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Added deletion to custom attributes
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This follows from enabling tag deletion, however does require some
consideration with the APIs.

Now we can remove custom attributes, as well as determine if an attribute
exists or not.
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@geky
geky committed Oct 18, 2018
1 parent c67a41a commit 617dd87
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Showing 5 changed files with 63 additions and 22 deletions.
39 changes: 27 additions & 12 deletions lfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -401,7 +401,7 @@ static inline lfs_size_t lfs_tag_size(uint32_t tag) {
}

static inline lfs_size_t lfs_tag_dsize(uint32_t tag) {
return sizeof(tag) + lfs_tag_size(tag) + lfs_tag_isdelete(tag);
return sizeof(tag) + lfs_tag_size(tag + lfs_tag_isdelete(tag));
}

// operations on set of globals
Expand Down Expand Up @@ -472,15 +472,15 @@ struct lfs_diskoff {
};

static int32_t lfs_commit_get(lfs_t *lfs,
lfs_block_t block, lfs_off_t off, uint32_t tag, bool stopatcommit,
lfs_block_t block, lfs_off_t off, uint32_t tag, bool compacting,
uint32_t getmask, uint32_t gettag, int32_t getdiff, void *buffer) {
gettag += getdiff;

// iterate over dir block backwards (for faster lookups)
while (off >= sizeof(uint32_t) + lfs_tag_dsize(tag)) {
off -= lfs_tag_dsize(tag);

if (lfs_tag_subtype(tag) == LFS_TYPE_CRC && stopatcommit) {
if (lfs_tag_subtype(tag) == LFS_TYPE_CRC && compacting) {
break;
} else if (lfs_tag_subtype(tag) == LFS_TYPE_DELETE) {
// something was deleted, need to move around it
Expand All @@ -489,8 +489,11 @@ static int32_t lfs_commit_get(lfs_t *lfs,
}
}

if (!lfs_tag_isdelete(tag) &&
(tag & getmask) == ((gettag - getdiff) & getmask)) {
if ((tag & getmask) == ((gettag - getdiff) & getmask)) {
if (lfs_tag_isdelete(tag) && !compacting) {
return LFS_ERR_NOENT;
}

if (buffer) {
lfs_size_t diff = lfs_min(
lfs_tag_size(gettag), lfs_tag_size(tag));
Expand Down Expand Up @@ -2912,19 +2915,18 @@ lfs_ssize_t lfs_getattr(lfs_t *lfs, const char *path,
res = lfs_dir_get(lfs, &cwd, 0x7ffff000,
LFS_MKTAG(0x100 | type, id, lfs_min(size, lfs->attr_max)),
buffer);
if (res < 0 && res != LFS_ERR_NOENT) {
if (res < 0) {
if (res == LFS_ERR_NOENT) {
return LFS_ERR_NOATTR;
}
return res;
}

return (res == LFS_ERR_NOENT) ? 0 : lfs_tag_size(res);
return lfs_tag_size(res);
}

int lfs_setattr(lfs_t *lfs, const char *path,
static int lfs_commitattr(lfs_t *lfs, const char *path,
uint8_t type, const void *buffer, lfs_size_t size) {
if (size > lfs->attr_max) {
return LFS_ERR_NOSPC;
}

lfs_mdir_t cwd;
int32_t res = lfs_dir_lookup(lfs, &cwd, &path);
if (res < 0) {
Expand All @@ -2946,6 +2948,19 @@ int lfs_setattr(lfs_t *lfs, const char *path,
NULL));
}

int lfs_setattr(lfs_t *lfs, const char *path,
uint8_t type, const void *buffer, lfs_size_t size) {
if (size > lfs->attr_max) {
return LFS_ERR_NOSPC;
}

return lfs_commitattr(lfs, path, type, buffer, size);
}

int lfs_removeattr(lfs_t *lfs, const char *path, uint8_t type) {
return lfs_commitattr(lfs, path, type, NULL, 0xfff);
}


/// Filesystem operations ///
static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
Expand Down
14 changes: 11 additions & 3 deletions lfs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,7 @@ enum lfs_error {
LFS_ERR_INVAL = -22, // Invalid parameter
LFS_ERR_NOSPC = -28, // No space left on device
LFS_ERR_NOMEM = -12, // No more memory available
LFS_ERR_NOATTR = -61, // No data/attr available
LFS_ERR_NAMETOOLONG = -36, // File name too long
};

Expand Down Expand Up @@ -456,7 +457,8 @@ int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info);
// Custom attributes are uniquely identified by an 8-bit type and limited
// to LFS_ATTR_MAX bytes. When read, if the stored attribute is smaller than
// the buffer, it will be padded with zeros. If the stored attribute is larger,
// then it will be silently truncated.
// then it will be silently truncated. If no attribute is found, the error
// LFS_ERR_NOATTR is returned and the buffer is filled with zeros.
//
// Returns the size of the attribute, or a negative error code on failure.
// Note, the returned size is the size of the attribute on disk, irrespective
Expand All @@ -469,13 +471,19 @@ lfs_ssize_t lfs_getattr(lfs_t *lfs, const char *path,
//
// Custom attributes are uniquely identified by an 8-bit type and limited
// to LFS_ATTR_MAX bytes. If an attribute is not found, it will be
// implicitly created, and setting the size of an attribute to zero deletes
// the attribute.
// implicitly created.
//
// Returns a negative error code on failure.
int lfs_setattr(lfs_t *lfs, const char *path,
uint8_t type, const void *buffer, lfs_size_t size);

// Removes a custom attribute
//
// If an attribute is not found, nothing happens.
//
// Returns a negative error code on failure.
int lfs_removeattr(lfs_t *lfs, const char *path, uint8_t type);


/// File operations ///

Expand Down
5 changes: 3 additions & 2 deletions tests/corrupt.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,11 @@ def corrupt(block):
break

tag ^= ntag
file.seek(tag & 0xfff, os.SEEK_CUR)
size = (tag & 0xfff) if (tag & 0xfff) != 0xfff else 0
file.seek(size, os.SEEK_CUR)

# lob off last 3 bytes
file.seek(-((tag & 0xfff) + 3), os.SEEK_CUR)
file.seek(-(size + 3), os.SEEK_CUR)
file.truncate()

def main(args):
Expand Down
9 changes: 5 additions & 4 deletions tests/debug.py
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Original file line number Diff line number Diff line change
Expand Up @@ -81,20 +81,21 @@ def main(*blocks):
size = (tag & 0x00000fff) >> 0
iscrc = (type & 0x1f0) == 0x0f0

data = file.read(size)
data = file.read(size if size != 0xfff else 0)
if iscrc:
crc = binascii.crc32(data[:4], crc)
else:
crc = binascii.crc32(data, crc)

print '%04x: %08x %-14s %3s %3d %-23s %-8s' % (
print '%04x: %08x %-14s %3s %3s %-23s %-8s' % (
off, tag,
typeof(type) + (' bad!' if iscrc and ~crc else ''),
id if id != 0x3ff else '.', size,
id if id != 0x3ff else '.',
size if size != 0xfff else 'x',
' '.join('%02x' % ord(c) for c in data[:8]),
''.join(c if c >= ' ' and c <= '~' else '.' for c in data[:8]))

off += tag & 0xfff
off += size if size != 0xfff else 0
if iscrc:
crc = 0
tag ^= (type & 1) << 31
Expand Down
18 changes: 17 additions & 1 deletion tests/test_attrs.sh
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,14 @@ tests/test.py << TEST
memcmp(buffer+4, "\0\0\0\0\0\0", 6) => 0;
memcmp(buffer+10, "ccccc", 5) => 0;
lfs_removeattr(&lfs, "hello", 'B') => 0;
lfs_getattr(&lfs, "hello", 'A', buffer, 4) => 4;
lfs_getattr(&lfs, "hello", 'B', buffer+4, 6) => LFS_ERR_NOATTR;
lfs_getattr(&lfs, "hello", 'C', buffer+10, 5) => 5;
memcmp(buffer, "aaaa", 4) => 0;
memcmp(buffer+4, "\0\0\0\0\0\0", 6) => 0;
memcmp(buffer+10, "ccccc", 5) => 0;
lfs_setattr(&lfs, "hello", 'B', "dddddd", 6) => 0;
lfs_getattr(&lfs, "hello", 'A', buffer, 4) => 4;
lfs_getattr(&lfs, "hello", 'B', buffer+4, 6) => 6;
Expand Down Expand Up @@ -98,6 +106,14 @@ tests/test.py << TEST
memcmp(buffer+4, "\0\0\0\0\0\0", 6) => 0;
memcmp(buffer+10, "ccccc", 5) => 0;
lfs_removeattr(&lfs, "/", 'B') => 0;
lfs_getattr(&lfs, "/", 'A', buffer, 4) => 4;
lfs_getattr(&lfs, "/", 'B', buffer+4, 6) => LFS_ERR_NOATTR;
lfs_getattr(&lfs, "/", 'C', buffer+10, 5) => 5;
memcmp(buffer, "aaaa", 4) => 0;
memcmp(buffer+4, "\0\0\0\0\0\0", 6) => 0;
memcmp(buffer+10, "ccccc", 5) => 0;
lfs_setattr(&lfs, "/", 'B', "dddddd", 6) => 0;
lfs_getattr(&lfs, "/", 'A', buffer, 4) => 4;
lfs_getattr(&lfs, "/", 'B', buffer+4, 6) => 6;
Expand Down Expand Up @@ -241,7 +257,7 @@ tests/test.py << TEST
lfs_getattr(&lfs, "hello/hello", 'B', buffer, 9) => 9;
lfs_getattr(&lfs, "hello/hello", 'C', buffer+9, 9) => 5;
lfs_getattr(&lfs, "hello/hello", 'D', buffer+18, 9) => 0;
lfs_getattr(&lfs, "hello/hello", 'D', buffer+18, 9) => LFS_ERR_NOATTR;
memcmp(buffer, "fffffffff", 9) => 0;
memcmp(buffer+9, "ccccc\0\0\0\0", 9) => 0;
memcmp(buffer+18, "\0\0\0\0\0\0\0\0\0", 9) => 0;
Expand Down

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