/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include #include #include #include #include #include "alloc-util.h" #include "dirent-util.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "hostname-util.h" #include "lock-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 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 β€” 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 β€” 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(*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 (πŸ‘Š) 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 (πŸ”ͺ), as our goal of deallocating the data space trumps our goal of being nice to readers (πŸ’). * * 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_at(int dir_fd, const char *path, int flags, mode_t mode) { _cleanup_free_ char *parent = NULL; int r; assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(path); r = path_extract_directory(path, &parent); if (r == -EDESTADDRREQ) { parent = strdup("."); if (!parent) return -ENOMEM; } else if (r == -EADDRNOTAVAIL) { parent = strdup(path); if (!parent) return -ENOMEM; } else 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(openat(dir_fd, 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 the new path, much like renameat() β€” 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 "\" β†’ 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, *parent = NULL; 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 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) { if (!IN_SET(r, -EDESTADDRREQ, -EADDRNOTAVAIL)) return r; } else { 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; } fd = xopenat(dirfd, path, flags|O_CREAT|O_DIRECTORY|O_NOFOLLOW, mode); if (IN_SET(fd, -ELOOP, -ENOTDIR)) return -EEXIST; if (fd < 0) 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; } } int xopenat(int dir_fd, const char *path, int flags, mode_t mode) { _cleanup_close_ int fd = -EBADF; bool made = false; int r; assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(path); if (isempty(path)) { assert(!FLAGS_SET(flags, O_CREAT|O_EXCL)); return fd_reopen(dir_fd, flags & ~O_NOFOLLOW); } if (FLAGS_SET(flags, O_DIRECTORY|O_CREAT)) { r = RET_NERRNO(mkdirat(dir_fd, path, mode)); if (r == -EEXIST) { if (FLAGS_SET(flags, O_EXCL)) return -EEXIST; made = false; } else if (r < 0) return r; else made = true; flags &= ~(O_EXCL|O_CREAT); } fd = RET_NERRNO(openat(dir_fd, path, flags, mode)); if (fd < 0) { if (IN_SET(fd, /* 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. */ -ENOENT, /* is a symlink? exists already β†’ created by someone else, don't unlink */ -ELOOP, /* not a directory? exists already β†’ created by someone else, don't unlink */ -ENOTDIR)) return fd; if (made) (void) unlinkat(dir_fd, path, AT_REMOVEDIR); return fd; } return TAKE_FD(fd); } int xopenat_lock(int dir_fd, const char *path, int flags, mode_t mode, LockType locktype, int operation) { _cleanup_close_ int fd = -EBADF; int r; assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(path); assert(IN_SET(operation & ~LOCK_NB, LOCK_EX, LOCK_SH)); /* POSIX/UNPOSIX locks don't work on directories (errno is set to -EBADF so let's return early with * the same error here). */ if (FLAGS_SET(flags, O_DIRECTORY) && locktype != LOCK_BSD) return -EBADF; for (;;) { struct stat st; fd = xopenat(dir_fd, path, flags, mode); if (fd < 0) return fd; r = lock_generic(fd, locktype, operation); if (r < 0) return r; /* If we acquired the lock, let's check if the file/directory still exists in the file * system. If not, then the previous exclusive owner removed it and then closed it. In such a * case our acquired lock is worthless, hence try again. */ if (fstat(fd, &st) < 0) return -errno; if (st.st_nlink > 0) break; fd = safe_close(fd); } return TAKE_FD(fd); }