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rm-rf: refactor rm_rf_children(), split out body of directory iteration loop

Browse source 
This splits out rm_rf_children_inner() as body of the loop. We can use
that to implement rm_rf_child() for deleting one specific entry in a
directory.
This commit is contained in:
Lennart Poettering 2021-01-26 16:30:06 +01:00
parent a4d9c121cc
commit 1f0fb7d544
2 changed files with 140 additions and 104 deletions
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241
src/shared/rm-rf.c
View file

@ -19,6 +19,9 @@
#include "stat-util.h"
#include "string-util.h"
/* We treat tmpfs/ramfs + cgroupfs as non-physical file sytems. cgroupfs is similar to tmpfs in a way after
* all: we can create arbitrary directory hierarchies in it, and hence can also use rm_rf() on it to remove
* those again. */
static bool is_physical_fs(const struct statfs *sfs) {
return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
}
@ -113,133 +116,145 @@ int fstatat_harder(int dfd,
return 0;
}
int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
static int rm_rf_children_inner(
int fd,
const char *fname,
int is_dir,
RemoveFlags flags,
const struct stat *root_dev) {
struct stat st;
int r;
assert(fd >= 0);
assert(fname);
if (is_dir < 0 || (is_dir > 0 && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
r = fstatat_harder(fd, fname, &st, AT_SYMLINK_NOFOLLOW, flags);
if (r < 0)
return r;
is_dir = S_ISDIR(st.st_mode);
}
if (is_dir) {
_cleanup_close_ int subdir_fd = -1;
int q;
/* if root_dev is set, remove subdirectories only if device is same */
if (root_dev && st.st_dev != root_dev->st_dev)
return 0;
/* Stop at mount points */
r = fd_is_mount_point(fd, fname, 0);
if (r < 0)
return r;
if (r > 0)
return 0;
if ((flags & REMOVE_SUBVOLUME) && btrfs_might_be_subvol(&st)) {
/* This could be a subvolume, try to remove it */
r = btrfs_subvol_remove_fd(fd, fname, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
if (r < 0) {
if (!IN_SET(r, -ENOTTY, -EINVAL))
return r;
/* ENOTTY, then it wasn't a btrfs subvolume, continue below. */
} else
/* It was a subvolume, done. */
return 1;
}
subdir_fd = openat(fd, fname, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
if (subdir_fd < 0)
return -errno;
/* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file system type
* again for each directory */
q = rm_rf_children(TAKE_FD(subdir_fd), flags | REMOVE_PHYSICAL, root_dev);
r = unlinkat_harder(fd, fname, AT_REMOVEDIR, flags);
if (r < 0)
return r;
if (q < 0)
return q;
return 1;
} else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
r = unlinkat_harder(fd, fname, 0, flags);
if (r < 0)
return r;
return 1;
}
return 0;
}
int rm_rf_children(
int fd,
RemoveFlags flags,
const struct stat *root_dev) {
_cleanup_closedir_ DIR *d = NULL;
struct dirent *de;
int ret = 0, r;
struct statfs sfs;
assert(fd >= 0);
/* This returns the first error we run into, but nevertheless tries to go on. This closes the passed
* fd, in all cases, including on failure.. */
if (!(flags & REMOVE_PHYSICAL)) {
r = fstatfs(fd, &sfs);
if (r < 0) {
safe_close(fd);
return -errno;
}
if (is_physical_fs(&sfs)) {
/* We refuse to clean physical file systems with this call,
* unless explicitly requested. This is extra paranoia just
* to be sure we never ever remove non-state data. */
_cleanup_free_ char *path = NULL;
(void) fd_get_path(fd, &path);
log_error("Attempted to remove disk file system under \"%s\", and we can't allow that.",
strna(path));
safe_close(fd);
return -EPERM;
}
}
* fd, in all cases, including on failure. */
d = fdopendir(fd);
if (!d) {
safe_close(fd);
return errno == ENOENT ? 0 : -errno;
return -errno;
}
if (!(flags & REMOVE_PHYSICAL)) {
struct statfs sfs;
if (fstatfs(dirfd(d), &sfs) < 0)
return -errno;
if (is_physical_fs(&sfs)) {
/* We refuse to clean physical file systems with this call, unless explicitly
* requested. This is extra paranoia just to be sure we never ever remove non-state
* data. */
_cleanup_free_ char *path = NULL;
(void) fd_get_path(fd, &path);
return log_error_errno(SYNTHETIC_ERRNO(EPERM),
"Attempted to remove disk file system under \"%s\", and we can't allow that.",
strna(path));
}
}
FOREACH_DIRENT_ALL(de, d, return -errno) {
bool is_dir;
struct stat st;
int is_dir;
if (dot_or_dot_dot(de->d_name))
continue;
if (de->d_type == DT_UNKNOWN ||
(de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
r = fstatat_harder(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW, flags);
if (r < 0) {
if (ret == 0 && r != -ENOENT)
ret = r;
continue;
}
is_dir =
de->d_type == DT_UNKNOWN ? -1 :
de->d_type == DT_DIR;
is_dir = S_ISDIR(st.st_mode);
} else
is_dir = de->d_type == DT_DIR;
if (is_dir) {
_cleanup_close_ int subdir_fd = -1;
/* if root_dev is set, remove subdirectories only if device is same */
if (root_dev && st.st_dev != root_dev->st_dev)
continue;
subdir_fd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
if (subdir_fd < 0) {
if (ret == 0 && errno != ENOENT)
ret = -errno;
continue;
}
/* Stop at mount points */
r = fd_is_mount_point(fd, de->d_name, 0);
if (r < 0) {
if (ret == 0 && r != -ENOENT)
ret = r;
continue;
}
if (r > 0)
continue;
if ((flags & REMOVE_SUBVOLUME) && btrfs_might_be_subvol(&st)) {
/* This could be a subvolume, try to remove it */
r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
if (r < 0) {
if (!IN_SET(r, -ENOTTY, -EINVAL)) {
if (ret == 0)
ret = r;
continue;
}
/* ENOTTY, then it wasn't a btrfs subvolume, continue below. */
} else
/* It was a subvolume, continue. */
continue;
}
/* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file
* system type again for each directory */
r = rm_rf_children(TAKE_FD(subdir_fd), flags | REMOVE_PHYSICAL, root_dev);
if (r < 0 && ret == 0)
ret = r;
r = unlinkat_harder(fd, de->d_name, AT_REMOVEDIR, flags);
if (r < 0 && r != -ENOENT && ret == 0)
ret = r;
} else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
r = unlinkat_harder(fd, de->d_name, 0, flags);
if (r < 0 && r != -ENOENT && ret == 0)
ret = r;
}
r = rm_rf_children_inner(dirfd(d), de->d_name, is_dir, flags, root_dev);
if (r < 0 && r != -ENOENT && ret == 0)
ret = r;
}
return ret;
}
int rm_rf(const char *path, RemoveFlags flags) {
int fd, r;
struct statfs s;
assert(path);
@ -284,9 +299,10 @@ int rm_rf(const char *path, RemoveFlags flags) {
if (FLAGS_SET(flags, REMOVE_ROOT)) {
if (!FLAGS_SET(flags, REMOVE_PHYSICAL)) {
struct statfs s;
if (statfs(path, &s) < 0)
return -errno;
if (is_physical_fs(&s))
return log_error_errno(SYNTHETIC_ERRNO(EPERM),
"Attempted to remove files from a disk file system under \"%s\", refusing.",
@ -314,3 +330,22 @@ int rm_rf(const char *path, RemoveFlags flags) {
return r;
}
int rm_rf_child(int fd, const char *name, RemoveFlags flags) {
/* Removes one specific child of the specified directory */
if (fd < 0)
return -EBADF;
if (!filename_is_valid(name))
return -EINVAL;
if ((flags & (REMOVE_ROOT|REMOVE_MISSING_OK)) != 0) /* Doesn't really make sense here, we are not supposed to remove 'fd' anyway */
return -EINVAL;
if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES|REMOVE_SUBVOLUME))
return -EINVAL;
return rm_rf_children_inner(fd, name, -1, flags, NULL);
}

3
src/shared/rm-rf.h
View file

@ -23,7 +23,8 @@ int fstatat_harder(int dfd,
int fstatat_flags,
RemoveFlags remove_flags);
int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev);
int rm_rf_children(int fd, RemoveFlags flags, const struct stat *root_dev);
int rm_rf_child(int fd, const char *name, RemoveFlags flags);
int rm_rf(const char *path, RemoveFlags flags);
/* Useful for usage with _cleanup_(), destroys a directory and frees the pointer */