util: rework rm_rf() logic

- Move to its own file rm-rf.c

- Change parameters into a single flags parameter

- Remove "honour sticky" logic, it's unused these days

1 files changed, 173 insertions, 0 deletions

diff --git a/src/shared/rm-rf.c b/src/shared/rm-rf.c
new file mode 100644
index 0000000000..99d12b11c6
--- /dev/null
+++ b/src/shared/rm-rf.c
@@ -0,0 +1,173 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "util.h"
+#include "path-util.h"
+#include "rm-rf.h"
+
+int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
+        _cleanup_closedir_ DIR *d = NULL;
+        int ret = 0, r;
+
+        assert(fd >= 0);
+
+        /* This returns the first error we run into, but nevertheless
+         * tries to go on. This closes the passed fd. */
+
+        if (!(flags & REMOVE_PHYSICAL)) {
+
+                r = fd_is_temporary_fs(fd);
+                if (r < 0) {
+                        safe_close(fd);
+                        return r;
+                }
+
+                if (!r) {
+                        /* 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 */
+
+                        log_error("Attempted to remove disk file system, and we can't allow that.");
+                        safe_close(fd);
+                        return -EPERM;
+                }
+        }
+
+        d = fdopendir(fd);
+        if (!d) {
+                safe_close(fd);
+                return errno == ENOENT ? 0 : -errno;
+        }
+
+        for (;;) {
+                struct dirent *de;
+                bool is_dir;
+                struct stat st;
+
+                errno = 0;
+                de = readdir(d);
+                if (!de) {
+                        if (errno != 0 && ret == 0)
+                                ret = -errno;
+                        return ret;
+                }
+
+                if (streq(de->d_name, ".") || streq(de->d_name, ".."))
+                        continue;
+
+                if (de->d_type == DT_UNKNOWN || (de->d_type == DT_DIR && root_dev)) {
+                        if (fstatat(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
+                                if (ret == 0 && errno != ENOENT)
+                                        ret = -errno;
+                                continue;
+                        }
+
+                        is_dir = S_ISDIR(st.st_mode);
+                } else
+                        is_dir = de->d_type == DT_DIR;
+
+                if (is_dir) {
+                        int subdir_fd;
+
+                        /* if root_dev is set, remove subdirectories only, if device is same as dir */
+                        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;
+                        }
+
+                        /* We pass REMOVE_PHYSICAL here, to avoid
+                         * doing the fstatfs() to check the file
+                         * system type again for each directory */
+                        r = rm_rf_children(subdir_fd, flags | REMOVE_PHYSICAL, root_dev);
+                        if (r < 0 && ret == 0)
+                                ret = r;
+
+                        if (unlinkat(fd, de->d_name, AT_REMOVEDIR) < 0) {
+                                if (ret == 0 && errno != ENOENT)
+                                        ret = -errno;
+                        }
+
+                } else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
+
+                        if (unlinkat(fd, de->d_name, 0) < 0) {
+                                if (ret == 0 && errno != ENOENT)
+                                        ret = -errno;
+                        }
+                }
+        }
+}
+
+int rm_rf(const char *path, RemoveFlags flags) {
+        int fd, r;
+        struct statfs s;
+
+        assert(path);
+
+        /* We refuse to clean the root file system with this
+         * call. This is extra paranoia to never cause a really
+         * seriously broken system. */
+        if (path_equal(path, "/")) {
+                log_error("Attempted to remove entire root file system, and we can't allow that.");
+                return -EPERM;
+        }
+
+        fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
+        if (fd < 0) {
+
+                if (errno != ENOTDIR && errno != ELOOP)
+                        return -errno;
+
+                if (!(flags & REMOVE_PHYSICAL)) {
+                        if (statfs(path, &s) < 0)
+                                return -errno;
+
+                        if (!is_temporary_fs(&s)) {
+                                log_error("Attempted to remove disk file system, and we can't allow that.");
+                                return -EPERM;
+                        }
+                }
+
+                if ((flags & REMOVE_ROOT) && !(flags & REMOVE_ONLY_DIRECTORIES))
+                        if (unlink(path) < 0 && errno != ENOENT)
+                                return -errno;
+
+                return 0;
+        }
+
+        r = rm_rf_children(fd, flags, NULL);
+
+        if (flags & REMOVE_ROOT) {
+
+                if (rmdir(path) < 0 && errno != ENOENT) {
+                        if (r == 0)
+                                r = -errno;
+                }
+        }
+
+        return r;
+}