/**
* copy a directory between branches (includes all contents of the directory)
*/
int copy_directory(const char *path, int branch_ro, int branch_rw) {
DBG_IN();
/* create the directory on the destination branch */
int res = path_create(path, branch_ro, branch_rw);
if (res != 0) {
return res;
}
/* determine path to source directory on read-only branch */
char from[PATHLEN_MAX];
if (BUILD_PATH(from, uopt.branches[branch_ro].path, path)) return 1;
DIR *dp = opendir(from);
if (dp == NULL) return 1;
struct dirent *de;
while ((de = readdir(dp)) != NULL) {
if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0) continue;
char member[PATHLEN_MAX];
if (BUILD_PATH(member, path, de->d_name)) return 1;
res = cow_cp(member, branch_ro, branch_rw);
if (res != 0) return res;
}
closedir(dp);
return 0;
}
/**
* Create a file or directory that hides path below root_rw
*/
static int do_create_whiteout(const char *path, int root_rw, enum whiteout mode) {
char metapath[PATHLEN_MAX];
int res = -1;
to_root(); // whiteouts are root business
if (BUILD_PATH(metapath, METADIR, path)) {
syslog (LOG_WARNING, "%s(): Path too long\n", __func__);
goto out;
}
// p MUST be without path to branch prefix here! 2 x root_rw is correct here!
// this creates e.g. branch/.unionfs/some_directory
path_create_cutlast(metapath, root_rw, root_rw);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.roots[root_rw].path, metapath, HIDETAG)) {
syslog (LOG_WARNING, "%s(): Path too long\n", __func__);
goto out;
}
if (mode == WHITEOUT_FILE) {
res = open(p, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
if (res == -1)
goto out;
res = close(res);
} else
res = mkdir(p, S_IRWXU);
out:
to_user();
return res;
}
/**
* copy a directory between branches (includes all contents of the directory)
*/
int copy_directory(const char *path, int branch_ro, int branch_rw) {
DBG("%s\n", path);
/* create the directory on the destination branch */
int res = path_create(path, branch_ro, branch_rw);
if (res != 0) {
RETURN(res);
}
/* determine path to source directory on read-only branch */
char from[PATHLEN_MAX];
if (BUILD_PATH(from, uopt.branches[branch_ro].path, path)) RETURN(1);
DIR *dp = opendir(from);
if (dp == NULL) RETURN(1);
struct dirent *de;
while ((de = readdir(dp)) != NULL) {
if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0) continue;
char member[PATHLEN_MAX];
if (BUILD_PATH(member, path, "/", de->d_name)) {
res = 1;
break;
}
res = cow_cp(member, branch_ro, branch_rw, true);
if (res != 0) break;
}
closedir(dp);
struct stat buf;
lstat(from, &buf);
setfile(from, &buf);
RETURN(res);
}
/**
* Create a file or directory that hides path below branch_rw
*/
static int do_create_whiteout(const char *path, int branch_rw, enum whiteout mode) {
DBG("%s\n", path);
char metapath[PATHLEN_MAX];
if (BUILD_PATH(metapath, METADIR, path)) RETURN(-1);
// p MUST be without path to branch prefix here! 2 x branch_rw is correct here!
// this creates e.g. branch/.unionfs/some_directory
path_create_cutlast(metapath, branch_rw, branch_rw);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[branch_rw].path, metapath)) RETURN(-1);
strcat(p, HIDETAG); // TODO check length
int res;
if (mode == WHITEOUT_FILE) {
res = open(p, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
if (res == -1) RETURN(-1);
res = close(res);
} else {
res = mkdir(p, S_IRWXU);
if (res)
USYSLOG(LOG_ERR, "Creating %s failed: %s\n", p, strerror(errno));
}
RETURN(res);
}
/**
* initiate the cow-copy action
*/
int cow_cp(const char *path, int branch_ro, int branch_rw, bool copy_dir) {
DBG("%s\n", path);
// create the path to the file
path_create_cutlast(path, branch_ro, branch_rw);
char from[PATHLEN_MAX], to[PATHLEN_MAX];
if (BUILD_PATH(from, uopt.branches[branch_ro].path, path))
RETURN(-ENAMETOOLONG);
if (BUILD_PATH(to, uopt.branches[branch_rw].path, path))
RETURN(-ENAMETOOLONG);
setlocale(LC_ALL, "");
struct cow cow;
cow.uid = getuid();
// Copy the umask for explicit mode setting.
cow.umask = umask(0);
umask(cow.umask);
cow.from_path = from;
cow.to_path = to;
struct stat buf;
lstat(cow.from_path, &buf);
cow.stat = &buf;
int res;
switch (buf.st_mode & S_IFMT) {
case S_IFLNK:
res = copy_link(&cow);
break;
case S_IFDIR:
if (copy_dir) {
res = copy_directory(path, branch_ro, branch_rw);
} else {
res = path_create(path, branch_ro, branch_rw);
}
break;
case S_IFBLK:
case S_IFCHR:
res = copy_special(&cow);
break;
case S_IFIFO:
res = copy_fifo(&cow);
break;
case S_IFSOCK:
USYSLOG(LOG_WARNING, "COW of sockets not supported: %s\n", cow.from_path);
RETURN(1);
default:
res = copy_file(&cow);
}
RETURN(res);
}
/**
* unionfs implementation of the create call
* libfuse will call this to create regular files
*/
static int unionfs_create(const char *path, mode_t mode, struct fuse_file_info *fi) {
DBG("%s\n", path);
int i = find_rw_branch_cutlast(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
// NOTE: We should do:
// Create the file with mode=0 first, otherwise we might create
// a file as root + x-bit + suid bit set, which might be used for
// security racing!
int res = open(p, fi->flags, 0);
if (res == -1) RETURN(-errno);
set_owner(p); // no error check, since creating the file succeeded
// NOW, that the file has the proper owner we may set the requested mode
fchmod(res, mode);
fi->fh = res;
remove_hidden(path, i);
DBG("fd = %" PRIx64 "\n", fi->fh);
RETURN(0);
}
static int unionfs_open(const char *path, struct fuse_file_info *fi) {
DBG("%s\n", path);
int i;
if (fi->flags & (O_WRONLY | O_RDWR)) {
i = find_rw_branch_cutlast(path);
} else {
i = find_rorw_branch(path);
}
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int fd = open(p, fi->flags);
if (fd == -1) RETURN(-errno);
if (fi->flags & (O_WRONLY | O_RDWR)) {
// There might have been a hide file, but since we successfully
// wrote to the real file, a hide file must not exist anymore
remove_hidden(path, i);
}
// This makes exec() fail
//fi->direct_io = 1;
fi->fh = (unsigned long)fd;
DBG("fd = %"PRIx64"\n", fi->fh);
RETURN(0);
}
/**
* l_nbranch (lower nbranch than nbranch) is write protected, create the dir path on
* nbranch for an other COW operation.
*/
int path_create(const char *path, int nbranch_ro, int nbranch_rw) {
DBG("%s\n", path);
if (!uopt.cow_enabled) RETURN(0);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[nbranch_rw].path, path)) RETURN(-ENAMETOOLONG);
struct stat st;
if (!stat(p, &st)) {
// path does already exists, no need to create it
RETURN(0);
}
char *walk = (char *)path;
// first slashes, e.g. we have path = /dir1/dir2/, will set walk = dir1/dir2/
while (*walk == '/') walk++;
do {
// walk over the directory name, walk will now be /dir2
while (*walk != '\0' && *walk != '/') walk++;
// +1 due to \0, which gets added automatically
snprintf(p, (walk - path) + 1, "%s", path); // walk - path = strlen(/dir1)
int res = do_create(p, nbranch_ro, nbranch_rw);
if (res) RETURN(res); // creating the directory failed
// as above the do loop, walk over the next slashes, walk = dir2/
while (*walk == '/') walk++;
} while (*walk != '\0');
RETURN(0);
}
/**
* Remove a hide-file in all roots up to maxroot
* If maxroot == -1, try to delete it in all roots.
*/
int remove_hidden(const char *path, int maxroot) {
if (!uopt.cow_enabled) return 0;
if (maxroot == -1) maxroot = uopt.nroots;
int i;
for (i = 0; i <= maxroot; i++) {
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.roots[i].path, METADIR, path, HIDETAG)) {
syslog(LOG_WARNING, "%s: Path too long\n", __func__);
return 1;
}
struct stat buf;
int res = lstat(p, &buf);
if (res == -1) continue;
switch (buf.st_mode & S_IFMT) {
case S_IFDIR: rmdir(p); break;
default: unlink(p); break;
}
}
return 0;
}
/**
* check if any dir or file within path is hidden
*/
int path_hidden(const char *path, int branch) {
DBG("%s\n", path);
if (!uopt.cow_enabled) RETURN(false);
char whiteoutpath[PATHLEN_MAX];
if (BUILD_PATH(whiteoutpath, uopt.branches[branch].path, METADIR, path)) RETURN(false);
// -1 as we MUST not end on the next path element
char *walk = whiteoutpath + uopt.branches[branch].path_len + strlen(METADIR) - 1;
// first slashes, e.g. we have path = /dir1/dir2/, will set walk = dir1/dir2/
while (*walk == '/') walk++;
do {
// walk over the directory name, walk will now be /dir2
while (*walk != '\0' && *walk != '/') walk++;
// +1 due to \0, which gets added automatically
char p[PATHLEN_MAX];
// walk - path = strlen(/dir1)
snprintf(p, (walk - whiteoutpath) + 1, "%s", whiteoutpath);
int res = filedir_hidden(p);
if (res) RETURN(res); // path is hidden or error
// as above the do loop, walk over the next slashes, walk = dir2/
while (*walk == '/') walk++;
} while (*walk != '\0');
RETURN(0);
}
static int unionfs_getattr(const char *path, struct stat *stbuf) {
DBG("%s\n", path);
if (uopt.stats_enabled && strcmp(path, STATS_FILENAME) == 0) {
memset(stbuf, 0, sizeof(stbuf));
stbuf->st_mode = S_IFREG | 0444;
stbuf->st_nlink = 1;
stbuf->st_size = STATS_SIZE;
RETURN(0);
}
int i = find_rorw_branch(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = lstat(p, stbuf);
if (res == -1) RETURN(-errno);
/* This is a workaround for broken gnu find implementations. Actually,
* n_links is not defined at all for directories by posix. However, it
* seems to be common for filesystems to set it to one if the actual value
* is unknown. Since nlink_t is unsigned and since these broken implementations
* always substract 2 (for . and ..) this will cause an underflow, setting
* it to max(nlink_t).
*/
if (S_ISDIR(stbuf->st_mode)) stbuf->st_nlink = 1;
RETURN(0);
}
/**
* This method is to post-process options once we know all of them
*/
void unionfs_post_opts(void) {
// chdir to the given chroot, we
if (uopt.chroot) {
int res = chdir(uopt.chroot);
if (res) {
fprintf(stderr, "Chdir to %s failed: %s ! Aborting!\n",
uopt.chroot, strerror(errno));
exit(1);
}
}
// Make the pathes absolute and add trailing slashes
int i;
for (i = 0; i<uopt.nbranches; i++) {
// if -ochroot= is specified, the path has to be given absolute
// or relative to the chroot, so no need to make it absolute
// also won't work, since we are not yet in the chroot here
if (!uopt.chroot) {
uopt.branches[i].path = make_absolute(uopt.branches[i].path);
}
uopt.branches[i].path = add_trailing_slash(uopt.branches[i].path);
// Prevent accidental umounts. Especially system shutdown scripts tend
// to umount everything they can. If we don't have an open file descriptor,
// this might cause unexpected behaviour.
char path[PATHLEN_MAX];
if (!uopt.chroot) {
BUILD_PATH(path, uopt.branches[i].path);
} else {
BUILD_PATH(path, uopt.chroot, uopt.branches[i].path);
}
int fd = open(path, O_RDONLY);
if (fd == -1) {
fprintf(stderr, "\nFailed to open %s: %s. Aborting!\n\n",
path, strerror(errno));
exit(1);
}
uopt.branches[i].fd = fd;
uopt.branches[i].path_len = strlen(path);
}
}
static int unionfs_chmod(const char *path, mode_t mode) {
DBG("%s\n", path);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = chmod(p, mode);
if (res == -1) RETURN(-errno);
RETURN(0);
}
static int unionfs_chown(const char *path, uid_t uid, gid_t gid) {
DBG("%s\n", path);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = lchown(p, uid, gid);
if (res == -1) RETURN(-errno);
RETURN(0);
}
static int unionfs_link(const char *from, const char *to) {
DBG("from %s to %s\n", from, to);
// hardlinks do not work across different filesystems so we need a copy of from first
int i = find_rw_branch_cow(from);
if (i == -1) RETURN(-errno);
int j = __find_rw_branch_cutlast(to, i);
if (j == -1) RETURN(-errno);
DBG("from branch: %d to branch: %d\n", i, j);
char f[PATHLEN_MAX], t[PATHLEN_MAX];
if (BUILD_PATH(f, uopt.branches[i].path, from)) RETURN(-ENAMETOOLONG);
if (BUILD_PATH(t, uopt.branches[j].path, to)) RETURN(-ENAMETOOLONG);
int res = link(f, t);
if (res == -1) RETURN(-errno);
// no need for set_owner(), since owner and permissions are copied over by link()
remove_hidden(to, i); // remove hide file (if any)
RETURN(0);
}
static int unionfs_setxattr(const char *path, const char *name, const char *value, size_t size, int flags) {
DBG("%s\n", path);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = lsetxattr(p, name, value, size, flags);
if (res == -1) RETURN(-errno);
RETURN(res);
}
static int unionfs_listxattr(const char *path, char *list, size_t size) {
DBG("%s\n", path);
int i = find_rorw_branch(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = llistxattr(p, list, size);
if (res == -1) RETURN(-errno);
RETURN(res);
}
static int unionfs_removexattr(const char *path, const char *name) {
DBG("%s\n", path);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = lremovexattr(p, name);
if (res == -1) RETURN(-errno);
RETURN(res);
}
static int unionfs_truncate(const char *path, off_t size) {
DBG("%s\n", path);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = truncate(p, size);
if (res == -1) RETURN(-errno);
RETURN(0);
}
static int unionfs_symlink(const char *from, const char *to) {
DBG("from %s to %s\n", from, to);
int i = find_rw_branch_cutlast(to);
if (i == -1) RETURN(-errno);
char t[PATHLEN_MAX];
if (BUILD_PATH(t, uopt.branches[i].path, to)) RETURN(-ENAMETOOLONG);
int res = symlink(from, t);
if (res == -1) RETURN(-errno);
set_owner(t); // no error check, since creating the file succeeded
remove_hidden(to, i); // remove hide file (if any)
RETURN(0);
}
static int unionfs_readlink(const char *path, char *buf, size_t size) {
DBG("%s\n", path);
int i = find_rorw_branch(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = readlink(p, buf, size - 1);
if (res == -1) RETURN(-errno);
buf[res] = '\0';
RETURN(0);
}
static int unionfs_utimens(const char *path, const struct timespec ts[2]) {
DBG("%s\n", path);
if (uopt.stats_enabled && strcmp(path, STATS_FILENAME) == 0) RETURN(0);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = utimensat(0, p, ts, AT_SYMLINK_NOFOLLOW);
if (res == -1) RETURN(-errno);
RETURN(0);
}
/**
* unionfs mkdir() implementation
*
* NOTE: Never delete whiteouts directories here, since this will just
* make already hidden sub-branches visible again.
*/
static int unionfs_mkdir(const char *path, mode_t mode) {
DBG("%s\n", path);
int i = find_rw_branch_cutlast(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int res = mkdir(p, 0);
if (res == -1) RETURN(-errno);
set_owner(p); // no error check, since creating the file succeeded
// NOW, that the file has the proper owner we may set the requested mode
chmod(p, mode);
RETURN(0);
}
/**
* l_nbranch (lower nbranch than nbranch) is write protected, create the dir path on
* nbranch for an other COW operation.
*/
int path_create(const char *path, int nbranch_ro, int nbranch_rw) {
DBG("%s\n", path);
if (!uopt.cow_enabled) RETURN(0);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[nbranch_rw].path, path)) RETURN(-ENAMETOOLONG);
struct stat st;
if (!stat(p, &st)) {
// path does already exists, no need to create it
RETURN(0);
}
char *walk = (char *)path;
int res = path_create_by_step(path, walk, nbranch_ro, nbranch_rw);
RETURN(res);
}
static int unionfs_setxattr(const char *path, const char *name, const char *value, size_t size, int flags, uint32_t position) {
#else
static int unionfs_setxattr(const char *path, const char *name, const char *value, size_t size, int flags) {
#endif
DBG("%s\n", path);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
#if __APPLE__
int res = setxattr(p, name, value, size, position, flags | XATTR_NOFOLLOW);
#else
int res = lsetxattr(p, name, value, size, flags);
#endif
if (res == -1) RETURN(-errno);
RETURN(res);
}
/**
* Remove a hide-file in all branches up to maxbranch
* If maxbranch == -1, try to delete it in all branches.
*/
int remove_hidden(const char *path, int maxbranch) {
DBG("%s\n", path);
if (!uopt.cow_enabled) RETURN(0);
if (maxbranch == -1) maxbranch = uopt.nbranches;
int i;
for (i = 0; i <= maxbranch; i++) {
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, METADIR, path)) RETURN(-ENAMETOOLONG);
if (strlen(p) + strlen(HIDETAG) > PATHLEN_MAX) RETURN(-ENAMETOOLONG);
strcat(p, HIDETAG); // TODO check length
switch (path_is_dir(p)) {
case IS_FILE: unlink(p); break;
case IS_DIR: rmdir(p); break;
case NOT_EXISTING: continue;
}
}
RETURN(0);
}
static int unionfs_mknod(const char *path, mode_t mode, dev_t rdev) {
DBG("%s\n", path);
int i = find_rw_branch_cutlast(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
int file_type = mode & S_IFMT;
int file_perm = mode & (S_PROT_MASK);
int res = -1;
if ((file_type) == S_IFREG) {
// under FreeBSD, only the super-user can create ordinary files using mknod
// Actually this workaround should not be required any more
// since we now have the unionfs_create() method
// So can we remove it?
USYSLOG (LOG_INFO, "deprecated mknod workaround, tell the unionfs-fuse authors if you see this!\n");
res = creat(p, 0);
if (res > 0 && close(res) == -1) USYSLOG(LOG_WARNING, "Warning, cannot close file\n");
} else {
res = mknod(p, file_type, rdev);
}
if (res == -1) RETURN(-errno);
set_owner(p); // no error check, since creating the file succeeded
// NOW, that the file has the proper owner we may set the requested mode
chmod(p, file_perm);
remove_hidden(path, i);
RETURN(0);
}
/**
* check if any dir or file within path is hidden
*/
bool path_hidden(const char *path, int branch) {
if (!uopt.cow_enabled) return false;
char whiteoutpath[PATHLEN_MAX];
if (BUILD_PATH(whiteoutpath, uopt.roots[branch].path, METADIR, path)) {
syslog (LOG_WARNING, "%s(): Path too long\n", __func__);
return false;
}
char *walk = whiteoutpath;
// first slashes, e.g. we have path = /dir1/dir2/, will set walk = dir1/dir2/
while (*walk != '\0' && *walk == '/') walk++;
bool first = true;
do {
// walk over the directory name, walk will now be /dir2
while (*walk != '\0' && *walk != '/') walk++;
if (first) {
// first dir in path is our branch, no need to check if it is hidden
first = false;
continue;
}
// +1 due to \0, which gets added automatically
char p[PATHLEN_MAX];
snprintf(p, (walk - whiteoutpath) + 1, "%s", whiteoutpath); // walk - path = strlen(/dir1)
bool res = filedir_hidden(p);
if (res) return res; // path is hidden
// as above the do loop, walk over the next slashes, walk = dir2/
while (*walk != '\0' && *walk == '/') walk++;
} while (*walk != '\0');
return 0;
}
static int unionfs_utimens(const char *path, const struct timespec ts[2]) {
DBG("%s\n", path);
int i = find_rw_branch_cow(path);
if (i == -1) RETURN(-errno);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[i].path, path)) RETURN(-ENAMETOOLONG);
#ifdef UNIONFS_HAVE_AT
int res = utimensat(0, p, ts, AT_SYMLINK_NOFOLLOW);
#else
struct timeval tv[2];
tv[0].tv_sec = ts[0].tv_sec;
tv[0].tv_usec = ts[0].tv_nsec / 1000;
tv[1].tv_sec = ts[1].tv_sec;
tv[1].tv_usec = ts[1].tv_nsec / 1000;
int res = utimes(p, tv);
#endif
if (res == -1) RETURN(-errno);
RETURN(0);
}
/**
* unionfs rename function
* TODO: If we rename a directory on a read-only branch, we need to copy over
* all files to the renamed directory on the read-write branch.
*/
static int unionfs_rename(const char *from, const char *to) {
DBG("from %s to %s\n", from, to);
bool is_dir = false; // is 'from' a file or directory
int j = find_rw_branch_cutlast(to);
if (j == -1) RETURN(-errno);
int i = find_rorw_branch(from);
if (i == -1) RETURN(-errno);
if (!uopt.branches[i].rw) {
i = find_rw_branch_cow_common(from, true);
if (i == -1) RETURN(-errno);
}
if (i != j) {
USYSLOG(LOG_ERR, "%s: from and to are on different writable branches %d vs %d, which"
"is not supported yet.\n", __func__, i, j);
RETURN(-EXDEV);
}
char f[PATHLEN_MAX], t[PATHLEN_MAX];
if (BUILD_PATH(f, uopt.branches[i].path, from)) RETURN(-ENAMETOOLONG);
if (BUILD_PATH(t, uopt.branches[i].path, to)) RETURN(-ENAMETOOLONG);
filetype_t ftype = path_is_dir(f);
if (ftype == NOT_EXISTING)
RETURN(-ENOENT);
else if (ftype == IS_DIR)
is_dir = true;
int res;
if (!uopt.branches[i].rw) {
// since original file is on a read-only branch, we copied the from file to a writable branch,
// but since we will rename from, we also need to hide the from file on the read-only branch
if (is_dir)
res = hide_dir(from, i);
else
res = hide_file(from, i);
if (res) RETURN(-errno);
}
res = rename(f, t);
if (res == -1) {
int err = errno; // unlink() might overwrite errno
// if from was on a read-only branch we copied it, but now rename failed so we need to delete it
if (!uopt.branches[i].rw) {
if (unlink(f))
USYSLOG(LOG_ERR, "%s: cow of %s succeeded, but rename() failed and now "
"also unlink() failed\n", __func__, from);
if (remove_hidden(from, i))
USYSLOG(LOG_ERR, "%s: cow of %s succeeded, but rename() failed and now "
"also removing the whiteout failed\n", __func__, from);
}
RETURN(-err);
}
if (uopt.branches[i].rw) {
// A lower branch still *might* have a file called 'from', we need to delete this.
// We only need to do this if we have been on a rw-branch, since we created
// a whiteout for read-only branches anyway.
if (is_dir)
maybe_whiteout(from, i, WHITEOUT_DIR);
else
maybe_whiteout(from, i, WHITEOUT_FILE);
}
remove_hidden(to, i); // remove hide file (if any)
RETURN(0);
}