util-lib: move a number of fs operations into fs-util.[ch]

1 files changed, 477 insertions, 0 deletions

diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
new file mode 100644
index 0000000000..bd775b7b6f
--- /dev/null
+++ b/src/basic/fs-util.c
@@ -0,0 +1,477 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 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 "dirent-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "mkdir.h"
+#include "path-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "util.h"
+
+int unlink_noerrno(const char *path) {
+        PROTECT_ERRNO;
+        int r;
+
+        r = unlink(path);
+        if (r < 0)
+                return -errno;
+
+        return 0;
+}
+
+int rmdir_parents(const char *path, const char *stop) {
+        size_t l;
+        int r = 0;
+
+        assert(path);
+        assert(stop);
+
+        l = strlen(path);
+
+        /* Skip trailing slashes */
+        while (l > 0 && path[l-1] == '/')
+                l--;
+
+        while (l > 0) {
+                char *t;
+
+                /* Skip last component */
+                while (l > 0 && path[l-1] != '/')
+                        l--;
+
+                /* Skip trailing slashes */
+                while (l > 0 && path[l-1] == '/')
+                        l--;
+
+                if (l <= 0)
+                        break;
+
+                t = strndup(path, l);
+                if (!t)
+                        return -ENOMEM;
+
+                if (path_startswith(stop, t)) {
+                        free(t);
+                        return 0;
+                }
+
+                r = rmdir(t);
+                free(t);
+
+                if (r < 0)
+                        if (errno != ENOENT)
+                                return -errno;
+        }
+
+        return 0;
+}
+
+
+int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) {
+        struct stat buf;
+        int ret;
+
+        ret = renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE);
+        if (ret >= 0)
+                return 0;
+
+        /* renameat2() exists since Linux 3.15, btrfs added support for it later.
+         * If it is not implemented, fallback to another method. */
+        if (!IN_SET(errno, EINVAL, ENOSYS))
+                return -errno;
+
+        /* The link()/unlink() fallback does not work on directories. But
+         * renameat() without RENAME_NOREPLACE gives the same semantics on
+         * directories, except when newpath is an *empty* directory. This is
+         * good enough. */
+        ret = fstatat(olddirfd, oldpath, &buf, AT_SYMLINK_NOFOLLOW);
+        if (ret >= 0 && S_ISDIR(buf.st_mode)) {
+                ret = renameat(olddirfd, oldpath, newdirfd, newpath);
+                return ret >= 0 ? 0 : -errno;
+        }
+
+        /* If it is not a directory, use the link()/unlink() fallback. */
+        ret = linkat(olddirfd, oldpath, newdirfd, newpath, 0);
+        if (ret < 0)
+                return -errno;
+
+        ret = unlinkat(olddirfd, oldpath, 0);
+        if (ret < 0) {
+                /* backup errno before the following unlinkat() alters it */
+                ret = errno;
+                (void) unlinkat(newdirfd, newpath, 0);
+                errno = ret;
+                return -errno;
+        }
+
+        return 0;
+}
+
+int readlinkat_malloc(int fd, const char *p, char **ret) {
+        size_t l = 100;
+        int r;
+
+        assert(p);
+        assert(ret);
+
+        for (;;) {
+                char *c;
+                ssize_t n;
+
+                c = new(char, l);
+                if (!c)
+                        return -ENOMEM;
+
+                n = readlinkat(fd, p, c, l-1);
+                if (n < 0) {
+                        r = -errno;
+                        free(c);
+                        return r;
+                }
+
+                if ((size_t) n < l-1) {
+                        c[n] = 0;
+                        *ret = c;
+                        return 0;
+                }
+
+                free(c);
+                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;
+        char *value;
+        int r;
+
+        r = readlink_malloc(p, &link);
+        if (r < 0)
+                return r;
+
+        value = basename(link);
+        if (!value)
+                return -ENOENT;
+
+        value = strdup(value);
+        if (!value)
+                return -ENOMEM;
+
+        *ret = value;
+
+        return 0;
+}
+
+int readlink_and_make_absolute(const char *p, char **r) {
+        _cleanup_free_ char *target = NULL;
+        char *k;
+        int j;
+
+        assert(p);
+        assert(r);
+
+        j = readlink_malloc(p, &target);
+        if (j < 0)
+                return j;
+
+        k = file_in_same_dir(p, target);
+        if (!k)
+                return -ENOMEM;
+
+        *r = k;
+        return 0;
+}
+
+int readlink_and_canonicalize(const char *p, char **r) {
+        char *t, *s;
+        int j;
+
+        assert(p);
+        assert(r);
+
+        j = readlink_and_make_absolute(p, &t);
+        if (j < 0)
+                return j;
+
+        s = canonicalize_file_name(t);
+        if (s) {
+                free(t);
+                *r = s;
+        } else
+                *r = t;
+
+        path_kill_slashes(*r);
+
+        return 0;
+}
+
+int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) {
+        assert(path);
+
+        /* Under the assumption that we are running privileged we
+         * first change the access mode and only then hand out
+         * ownership to avoid a window where access is too open. */
+
+        if (mode != MODE_INVALID)
+                if (chmod(path, mode) < 0)
+                        return -errno;
+
+        if (uid != UID_INVALID || gid != GID_INVALID)
+                if (chown(path, uid, gid) < 0)
+                        return -errno;
+
+        return 0;
+}
+
+int fchmod_and_fchown(int fd, mode_t mode, uid_t uid, gid_t gid) {
+        assert(fd >= 0);
+
+        /* Under the assumption that we are running privileged we
+         * first change the access mode and only then hand out
+         * ownership to avoid a window where access is too open. */
+
+        if (mode != MODE_INVALID)
+                if (fchmod(fd, mode) < 0)
+                        return -errno;
+
+        if (uid != UID_INVALID || gid != GID_INVALID)
+                if (fchown(fd, uid, gid) < 0)
+                        return -errno;
+
+        return 0;
+}
+
+int fchmod_umask(int fd, mode_t m) {
+        mode_t u;
+        int r;
+
+        u = umask(0777);
+        r = fchmod(fd, m & (~u)) < 0 ? -errno : 0;
+        umask(u);
+
+        return r;
+}
+
+int fd_warn_permissions(const char *path, int fd) {
+        struct stat st;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        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() == 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 touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode) {
+        _cleanup_close_ int fd;
+        int r;
+
+        assert(path);
+
+        if (parents)
+                mkdir_parents(path, 0755);
+
+        fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, mode > 0 ? mode : 0644);
+        if (fd < 0)
+                return -errno;
+
+        if (mode > 0) {
+                r = fchmod(fd, mode);
+                if (r < 0)
+                        return -errno;
+        }
+
+        if (uid != UID_INVALID || gid != GID_INVALID) {
+                r = fchown(fd, uid, gid);
+                if (r < 0)
+                        return -errno;
+        }
+
+        if (stamp != USEC_INFINITY) {
+                struct timespec ts[2];
+
+                timespec_store(&ts[0], stamp);
+                ts[1] = ts[0];
+                r = futimens(fd, ts);
+        } else
+                r = futimens(fd, NULL);
+        if (r < 0)
+                return -errno;
+
+        return 0;
+}
+
+int touch(const char *path) {
+        return touch_file(path, false, USEC_INFINITY, UID_INVALID, GID_INVALID, 0);
+}
+
+int symlink_idempotent(const char *from, const char *to) {
+        _cleanup_free_ char *p = NULL;
+        int r;
+
+        assert(from);
+        assert(to);
+
+        if (symlink(from, to) < 0) {
+                if (errno != EEXIST)
+                        return -errno;
+
+                r = readlink_malloc(to, &p);
+                if (r < 0)
+                        return r;
+
+                if (!streq(p, from))
+                        return -EINVAL;
+        }
+
+        return 0;
+}
+
+int symlink_atomic(const char *from, const char *to) {
+        _cleanup_free_ char *t = NULL;
+        int r;
+
+        assert(from);
+        assert(to);
+
+        r = tempfn_random(to, NULL, &t);
+        if (r < 0)
+                return r;
+
+        if (symlink(from, t) < 0)
+                return -errno;
+
+        if (rename(t, to) < 0) {
+                unlink_noerrno(t);
+                return -errno;
+        }
+
+        return 0;
+}
+
+int mknod_atomic(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 (mknod(t, mode, dev) < 0)
+                return -errno;
+
+        if (rename(t, path) < 0) {
+                unlink_noerrno(t);
+                return -errno;
+        }
+
+        return 0;
+}
+
+int mkfifo_atomic(const char *path, mode_t mode) {
+        _cleanup_free_ char *t = NULL;
+        int r;
+
+        assert(path);
+
+        r = tempfn_random(path, NULL, &t);
+        if (r < 0)
+                return r;
+
+        if (mkfifo(t, mode) < 0)
+                return -errno;
+
+        if (rename(t, path) < 0) {
+                unlink_noerrno(t);
+                return -errno;
+        }
+
+        return 0;
+}
+
+int get_files_in_directory(const char *path, char ***list) {
+        _cleanup_closedir_ DIR *d = NULL;
+        size_t bufsize = 0, n = 0;
+        _cleanup_strv_free_ char **l = NULL;
+
+        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;
+
+        for (;;) {
+                struct dirent *de;
+
+                errno = 0;
+                de = readdir(d);
+                if (!de && errno != 0)
+                        return -errno;
+                if (!de)
+                        break;
+
+                dirent_ensure_type(d, de);
+
+                if (!dirent_is_file(de))
+                        continue;
+
+                if (list) {
+                        /* one extra slot is needed for the terminating NULL */
+                        if (!GREEDY_REALLOC(l, bufsize, n + 2))
+                                return -ENOMEM;
+
+                        l[n] = strdup(de->d_name);
+                        if (!l[n])
+                                return -ENOMEM;
+
+                        l[++n] = NULL;
+                } else
+                        n++;
+        }
+
+        if (list) {
+                *list = l;
+                l = NULL; /* avoid freeing */
+        }
+
+        return n;
+}