openharmony/third_party_littlefs
1
0
Fork 0
mirror of https://gitee.com/openharmony/third_party_littlefs synced 2025-02-09 01:07:39 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Fixed issue with big-endian CTZ lists intertwined in commit logic

Browse Source 
Found while testing big-endian support. Basically, if littlefs is really
really unlucky, the block allocator could kick in while committing a
file's CTZ reference. If this happens, the block allocator will need to
traverse all CTZ skip-lists in memory, including the skip-list we're
committing. This means we can't convert the CTZ's endianness in place,
and need to make a copy on big-endian systems.

We rely on dead-code elimination from the compiler to make the
conditional behaviour for big-endian vs little-endian system a noop
determined by the lfs_tole32 intrinsic.
This commit is contained in:
Christopher Haster 2018-08-08 09:37:43 -05:00
parent 10f45ac02f
commit 20b669a23d
2 changed files with 18 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
lfs.c
View File

@ -2199,25 +2199,27 @@ int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
uint16_t type;
const void *buffer;
lfs_size_t size;
struct lfs_ctz ctz;
if (file->flags & LFS_F_INLINE) {
// inline the whole file
type = LFS_TYPE_INLINESTRUCT;
buffer = file->cache.buffer;
size = file->ctz.size;
} else {
} else if (lfs_tole32(0x11223344) == 0x11223344) {
// update the ctz reference
type = LFS_TYPE_CTZSTRUCT;
buffer = &file->ctz;
size = sizeof(file->ctz);
// copy ctz so alloc will work during a relocate
ctz = file->ctz;
lfs_ctz_tole32(&ctz);
buffer = &ctz;
size = sizeof(ctz);
}
// commit file data and attributes
lfs_ctz_tole32(&file->ctz);
err = lfs_dir_commit(lfs, &file->m,
LFS_MKATTR(type, file->id, buffer, size,
LFS_MKATTR(LFS_FROM_ATTRS, file->id, file->cfg->attrs, 0,
NULL)));
lfs_ctz_fromle32(&file->ctz);
if (err) {
if (err == LFS_ERR_NOSPC && (file->flags & LFS_F_INLINE)) {
goto relocate;

22
lfs_util.h
View File

@ -11,8 +11,8 @@
// LFS_CONFIG as a header file to include (-DLFS_CONFIG=lfs_config.h).
//
// If LFS_CONFIG is used, none of the default utils will be emitted and must be
// provided by the config file. To start I would suggest copying lfs_util.h and
// modifying as needed.
// provided by the config file. To start, I would suggest copying lfs_util.h
// and modifying as needed.
#ifdef LFS_CONFIG
#define LFS_STRINGIZE(x) LFS_STRINGIZE2(x)
#define LFS_STRINGIZE2(x) #x
@ -88,6 +88,15 @@ static inline uint32_t lfs_min(uint32_t a, uint32_t b) {
return (a < b) ? a : b;
}
// Align to nearest multiple of a size
static inline uint32_t lfs_aligndown(uint32_t a, uint32_t alignment) {
return a - (a % alignment);
}
static inline uint32_t lfs_alignup(uint32_t a, uint32_t alignment) {
return lfs_aligndown(a + alignment-1, alignment);
}
// Find the next smallest power of 2 less than or equal to a
static inline uint32_t lfs_npw2(uint32_t a) {
#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM))
@ -177,15 +186,6 @@ static inline uint16_t lfs_tole16(uint16_t a) {
return lfs_fromle16(a);
}
// Align to nearest multiple of a size
static inline uint32_t lfs_aligndown(uint32_t a, uint32_t alignment) {
return a - (a % alignment);
}
static inline uint32_t lfs_alignup(uint32_t a, uint32_t alignment) {
return lfs_aligndown(a + alignment-1, alignment);
}
// Calculate CRC-32 with polynomial = 0x04c11db7
uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size);