fs-util.c revision 06eeacb6fe029804f296b065b3ce91e796e1cd0e
/*-*- 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.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#include "alloc-util.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "mkdir.h"
#include "parse-util.h"
#include "path-util.h"
#include "string-util.h"
#include "strv.h"
#include "time-util.h"
#include "user-util.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 readlink_and_make_absolute_root(const char *root, const char *path, char **ret) {
_cleanup_free_ char *target = NULL, *t = NULL;
const char *full;
int r;
full = prefix_roota(root, path);
r = readlink_malloc(full, &target);
if (r < 0)
return r;
t = file_in_same_dir(path, target);
if (!t)
return -ENOMEM;
*ret = t;
t = NULL;
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 == MODE_INVALID) ? 0644 : mode);
if (fd < 0)
return -errno;
if (mode != MODE_INVALID) {
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, MODE_INVALID);
}
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;
}