Added handling for corrupt as initial state of blocks

Before this, littlefs incorrectly assumed corrupt blocks were only the result
of our own modification. This would be fine for most cases of freshly
erased storage, but for storage with block-level ECC this wasn't always
true.

Fortunately, it's quite easy for littlefs to handle this case correctly,
as long as corrupt storage always reports that it is corrupt, which for
most forms of ECC is the case unless we perform a write on the storage.

found by rojer

.travis.yml

@@ -27,7 +27,7 @@ script:
   # compile and find the code size with the smallest configuration
   - make clean size
         OBJ="$(ls lfs*.o | tr '\n' ' ')"
-        CFLAGS+="-DLFS_NO{ASSERT,DEBUG,WARN,ERROR}"
+        CFLAGS+="-DLFS_NO_ASSERT -DLFS_NO_DEBUG -DLFS_NO_WARN -DLFS_NO_ERROR"
         | tee sizes
 
   # update status if we succeeded, compare with master if possible

LICENSE.md

@@ -1,165 +1,36 @@
-Apache License
-Version 2.0, January 2004
-http://www.apache.org/licenses/
+Copyright (c) 2017, Arm Limited. All rights reserved.
 
-TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
 
-1. Definitions.
+-  Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+-  Redistributions in binary form must reproduce the above copyright notice, this
+   list of conditions and the following disclaimer in the documentation and/or
+   other materials provided with the distribution.
+-  Neither the name of ARM nor the names of its contributors may be used to
+   endorse or promote products derived from this software without specific prior
+   written permission.
 
-"License" shall mean the terms and conditions for use, reproduction, and
-distribution as defined by Sections 1 through 9 of this document.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-"Licensor" shall mean the copyright owner or entity authorized by the copyright
-owner that is granting the License.
+---
 
-"Legal Entity" shall mean the union of the acting entity and all other entities
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-outstanding shares, or (iii) beneficial ownership of such entity.
+*Note*:
+Individual files contain the following tag instead of the full license text.
 
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-files.
 
-"Object" form shall mean any form resulting from mechanical transformation or
-translation of a Source form, including but not limited to compiled object code,
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+    SPDX-License-Identifier:    BSD-3-Clause
 
-"Work" shall mean the work of authorship, whether in Source or Object form, made
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-for inclusion in the Work by You to the Licensor shall be under the terms and
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-Notwithstanding the above, nothing herein shall supersede or modify the terms of
-any separate license agreement you may have executed with Licensor regarding
-such Contributions.
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-6. Trademarks.
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-including, without limitation, any warranties or conditions of TITLE,
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-solely responsible for determining the appropriateness of using or
-redistributing the Work and assume any risks associated with Your exercise of
-permissions under this License.
-
-8. Limitation of Liability.
-
-In no event and under no legal theory, whether in tort (including negligence),
-contract, or otherwise, unless required by applicable law (such as deliberate
-and grossly negligent acts) or agreed to in writing, shall any Contributor be
-liable to You for damages, including any direct, indirect, special, incidental,
-or consequential damages of any character arising as a result of this License or
-out of the use or inability to use the Work (including but not limited to
-damages for loss of goodwill, work stoppage, computer failure or malfunction, or
-any and all other commercial damages or losses), even if such Contributor has
-been advised of the possibility of such damages.
-
-9. Accepting Warranty or Additional Liability.
-
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-offer, and charge a fee for, acceptance of support, warranty, indemnity, or
-other liability obligations and/or rights consistent with this License. However,
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-sole responsibility, not on behalf of any other Contributor, and only if You
-agree to indemnify, defend, and hold each Contributor harmless for any liability
-incurred by, or claims asserted against, such Contributor by reason of your
-accepting any such warranty or additional liability.
+This enables machine processing of license information based on the SPDX
+License Identifiers that are here available: http://spdx.org/licenses/

Makefile

@@ -1,4 +1,7 @@
-TARGET = lfs
+TARGET = lfs.a
+ifneq ($(wildcard test.c main.c),)
+override TARGET = lfs
+endif
 
 CC ?= gcc
 AR ?= ar
@@ -22,7 +25,7 @@ ifdef WORD
 override CFLAGS += -m$(WORD)
 endif
 override CFLAGS += -I.
-override CFLAGS += -std=c99 -Wall -pedantic
+override CFLAGS += -std=c99 -Wall -pedantic -Wshadow -Wunused-parameter
 
 
 all: $(TARGET)
@@ -35,7 +38,9 @@ size: $(OBJ)
 .SUFFIXES:
 test: test_format test_dirs test_files test_seek test_truncate \
 	test_interspersed test_alloc test_paths test_orphan test_move test_corrupt
+	@rm test.c
 test_%: tests/test_%.sh
+
 ifdef QUIET
 	@./$< | sed -n '/^[-=]/p'
 else
@@ -44,7 +49,7 @@ endif
 
 -include $(DEP)
 
-$(TARGET): $(OBJ)
+lfs: $(OBJ)
 	$(CC) $(CFLAGS) $^ $(LFLAGS) -o $@
 
 %.a: $(OBJ)

emubd/lfs_emubd.c

@@ -1,19 +1,8 @@
 /*
  * Block device emulated on standard files
  *
- * Copyright (c) 2017 ARM Limited
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
  */
 #include "emubd/lfs_emubd.h"
 
@@ -27,6 +16,7 @@
 #include <unistd.h>
 #include <assert.h>
 #include <stdbool.h>
+#include <inttypes.h>
 
 
 // Block device emulated on existing filesystem
@@ -96,7 +86,7 @@ int lfs_emubd_read(const struct lfs_config *cfg, lfs_block_t block,
     memset(data, 0, size);
 
     // Read data
-    snprintf(emu->child, LFS_NAME_MAX, "%x", block);
+    snprintf(emu->child, LFS_NAME_MAX, "%" PRIx32, block);
 
     FILE *f = fopen(emu->path, "rb");
     if (!f && errno != ENOENT) {
@@ -135,7 +125,7 @@ int lfs_emubd_prog(const struct lfs_config *cfg, lfs_block_t block,
     assert(block < cfg->block_count);
 
     // Program data
-    snprintf(emu->child, LFS_NAME_MAX, "%x", block);
+    snprintf(emu->child, LFS_NAME_MAX, "%" PRIx32, block);
 
     FILE *f = fopen(emu->path, "r+b");
     if (!f) {
@@ -182,7 +172,7 @@ int lfs_emubd_erase(const struct lfs_config *cfg, lfs_block_t block) {
     assert(block < cfg->block_count);
 
     // Erase the block
-    snprintf(emu->child, LFS_NAME_MAX, "%x", block);
+    snprintf(emu->child, LFS_NAME_MAX, "%" PRIx32, block);
     struct stat st;
     int err = stat(emu->path, &st);
     if (err && errno != ENOENT) {
@@ -250,4 +240,3 @@ int lfs_emubd_sync(const struct lfs_config *cfg) {
 
     return 0;
 }
-

emubd/lfs_emubd.h

@@ -1,19 +1,8 @@
 /*
  * Block device emulated on standard files
  *
- * Copyright (c) 2017 ARM Limited
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
  */
 #ifndef LFS_EMUBD_H
 #define LFS_EMUBD_H
@@ -21,6 +10,11 @@
 #include "lfs.h"
 #include "lfs_util.h"
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
 
 // Config options
 #ifndef LFS_EMUBD_READ_SIZE
@@ -86,4 +80,8 @@ int lfs_emubd_erase(const struct lfs_config *cfg, lfs_block_t block);
 int lfs_emubd_sync(const struct lfs_config *cfg);
 
 
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
 #endif

lfs.c

@@ -1,23 +1,14 @@
 /*
  * The little filesystem
  *
- * Copyright (c) 2017 ARM Limited
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
  */
 #include "lfs.h"
 #include "lfs_util.h"
 
+#include <inttypes.h>
+
 
 /// Caching block device operations ///
 static int lfs_cache_read(lfs_t *lfs, lfs_cache_t *rcache,
@@ -118,6 +109,19 @@ static int lfs_cache_crc(lfs_t *lfs, lfs_cache_t *rcache,
     return 0;
 }
 
+static inline void lfs_cache_drop(lfs_t *lfs, lfs_cache_t *rcache) {
+    // do not zero, cheaper if cache is readonly or only going to be
+    // written with identical data (during relocates)
+    (void)lfs;
+    rcache->block = 0xffffffff;
+}
+
+static inline void lfs_cache_zero(lfs_t *lfs, lfs_cache_t *pcache) {
+    // zero to avoid information leak
+    memset(pcache->buffer, 0xff, lfs->cfg->prog_size);
+    pcache->block = 0xffffffff;
+}
+
 static int lfs_cache_flush(lfs_t *lfs,
         lfs_cache_t *pcache, lfs_cache_t *rcache) {
     if (pcache->block != 0xffffffff) {
@@ -139,7 +143,7 @@ static int lfs_cache_flush(lfs_t *lfs,
             }
         }
 
-        pcache->block = 0xffffffff;
+        lfs_cache_zero(lfs, pcache);
     }
 
     return 0;
@@ -244,7 +248,7 @@ static int lfs_bd_erase(lfs_t *lfs, lfs_block_t block) {
 }
 
 static int lfs_bd_sync(lfs_t *lfs) {
-    lfs->rcache.block = 0xffffffff;
+    lfs_cache_drop(lfs, &lfs->rcache);
 
     int err = lfs_cache_flush(lfs, &lfs->pcache, NULL);
     if (err) {
@@ -270,8 +274,7 @@ int lfs_deorphan(lfs_t *lfs);
 static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
     lfs_t *lfs = p;
 
-    lfs_block_t off = (((lfs_soff_t)(block - lfs->free.begin)
-                % (lfs_soff_t)(lfs->cfg->block_count))
+    lfs_block_t off = ((block - lfs->free.off)
             + lfs->cfg->block_count) % lfs->cfg->block_count;
 
     if (off < lfs->free.size) {
@@ -283,20 +286,22 @@ static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
 
 static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
     while (true) {
-        while (lfs->free.off != lfs->free.size) {
-            lfs_block_t off = lfs->free.off;
-            lfs->free.off += 1;
+        while (lfs->free.i != lfs->free.size) {
+            lfs_block_t off = lfs->free.i;
+            lfs->free.i += 1;
+            lfs->free.ack -= 1;
 
             if (!(lfs->free.buffer[off / 32] & (1U << (off % 32)))) {
                 // found a free block
-                *block = (lfs->free.begin + off) % lfs->cfg->block_count;
+                *block = (lfs->free.off + off) % lfs->cfg->block_count;
 
                 // eagerly find next off so an alloc ack can
                 // discredit old lookahead blocks
-                while (lfs->free.off != lfs->free.size &&
-                        (lfs->free.buffer[lfs->free.off / 32] &
-                            (1U << (lfs->free.off % 32)))) {
-                    lfs->free.off += 1;
+                while (lfs->free.i != lfs->free.size &&
+                        (lfs->free.buffer[lfs->free.i / 32]
+                            & (1U << (lfs->free.i % 32)))) {
+                    lfs->free.i += 1;
+                    lfs->free.ack -= 1;
                 }
 
                 return 0;
@@ -304,15 +309,16 @@ static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
         }
 
         // check if we have looked at all blocks since last ack
-        if (lfs->free.off == lfs->free.ack - lfs->free.begin) {
-            LFS_WARN("No more free space %d", lfs->free.off + lfs->free.begin);
+        if (lfs->free.ack == 0) {
+            LFS_WARN("No more free space %" PRIu32,
+                    lfs->free.i + lfs->free.off);
             return LFS_ERR_NOSPC;
         }
 
-        lfs->free.begin += lfs->free.size;
-        lfs->free.size = lfs_min(lfs->cfg->lookahead,
-                lfs->free.ack - lfs->free.begin);
-        lfs->free.off = 0;
+        lfs->free.off = (lfs->free.off + lfs->free.size)
+                % lfs->cfg->block_count;
+        lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->free.ack);
+        lfs->free.i = 0;
 
         // find mask of free blocks from tree
         memset(lfs->free.buffer, 0, lfs->cfg->lookahead/8);
@@ -324,7 +330,7 @@ static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
 }
 
 static void lfs_alloc_ack(lfs_t *lfs) {
-    lfs->free.ack = lfs->free.begin+lfs->free.off + lfs->cfg->block_count;
+    lfs->free.ack = lfs->cfg->block_count;
 }
 
 
@@ -411,11 +417,14 @@ static int lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
     // rather than clobbering one of the blocks we just pretend
     // the revision may be valid
     int err = lfs_bd_read(lfs, dir->pair[0], 0, &dir->d.rev, 4);
-    dir->d.rev = lfs_fromle32(dir->d.rev);
-    if (err) {
+    if (err && err != LFS_ERR_CORRUPT) {
         return err;
     }
 
+    if (err != LFS_ERR_CORRUPT) {
+        dir->d.rev = lfs_fromle32(dir->d.rev);
+    }
+
     // set defaults
     dir->d.rev += 1;
     dir->d.size = sizeof(dir->d)+4;
@@ -439,6 +448,9 @@ static int lfs_dir_fetch(lfs_t *lfs,
         int err = lfs_bd_read(lfs, tpair[i], 0, &test, sizeof(test));
         lfs_dir_fromle32(&test);
         if (err) {
+            if (err == LFS_ERR_CORRUPT) {
+                continue;
+            }
             return err;
         }
 
@@ -458,6 +470,9 @@ static int lfs_dir_fetch(lfs_t *lfs,
         err = lfs_bd_crc(lfs, tpair[i], sizeof(test),
                 (0x7fffffff & test.size) - sizeof(test), &crc);
         if (err) {
+            if (err == LFS_ERR_CORRUPT) {
+                continue;
+            }
             return err;
         }
 
@@ -475,7 +490,8 @@ static int lfs_dir_fetch(lfs_t *lfs,
     }
 
     if (!valid) {
-        LFS_ERROR("Corrupted dir pair at %d %d", tpair[0], tpair[1]);
+        LFS_ERROR("Corrupted dir pair at %" PRIu32 " %" PRIu32 ,
+                tpair[0], tpair[1]);
         return LFS_ERR_CORRUPT;
     }
 
@@ -598,15 +614,16 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
         break;
 relocate:
         //commit was corrupted
-        LFS_DEBUG("Bad block at %d", dir->pair[0]);
+        LFS_DEBUG("Bad block at %" PRIu32, dir->pair[0]);
 
         // drop caches and prepare to relocate block
         relocated = true;
-        lfs->pcache.block = 0xffffffff;
+        lfs_cache_drop(lfs, &lfs->pcache);
 
         // can't relocate superblock, filesystem is now frozen
         if (lfs_paircmp(oldpair, (const lfs_block_t[2]){0, 1}) == 0) {
-            LFS_WARN("Superblock %d has become unwritable", oldpair[0]);
+            LFS_WARN("Superblock %" PRIu32 " has become unwritable",
+                    oldpair[0]);
             return LFS_ERR_CORRUPT;
         }
 
@@ -619,7 +636,7 @@ relocate:
 
     if (relocated) {
         // update references if we relocated
-        LFS_DEBUG("Relocating %d %d to %d %d",
+        LFS_DEBUG("Relocating %" PRIu32 " %" PRIu32 " to %" PRIu32 " %" PRIu32,
                 oldpair[0], oldpair[1], dir->pair[0], dir->pair[1]);
         int err = lfs_relocate(lfs, oldpair, dir->pair);
         if (err) {
@@ -782,6 +799,12 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
         lfs_entry_t *entry, const char **path) {
     const char *pathname = *path;
     size_t pathlen;
+    entry->d.type = LFS_TYPE_DIR;
+    entry->d.elen = sizeof(entry->d) - 4;
+    entry->d.alen = 0;
+    entry->d.nlen = 0;
+    entry->d.u.dir[0] = lfs->root[0];
+    entry->d.u.dir[1] = lfs->root[1];
 
     while (true) {
 nextname:
@@ -789,19 +812,6 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
         pathname += strspn(pathname, "/");
         pathlen = strcspn(pathname, "/");
 
-        // special case for root dir
-        if (pathname[0] == '\0') {
-            *entry = (lfs_entry_t){
-                .d.type = LFS_TYPE_DIR,
-                .d.elen = sizeof(entry->d) - 4,
-                .d.alen = 0,
-                .d.nlen = 0,
-                .d.u.dir[0] = lfs->root[0],
-                .d.u.dir[1] = lfs->root[1],
-            };
-            return 0;
-        }
-
         // skip '.' and root '..'
         if ((pathlen == 1 && memcmp(pathname, ".", 1) == 0) ||
             (pathlen == 2 && memcmp(pathname, "..", 2) == 0)) {
@@ -833,12 +843,27 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
             suffix += sufflen;
         }
 
+        // found path
+        if (pathname[0] == '\0') {
+            return 0;
+        }
+
         // update what we've found
         *path = pathname;
 
-        // find path
+        // continue on if we hit a directory
+        if (entry->d.type != LFS_TYPE_DIR) {
+            return LFS_ERR_NOTDIR;
+        }
+
+        int err = lfs_dir_fetch(lfs, dir, entry->d.u.dir);
+        if (err) {
+            return err;
+        }
+
+        // find entry matching name
         while (true) {
-            int err = lfs_dir_next(lfs, dir, entry);
+            err = lfs_dir_next(lfs, dir, entry);
             if (err) {
                 return err;
             }
@@ -872,21 +897,8 @@ static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
             entry->d.type &= ~0x80;
         }
 
+        // to next name
         pathname += pathlen;
-        pathname += strspn(pathname, "/");
-        if (pathname[0] == '\0') {
-            return 0;
-        }
-
-        // continue on if we hit a directory
-        if (entry->d.type != LFS_TYPE_DIR) {
-            return LFS_ERR_NOTDIR;
-        }
-
-        int err = lfs_dir_fetch(lfs, dir, entry->d.u.dir);
-        if (err) {
-            return err;
-        }
     }
 }
 
@@ -903,13 +915,8 @@ int lfs_mkdir(lfs_t *lfs, const char *path) {
 
     // fetch parent directory
     lfs_dir_t cwd;
-    int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
-    if (err) {
-        return err;
-    }
-
     lfs_entry_t entry;
-    err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
     if (err != LFS_ERR_NOENT || strchr(path, '/') != NULL) {
         return err ? err : LFS_ERR_EXIST;
     }
@@ -953,13 +960,8 @@ int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path) {
     dir->pair[0] = lfs->root[0];
     dir->pair[1] = lfs->root[1];
 
-    int err = lfs_dir_fetch(lfs, dir, dir->pair);
-    if (err) {
-        return err;
-    }
-
     lfs_entry_t entry;
-    err = lfs_dir_find(lfs, dir, &entry, &path);
+    int err = lfs_dir_find(lfs, dir, &entry, &path);
     if (err) {
         return err;
     } else if (entry.d.type != LFS_TYPE_DIR) {
@@ -1239,10 +1241,10 @@ static int lfs_ctz_extend(lfs_t *lfs,
         }
 
 relocate:
-        LFS_DEBUG("Bad block at %d", nblock);
+        LFS_DEBUG("Bad block at %" PRIu32, nblock);
 
         // just clear cache and try a new block
-        pcache->block = 0xffffffff;
+        lfs_cache_drop(lfs, &lfs->pcache);
     }
 }
 
@@ -1301,13 +1303,8 @@ int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
 
     // allocate entry for file if it doesn't exist
     lfs_dir_t cwd;
-    int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
-    if (err) {
-        return err;
-    }
-
     lfs_entry_t entry;
-    err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
     if (err && (err != LFS_ERR_NOENT || strchr(path, '/') != NULL)) {
         return err;
     }
@@ -1352,8 +1349,11 @@ int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
     }
 
     // allocate buffer if needed
-    file->cache.block = 0xffffffff;
     if (lfs->cfg->file_buffer) {
+        if (lfs->files) {
+            // already in use
+            return LFS_ERR_NOMEM;
+        }
         file->cache.buffer = lfs->cfg->file_buffer;
     } else if ((file->flags & 3) == LFS_O_RDONLY) {
         file->cache.buffer = lfs_malloc(lfs->cfg->read_size);
@@ -1367,6 +1367,9 @@ int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
         }
     }
 
+    // zero to avoid information leak
+    lfs_cache_zero(lfs, &file->cache);
+
     // add to list of files
     file->next = lfs->files;
     lfs->files = file;
@@ -1395,7 +1398,7 @@ int lfs_file_close(lfs_t *lfs, lfs_file_t *file) {
 
 static int lfs_file_relocate(lfs_t *lfs, lfs_file_t *file) {
 relocate:
-    LFS_DEBUG("Bad block at %d", file->block);
+    LFS_DEBUG("Bad block at %" PRIu32, file->block);
 
     // just relocate what exists into new block
     lfs_block_t nblock;
@@ -1435,7 +1438,7 @@ relocate:
     memcpy(file->cache.buffer, lfs->pcache.buffer, lfs->cfg->prog_size);
     file->cache.block = lfs->pcache.block;
     file->cache.off = lfs->pcache.off;
-    lfs->pcache.block = 0xffffffff;
+    lfs_cache_zero(lfs, &lfs->pcache);
 
     file->block = nblock;
     return 0;
@@ -1444,7 +1447,7 @@ relocate:
 static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file) {
     if (file->flags & LFS_F_READING) {
         // just drop read cache
-        file->cache.block = 0xffffffff;
+        lfs_cache_drop(lfs, &file->cache);
         file->flags &= ~LFS_F_READING;
     }
 
@@ -1459,7 +1462,7 @@ static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file) {
             .pos = file->pos,
             .cache = lfs->rcache,
         };
-        lfs->rcache.block = 0xffffffff;
+        lfs_cache_drop(lfs, &lfs->rcache);
 
         while (file->pos < file->size) {
             // copy over a byte at a time, leave it up to caching
@@ -1477,8 +1480,8 @@ static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file) {
 
             // keep our reference to the rcache in sync
             if (lfs->rcache.block != 0xffffffff) {
-                orig.cache.block = 0xffffffff;
-                lfs->rcache.block = 0xffffffff;
+                lfs_cache_drop(lfs, &orig.cache);
+                lfs_cache_drop(lfs, &lfs->rcache);
             }
         }
 
@@ -1656,7 +1659,7 @@ lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file,
                 }
 
                 // mark cache as dirty since we may have read data into it
-                file->cache.block = 0xffffffff;
+                lfs_cache_zero(lfs, &file->cache);
             }
 
             // extend file with new blocks
@@ -1813,13 +1816,8 @@ lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) {
 /// General fs operations ///
 int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
     lfs_dir_t cwd;
-    int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
-    if (err) {
-        return err;
-    }
-
     lfs_entry_t entry;
-    err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
     if (err) {
         return err;
     }
@@ -1854,13 +1852,8 @@ int lfs_remove(lfs_t *lfs, const char *path) {
     }
 
     lfs_dir_t cwd;
-    int err = lfs_dir_fetch(lfs, &cwd, lfs->root);
-    if (err) {
-        return err;
-    }
-
     lfs_entry_t entry;
-    err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
     if (err) {
         return err;
     }
@@ -1915,24 +1908,14 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
 
     // find old entry
     lfs_dir_t oldcwd;
-    int err = lfs_dir_fetch(lfs, &oldcwd, lfs->root);
-    if (err) {
-        return err;
-    }
-
     lfs_entry_t oldentry;
-    err = lfs_dir_find(lfs, &oldcwd, &oldentry, &oldpath);
+    int err = lfs_dir_find(lfs, &oldcwd, &oldentry, &oldpath);
     if (err) {
         return err;
     }
 
     // allocate new entry
     lfs_dir_t newcwd;
-    err = lfs_dir_fetch(lfs, &newcwd, lfs->root);
-    if (err) {
-        return err;
-    }
-
     lfs_entry_t preventry;
     err = lfs_dir_find(lfs, &newcwd, &preventry, &newpath);
     if (err && (err != LFS_ERR_NOENT || strchr(newpath, '/') != NULL)) {
@@ -2027,7 +2010,6 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
     lfs->cfg = cfg;
 
     // setup read cache
-    lfs->rcache.block = 0xffffffff;
     if (lfs->cfg->read_buffer) {
         lfs->rcache.buffer = lfs->cfg->read_buffer;
     } else {
@@ -2038,7 +2020,6 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
     }
 
     // setup program cache
-    lfs->pcache.block = 0xffffffff;
     if (lfs->cfg->prog_buffer) {
         lfs->pcache.buffer = lfs->cfg->prog_buffer;
     } else {
@@ -2048,6 +2029,10 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
         }
     }
 
+    // zero to avoid information leaks
+    lfs_cache_zero(lfs, &lfs->rcache);
+    lfs_cache_zero(lfs, &lfs->pcache);
+
     // setup lookahead, round down to nearest 32-bits
     LFS_ASSERT(lfs->cfg->lookahead % 32 == 0);
     LFS_ASSERT(lfs->cfg->lookahead > 0);
@@ -2103,9 +2088,9 @@ int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
 
     // create free lookahead
     memset(lfs->free.buffer, 0, lfs->cfg->lookahead/8);
-    lfs->free.begin = 0;
-    lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
     lfs->free.off = 0;
+    lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
+    lfs->free.i = 0;
     lfs_alloc_ack(lfs);
 
     // create superblock dir
@@ -2182,9 +2167,9 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
     }
 
     // setup free lookahead
-    lfs->free.begin = 0;
-    lfs->free.size = 0;
     lfs->free.off = 0;
+    lfs->free.size = 0;
+    lfs->free.i = 0;
     lfs_alloc_ack(lfs);
 
     // load superblock
@@ -2424,7 +2409,8 @@ static int lfs_relocate(lfs_t *lfs,
 
         // update internal root
         if (lfs_paircmp(oldpair, lfs->root) == 0) {
-            LFS_DEBUG("Relocating root %d %d", newpair[0], newpair[1]);
+            LFS_DEBUG("Relocating root %" PRIu32 " %" PRIu32,
+                    newpair[0], newpair[1]);
             lfs->root[0] = newpair[0];
             lfs->root[1] = newpair[1];
         }
@@ -2480,7 +2466,7 @@ int lfs_deorphan(lfs_t *lfs) {
 
             if (!res) {
                 // we are an orphan
-                LFS_DEBUG("Found orphan %d %d",
+                LFS_DEBUG("Found orphan %" PRIu32 " %" PRIu32,
                         pdir.d.tail[0], pdir.d.tail[1]);
 
                 pdir.d.tail[0] = cwd.d.tail[0];
@@ -2496,7 +2482,7 @@ int lfs_deorphan(lfs_t *lfs) {
 
             if (!lfs_pairsync(entry.d.u.dir, pdir.d.tail)) {
                 // we have desynced
-                LFS_DEBUG("Found desync %d %d",
+                LFS_DEBUG("Found desync %" PRIu32 " %" PRIu32,
                         entry.d.u.dir[0], entry.d.u.dir[1]);
 
                 pdir.d.tail[0] = entry.d.u.dir[0];
@@ -2531,14 +2517,14 @@ int lfs_deorphan(lfs_t *lfs) {
                 }
 
                 if (moved) {
-                    LFS_DEBUG("Found move %d %d",
+                    LFS_DEBUG("Found move %" PRIu32 " %" PRIu32,
                             entry.d.u.dir[0], entry.d.u.dir[1]);
                     err = lfs_dir_remove(lfs, &cwd, &entry);
                     if (err) {
                         return err;
                     }
                 } else {
-                    LFS_DEBUG("Found partial move %d %d",
+                    LFS_DEBUG("Found partial move %" PRIu32 " %" PRIu32,
                             entry.d.u.dir[0], entry.d.u.dir[1]);
                     entry.d.type &= ~0x80;
                     err = lfs_dir_update(lfs, &cwd, &entry, NULL);
@@ -2554,4 +2540,3 @@ int lfs_deorphan(lfs_t *lfs) {
 
     return 0;
 }
-

lfs.h

@@ -1,19 +1,8 @@
 /*
  * The little filesystem
  *
- * Copyright (c) 2017 ARM Limited
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
  */
 #ifndef LFS_H
 #define LFS_H
@@ -21,13 +10,18 @@
 #include <stdint.h>
 #include <stdbool.h>
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
 
 /// Version info ///
 
 // Software library version
 // Major (top-nibble), incremented on backwards incompatible changes
 // Minor (bottom-nibble), incremented on feature additions
-#define LFS_VERSION 0x00010003
+#define LFS_VERSION 0x00010004
 #define LFS_VERSION_MAJOR (0xffff & (LFS_VERSION >> 16))
 #define LFS_VERSION_MINOR (0xffff & (LFS_VERSION >>  0))
 
@@ -259,9 +253,9 @@ typedef struct lfs_superblock {
 } lfs_superblock_t;
 
 typedef struct lfs_free {
-    lfs_block_t begin;
-    lfs_block_t size;
     lfs_block_t off;
+    lfs_block_t size;
+    lfs_block_t i;
     lfs_block_t ack;
     uint32_t *buffer;
 } lfs_free_t;
@@ -471,4 +465,8 @@ int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data);
 int lfs_deorphan(lfs_t *lfs);
 
 
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
 #endif

lfs_util.c

@@ -1,19 +1,8 @@
 /*
  * lfs util functions
  *
- * Copyright (c) 2017 ARM Limited
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
  */
 #include "lfs_util.h"
 

lfs_util.h

@@ -1,19 +1,8 @@
 /*
  * lfs utility functions
  *
- * Copyright (c) 2017 ARM Limited
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
  */
 #ifndef LFS_UTIL_H
 #define LFS_UTIL_H
@@ -45,6 +34,11 @@
 #include <stdio.h>
 #endif
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
 
 // Macros, may be replaced by system specific wrappers. Arguments to these
 // macros must not have side-effects as the macros can be removed for a smaller
@@ -169,6 +163,7 @@ static inline void *lfs_malloc(size_t size) {
 #ifndef LFS_NO_MALLOC
     return malloc(size);
 #else
+    (void)size;
     return NULL;
 #endif
 }
@@ -177,9 +172,15 @@ static inline void *lfs_malloc(size_t size) {
 static inline void lfs_free(void *p) {
 #ifndef LFS_NO_MALLOC
     free(p);
+#else
+    (void)p;
 #endif
 }
 
 
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
 #endif
 #endif

tests/test_files.sh

@@ -30,7 +30,7 @@ TEST
 
 w_test() {
 tests/test.py << TEST
-    lfs_size_t size = $1;
+    size = $1;
     lfs_size_t chunk = 31;
     srand(0);
     lfs_mount(&lfs, &cfg) => 0;
@@ -50,7 +50,7 @@ TEST
 
 r_test() {
 tests/test.py << TEST
-    lfs_size_t size = $1;
+    size = $1;
     lfs_size_t chunk = 29;
     srand(0);
     lfs_mount(&lfs, &cfg) => 0;

tests/test_paths.sh

@@ -90,6 +90,22 @@ tests/test.py << TEST
     lfs_unmount(&lfs) => 0;
 TEST
 
+echo "--- Trailing dot path tests ---"
+tests/test.py << TEST
+    lfs_mount(&lfs, &cfg) => 0;
+    lfs_stat(&lfs, "tea/hottea/", &info) => 0;
+    strcmp(info.name, "hottea") => 0;
+    lfs_stat(&lfs, "tea/hottea/.", &info) => 0;
+    strcmp(info.name, "hottea") => 0;
+    lfs_stat(&lfs, "tea/hottea/./.", &info) => 0;
+    strcmp(info.name, "hottea") => 0;
+    lfs_stat(&lfs, "tea/hottea/..", &info) => 0;
+    strcmp(info.name, "tea") => 0;
+    lfs_stat(&lfs, "tea/hottea/../.", &info) => 0;
+    strcmp(info.name, "tea") => 0;
+    lfs_unmount(&lfs) => 0;
+TEST
+
 echo "--- Root dot dot path tests ---"
 tests/test.py << TEST
     lfs_mount(&lfs, &cfg) => 0;

tests/test_seek.sh

@@ -153,7 +153,7 @@ tests/test.py << TEST
     lfs_file_read(&lfs, &file[0], buffer, size) => size;
     memcmp(buffer, "kittycatcat", size) => 0;
 
-    lfs_size_t size = lfs_file_size(&lfs, &file[0]);
+    size = lfs_file_size(&lfs, &file[0]);
     lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
 
     lfs_file_close(&lfs, &file[0]) => 0;
@@ -202,7 +202,7 @@ tests/test.py << TEST
     lfs_file_read(&lfs, &file[0], buffer, size) => size;
     memcmp(buffer, "kittycatcat", size) => 0;
 
-    lfs_size_t size = lfs_file_size(&lfs, &file[0]);
+    size = lfs_file_size(&lfs, &file[0]);
     lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
 
     lfs_file_close(&lfs, &file[0]) => 0;
@@ -243,7 +243,7 @@ tests/test.py << TEST
     lfs_file_read(&lfs, &file[0], buffer, size) => size;
     memcmp(buffer, "kittycatcat", size) => 0;
 
-    lfs_size_t size = lfs_file_size(&lfs, &file[0]);
+    size = lfs_file_size(&lfs, &file[0]);
     lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
 
     lfs_file_close(&lfs, &file[0]) => 0;
@@ -286,7 +286,7 @@ tests/test.py << TEST
     lfs_file_read(&lfs, &file[0], buffer, size) => size;
     memcmp(buffer, "kittycatcat", size) => 0;
 
-    lfs_size_t size = lfs_file_size(&lfs, &file[0]);
+    size = lfs_file_size(&lfs, &file[0]);
     lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
 
     lfs_file_close(&lfs, &file[0]) => 0;