Tighten bound on mlist isopen asserts

Unbalanced open/close calls continue to be a pain point for users, it
doesn't help that this sometimes results in hard-to-debug infinite loops
caused by the open-file linked-list (the mlist) getting tangled up in
itself.

Moving the mlist isopen asserts lower into the actual list append/remove
functions will help:

1. Make sure coverage of potential linked-list issues is complete.

2. Also assert against multiple close calls, which isn't an issue for
   the mlist, but can result in double free and memory corruption.

.github/workflows/release.yml

@@ -112,7 +112,7 @@ jobs:
             table[$i,$j]=$c_camel
             ((j+=1))
 
-            for s in code stack struct
+            for s in code stack structs
             do
               f=sizes/thumb${c:+-$c}.$s.csv
               [ -e $f ] && table[$i,$j]=$( \

DESIGN.md

@@ -59,7 +59,7 @@ This leaves us with three major requirements for an embedded filesystem.
    RAM to temporarily store filesystem metadata.
 
    For ROM, this means we need to keep our design simple and reuse code paths
-   were possible. For RAM we have a stronger requirement, all RAM usage is
+   where possible. For RAM we have a stronger requirement, all RAM usage is
    bounded. This means RAM usage does not grow as the filesystem changes in
    size or number of files. This creates a unique challenge as even presumably
    simple operations, such as traversing the filesystem, become surprisingly
@@ -626,7 +626,7 @@ log₂_n_ pointers that skip to different preceding elements of the
 skip-list.
 
 The name comes from heavy use of the [CTZ instruction][wikipedia-ctz], which
-lets us calculate the power-of-two factors efficiently. For a give block _n_,
+lets us calculate the power-of-two factors efficiently. For a given block _n_,
 that block contains ctz(_n_)+1 pointers.
 
 ```

Makefile

@@ -63,6 +63,7 @@ CFLAGS += -fcallgraph-info=su
 CFLAGS += -g3
 CFLAGS += -I.
 CFLAGS += -std=c99 -Wall -Wextra -pedantic
+CFLAGS += -Wmissing-prototypes
 CFLAGS += -ftrack-macro-expansion=0
 ifdef DEBUG
 CFLAGS += -O0
@@ -354,6 +355,7 @@ summary-diff sizes-diff: $(OBJ) $(CI)
 
 ## Build the test-runner
 .PHONY: test-runner build-test
+test-runner build-test: CFLAGS+=-Wno-missing-prototypes
 ifndef NO_COV
 test-runner build-test: CFLAGS+=--coverage
 endif
@@ -405,6 +407,7 @@ testmarks-diff: $(TEST_CSV)
 
 ## Build the bench-runner
 .PHONY: bench-runner build-bench
+bench-runner build-bench: CFLAGS+=-Wno-missing-prototypes
 ifdef YES_COV
 bench-runner build-bench: CFLAGS+=--coverage
 endif

lfs.c

@@ -505,6 +505,7 @@ static bool lfs_mlist_isopen(struct lfs_mlist *head,
 #endif
 
 static void lfs_mlist_remove(lfs_t *lfs, struct lfs_mlist *mlist) {
+    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, mlist));
     for (struct lfs_mlist **p = &lfs->mlist; *p; p = &(*p)->next) {
         if (*p == mlist) {
             *p = (*p)->next;
@@ -514,6 +515,7 @@ static void lfs_mlist_remove(lfs_t *lfs, struct lfs_mlist *mlist) {
 }
 
 static void lfs_mlist_append(lfs_t *lfs, struct lfs_mlist *mlist) {
+    LFS_ASSERT(!lfs_mlist_isopen(lfs->mlist, mlist));
     mlist->next = lfs->mlist;
     lfs->mlist = mlist;
 }
@@ -2151,9 +2153,11 @@ static int lfs_dir_splittingcompact(lfs_t *lfs, lfs_mdir_t *dir,
             return size;
         }
 
-        // do we have extra space? littlefs can't reclaim this space
-        // by itself, so expand cautiously
-        if ((lfs_size_t)size < lfs->block_count/2) {
+        // littlefs cannot reclaim expanded superblocks, so expand cautiously
+        //
+        // if our filesystem is more than ~88% full, don't expand, this is
+        // somewhat arbitrary
+        if (lfs->block_count - size > lfs->block_count/8) {
             LFS_DEBUG("Expanding superblock at rev %"PRIu32, dir->rev);
             int err = lfs_dir_split(lfs, dir, attrs, attrcount,
                     source, begin, end);
@@ -3030,8 +3034,7 @@ static int lfs_file_rawopencfg(lfs_t *lfs, lfs_file_t *file,
     // allocate entry for file if it doesn't exist
     lfs_stag_t tag = lfs_dir_find(lfs, &file->m, &path, &file->id);
     if (tag < 0 && !(tag == LFS_ERR_NOENT && file->id != 0x3ff)) {
-        err = tag;
-        goto cleanup;
+        return tag;
     }
 
     // get id, add to list of mdirs to catch update changes
@@ -4999,7 +5002,7 @@ static int lfs_fs_forceconsistency(lfs_t *lfs) {
 #endif
 
 #ifndef LFS_READONLY
-int lfs_fs_rawmkconsistent(lfs_t *lfs) {
+static int lfs_fs_rawmkconsistent(lfs_t *lfs) {
     // lfs_fs_forceconsistency does most of the work here
     int err = lfs_fs_forceconsistency(lfs);
     if (err) {
@@ -5046,7 +5049,7 @@ static lfs_ssize_t lfs_fs_rawsize(lfs_t *lfs) {
 }
 
 #ifndef LFS_READONLY
-int lfs_fs_rawgrow(lfs_t *lfs, lfs_size_t block_count) {
+static int lfs_fs_rawgrow(lfs_t *lfs, lfs_size_t block_count) {
     // shrinking is not supported
     LFS_ASSERT(block_count >= lfs->block_count);
 
@@ -5927,7 +5930,6 @@ int lfs_file_open(lfs_t *lfs, lfs_file_t *file, const char *path, int flags) {
     }
     LFS_TRACE("lfs_file_open(%p, %p, \"%s\", %x)",
             (void*)lfs, (void*)file, path, flags);
-    LFS_ASSERT(!lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     err = lfs_file_rawopen(lfs, file, path, flags);
 
@@ -5948,7 +5950,6 @@ int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file,
                  ".buffer=%p, .attrs=%p, .attr_count=%"PRIu32"})",
             (void*)lfs, (void*)file, path, flags,
             (void*)cfg, cfg->buffer, (void*)cfg->attrs, cfg->attr_count);
-    LFS_ASSERT(!lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     err = lfs_file_rawopencfg(lfs, file, path, flags, cfg);
 
@@ -5963,7 +5964,6 @@ int lfs_file_close(lfs_t *lfs, lfs_file_t *file) {
         return err;
     }
     LFS_TRACE("lfs_file_close(%p, %p)", (void*)lfs, (void*)file);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     err = lfs_file_rawclose(lfs, file);
 
@@ -5979,7 +5979,6 @@ int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
         return err;
     }
     LFS_TRACE("lfs_file_sync(%p, %p)", (void*)lfs, (void*)file);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     err = lfs_file_rawsync(lfs, file);
 
@@ -5997,7 +5996,6 @@ lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file,
     }
     LFS_TRACE("lfs_file_read(%p, %p, %p, %"PRIu32")",
             (void*)lfs, (void*)file, buffer, size);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     lfs_ssize_t res = lfs_file_rawread(lfs, file, buffer, size);
 
@@ -6015,7 +6013,6 @@ lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file,
     }
     LFS_TRACE("lfs_file_write(%p, %p, %p, %"PRIu32")",
             (void*)lfs, (void*)file, buffer, size);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     lfs_ssize_t res = lfs_file_rawwrite(lfs, file, buffer, size);
 
@@ -6033,7 +6030,6 @@ lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file,
     }
     LFS_TRACE("lfs_file_seek(%p, %p, %"PRId32", %d)",
             (void*)lfs, (void*)file, off, whence);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     lfs_soff_t res = lfs_file_rawseek(lfs, file, off, whence);
 
@@ -6050,7 +6046,6 @@ int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
     }
     LFS_TRACE("lfs_file_truncate(%p, %p, %"PRIu32")",
             (void*)lfs, (void*)file, size);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     err = lfs_file_rawtruncate(lfs, file, size);
 
@@ -6066,7 +6061,6 @@ lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file) {
         return err;
     }
     LFS_TRACE("lfs_file_tell(%p, %p)", (void*)lfs, (void*)file);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     lfs_soff_t res = lfs_file_rawtell(lfs, file);
 
@@ -6095,7 +6089,6 @@ lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) {
         return err;
     }
     LFS_TRACE("lfs_file_size(%p, %p)", (void*)lfs, (void*)file);
-    LFS_ASSERT(lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)file));
 
     lfs_soff_t res = lfs_file_rawsize(lfs, file);
 
@@ -6126,7 +6119,6 @@ int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path) {
         return err;
     }
     LFS_TRACE("lfs_dir_open(%p, %p, \"%s\")", (void*)lfs, (void*)dir, path);
-    LFS_ASSERT(!lfs_mlist_isopen(lfs->mlist, (struct lfs_mlist*)dir));
 
     err = lfs_dir_rawopen(lfs, dir, path);