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Allow fs_getattr and fs_setattr to work on unlinked files #20

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Allow fs_getattr and fs_setattr to work on unlinked files #20

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81 changes: 67 additions & 14 deletions backend/fs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2408,6 +2408,67 @@ fs_readlink(void *softc __unused, struct l9p_request *req)
return (error);
}

static int
fs_fstat_fid(struct fs_fid *file, struct stat *st)
{
if (file->ff_fd < 0) {
return fstatat(file->ff_dirfd, file->ff_name, st, AT_SYMLINK_NOFOLLOW);
} else {
return fstat(file->ff_fd, st);
}
}

static int
fs_fchmod_fid(struct fs_fid *file, int mode)
{
if (file->ff_fd < 0) {
return fchmodat(file->ff_dirfd, file->ff_name, mode,
AT_SYMLINK_NOFOLLOW);
} else {
return fchmod(file->ff_fd, mode);
}
}

static int
fs_fchown_fid(struct fs_fid *file, int uid, int gid)
{
if (file->ff_fd < 0) {
return fchownat(file->ff_dirfd, file->ff_name, uid, gid,
AT_SYMLINK_NOFOLLOW);
} else {
return fchown(file->ff_fd, uid, gid);
}
}

static int
fs_ftruncate_fid(struct fs_fid *file, off_t length)
{
if (file->ff_fd < 0) {
/* Truncate follows symlinks, is this OK? */
int fd = openat(file->ff_dirfd, file->ff_name, O_RDWR);
int ret = ftruncate(fd, length);
int error = errno;
(void) close(fd);
errno = error;
return ret;
} else {
L9P_LOG(L9P_DEBUG, "calling ftruncate(%d, %lu)", file->ff_fd, length);
return ftruncate(file->ff_fd, length);
}
}

static int
fs_futimens_fid(struct fs_fid *file, const struct timespec times[2])
{
if (file->ff_fd < 0) {
return utimensat(file->ff_dirfd, file->ff_name, times,
AT_SYMLINK_NOFOLLOW);
} else {
return futimens(file->ff_fd, times);
}
}


static int
fs_getattr(void *softc __unused, struct l9p_request *req)
{
Expand All @@ -2420,7 +2481,7 @@ fs_getattr(void *softc __unused, struct l9p_request *req)
assert(file);

valid = 0;
if (fstatat(file->ff_dirfd, file->ff_name, &st, AT_SYMLINK_NOFOLLOW)) {
if (fs_fstat_fid(file, &st)) {
error = errno;
goto out;
}
Expand Down Expand Up @@ -2531,7 +2592,7 @@ fs_setattr(void *softc, struct l9p_request *req)
*/
mask = req->lr_req.tsetattr.valid;

if (fstatat(file->ff_dirfd, file->ff_name, &st, AT_SYMLINK_NOFOLLOW)) {
if (fs_fstat_fid(file, &st)) {
error = errno;
goto out;
}
Expand All @@ -2542,9 +2603,7 @@ fs_setattr(void *softc, struct l9p_request *req)
}

if (mask & L9PL_SETATTR_MODE) {
if (fchmodat(file->ff_dirfd, file->ff_name,
req->lr_req.tsetattr.mode & 0777,
AT_SYMLINK_NOFOLLOW)) {
if (fs_fchmod_fid(file, req->lr_req.tsetattr.mode & 0777)) {
error = errno;
goto out;
}
Expand All @@ -2559,22 +2618,17 @@ fs_setattr(void *softc, struct l9p_request *req)
? req->lr_req.tsetattr.gid
: (gid_t)-1;

if (fchownat(file->ff_dirfd, file->ff_name, uid, gid,
AT_SYMLINK_NOFOLLOW)) {
if (fs_fchown_fid(file, uid, gid)) {
error = errno;
goto out;
}
}

if (mask & L9PL_SETATTR_SIZE) {
/* Truncate follows symlinks, is this OK? */
int fd = openat(file->ff_dirfd, file->ff_name, O_RDWR);
if (ftruncate(fd, (off_t)req->lr_req.tsetattr.size)) {
if (fs_ftruncate_fid(file, (off_t)req->lr_req.tsetattr.size)) {
error = errno;
(void) close(fd);
goto out;
}
(void) close(fd);
}

if (mask & (L9PL_SETATTR_ATIME | L9PL_SETATTR_MTIME)) {
Expand Down Expand Up @@ -2607,8 +2661,7 @@ fs_setattr(void *softc, struct l9p_request *req)
}
}

if (utimensat(file->ff_dirfd, file->ff_name, ts,
AT_SYMLINK_NOFOLLOW)) {
if (fs_futimens_fid(file, ts)) {
error = errno;
goto out;
}
Expand Down