| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <errno.h> |
| #include <stddef.h> |
| #include <stdlib.h> |
| #include <linux/falloc.h> |
| #include <linux/magic.h> |
| #include <unistd.h> |
| |
| #include "alloc-util.h" |
| #include "dirent-util.h" |
| #include "fd-util.h" |
| #include "fileio.h" |
| #include "fs-util.h" |
| #include "hostname-util.h" |
| #include "log.h" |
| #include "macro.h" |
| #include "missing_fcntl.h" |
| #include "missing_fs.h" |
| #include "missing_syscall.h" |
| #include "mkdir.h" |
| #include "parse-util.h" |
| #include "path-util.h" |
| #include "process-util.h" |
| #include "random-util.h" |
| #include "ratelimit.h" |
| #include "stat-util.h" |
| #include "stdio-util.h" |
| #include "string-util.h" |
| #include "strv.h" |
| #include "time-util.h" |
| #include "tmpfile-util.h" |
| #include "umask-util.h" |
| #include "user-util.h" |
| |
| int unlink_noerrno(const char *path) { |
| PROTECT_ERRNO; |
| return RET_NERRNO(unlink(path)); |
| } |
| |
| int rmdir_parents(const char *path, const char *stop) { |
| char *p; |
| int r; |
| |
| assert(path); |
| assert(stop); |
| |
| if (!path_is_safe(path)) |
| return -EINVAL; |
| |
| if (!path_is_safe(stop)) |
| return -EINVAL; |
| |
| p = strdupa_safe(path); |
| |
| for (;;) { |
| char *slash = NULL; |
| |
| /* skip the last component. */ |
| r = path_find_last_component(p, /* accept_dot_dot= */ false, (const char **) &slash, NULL); |
| if (r <= 0) |
| return r; |
| if (slash == p) |
| return 0; |
| |
| assert(*slash == '/'); |
| *slash = '\0'; |
| |
| if (path_startswith_full(stop, p, /* accept_dot_dot= */ false)) |
| return 0; |
| |
| if (rmdir(p) < 0 && errno != ENOENT) |
| return -errno; |
| } |
| } |
| |
| int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) { |
| int r; |
| |
| /* Try the ideal approach first */ |
| if (renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE) >= 0) |
| return 0; |
| |
| /* renameat2() exists since Linux 3.15, btrfs and FAT added support for it later. If it is not implemented, |
| * fall back to a different method. */ |
| if (!ERRNO_IS_NOT_SUPPORTED(errno) && errno != EINVAL) |
| return -errno; |
| |
| /* Let's try to use linkat()+unlinkat() as fallback. This doesn't work on directories and on some file systems |
| * that do not support hard links (such as FAT, most prominently), but for files it's pretty close to what we |
| * want — though not atomic (i.e. for a short period both the new and the old filename will exist). */ |
| if (linkat(olddirfd, oldpath, newdirfd, newpath, 0) >= 0) { |
| |
| r = RET_NERRNO(unlinkat(olddirfd, oldpath, 0)); |
| if (r < 0) { |
| (void) unlinkat(newdirfd, newpath, 0); |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| if (!ERRNO_IS_NOT_SUPPORTED(errno) && !IN_SET(errno, EINVAL, EPERM)) /* FAT returns EPERM on link()… */ |
| return -errno; |
| |
| /* OK, neither RENAME_NOREPLACE nor linkat()+unlinkat() worked. Let's then fall back to the racy TOCTOU |
| * vulnerable accessat(F_OK) check followed by classic, replacing renameat(), we have nothing better. */ |
| |
| if (faccessat(newdirfd, newpath, F_OK, AT_SYMLINK_NOFOLLOW) >= 0) |
| return -EEXIST; |
| if (errno != ENOENT) |
| return -errno; |
| |
| return RET_NERRNO(renameat(olddirfd, oldpath, newdirfd, newpath)); |
| } |
| |
| int readlinkat_malloc(int fd, const char *p, char **ret) { |
| size_t l = PATH_MAX; |
| |
| assert(p); |
| |
| for (;;) { |
| _cleanup_free_ char *c = NULL; |
| ssize_t n; |
| |
| c = new(char, l+1); |
| if (!c) |
| return -ENOMEM; |
| |
| n = readlinkat(fd, p, c, l); |
| if (n < 0) |
| return -errno; |
| |
| if ((size_t) n < l) { |
| c[n] = 0; |
| |
| if (ret) |
| *ret = TAKE_PTR(c); |
| |
| return 0; |
| } |
| |
| if (l > (SSIZE_MAX-1)/2) /* readlinkat() returns an ssize_t, and we want an extra byte for a |
| * trailing NUL, hence do an overflow check relative to SSIZE_MAX-1 |
| * here */ |
| return -EFBIG; |
| |
| l *= 2; |
| } |
| } |
| |
| int readlink_malloc(const char *p, char **ret) { |
| return readlinkat_malloc(AT_FDCWD, p, ret); |
| } |
| |
| int readlink_value(const char *p, char **ret) { |
| _cleanup_free_ char *link = NULL, *name = NULL; |
| int r; |
| |
| assert(p); |
| assert(ret); |
| |
| r = readlink_malloc(p, &link); |
| if (r < 0) |
| return r; |
| |
| r = path_extract_filename(link, &name); |
| if (r < 0) |
| return r; |
| if (r == O_DIRECTORY) |
| return -EINVAL; |
| |
| *ret = TAKE_PTR(name); |
| return 0; |
| } |
| |
| int readlink_and_make_absolute(const char *p, char **ret) { |
| _cleanup_free_ char *target = NULL; |
| int r; |
| |
| assert(p); |
| assert(ret); |
| |
| r = readlink_malloc(p, &target); |
| if (r < 0) |
| return r; |
| |
| return file_in_same_dir(p, target, ret); |
| } |
| |
| int chmod_and_chown_at(int dir_fd, const char *path, mode_t mode, uid_t uid, gid_t gid) { |
| _cleanup_close_ int fd = -EBADF; |
| |
| assert(dir_fd >= 0 || dir_fd == AT_FDCWD); |
| |
| if (path) { |
| /* Let's acquire an O_PATH fd, as precaution to change mode/owner on the same file */ |
| fd = openat(dir_fd, path, O_PATH|O_CLOEXEC|O_NOFOLLOW); |
| if (fd < 0) |
| return -errno; |
| dir_fd = fd; |
| |
| } else if (dir_fd == AT_FDCWD) { |
| /* Let's acquire an O_PATH fd of the current directory */ |
| fd = openat(dir_fd, ".", O_PATH|O_CLOEXEC|O_NOFOLLOW|O_DIRECTORY); |
| if (fd < 0) |
| return -errno; |
| dir_fd = fd; |
| } |
| |
| return fchmod_and_chown(dir_fd, mode, uid, gid); |
| } |
| |
| int fchmod_and_chown_with_fallback(int fd, const char *path, mode_t mode, uid_t uid, gid_t gid) { |
| bool do_chown, do_chmod; |
| struct stat st; |
| int r; |
| |
| /* Change ownership and access mode of the specified fd. Tries to do so safely, ensuring that at no |
| * point in time the access mode is above the old access mode under the old ownership or the new |
| * access mode under the new ownership. Note: this call tries hard to leave the access mode |
| * unaffected if the uid/gid is changed, i.e. it undoes implicit suid/sgid dropping the kernel does |
| * on chown(). |
| * |
| * This call is happy with O_PATH fds. |
| * |
| * If path is given, allow a fallback path which does not use /proc/self/fd/. On any normal system |
| * /proc will be mounted, but in certain improperly assembled environments it might not be. This is |
| * less secure (potential TOCTOU), so should only be used after consideration. */ |
| |
| if (fstat(fd, &st) < 0) |
| return -errno; |
| |
| do_chown = |
| (uid != UID_INVALID && st.st_uid != uid) || |
| (gid != GID_INVALID && st.st_gid != gid); |
| |
| do_chmod = |
| !S_ISLNK(st.st_mode) && /* chmod is not defined on symlinks */ |
| ((mode != MODE_INVALID && ((st.st_mode ^ mode) & 07777) != 0) || |
| do_chown); /* If we change ownership, make sure we reset the mode afterwards, since chown() |
| * modifies the access mode too */ |
| |
| if (mode == MODE_INVALID) |
| mode = st.st_mode; /* If we only shall do a chown(), save original mode, since chown() might break it. */ |
| else if ((mode & S_IFMT) != 0 && ((mode ^ st.st_mode) & S_IFMT) != 0) |
| return -EINVAL; /* insist on the right file type if it was specified */ |
| |
| if (do_chown && do_chmod) { |
| mode_t minimal = st.st_mode & mode; /* the subset of the old and the new mask */ |
| |
| if (((minimal ^ st.st_mode) & 07777) != 0) { |
| r = fchmod_opath(fd, minimal & 07777); |
| if (r < 0) { |
| if (!path || r != -ENOSYS) |
| return r; |
| |
| /* Fallback path which doesn't use /proc/self/fd/. */ |
| if (chmod(path, minimal & 07777) < 0) |
| return -errno; |
| } |
| } |
| } |
| |
| if (do_chown) |
| if (fchownat(fd, "", uid, gid, AT_EMPTY_PATH) < 0) |
| return -errno; |
| |
| if (do_chmod) { |
| r = fchmod_opath(fd, mode & 07777); |
| if (r < 0) { |
| if (!path || r != -ENOSYS) |
| return r; |
| |
| /* Fallback path which doesn't use /proc/self/fd/. */ |
| if (chmod(path, mode & 07777) < 0) |
| return -errno; |
| } |
| } |
| |
| return do_chown || do_chmod; |
| } |
| |
| int fchmod_umask(int fd, mode_t m) { |
| _cleanup_umask_ mode_t u = umask(0777); |
| |
| return RET_NERRNO(fchmod(fd, m & (~u))); |
| } |
| |
| int fchmod_opath(int fd, mode_t m) { |
| /* This function operates also on fd that might have been opened with |
| * O_PATH. Indeed fchmodat() doesn't have the AT_EMPTY_PATH flag like |
| * fchownat() does. */ |
| |
| if (chmod(FORMAT_PROC_FD_PATH(fd), m) < 0) { |
| if (errno != ENOENT) |
| return -errno; |
| |
| if (proc_mounted() == 0) |
| return -ENOSYS; /* if we have no /proc/, the concept is not implementable */ |
| |
| return -ENOENT; |
| } |
| |
| return 0; |
| } |
| |
| int futimens_opath(int fd, const struct timespec ts[2]) { |
| /* Similar to fchmod_path() but for futimens() */ |
| |
| if (utimensat(AT_FDCWD, FORMAT_PROC_FD_PATH(fd), ts, 0) < 0) { |
| if (errno != ENOENT) |
| return -errno; |
| |
| if (proc_mounted() == 0) |
| return -ENOSYS; /* if we have no /proc/, the concept is not implementable */ |
| |
| return -ENOENT; |
| } |
| |
| return 0; |
| } |
| |
| int stat_warn_permissions(const char *path, const struct stat *st) { |
| assert(path); |
| assert(st); |
| |
| /* Don't complain if we are reading something that is not a file, for example /dev/null */ |
| if (!S_ISREG(st->st_mode)) |
| return 0; |
| |
| if (st->st_mode & 0111) |
| log_warning("Configuration file %s is marked executable. Please remove executable permission bits. Proceeding anyway.", path); |
| |
| if (st->st_mode & 0002) |
| log_warning("Configuration file %s is marked world-writable. Please remove world writability permission bits. Proceeding anyway.", path); |
| |
| if (getpid_cached() == 1 && (st->st_mode & 0044) != 0044) |
| log_warning("Configuration file %s is marked world-inaccessible. This has no effect as configuration data is accessible via APIs without restrictions. Proceeding anyway.", path); |
| |
| return 0; |
| } |
| |
| int fd_warn_permissions(const char *path, int fd) { |
| struct stat st; |
| |
| assert(path); |
| assert(fd >= 0); |
| |
| if (fstat(fd, &st) < 0) |
| return -errno; |
| |
| return stat_warn_permissions(path, &st); |
| } |
| |
| int touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode) { |
| _cleanup_close_ int fd = -EBADF; |
| int r, ret; |
| |
| assert(path); |
| |
| /* Note that touch_file() does not follow symlinks: if invoked on an existing symlink, then it is the symlink |
| * itself which is updated, not its target |
| * |
| * Returns the first error we encounter, but tries to apply as much as possible. */ |
| |
| if (parents) |
| (void) mkdir_parents(path, 0755); |
| |
| /* Initially, we try to open the node with O_PATH, so that we get a reference to the node. This is useful in |
| * case the path refers to an existing device or socket node, as we can open it successfully in all cases, and |
| * won't trigger any driver magic or so. */ |
| fd = open(path, O_PATH|O_CLOEXEC|O_NOFOLLOW); |
| if (fd < 0) { |
| if (errno != ENOENT) |
| return -errno; |
| |
| /* if the node doesn't exist yet, we create it, but with O_EXCL, so that we only create a regular file |
| * here, and nothing else */ |
| fd = open(path, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, IN_SET(mode, 0, MODE_INVALID) ? 0644 : mode); |
| if (fd < 0) |
| return -errno; |
| } |
| |
| /* Let's make a path from the fd, and operate on that. With this logic, we can adjust the access mode, |
| * ownership and time of the file node in all cases, even if the fd refers to an O_PATH object — which is |
| * something fchown(), fchmod(), futimensat() don't allow. */ |
| ret = fchmod_and_chown(fd, mode, uid, gid); |
| |
| if (stamp != USEC_INFINITY) { |
| struct timespec ts[2]; |
| |
| timespec_store(&ts[0], stamp); |
| ts[1] = ts[0]; |
| r = futimens_opath(fd, ts); |
| } else |
| r = futimens_opath(fd, NULL); |
| if (r < 0 && ret >= 0) |
| return r; |
| |
| return ret; |
| } |
| |
| int symlink_idempotent(const char *from, const char *to, bool make_relative) { |
| _cleanup_free_ char *relpath = NULL; |
| int r; |
| |
| assert(from); |
| assert(to); |
| |
| if (make_relative) { |
| r = path_make_relative_parent(to, from, &relpath); |
| if (r < 0) |
| return r; |
| |
| from = relpath; |
| } |
| |
| if (symlink(from, to) < 0) { |
| _cleanup_free_ char *p = NULL; |
| |
| if (errno != EEXIST) |
| return -errno; |
| |
| r = readlink_malloc(to, &p); |
| if (r == -EINVAL) /* Not a symlink? In that case return the original error we encountered: -EEXIST */ |
| return -EEXIST; |
| if (r < 0) /* Any other error? In that case propagate it as is */ |
| return r; |
| |
| if (!streq(p, from)) /* Not the symlink we want it to be? In that case, propagate the original -EEXIST */ |
| return -EEXIST; |
| } |
| |
| return 0; |
| } |
| |
| int symlinkat_atomic_full(const char *from, int atfd, const char *to, bool make_relative) { |
| _cleanup_free_ char *relpath = NULL, *t = NULL; |
| int r; |
| |
| assert(from); |
| assert(to); |
| |
| if (make_relative) { |
| r = path_make_relative_parent(to, from, &relpath); |
| if (r < 0) |
| return r; |
| |
| from = relpath; |
| } |
| |
| r = tempfn_random(to, NULL, &t); |
| if (r < 0) |
| return r; |
| |
| if (symlinkat(from, atfd, t) < 0) |
| return -errno; |
| |
| r = RET_NERRNO(renameat(atfd, t, atfd, to)); |
| if (r < 0) { |
| (void) unlinkat(atfd, t, 0); |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| int mknodat_atomic(int atfd, const char *path, mode_t mode, dev_t dev) { |
| _cleanup_free_ char *t = NULL; |
| int r; |
| |
| assert(path); |
| |
| r = tempfn_random(path, NULL, &t); |
| if (r < 0) |
| return r; |
| |
| if (mknodat(atfd, t, mode, dev) < 0) |
| return -errno; |
| |
| r = RET_NERRNO(renameat(atfd, t, atfd, path)); |
| if (r < 0) { |
| (void) unlinkat(atfd, t, 0); |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| int mkfifoat_atomic(int atfd, const char *path, mode_t mode) { |
| _cleanup_free_ char *t = NULL; |
| int r; |
| |
| assert(path); |
| |
| /* We're only interested in the (random) filename. */ |
| r = tempfn_random(path, NULL, &t); |
| if (r < 0) |
| return r; |
| |
| if (mkfifoat(atfd, t, mode) < 0) |
| return -errno; |
| |
| r = RET_NERRNO(renameat(atfd, t, atfd, path)); |
| if (r < 0) { |
| (void) unlinkat(atfd, t, 0); |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| int get_files_in_directory(const char *path, char ***list) { |
| _cleanup_strv_free_ char **l = NULL; |
| _cleanup_closedir_ DIR *d = NULL; |
| size_t n = 0; |
| |
| assert(path); |
| |
| /* Returns all files in a directory in *list, and the number |
| * of files as return value. If list is NULL returns only the |
| * number. */ |
| |
| d = opendir(path); |
| if (!d) |
| return -errno; |
| |
| FOREACH_DIRENT_ALL(de, d, return -errno) { |
| if (!dirent_is_file(de)) |
| continue; |
| |
| if (list) { |
| /* one extra slot is needed for the terminating NULL */ |
| if (!GREEDY_REALLOC(l, n + 2)) |
| return -ENOMEM; |
| |
| l[n] = strdup(de->d_name); |
| if (!l[n]) |
| return -ENOMEM; |
| |
| l[++n] = NULL; |
| } else |
| n++; |
| } |
| |
| if (list) |
| *list = TAKE_PTR(l); |
| |
| return n; |
| } |
| |
| static int getenv_tmp_dir(const char **ret_path) { |
| int r, ret = 0; |
| |
| assert(ret_path); |
| |
| /* We use the same order of environment variables python uses in tempfile.gettempdir(): |
| * https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir */ |
| FOREACH_STRING(n, "TMPDIR", "TEMP", "TMP") { |
| const char *e; |
| |
| e = secure_getenv(n); |
| if (!e) |
| continue; |
| if (!path_is_absolute(e)) { |
| r = -ENOTDIR; |
| goto next; |
| } |
| if (!path_is_normalized(e)) { |
| r = -EPERM; |
| goto next; |
| } |
| |
| r = is_dir(e, true); |
| if (r < 0) |
| goto next; |
| if (r == 0) { |
| r = -ENOTDIR; |
| goto next; |
| } |
| |
| *ret_path = e; |
| return 1; |
| |
| next: |
| /* Remember first error, to make this more debuggable */ |
| if (ret >= 0) |
| ret = r; |
| } |
| |
| if (ret < 0) |
| return ret; |
| |
| *ret_path = NULL; |
| return ret; |
| } |
| |
| static int tmp_dir_internal(const char *def, const char **ret) { |
| const char *e; |
| int r, k; |
| |
| assert(def); |
| assert(ret); |
| |
| r = getenv_tmp_dir(&e); |
| if (r > 0) { |
| *ret = e; |
| return 0; |
| } |
| |
| k = is_dir(def, true); |
| if (k == 0) |
| k = -ENOTDIR; |
| if (k < 0) |
| return r < 0 ? r : k; |
| |
| *ret = def; |
| return 0; |
| } |
| |
| int var_tmp_dir(const char **ret) { |
| |
| /* Returns the location for "larger" temporary files, that is backed by physical storage if available, and thus |
| * even might survive a boot: /var/tmp. If $TMPDIR (or related environment variables) are set, its value is |
| * returned preferably however. Note that both this function and tmp_dir() below are affected by $TMPDIR, |
| * making it a variable that overrides all temporary file storage locations. */ |
| |
| return tmp_dir_internal("/var/tmp", ret); |
| } |
| |
| int tmp_dir(const char **ret) { |
| |
| /* Similar to var_tmp_dir() above, but returns the location for "smaller" temporary files, which is usually |
| * backed by an in-memory file system: /tmp. */ |
| |
| return tmp_dir_internal("/tmp", ret); |
| } |
| |
| int unlink_or_warn(const char *filename) { |
| if (unlink(filename) < 0 && errno != ENOENT) |
| /* If the file doesn't exist and the fs simply was read-only (in which |
| * case unlink() returns EROFS even if the file doesn't exist), don't |
| * complain */ |
| if (errno != EROFS || access(filename, F_OK) >= 0) |
| return log_error_errno(errno, "Failed to remove \"%s\": %m", filename); |
| |
| return 0; |
| } |
| |
| int access_fd(int fd, int mode) { |
| /* Like access() but operates on an already open fd */ |
| |
| if (access(FORMAT_PROC_FD_PATH(fd), mode) < 0) { |
| if (errno != ENOENT) |
| return -errno; |
| |
| /* ENOENT can mean two things: that the fd does not exist or that /proc is not mounted. Let's |
| * make things debuggable and distinguish the two. */ |
| |
| if (proc_mounted() == 0) |
| return -ENOSYS; /* /proc is not available or not set up properly, we're most likely in some chroot |
| * environment. */ |
| |
| return -EBADF; /* The directory exists, hence it's the fd that doesn't. */ |
| } |
| |
| return 0; |
| } |
| |
| void unlink_tempfilep(char (*p)[]) { |
| /* If the file is created with mkstemp(), it will (almost always) |
| * change the suffix. Treat this as a sign that the file was |
| * successfully created. We ignore both the rare case where the |
| * original suffix is used and unlink failures. */ |
| if (!endswith(*p, ".XXXXXX")) |
| (void) unlink_noerrno(*p); |
| } |
| |
| int unlinkat_deallocate(int fd, const char *name, UnlinkDeallocateFlags flags) { |
| _cleanup_close_ int truncate_fd = -EBADF; |
| struct stat st; |
| off_t l, bs; |
| |
| assert((flags & ~(UNLINK_REMOVEDIR|UNLINK_ERASE)) == 0); |
| |
| /* Operates like unlinkat() but also deallocates the file contents if it is a regular file and there's no other |
| * link to it. This is useful to ensure that other processes that might have the file open for reading won't be |
| * able to keep the data pinned on disk forever. This call is particular useful whenever we execute clean-up |
| * jobs ("vacuuming"), where we want to make sure the data is really gone and the disk space released and |
| * returned to the free pool. |
| * |
| * Deallocation is preferably done by FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE (👊) if supported, which means |
| * the file won't change size. That's a good thing since we shouldn't needlessly trigger SIGBUS in other |
| * programs that have mmap()ed the file. (The assumption here is that changing file contents to all zeroes |
| * underneath those programs is the better choice than simply triggering SIGBUS in them which truncation does.) |
| * However if hole punching is not implemented in the kernel or file system we'll fall back to normal file |
| * truncation (🔪), as our goal of deallocating the data space trumps our goal of being nice to readers (💐). |
| * |
| * Note that we attempt deallocation, but failure to succeed with that is not considered fatal, as long as the |
| * primary job – to delete the file – is accomplished. */ |
| |
| if (!FLAGS_SET(flags, UNLINK_REMOVEDIR)) { |
| truncate_fd = openat(fd, name, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_NONBLOCK); |
| if (truncate_fd < 0) { |
| |
| /* If this failed because the file doesn't exist propagate the error right-away. Also, |
| * AT_REMOVEDIR wasn't set, and we tried to open the file for writing, which means EISDIR is |
| * returned when this is a directory but we are not supposed to delete those, hence propagate |
| * the error right-away too. */ |
| if (IN_SET(errno, ENOENT, EISDIR)) |
| return -errno; |
| |
| if (errno != ELOOP) /* don't complain if this is a symlink */ |
| log_debug_errno(errno, "Failed to open file '%s' for deallocation, ignoring: %m", name); |
| } |
| } |
| |
| if (unlinkat(fd, name, FLAGS_SET(flags, UNLINK_REMOVEDIR) ? AT_REMOVEDIR : 0) < 0) |
| return -errno; |
| |
| if (truncate_fd < 0) /* Don't have a file handle, can't do more ☹️ */ |
| return 0; |
| |
| if (fstat(truncate_fd, &st) < 0) { |
| log_debug_errno(errno, "Failed to stat file '%s' for deallocation, ignoring: %m", name); |
| return 0; |
| } |
| |
| if (!S_ISREG(st.st_mode)) |
| return 0; |
| |
| if (FLAGS_SET(flags, UNLINK_ERASE) && st.st_size > 0 && st.st_nlink == 0) { |
| uint64_t left = st.st_size; |
| char buffer[64 * 1024]; |
| |
| /* If erasing is requested, let's overwrite the file with random data once before deleting |
| * it. This isn't going to give you shred(1) semantics, but hopefully should be good enough |
| * for stuff backed by tmpfs at least. |
| * |
| * Note that we only erase like this if the link count of the file is zero. If it is higher it |
| * is still linked by someone else and we'll leave it to them to remove it securely |
| * eventually! */ |
| |
| random_bytes(buffer, sizeof(buffer)); |
| |
| while (left > 0) { |
| ssize_t n; |
| |
| n = write(truncate_fd, buffer, MIN(sizeof(buffer), left)); |
| if (n < 0) { |
| log_debug_errno(errno, "Failed to erase data in file '%s', ignoring.", name); |
| break; |
| } |
| |
| assert(left >= (size_t) n); |
| left -= n; |
| } |
| |
| /* Let's refresh metadata */ |
| if (fstat(truncate_fd, &st) < 0) { |
| log_debug_errno(errno, "Failed to stat file '%s' for deallocation, ignoring: %m", name); |
| return 0; |
| } |
| } |
| |
| /* Don't dallocate if there's nothing to deallocate or if the file is linked elsewhere */ |
| if (st.st_blocks == 0 || st.st_nlink > 0) |
| return 0; |
| |
| /* If this is a regular file, it actually took up space on disk and there are no other links it's time to |
| * punch-hole/truncate this to release the disk space. */ |
| |
| bs = MAX(st.st_blksize, 512); |
| l = DIV_ROUND_UP(st.st_size, bs) * bs; /* Round up to next block size */ |
| |
| if (fallocate(truncate_fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE, 0, l) >= 0) |
| return 0; /* Successfully punched a hole! 😊 */ |
| |
| /* Fall back to truncation */ |
| if (ftruncate(truncate_fd, 0) < 0) { |
| log_debug_errno(errno, "Failed to truncate file to 0, ignoring: %m"); |
| return 0; |
| } |
| |
| return 0; |
| } |
| |
| int open_parent(const char *path, int flags, mode_t mode) { |
| _cleanup_free_ char *parent = NULL; |
| int r; |
| |
| r = path_extract_directory(path, &parent); |
| if (r < 0) |
| return r; |
| |
| /* Let's insist on O_DIRECTORY since the parent of a file or directory is a directory. Except if we open an |
| * O_TMPFILE file, because in that case we are actually create a regular file below the parent directory. */ |
| |
| if (FLAGS_SET(flags, O_PATH)) |
| flags |= O_DIRECTORY; |
| else if (!FLAGS_SET(flags, O_TMPFILE)) |
| flags |= O_DIRECTORY|O_RDONLY; |
| |
| return RET_NERRNO(open(parent, flags, mode)); |
| } |
| |
| int conservative_renameat( |
| int olddirfd, const char *oldpath, |
| int newdirfd, const char *newpath) { |
| |
| _cleanup_close_ int old_fd = -EBADF, new_fd = -EBADF; |
| struct stat old_stat, new_stat; |
| |
| /* Renames the old path to thew new path, much like renameat() — except if both are regular files and |
| * have the exact same contents and basic file attributes already. In that case remove the new file |
| * instead. This call is useful for reducing inotify wakeups on files that are updated but don't |
| * actually change. This function is written in a style that we rather rename too often than suppress |
| * too much. i.e. whenever we are in doubt we rather rename than fail. After all reducing inotify |
| * events is an optimization only, not more. */ |
| |
| old_fd = openat(olddirfd, oldpath, O_CLOEXEC|O_RDONLY|O_NOCTTY|O_NOFOLLOW); |
| if (old_fd < 0) |
| goto do_rename; |
| |
| new_fd = openat(newdirfd, newpath, O_CLOEXEC|O_RDONLY|O_NOCTTY|O_NOFOLLOW); |
| if (new_fd < 0) |
| goto do_rename; |
| |
| if (fstat(old_fd, &old_stat) < 0) |
| goto do_rename; |
| |
| if (!S_ISREG(old_stat.st_mode)) |
| goto do_rename; |
| |
| if (fstat(new_fd, &new_stat) < 0) |
| goto do_rename; |
| |
| if (stat_inode_same(&new_stat, &old_stat)) |
| goto is_same; |
| |
| if (old_stat.st_mode != new_stat.st_mode || |
| old_stat.st_size != new_stat.st_size || |
| old_stat.st_uid != new_stat.st_uid || |
| old_stat.st_gid != new_stat.st_gid) |
| goto do_rename; |
| |
| for (;;) { |
| uint8_t buf1[16*1024]; |
| uint8_t buf2[sizeof(buf1)]; |
| ssize_t l1, l2; |
| |
| l1 = read(old_fd, buf1, sizeof(buf1)); |
| if (l1 < 0) |
| goto do_rename; |
| |
| if (l1 == sizeof(buf1)) |
| /* Read the full block, hence read a full block in the other file too */ |
| |
| l2 = read(new_fd, buf2, l1); |
| else { |
| assert((size_t) l1 < sizeof(buf1)); |
| |
| /* Short read. This hence was the last block in the first file, and then came |
| * EOF. Read one byte more in the second file, so that we can verify we hit EOF there |
| * too. */ |
| |
| assert((size_t) (l1 + 1) <= sizeof(buf2)); |
| l2 = read(new_fd, buf2, l1 + 1); |
| } |
| if (l2 != l1) |
| goto do_rename; |
| |
| if (memcmp(buf1, buf2, l1) != 0) |
| goto do_rename; |
| |
| if ((size_t) l1 < sizeof(buf1)) /* We hit EOF on the first file, and the second file too, hence exit |
| * now. */ |
| break; |
| } |
| |
| is_same: |
| /* Everything matches? Then don't rename, instead remove the source file, and leave the existing |
| * destination in place */ |
| |
| if (unlinkat(olddirfd, oldpath, 0) < 0) |
| goto do_rename; |
| |
| return 0; |
| |
| do_rename: |
| if (renameat(olddirfd, oldpath, newdirfd, newpath) < 0) |
| return -errno; |
| |
| return 1; |
| } |
| |
| int posix_fallocate_loop(int fd, uint64_t offset, uint64_t size) { |
| RateLimit rl; |
| int r; |
| |
| r = posix_fallocate(fd, offset, size); /* returns positive errnos on error */ |
| if (r != EINTR) |
| return -r; /* Let's return negative errnos, like common in our codebase */ |
| |
| /* On EINTR try a couple of times more, but protect against busy looping |
| * (not more than 16 times per 10s) */ |
| rl = (const RateLimit) { 10 * USEC_PER_SEC, 16 }; |
| while (ratelimit_below(&rl)) { |
| r = posix_fallocate(fd, offset, size); |
| if (r != EINTR) |
| return -r; |
| } |
| |
| return -EINTR; |
| } |
| |
| int parse_cifs_service( |
| const char *s, |
| char **ret_host, |
| char **ret_service, |
| char **ret_path) { |
| |
| _cleanup_free_ char *h = NULL, *ss = NULL, *x = NULL; |
| const char *p, *e, *d; |
| char delimiter; |
| |
| /* Parses a CIFS service in form of //host/service/path… and splitting it in three parts. The last |
| * part is optional, in which case NULL is returned there. To maximize compatibility syntax with |
| * backslashes instead of slashes is accepted too. */ |
| |
| if (!s) |
| return -EINVAL; |
| |
| p = startswith(s, "//"); |
| if (!p) { |
| p = startswith(s, "\\\\"); |
| if (!p) |
| return -EINVAL; |
| } |
| |
| delimiter = s[0]; |
| e = strchr(p, delimiter); |
| if (!e) |
| return -EINVAL; |
| |
| h = strndup(p, e - p); |
| if (!h) |
| return -ENOMEM; |
| |
| if (!hostname_is_valid(h, 0)) |
| return -EINVAL; |
| |
| e++; |
| |
| d = strchrnul(e, delimiter); |
| |
| ss = strndup(e, d - e); |
| if (!ss) |
| return -ENOMEM; |
| |
| if (!filename_is_valid(ss)) |
| return -EINVAL; |
| |
| if (!isempty(d)) { |
| x = strdup(skip_leading_chars(d, CHAR_TO_STR(delimiter))); |
| if (!x) |
| return -EINVAL; |
| |
| /* Make sure to convert Windows-style "\" → Unix-style / */ |
| for (char *i = x; *i; i++) |
| if (*i == delimiter) |
| *i = '/'; |
| |
| if (!path_is_valid(x)) |
| return -EINVAL; |
| |
| path_simplify(x); |
| if (!path_is_normalized(x)) |
| return -EINVAL; |
| } |
| |
| if (ret_host) |
| *ret_host = TAKE_PTR(h); |
| if (ret_service) |
| *ret_service = TAKE_PTR(ss); |
| if (ret_path) |
| *ret_path = TAKE_PTR(x); |
| |
| return 0; |
| } |
| |
| int open_mkdir_at(int dirfd, const char *path, int flags, mode_t mode) { |
| _cleanup_close_ int fd = -EBADF, parent_fd = -EBADF; |
| _cleanup_free_ char *fname = NULL; |
| bool made; |
| int r; |
| |
| /* Creates a directory with mkdirat() and then opens it, in the "most atomic" fashion we can |
| * do. Guarantees that the returned fd refers to a directory. If O_EXCL is specified will fail if the |
| * dir already exists. Otherwise will open an existing dir, but only if it is one. */ |
| |
| if (flags & ~(O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_EXCL|O_NOATIME|O_NOFOLLOW|O_PATH)) |
| return -EINVAL; |
| if ((flags & O_ACCMODE) != O_RDONLY) |
| return -EINVAL; |
| |
| /* Note that O_DIRECTORY|O_NOFOLLOW is implied, but we allow specifying it anyway. The following |
| * flags actually make sense to specify: O_CLOEXEC, O_EXCL, O_NOATIME, O_PATH */ |
| |
| if (isempty(path)) |
| return -EINVAL; |
| |
| if (!filename_is_valid(path)) { |
| _cleanup_free_ char *parent = NULL; |
| |
| /* If this is not a valid filename, it's a path. Let's open the parent directory then, so |
| * that we can pin it, and operate below it. */ |
| |
| r = path_extract_directory(path, &parent); |
| if (r < 0) |
| return r; |
| |
| r = path_extract_filename(path, &fname); |
| if (r < 0) |
| return r; |
| |
| parent_fd = openat(dirfd, parent, O_PATH|O_DIRECTORY|O_CLOEXEC); |
| if (parent_fd < 0) |
| return -errno; |
| |
| dirfd = parent_fd; |
| path = fname; |
| } |
| |
| r = RET_NERRNO(mkdirat(dirfd, path, mode)); |
| if (r == -EEXIST) { |
| if (FLAGS_SET(flags, O_EXCL)) |
| return -EEXIST; |
| |
| made = false; |
| } else if (r < 0) |
| return r; |
| else |
| made = true; |
| |
| fd = RET_NERRNO(openat(dirfd, path, (flags & ~O_EXCL)|O_DIRECTORY|O_NOFOLLOW)); |
| if (fd < 0) { |
| if (fd == -ENOENT) /* We got ENOENT? then someone else immediately removed it after we |
| * created it. In that case let's return immediately without unlinking |
| * anything, because there simply isn't anything to unlink anymore. */ |
| return -ENOENT; |
| if (fd == -ELOOP) /* is a symlink? exists already → created by someone else, don't unlink */ |
| return -EEXIST; |
| if (fd == -ENOTDIR) /* not a directory? exists already → created by someone else, don't unlink */ |
| return -EEXIST; |
| |
| if (made) |
| (void) unlinkat(dirfd, path, AT_REMOVEDIR); |
| |
| return fd; |
| } |
| |
| return TAKE_FD(fd); |
| } |
| |
| int openat_report_new(int dirfd, const char *pathname, int flags, mode_t mode, bool *ret_newly_created) { |
| unsigned attempts = 7; |
| int fd; |
| |
| /* Just like openat(), but adds one thing: optionally returns whether we created the file anew or if |
| * it already existed before. This is only relevant if O_CREAT is set without O_EXCL, and thus will |
| * shortcut to openat() otherwise */ |
| |
| if (!ret_newly_created) |
| return RET_NERRNO(openat(dirfd, pathname, flags, mode)); |
| |
| if (!FLAGS_SET(flags, O_CREAT) || FLAGS_SET(flags, O_EXCL)) { |
| fd = openat(dirfd, pathname, flags, mode); |
| if (fd < 0) |
| return -errno; |
| |
| *ret_newly_created = FLAGS_SET(flags, O_CREAT); |
| return fd; |
| } |
| |
| for (;;) { |
| /* First, attempt to open without O_CREAT/O_EXCL, i.e. open existing file */ |
| fd = openat(dirfd, pathname, flags & ~(O_CREAT | O_EXCL), mode); |
| if (fd >= 0) { |
| *ret_newly_created = false; |
| return fd; |
| } |
| if (errno != ENOENT) |
| return -errno; |
| |
| /* So the file didn't exist yet, hence create it with O_CREAT/O_EXCL. */ |
| fd = openat(dirfd, pathname, flags | O_CREAT | O_EXCL, mode); |
| if (fd >= 0) { |
| *ret_newly_created = true; |
| return fd; |
| } |
| if (errno != EEXIST) |
| return -errno; |
| |
| /* Hmm, so now we got EEXIST? So it apparently exists now? If so, let's try to open again |
| * without the two flags. But let's not spin forever, hence put a limit on things */ |
| |
| if (--attempts == 0) /* Give up eventually, somebody is playing with us */ |
| return -EEXIST; |
| } |
| } |
