Generated v2 prefixes

README.md

@@ -231,11 +231,25 @@ License Identifiers that are here available: http://spdx.org/licenses/
   to use littlefs in a Rust-friendly API, reaping the benefits of Rust's memory
   safety and other guarantees.
 
+- [nim-littlefs] - A Nim wrapper and API for littlefs. Includes a fuse
+  implementation based on [littlefs-fuse]
+
+- [chamelon] - A pure-OCaml implementation of (most of) littlefs, designed for
+  use with the MirageOS library operating system project. It is interoperable
+  with the reference implementation, with some caveats.
+
 - [littlefs-disk-img-viewer] - A memory-efficient web application for viewing
   littlefs disk images in your web browser.
 
-- [mklfs] - A command line tool built by the [Lua RTOS] guys for making
+- [mklfs] - A command line tool for creating littlefs images. Used in the Lua
-  littlefs images from a host PC. Supports Windows, Mac OS, and Linux.
+  RTOS ecosystem.
+
+- [mklittlefs] - A command line tool for creating littlefs images. Used in the
+  ESP8266 and RP2040 ecosystem.
+
+- [pico-littlefs-usb] - An interface for littlefs that emulates a FAT12
+  filesystem over USB. Allows mounting littlefs on a host PC without additional
+  drivers.
 
 - [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.
@@ -254,27 +268,21 @@ License Identifiers that are here available: http://spdx.org/licenses/
   for microcontroller-scale devices. Due to limitations of FAT it can't provide
   power-loss resilience, but it does allow easy interop with PCs.
 
-- [chamelon] - A pure-OCaml implementation of (most of) littlefs, designed for
-  use with the MirageOS library operating system project. It is interoperable
-  with the reference implementation, with some caveats.
-
-- [nim-littlefs] - A Nim wrapper and API for littlefs. Includes a fuse 
-  implementation based on [littlefs-fuse]
-
 [BSD-3-Clause]: https://spdx.org/licenses/BSD-3-Clause.html
-[littlefs-disk-img-viewer]: https://github.com/tniessen/littlefs-disk-img-viewer
 [littlefs-fuse]: https://github.com/geky/littlefs-fuse
 [FUSE]: https://github.com/libfuse/libfuse
 [littlefs-js]: https://github.com/geky/littlefs-js
 [littlefs-js-demo]:http://littlefs.geky.net/demo.html
+[littlefs-python]: https://pypi.org/project/littlefs-python/
+[littlefs2-rust]: https://crates.io/crates/littlefs2
+[nim-littlefs]: https://github.com/Graveflo/nim-littlefs
+[chamelon]: https://github.com/yomimono/chamelon
+[littlefs-disk-img-viewer]: https://github.com/tniessen/littlefs-disk-img-viewer
 [mklfs]: https://github.com/whitecatboard/Lua-RTOS-ESP32/tree/master/components/mklfs/src
-[Lua RTOS]: https://github.com/whitecatboard/Lua-RTOS-ESP32
+[mklittlefs]: https://github.com/earlephilhower/mklittlefs
+[pico-littlefs-usb]: https://github.com/oyama/pico-littlefs-usb
 [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
 [Dhara]: https://github.com/dlbeer/dhara
 [ChaN's FatFs]: http://elm-chan.org/fsw/ff/00index_e.html
-[littlefs-python]: https://pypi.org/project/littlefs-python/
-[littlefs2-rust]: https://crates.io/crates/littlefs2
-[chamelon]: https://github.com/yomimono/chamelon
-[nim-littlefs]: https://github.com/Graveflo/nim-littlefs

SPEC.md

@@ -441,9 +441,10 @@ Superblock fields:
 
 7. **Attr max (32-bits)** - Maximum size of file attributes in bytes.
 
-The superblock must always be the first entry (id 0) in a metadata pair as well
+The superblock must always be the first entry (id 0) in the metadata pair, and
-as be the first entry written to the block. This means that the superblock
+the name tag must always be the first tag in the metadata pair. This makes it
-entry can be read from a device using offsets alone.
+so that the magic string "littlefs" will always reside at offset=8 in a valid
+littlefs superblock.
 
 ---
 #### `0x2xx` LFS2_TYPE_STRUCT

lfs2.c

@@ -2191,7 +2191,8 @@ static int lfs2_dir_splittingcompact(lfs2_t *lfs2, lfs2_mdir_t *dir,
                 // we can do, we'll error later if we've become frozen
                 LFS2_WARN("Unable to expand superblock");
             } else {
-                end = begin;
+                // duplicate the superblock entry into the new superblock
+                end = 1;
             }
         }
     }
@@ -2358,7 +2359,9 @@ fixmlist:;
 
             while (d->id >= d->m.count && d->m.split) {
                 // we split and id is on tail now
-                d->id -= d->m.count;
+                if (lfs2_pair_cmp(d->m.tail, lfs2->root) != 0) {
+                    d->id -= d->m.count;
+                }
                 int err = lfs2_dir_fetch(lfs2, &d->m, d->m.tail);
                 if (err) {
                     return err;
@@ -4466,6 +4469,7 @@ static int lfs2_mount_(lfs2_t *lfs2, const struct lfs2_config *cfg) {
             // found older minor version? set an in-device only bit in the
             // gstate so we know we need to rewrite the superblock before
             // the first write
+            bool needssuperblock = false;
             if (minor_version < lfs2_fs_disk_version_minor(lfs2)) {
                 LFS2_DEBUG("Found older minor version "
                         "v%"PRIu16".%"PRIu16" < v%"PRIu16".%"PRIu16,
@@ -4473,10 +4477,11 @@ static int lfs2_mount_(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                         minor_version,
                         lfs2_fs_disk_version_major(lfs2),
                         lfs2_fs_disk_version_minor(lfs2));
-                // note this bit is reserved on disk, so fetching more gstate
+                needssuperblock = true;
-                // will not interfere here
-                lfs2_fs_prepsuperblock(lfs2, true);
             }
+            // note this bit is reserved on disk, so fetching more gstate
+            // will not interfere here
+            lfs2_fs_prepsuperblock(lfs2, needssuperblock);
 
             // check superblock configuration
             if (superblock.name_max) {

tests/test_superblocks.toml

@@ -14,6 +14,24 @@ code = '''
     lfs2_unmount(&lfs2) => 0;
 '''
 
+# make sure the magic string "littlefs" is always at offset=8
+[cases.test_superblocks_magic]
+code = '''
+    lfs2_t lfs2;
+    lfs2_format(&lfs2, cfg) => 0;
+
+    // check our magic string
+    //
+    // note if we lose power we may not have the magic string in both blocks!
+    // but we don't lose power in this test so we can assert the magic string
+    // is present in both
+    uint8_t magic[lfs2_max(16, READ_SIZE)];
+    cfg->read(cfg, 0, 0, magic, lfs2_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+    cfg->read(cfg, 1, 0, magic, lfs2_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+'''
+
 # mount/unmount from interpretting a previous superblock block_count
 [cases.test_superblocks_mount_unknown_block_count]
 code = '''
@@ -28,7 +46,6 @@ code = '''
     lfs2_unmount(&lfs2) => 0;
 '''
 
-
 # reentrant format
 [cases.test_superblocks_reentrant_format]
 reentrant = true
@@ -135,6 +152,39 @@ code = '''
     lfs2_unmount(&lfs2) => 0;
 '''
 
+# make sure the magic string "littlefs" is always at offset=8
+[cases.test_superblocks_magic_expand]
+defines.BLOCK_CYCLES = [32, 33, 1]
+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;
+        lfs2_file_open(&lfs2, &file, "dummy",
+                LFS2_O_WRONLY | LFS2_O_CREAT | LFS2_O_EXCL) => 0;
+        lfs2_file_close(&lfs2, &file) => 0;
+        struct lfs2_info info;
+        lfs2_stat(&lfs2, "dummy", &info) => 0;
+        assert(strcmp(info.name, "dummy") == 0);
+        assert(info.type == LFS2_TYPE_REG);
+        lfs2_remove(&lfs2, "dummy") => 0;
+    }
+    lfs2_unmount(&lfs2) => 0;
+
+    // check our magic string
+    //
+    // note if we lose power we may not have the magic string in both blocks!
+    // but we don't lose power in this test so we can assert the magic string
+    // is present in both
+    uint8_t magic[lfs2_max(16, READ_SIZE)];
+    cfg->read(cfg, 0, 0, magic, lfs2_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+    cfg->read(cfg, 1, 0, magic, lfs2_max(16, READ_SIZE)) => 0;
+    assert(memcmp(&magic[8], "littlefs", 8) == 0);
+'''
+
 # expanding superblock with power cycle
 [cases.test_superblocks_expand_power_cycle]
 defines.BLOCK_CYCLES = [32, 33, 1]
@@ -221,6 +271,7 @@ code = '''
     lfs2_unmount(&lfs2) => 0;
 '''
 
+
 # mount with unknown block_count
 [cases.test_superblocks_unknown_blocks]
 code = '''