPE_NAME, 0, namelen),
-                     // are we last name?
+                    id,
-                    (strchr(name, '/') == NULL) ? id : NULL,
                     lfs2_dir_find_match, &(struct lfs2_dir_find_match){
                         lfs2, name, namelen});
             if (tag < 0) {
@@ -2128,13 +2158,14 @@ static int lfs2_dir_splittingcompact(lfs2_t *lfs2, lfs2_mdir_t *dir,
             // And we cap at half a block to avoid degenerate cases with
             // nearly-full metadata blocks.
             //
+            lfs2_size_t metadata_max = (lfs2->cfg->metadata_max)
+                    ? lfs2->cfg->metadata_max
+                    : lfs2->cfg->block_size;
             if (end - split < 0xff
                     && size <= lfs2_min(
-                        lfs2->cfg->block_size - 40,
+                        metadata_max - 40,
                         lfs2_alignup(
-                            (lfs2->cfg->metadata_max
+                            metadata_max/2,
-                                ? lfs2->cfg->metadata_max
-                                : lfs2->cfg->block_size)/2,
                             lfs2->cfg->prog_size))) {
                 break;
             }
@@ -2603,12 +2634,12 @@ static int lfs2_mkdir_(lfs2_t *lfs2, const char *path) {
     cwd.next = lfs2->mlist;
     uint16_t id;
     err = lfs2_dir_find(lfs2, &cwd.m, &path, &id);
-    if (!(err == LFS2_ERR_NOENT && id != 0x3ff)) {
+    if (!(err == LFS2_ERR_NOENT && lfs2_path_islast(path))) {
         return (err < 0) ? err : LFS2_ERR_EXIST;
     }
 
     // check that name fits
-    lfs2_size_t nlen = strlen(path);
+    lfs2_size_t nlen = lfs2_path_namelen(path);
     if (nlen > lfs2->name_max) {
         return LFS2_ERR_NAMETOOLONG;
     }
@@ -3057,7 +3088,7 @@ static int lfs2_file_opencfg_(lfs2_t *lfs2, lfs2_file_t *file,
 
     // allocate entry for file if it doesn't exist
     lfs2_stag_t tag = lfs2_dir_find(lfs2, &file->m, &path, &file->id);
-    if (tag < 0 && !(tag == LFS2_ERR_NOENT && file->id != 0x3ff)) {
+    if (tag < 0 && !(tag == LFS2_ERR_NOENT && lfs2_path_islast(path))) {
         err = tag;
         goto cleanup;
     }
@@ -3077,8 +3108,14 @@ static int lfs2_file_opencfg_(lfs2_t *lfs2, lfs2_file_t *file,
             goto cleanup;
         }
 
+        // don't allow trailing slashes
+        if (lfs2_path_isdir(path)) {
+            err = LFS2_ERR_NOTDIR;
+            goto cleanup;
+        }
+
         // check that name fits
-        lfs2_size_t nlen = strlen(path);
+        lfs2_size_t nlen = lfs2_path_namelen(path);
         if (nlen > lfs2->name_max) {
             err = LFS2_ERR_NAMETOOLONG;
             goto cleanup;
@@ -3664,22 +3701,16 @@ static lfs2_ssize_t lfs2_file_write_(lfs2_t *lfs2, lfs2_file_t *file,
 static lfs2_soff_t lfs2_file_seek_(lfs2_t *lfs2, lfs2_file_t *file,
         lfs2_soff_t off, int whence) {
     // find new pos
+    //
+    // fortunately for us, littlefs is limited to 31-bit file sizes, so we
+    // don't have to worry too much about integer overflow
     lfs2_off_t npos = file->pos;
     if (whence == LFS2_SEEK_SET) {
         npos = off;
     } else if (whence == LFS2_SEEK_CUR) {
-        if ((lfs2_soff_t)file->pos + off < 0) {
+        npos = file->pos + (lfs2_off_t)off;
-            return LFS2_ERR_INVAL;
-        } else {
-            npos = file->pos + off;
-        }
     } else if (whence == LFS2_SEEK_END) {
-        lfs2_soff_t res = lfs2_file_size_(lfs2, file) + off;
+        npos = (lfs2_off_t)lfs2_file_size_(lfs2, file) + (lfs2_off_t)off;
-        if (res < 0) {
-            return LFS2_ERR_INVAL;
-        } else {
-            npos = res;
-        }
     }
 
     if (npos > lfs2->file_max) {
@@ -3842,6 +3873,12 @@ static int lfs2_stat_(lfs2_t *lfs2, const char *path, struct lfs2_info *info) {
         return (int)tag;
     }
 
+    // only allow trailing slashes on dirs
+    if (strchr(path, '/') != NULL
+            && lfs2_tag_type3(tag) != LFS2_TYPE_DIR) {
+        return LFS2_ERR_NOTDIR;
+    }
+
     return lfs2_dir_getinfo(lfs2, &cwd, lfs2_tag_id(tag), info);
 }
 
@@ -3944,7 +3981,7 @@ static int lfs2_rename_(lfs2_t *lfs2, const char *oldpath, const char *newpath)
     uint16_t newid;
     lfs2_stag_t prevtag = lfs2_dir_find(lfs2, &newcwd, &newpath, &newid);
     if ((prevtag < 0 || lfs2_tag_id(prevtag) == 0x3ff) &&
-            !(prevtag == LFS2_ERR_NOENT && newid != 0x3ff)) {
+            !(prevtag == LFS2_ERR_NOENT && lfs2_path_islast(newpath))) {
         return (prevtag < 0) ? (int)prevtag : LFS2_ERR_INVAL;
     }
 
@@ -3955,8 +3992,14 @@ static int lfs2_rename_(lfs2_t *lfs2, const char *oldpath, const char *newpath)
     struct lfs2_mlist prevdir;
     prevdir.next = lfs2->mlist;
     if (prevtag == LFS2_ERR_NOENT) {
+        // if we're a file, don't allow trailing slashes
+        if (lfs2_path_isdir(newpath)
+                && lfs2_tag_type3(oldtag) != LFS2_TYPE_DIR) {
+            return LFS2_ERR_NOTDIR;
+        }
+
         // check that name fits
-        lfs2_size_t nlen = strlen(newpath);
+        lfs2_size_t nlen = lfs2_path_namelen(newpath);
         if (nlen > lfs2->name_max) {
             return LFS2_ERR_NAMETOOLONG;
         }
@@ -4016,7 +4059,8 @@ static int lfs2_rename_(lfs2_t *lfs2, const char *oldpath, const char *newpath)
             {LFS2_MKTAG_IF(prevtag != LFS2_ERR_NOENT,
                 LFS2_TYPE_DELETE, newid, 0), NULL},
             {LFS2_MKTAG(LFS2_TYPE_CREATE, newid, 0), NULL},
-            {LFS2_MKTAG(lfs2_tag_type3(oldtag), newid, strlen(newpath)), newpath},
+            {LFS2_MKTAG(lfs2_tag_type3(oldtag),
+                newid, lfs2_path_namelen(newpath)), newpath},
             {LFS2_MKTAG(LFS2_FROM_MOVE, newid, lfs2_tag_id(oldtag)), &oldcwd},
             {LFS2_MKTAG_IF(samepair,
                 LFS2_TYPE_DELETE, newoldid, 0), NULL}));
@@ -4173,6 +4217,14 @@ static int lfs2_init(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     // which littlefs currently does not support
     LFS2_ASSERT((bool)0x80000000);
 
+    // check that the required io functions are provided
+    LFS2_ASSERT(lfs2->cfg->read != NULL);
+#ifndef LFS2_READONLY
+    LFS2_ASSERT(lfs2->cfg->prog != NULL);
+    LFS2_ASSERT(lfs2->cfg->erase != NULL);
+    LFS2_ASSERT(lfs2->cfg->sync != NULL);
+#endif
+
     // validate that the lfs2-cfg sizes were initiated properly before
     // performing any arithmetic logics with them
     LFS2_ASSERT(lfs2->cfg->read_size != 0);
@@ -4209,6 +4261,15 @@ static int lfs2_init(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     LFS2_ASSERT(lfs2->cfg->compact_thresh == (lfs2_size_t)-1
             || lfs2->cfg->compact_thresh <= lfs2->cfg->block_size);
 
+    // check that metadata_max is a multiple of read_size and prog_size,
+    // and a factor of the block_size
+    LFS2_ASSERT(!lfs2->cfg->metadata_max
+            || lfs2->cfg->metadata_max % lfs2->cfg->read_size == 0);
+    LFS2_ASSERT(!lfs2->cfg->metadata_max
+            || lfs2->cfg->metadata_max % lfs2->cfg->prog_size == 0);
+    LFS2_ASSERT(!lfs2->cfg->metadata_max
+            || lfs2->cfg->block_size % lfs2->cfg->metadata_max == 0);
+
     // setup read cache
     if (lfs2->cfg->read_buffer) {
         lfs2->rcache.buffer = lfs2->cfg->read_buffer;
@@ -4396,6 +4457,30 @@ cleanup:
 }
 #endif
 
+struct lfs2_tortoise_t {
+    lfs2_block_t pair[2];
+    lfs2_size_t i;
+    lfs2_size_t period;
+};
+
+static int lfs2_tortoise_detectcycles(
+    const lfs2_mdir_t *dir, struct lfs2_tortoise_t *tortoise) {
+    // detect cycles with Brent's algorithm
+    if (lfs2_pair_issync(dir->tail, tortoise->pair)) {
+        LFS2_WARN("Cycle detected in tail list");
+        return LFS2_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 LFS2_ERR_OK;
+}
+
 static int lfs2_mount_(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     int err = lfs2_init(lfs2, cfg);
     if (err) {
@@ -4404,23 +4489,16 @@ static int lfs2_mount_(lfs2_t *lfs2, const struct lfs2_config *cfg) {
 
     // scan directory blocks for superblock and any global updates
     lfs2_mdir_t dir = {.tail = {0, 1}};
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
+    struct lfs2_tortoise_t tortoise = {
-    lfs2_size_t tortoise_i = 1;
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
-    lfs2_size_t tortoise_period = 1;
+        .i = 1,
+        .period = 1,
+    };
     while (!lfs2_pair_isnull(dir.tail)) {
-        // detect cycles with Brent's algorithm
+        err = lfs2_tortoise_detectcycles(&dir, &tortoise);
-        if (lfs2_pair_issync(dir.tail, tortoise)) {
+        if (err < 0) {
-            LFS2_WARN("Cycle detected in tail list");
-            err = LFS2_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
         lfs2_stag_t tag = lfs2_dir_fetchmatch(lfs2, &dir, dir.tail,
@@ -4633,22 +4711,17 @@ int lfs2_fs_traverse_(lfs2_t *lfs2,
     }
 #endif
 
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
+    struct lfs2_tortoise_t tortoise = {
-    lfs2_size_t tortoise_i = 1;
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
-    lfs2_size_t tortoise_period = 1;
+        .i = 1,
+        .period = 1,
+    };
+    int err = LFS2_ERR_OK;
     while (!lfs2_pair_isnull(dir.tail)) {
-        // detect cycles with Brent's algorithm
+        err = lfs2_tortoise_detectcycles(&dir, &tortoise);
-        if (lfs2_pair_issync(dir.tail, tortoise)) {
+        if (err < 0) {
-            LFS2_WARN("Cycle detected in tail list");
             return LFS2_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 +4800,17 @@ static int lfs2_fs_pred(lfs2_t *lfs2,
     // iterate over all directory directory entries
     pdir->tail[0] = 0;
     pdir->tail[1] = 1;
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
+    struct lfs2_tortoise_t tortoise = {
-    lfs2_size_t tortoise_i = 1;
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
-    lfs2_size_t tortoise_period = 1;
+        .i = 1,
+        .period = 1,
+    };
+    int err = LFS2_ERR_OK;
     while (!lfs2_pair_isnull(pdir->tail)) {
-        // detect cycles with Brent's algorithm
+        err = lfs2_tortoise_detectcycles(pdir, &tortoise);
-        if (lfs2_pair_issync(pdir->tail, tortoise)) {
+        if (err < 0) {
-            LFS2_WARN("Cycle detected in tail list");
             return LFS2_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 (lfs2_pair_cmp(pdir->tail, pair) == 0) {
             return 0;
@@ -4792,22 +4860,17 @@ static lfs2_stag_t lfs2_fs_parent(lfs2_t *lfs2, const lfs2_block_t pair[2],
     // use fetchmatch with callback to find pairs
     parent->tail[0] = 0;
     parent->tail[1] = 1;
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
+    struct lfs2_tortoise_t tortoise = {
-    lfs2_size_t tortoise_i = 1;
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
-    lfs2_size_t tortoise_period = 1;
+        .i = 1,
+        .period = 1,
+    };
+    int err = LFS2_ERR_OK;
     while (!lfs2_pair_isnull(parent->tail)) {
-        // detect cycles with Brent's algorithm
+        err = lfs2_tortoise_detectcycles(parent, &tortoise);
-        if (lfs2_pair_issync(parent->tail, tortoise)) {
+        if (err < 0) {
-            LFS2_WARN("Cycle detected in tail list");
+            return err;
-            return LFS2_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;
 
         lfs2_stag_t tag = lfs2_dir_fetchmatch(lfs2, parent, parent->tail,
                 LFS2_MKTAG(0x7ff, 0, 0x3ff),
@@ -5890,7 +5953,7 @@ int lfs2_format(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                 ".read=%p, .prog=%p, .erase=%p, .sync=%p, "
                 ".read_size=%"PRIu32", .prog_size=%"PRIu32", "
                 ".block_size=%"PRIu32", .block_count=%"PRIu32", "
-                ".block_cycles=%"PRIu32", .cache_size=%"PRIu32", "
+                ".block_cycles=%"PRId32", .cache_size=%"PRIu32", "
                 ".lookahead_size=%"PRIu32", .read_buffer=%p, "
                 ".prog_buffer=%p, .lookahead_buffer=%p, "
                 ".name_max=%"PRIu32", .file_max=%"PRIu32", "
@@ -5920,7 +5983,7 @@ int lfs2_mount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                 ".read=%p, .prog=%p, .erase=%p, .sync=%p, "
                 ".read_size=%"PRIu32", .prog_size=%"PRIu32", "
                 ".block_size=%"PRIu32", .block_count=%"PRIu32", "
-                ".block_cycles=%"PRIu32", .cache_size=%"PRIu32", "
+                ".block_cycles=%"PRId32", .cache_size=%"PRIu32", "
                 ".lookahead_size=%"PRIu32", .read_buffer=%p, "
                 ".prog_buffer=%p, .lookahead_buffer=%p, "
                 ".name_max=%"PRIu32", .file_max=%"PRIu32", "
@@ -6057,7 +6120,7 @@ int lfs2_file_open(lfs2_t *lfs2, lfs2_file_t *file, const char *path, int flags)
         return err;
     }
     LFS2_TRACE("lfs2_file_open(%p, %p, \"%s\", %x)",
-            (void*)lfs2, (void*)file, path, flags);
+            (void*)lfs2, (void*)file, path, (unsigned)flags);
     LFS2_ASSERT(!lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
     err = lfs2_file_open_(lfs2, file, path, flags);
@@ -6077,7 +6140,7 @@ int lfs2_file_opencfg(lfs2_t *lfs2, lfs2_file_t *file,
     }
     LFS2_TRACE("lfs2_file_opencfg(%p, %p, \"%s\", %x, %p {"
                  ".buffer=%p, .attrs=%p, .attr_count=%"PRIu32"})",
-            (void*)lfs2, (void*)file, path, flags,
+            (void*)lfs2, (void*)file, path, (unsigned)flags,
             (void*)cfg, cfg->buffer, (void*)cfg->attrs, cfg->attr_count);
     LFS2_ASSERT(!lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
@@ -6439,7 +6502,7 @@ int lfs2_migrate(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                 ".read=%p, .prog=%p, .erase=%p, .sync=%p, "
                 ".read_size=%"PRIu32", .prog_size=%"PRIu32", "
                 ".block_size=%"PRIu32", .block_count=%"PRIu32", "
-                ".block_cycles=%"PRIu32", .cache_size=%"PRIu32", "
+                ".block_cycles=%"PRId32", .cache_size=%"PRIu32", "
                 ".lookahead_size=%"PRIu32", .read_buffer=%p, "
                 ".prog_buffer=%p, .lookahead_buffer=%p, "
                 ".name_max=%"PRIu32", .file_max=%"PRIu32", "

lfs2.h

@@ -21,7 +21,7 @@ extern "C"
 // Software library version
 // Major (top-nibble), incremented on backwards incompatible changes
 // Minor (bottom-nibble), incremented on feature additions
-#define LFS2_VERSION 0x00020009
+#define LFS2_VERSION 0x0002000a
 #define LFS2_VERSION_MAJOR (0xffff & (LFS2_VERSION >> 16))
 #define LFS2_VERSION_MINOR (0xffff & (LFS2_VERSION >>  0))
 

lfs2_util.h

@@ -8,6 +8,9 @@
 #ifndef LFS2_UTIL_H
 #define LFS2_UTIL_H
 
+#define LFS2_STRINGIZE(x) LFS2_STRINGIZE2(x)
+#define LFS2_STRINGIZE2(x) #x
+
 // Users can override lfs2_util.h with their own configuration by defining
 // LFS2_CONFIG as a header file to include (-DLFS2_CONFIG=lfs2_config.h).
 //
@@ -15,11 +18,26 @@
 // provided by the config file. To start, I would suggest copying lfs2_util.h
 // and modifying as needed.
 #ifdef LFS2_CONFIG
-#define LFS2_STRINGIZE(x) LFS2_STRINGIZE2(x)
-#define LFS2_STRINGIZE2(x) #x
 #include LFS2_STRINGIZE(LFS2_CONFIG)
 #else
 
+// Alternatively, users can provide a header file which defines
+// macros and other things consumed by littlefs.
+//
+// For example, provide my_defines.h, which contains
+// something like:
+//
+// #include <stddef.h>
+// extern void *my_malloc(size_t sz);
+// #define LFS2_MALLOC(sz) my_malloc(sz)
+//
+// And build littlefs with the header by defining LFS2_DEFINES.
+// (-DLFS2_DEFINES=my_defines.h)
+
+#ifdef LFS2_DEFINES
+#include LFS2_STRINGIZE(LFS2_DEFINES)
+#endif
+
 // System includes
 #include <stdint.h>
 #include <stdbool.h>

runners/bench_runner.c

@@ -1322,6 +1322,7 @@ void perm_run(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .metadata_max       = METADATA_MAX,
         .inline_max         = INLINE_MAX,
     };
 

runners/bench_runner.h

@@ -96,12 +96,13 @@ intmax_t bench_define(size_t define);
 #define CACHE_SIZE_i         6
 #define LOOKAHEAD_SIZE_i     7
 #define COMPACT_THRESH_i     8
-#define INLINE_MAX_i         9
+#define METADATA_MAX_i       9
-#define BLOCK_CYCLES_i       10
+#define INLINE_MAX_i         10
-#define ERASE_VALUE_i        11
+#define BLOCK_CYCLES_i       11
-#define ERASE_CYCLES_i       12
+#define ERASE_VALUE_i        12
-#define BADBLOCK_BEHAVIOR_i  13
+#define ERASE_CYCLES_i       13
-#define POWERLOSS_BEHAVIOR_i 14
+#define BADBLOCK_BEHAVIOR_i  14
+#define POWERLOSS_BEHAVIOR_i 15
 
 #define READ_SIZE           bench_define(READ_SIZE_i)
 #define PROG_SIZE           bench_define(PROG_SIZE_i)
@@ -112,6 +113,7 @@ intmax_t bench_define(size_t define);
 #define CACHE_SIZE          bench_define(CACHE_SIZE_i)
 #define LOOKAHEAD_SIZE      bench_define(LOOKAHEAD_SIZE_i)
 #define COMPACT_THRESH      bench_define(COMPACT_THRESH_i)
+#define METADATA_MAX        bench_define(METADATA_MAX_i)
 #define INLINE_MAX          bench_define(INLINE_MAX_i)
 #define BLOCK_CYCLES        bench_define(BLOCK_CYCLES_i)
 #define ERASE_VALUE         bench_define(ERASE_VALUE_i)
@@ -129,6 +131,7 @@ intmax_t bench_define(size_t define);
     BENCH_DEF(CACHE_SIZE,         lfs2_max(64,lfs2_max(READ_SIZE,PROG_SIZE))) \
     BENCH_DEF(LOOKAHEAD_SIZE,     16) \
     BENCH_DEF(COMPACT_THRESH,     0) \
+    BENCH_DEF(METADATA_MAX,       0) \
     BENCH_DEF(INLINE_MAX,         0) \
     BENCH_DEF(BLOCK_CYCLES,       -1) \
     BENCH_DEF(ERASE_VALUE,        0xff) \
@@ -137,7 +140,7 @@ intmax_t bench_define(size_t define);
     BENCH_DEF(POWERLOSS_BEHAVIOR, LFS2_EMUBD_POWERLOSS_NOOP)
 
 #define BENCH_GEOMETRY_DEFINE_COUNT 4
-#define BENCH_IMPLICIT_DEFINE_COUNT 15
+#define BENCH_IMPLICIT_DEFINE_COUNT 16
 
 
 #endif

runners/test_runner.c

@@ -1347,6 +1347,7 @@ static void run_powerloss_none(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .metadata_max       = METADATA_MAX,
         .inline_max         = INLINE_MAX,
     #ifdef LFS2_MULTIVERSION
         .disk_version       = DISK_VERSION,
@@ -1425,6 +1426,7 @@ static void run_powerloss_linear(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .metadata_max       = METADATA_MAX,
         .inline_max         = INLINE_MAX,
     #ifdef LFS2_MULTIVERSION
         .disk_version       = DISK_VERSION,
@@ -1520,6 +1522,7 @@ static void run_powerloss_log(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .metadata_max       = METADATA_MAX,
         .inline_max         = INLINE_MAX,
     #ifdef LFS2_MULTIVERSION
         .disk_version       = DISK_VERSION,
@@ -1613,6 +1616,7 @@ static void run_powerloss_cycles(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .metadata_max       = METADATA_MAX,
         .inline_max         = INLINE_MAX,
     #ifdef LFS2_MULTIVERSION
         .disk_version       = DISK_VERSION,
@@ -1804,6 +1808,7 @@ static void run_powerloss_exhaustive(
         .cache_size         = CACHE_SIZE,
         .lookahead_size     = LOOKAHEAD_SIZE,
         .compact_thresh     = COMPACT_THRESH,
+        .metadata_max       = METADATA_MAX,
         .inline_max         = INLINE_MAX,
     #ifdef LFS2_MULTIVERSION
         .disk_version       = DISK_VERSION,

runners/test_runner.h

@@ -89,13 +89,14 @@ intmax_t test_define(size_t define);
 #define CACHE_SIZE_i         6
 #define LOOKAHEAD_SIZE_i     7
 #define COMPACT_THRESH_i     8
-#define INLINE_MAX_i         9
+#define METADATA_MAX_i       9
-#define BLOCK_CYCLES_i       10
+#define INLINE_MAX_i         10
-#define ERASE_VALUE_i        11
+#define BLOCK_CYCLES_i       11
-#define ERASE_CYCLES_i       12
+#define ERASE_VALUE_i        12
-#define BADBLOCK_BEHAVIOR_i  13
+#define ERASE_CYCLES_i       13
-#define POWERLOSS_BEHAVIOR_i 14
+#define BADBLOCK_BEHAVIOR_i  14
-#define DISK_VERSION_i       15
+#define POWERLOSS_BEHAVIOR_i 15
+#define DISK_VERSION_i       16
 
 #define READ_SIZE           TEST_DEFINE(READ_SIZE_i)
 #define PROG_SIZE           TEST_DEFINE(PROG_SIZE_i)
@@ -106,6 +107,7 @@ intmax_t test_define(size_t define);
 #define CACHE_SIZE          TEST_DEFINE(CACHE_SIZE_i)
 #define LOOKAHEAD_SIZE      TEST_DEFINE(LOOKAHEAD_SIZE_i)
 #define COMPACT_THRESH      TEST_DEFINE(COMPACT_THRESH_i)
+#define METADATA_MAX        TEST_DEFINE(METADATA_MAX_i)
 #define INLINE_MAX          TEST_DEFINE(INLINE_MAX_i)
 #define BLOCK_CYCLES        TEST_DEFINE(BLOCK_CYCLES_i)
 #define ERASE_VALUE         TEST_DEFINE(ERASE_VALUE_i)
@@ -124,6 +126,7 @@ intmax_t test_define(size_t define);
     TEST_DEF(CACHE_SIZE,         lfs2_max(64,lfs2_max(READ_SIZE,PROG_SIZE))) \
     TEST_DEF(LOOKAHEAD_SIZE,     16) \
     TEST_DEF(COMPACT_THRESH,     0) \
+    TEST_DEF(METADATA_MAX,       0) \
     TEST_DEF(INLINE_MAX,         0) \
     TEST_DEF(BLOCK_CYCLES,       -1) \
     TEST_DEF(ERASE_VALUE,        0xff) \
@@ -133,7 +136,7 @@ intmax_t test_define(size_t define);
     TEST_DEF(DISK_VERSION,       0)
 
 #define TEST_GEOMETRY_DEFINE_COUNT 4
-#define TEST_IMPLICIT_DEFINE_COUNT 16
+#define TEST_IMPLICIT_DEFINE_COUNT 17
 
 
 #endif

scripts/prettyasserts.py

@@ -86,6 +86,13 @@ def write_header(f, limit=LIMIT):
     f.writeln("}")
     f.writeln()
     f.writeln("__attribute__((unused))")
+    f.writeln("static void __pretty_assert_print_ptr(")
+    f.writeln("        const void *v, size_t size) {")
+    f.writeln("    (void)size;")
+    f.writeln("    printf(\"%p\", v);")
+    f.writeln("}")
+    f.writeln()
+    f.writeln("__attribute__((unused))")
     f.writeln("static void __pretty_assert_print_mem(")
     f.writeln("        const void *v, size_t size) {")
     f.writeln("    const uint8_t *v_ = v;")
@@ -183,6 +190,23 @@ def write_header(f, limit=LIMIT):
         f.writeln("                _rh, strlen(_rh)); \\")
         f.writeln("    } \\")
         f.writeln("} while (0)")
+    for op, cmp in sorted(CMP.items()):
+        # Only EQ and NE are supported when compared to NULL.
+        if cmp not in ['eq', 'ne']:
+            continue
+        f.writeln("#define __PRETTY_ASSERT_PTR_%s(lh, rh) do { \\"
+            % cmp.upper())
+        f.writeln("    const void *_lh = (const void*)(uintptr_t)lh; \\")
+        f.writeln("    const void *_rh = (const void*)(uintptr_t)rh; \\")
+        f.writeln("    if (!(_lh %s _rh)) { \\" % op)
+        f.writeln("        __pretty_assert_fail( \\")
+        f.writeln("                __FILE__, __LINE__, \\")
+        f.writeln("                __pretty_assert_print_ptr, \"%s\", \\"
+            % cmp)
+        f.writeln("                (const void*){_lh}, 0, \\")
+        f.writeln("                (const void*){_rh}, 0); \\")
+        f.writeln("    } \\")
+        f.writeln("} while (0)")
     f.writeln()
     f.writeln()
 
@@ -301,6 +325,8 @@ def p_assert(p):
         cmp = p.expect('cmp') ; p.accept('ws')
         rh = p_expr(p) ; p.accept('ws')
         p.expect(')')
+        if rh == 'NULL' or lh == 'NULL':
+            return mkassert('ptr', CMP[cmp], lh, rh)
         return mkassert('int', CMP[cmp], lh, rh)
     except ParseFailure:
         p.pop(state)

tests/test_seek.toml

@@ -405,3 +405,111 @@ code = '''
     lfs2_file_close(&lfs2, &file) => 0;
     lfs2_unmount(&lfs2) => 0;
 '''
+
+
+# test possible overflow/underflow conditions
+#
+# note these need -fsanitize=undefined to consistently detect
+# overflow/underflow conditions
+
+[cases.test_seek_filemax]
+code = '''
+    lfs2_t lfs2;
+    lfs2_format(&lfs2, cfg) => 0;
+    lfs2_mount(&lfs2, cfg) => 0;
+    lfs2_file_t file;
+    lfs2_file_open(&lfs2, &file, "kitty",
+            LFS2_O_WRONLY | LFS2_O_CREAT | LFS2_O_APPEND) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "kittycatcat");
+    size_t size = strlen((char*)buffer);
+    lfs2_file_write(&lfs2, &file, buffer, size) => size;
+
+    // seek with LFS2_SEEK_SET
+    lfs2_file_seek(&lfs2, &file, LFS2_FILE_MAX, LFS2_SEEK_SET) => LFS2_FILE_MAX;
+
+    // seek with LFS2_SEEK_CUR
+    lfs2_file_seek(&lfs2, &file, 0, LFS2_SEEK_CUR) => LFS2_FILE_MAX;
+
+    // the file hasn't changed size, so seek end takes us back to the offset=0
+    lfs2_file_seek(&lfs2, &file, +10, LFS2_SEEK_END) => size+10;
+
+    lfs2_file_close(&lfs2, &file) => 0;
+    lfs2_unmount(&lfs2) => 0;
+'''
+
+[cases.test_seek_underflow]
+code = '''
+    lfs2_t lfs2;
+    lfs2_format(&lfs2, cfg) => 0;
+    lfs2_mount(&lfs2, cfg) => 0;
+    lfs2_file_t file;
+    lfs2_file_open(&lfs2, &file, "kitty",
+            LFS2_O_WRONLY | LFS2_O_CREAT | LFS2_O_APPEND) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "kittycatcat");
+    size_t size = strlen((char*)buffer);
+    lfs2_file_write(&lfs2, &file, buffer, size) => size;
+
+    // underflow with LFS2_SEEK_CUR, should error
+    lfs2_file_seek(&lfs2, &file, -(size+10), LFS2_SEEK_CUR) => LFS2_ERR_INVAL;
+    lfs2_file_seek(&lfs2, &file, -LFS2_FILE_MAX, LFS2_SEEK_CUR) => LFS2_ERR_INVAL;
+    lfs2_file_seek(&lfs2, &file, -(size+LFS2_FILE_MAX), LFS2_SEEK_CUR)
+            => LFS2_ERR_INVAL;
+
+    // underflow with LFS2_SEEK_END, should error
+    lfs2_file_seek(&lfs2, &file, -(size+10), LFS2_SEEK_END) => LFS2_ERR_INVAL;
+    lfs2_file_seek(&lfs2, &file, -LFS2_FILE_MAX, LFS2_SEEK_END) => LFS2_ERR_INVAL;
+    lfs2_file_seek(&lfs2, &file, -(size+LFS2_FILE_MAX), LFS2_SEEK_END)
+            => LFS2_ERR_INVAL;
+
+    // file pointer should not have changed
+    lfs2_file_tell(&lfs2, &file) => size;
+
+    lfs2_file_close(&lfs2, &file) => 0;
+    lfs2_unmount(&lfs2) => 0;
+'''
+
+[cases.test_seek_overflow]
+code = '''
+    lfs2_t lfs2;
+    lfs2_format(&lfs2, cfg) => 0;
+    lfs2_mount(&lfs2, cfg) => 0;
+    lfs2_file_t file;
+    lfs2_file_open(&lfs2, &file, "kitty",
+            LFS2_O_WRONLY | LFS2_O_CREAT | LFS2_O_APPEND) => 0;
+    uint8_t buffer[1024];
+    strcpy((char*)buffer, "kittycatcat");
+    size_t size = strlen((char*)buffer);
+    lfs2_file_write(&lfs2, &file, buffer, size) => size;
+
+    // seek to LFS2_FILE_MAX
+    lfs2_file_seek(&lfs2, &file, LFS2_FILE_MAX, LFS2_SEEK_SET) => LFS2_FILE_MAX;
+
+    // overflow with LFS2_SEEK_CUR, should error
+    lfs2_file_seek(&lfs2, &file, +10, LFS2_SEEK_CUR) => LFS2_ERR_INVAL;
+    lfs2_file_seek(&lfs2, &file, +LFS2_FILE_MAX, LFS2_SEEK_CUR) => LFS2_ERR_INVAL;
+
+    // LFS2_SEEK_SET/END don't care about the current file position, but we can
+    // still overflow with a large offset
+
+    // overflow with LFS2_SEEK_SET, should error
+    lfs2_file_seek(&lfs2, &file,
+            +((uint32_t)LFS2_FILE_MAX+10),
+            LFS2_SEEK_SET) => LFS2_ERR_INVAL;
+    lfs2_file_seek(&lfs2, &file,
+            +((uint32_t)LFS2_FILE_MAX+(uint32_t)LFS2_FILE_MAX),
+            LFS2_SEEK_SET) => LFS2_ERR_INVAL;
+
+    // overflow with LFS2_SEEK_END, should error
+    lfs2_file_seek(&lfs2, &file, +(LFS2_FILE_MAX-size+10), LFS2_SEEK_END)
+            => LFS2_ERR_INVAL;
+    lfs2_file_seek(&lfs2, &file, +(LFS2_FILE_MAX-size+LFS2_FILE_MAX), LFS2_SEEK_END)
+            => LFS2_ERR_INVAL;
+
+    // file pointer should not have changed
+    lfs2_file_tell(&lfs2, &file) => LFS2_FILE_MAX;
+
+    lfs2_file_close(&lfs2, &file) => 0;
+    lfs2_unmount(&lfs2) => 0;
+'''

tests/test_superblocks.toml

@@ -523,3 +523,30 @@ code = '''
     assert(memcmp(buffer, "hello!", 6) == 0);
     lfs2_unmount(&lfs2) => 0;
 '''
+
+# test that metadata_max does not cause problems for superblock compaction
+[cases.test_superblocks_metadata_max]
+defines.METADATA_MAX = [
+    'lfs2_max(512, PROG_SIZE)',
+    'lfs2_max(BLOCK_SIZE/2, PROG_SIZE)',
+    'BLOCK_SIZE'
+]
+defines.N = [10, 100, 1000]
+code = '''
+    lfs2_t lfs2;
+    lfs2_format(&lfs2, cfg) => 0;
+    lfs2_mount(&lfs2, cfg) => 0;
+    for (int i = 0; i < N; i++) {
+        lfs2_file_t file;
+        char name[256];
+        sprintf(name, "hello%03x", i);
+        lfs2_file_open(&lfs2, &file, name,
+                LFS2_O_WRONLY | LFS2_O_CREAT | LFS2_O_EXCL) => 0;
+        lfs2_file_close(&lfs2, &file) => 0;
+        struct lfs2_info info;
+        lfs2_stat(&lfs2, name, &info) => 0;
+        assert(strcmp(info.name, name) == 0);
+        assert(info.type == LFS2_TYPE_REG);
+    }
+    lfs2_unmount(&lfs2) => 0;
+'''