940 lines
26 KiB
C
940 lines
26 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010-2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/statvfs.h>
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#include <unistd.h>
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#include "fd-util.h"
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#include "fileio.h"
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#include "log.h"
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#include "macro.h"
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#include "missing.h"
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#include "parse-util.h"
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#include "path-util.h"
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#include "string-util.h"
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#include "strv.h"
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#include "util.h"
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bool path_is_absolute(const char *p) {
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return p[0] == '/';
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}
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bool is_path(const char *p) {
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return !!strchr(p, '/');
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}
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int path_get_parent(const char *path, char **_r) {
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const char *e, *a = NULL, *b = NULL, *p;
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char *r;
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bool slash = false;
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assert(path);
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assert(_r);
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if (!*path)
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return -EINVAL;
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for (e = path; *e; e++) {
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if (!slash && *e == '/') {
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a = b;
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b = e;
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slash = true;
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} else if (slash && *e != '/')
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slash = false;
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}
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if (*(e-1) == '/')
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p = a;
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else
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p = b;
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if (!p)
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return -EINVAL;
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if (p == path)
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r = strdup("/");
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else
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r = strndup(path, p-path);
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if (!r)
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return -ENOMEM;
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*_r = r;
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return 0;
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}
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int path_split_and_make_absolute(const char *p, char ***ret) {
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char **l;
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int r;
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assert(p);
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assert(ret);
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l = strv_split(p, ":");
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if (!l)
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return -ENOMEM;
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r = path_strv_make_absolute_cwd(l);
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if (r < 0) {
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strv_free(l);
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return r;
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}
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*ret = l;
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return r;
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}
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char *path_make_absolute(const char *p, const char *prefix) {
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assert(p);
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/* Makes every item in the list an absolute path by prepending
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* the prefix, if specified and necessary */
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if (path_is_absolute(p) || !prefix)
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return strdup(p);
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return strjoin(prefix, "/", p, NULL);
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}
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int path_make_absolute_cwd(const char *p, char **ret) {
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char *c;
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assert(p);
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assert(ret);
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/* Similar to path_make_absolute(), but prefixes with the
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* current working directory. */
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if (path_is_absolute(p))
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c = strdup(p);
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else {
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_cleanup_free_ char *cwd = NULL;
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cwd = get_current_dir_name();
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if (!cwd)
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return -errno;
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c = strjoin(cwd, "/", p, NULL);
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}
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if (!c)
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return -ENOMEM;
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*ret = c;
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return 0;
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}
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int path_make_relative(const char *from_dir, const char *to_path, char **_r) {
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char *r, *p;
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unsigned n_parents;
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assert(from_dir);
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assert(to_path);
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assert(_r);
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/* Strips the common part, and adds ".." elements as necessary. */
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if (!path_is_absolute(from_dir))
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return -EINVAL;
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if (!path_is_absolute(to_path))
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return -EINVAL;
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/* Skip the common part. */
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for (;;) {
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size_t a;
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size_t b;
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from_dir += strspn(from_dir, "/");
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to_path += strspn(to_path, "/");
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if (!*from_dir) {
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if (!*to_path)
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/* from_dir equals to_path. */
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r = strdup(".");
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else
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/* from_dir is a parent directory of to_path. */
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r = strdup(to_path);
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if (!r)
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return -ENOMEM;
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path_kill_slashes(r);
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*_r = r;
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return 0;
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}
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if (!*to_path)
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break;
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a = strcspn(from_dir, "/");
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b = strcspn(to_path, "/");
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if (a != b)
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break;
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if (memcmp(from_dir, to_path, a) != 0)
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break;
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from_dir += a;
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to_path += b;
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}
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/* If we're here, then "from_dir" has one or more elements that need to
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* be replaced with "..". */
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/* Count the number of necessary ".." elements. */
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for (n_parents = 0;;) {
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from_dir += strspn(from_dir, "/");
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if (!*from_dir)
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break;
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from_dir += strcspn(from_dir, "/");
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n_parents++;
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}
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r = malloc(n_parents * 3 + strlen(to_path) + 1);
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if (!r)
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return -ENOMEM;
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for (p = r; n_parents > 0; n_parents--, p += 3)
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memcpy(p, "../", 3);
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strcpy(p, to_path);
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path_kill_slashes(r);
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*_r = r;
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return 0;
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}
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int path_strv_make_absolute_cwd(char **l) {
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char **s;
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int r;
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/* Goes through every item in the string list and makes it
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* absolute. This works in place and won't rollback any
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* changes on failure. */
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STRV_FOREACH(s, l) {
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char *t;
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r = path_make_absolute_cwd(*s, &t);
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if (r < 0)
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return r;
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free(*s);
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*s = t;
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}
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return 0;
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}
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char **path_strv_resolve(char **l, const char *prefix) {
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char **s;
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unsigned k = 0;
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bool enomem = false;
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if (strv_isempty(l))
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return l;
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/* Goes through every item in the string list and canonicalize
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* the path. This works in place and won't rollback any
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* changes on failure. */
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STRV_FOREACH(s, l) {
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char *t, *u;
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_cleanup_free_ char *orig = NULL;
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if (!path_is_absolute(*s)) {
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free(*s);
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continue;
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}
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if (prefix) {
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orig = *s;
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t = strappend(prefix, orig);
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if (!t) {
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enomem = true;
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continue;
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}
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} else
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t = *s;
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errno = 0;
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u = canonicalize_file_name(t);
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if (!u) {
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if (errno == ENOENT) {
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if (prefix) {
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u = orig;
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orig = NULL;
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free(t);
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} else
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u = t;
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} else {
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free(t);
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if (errno == ENOMEM || errno == 0)
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enomem = true;
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continue;
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}
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} else if (prefix) {
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char *x;
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free(t);
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x = path_startswith(u, prefix);
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if (x) {
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/* restore the slash if it was lost */
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if (!startswith(x, "/"))
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*(--x) = '/';
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t = strdup(x);
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free(u);
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if (!t) {
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enomem = true;
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continue;
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}
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u = t;
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} else {
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/* canonicalized path goes outside of
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* prefix, keep the original path instead */
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free(u);
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u = orig;
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orig = NULL;
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}
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} else
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free(t);
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l[k++] = u;
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}
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l[k] = NULL;
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if (enomem)
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return NULL;
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return l;
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}
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char **path_strv_resolve_uniq(char **l, const char *prefix) {
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if (strv_isempty(l))
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return l;
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if (!path_strv_resolve(l, prefix))
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return NULL;
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return strv_uniq(l);
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}
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char *path_kill_slashes(char *path) {
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char *f, *t;
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bool slash = false;
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/* Removes redundant inner and trailing slashes. Modifies the
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* passed string in-place.
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*
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* ///foo///bar/ becomes /foo/bar
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*/
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for (f = path, t = path; *f; f++) {
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if (*f == '/') {
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slash = true;
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continue;
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}
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if (slash) {
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slash = false;
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*(t++) = '/';
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}
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*(t++) = *f;
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}
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/* Special rule, if we are talking of the root directory, a
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trailing slash is good */
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if (t == path && slash)
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*(t++) = '/';
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*t = 0;
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return path;
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}
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char* path_startswith(const char *path, const char *prefix) {
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assert(path);
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assert(prefix);
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if ((path[0] == '/') != (prefix[0] == '/'))
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return NULL;
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for (;;) {
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size_t a, b;
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path += strspn(path, "/");
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prefix += strspn(prefix, "/");
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if (*prefix == 0)
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return (char*) path;
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if (*path == 0)
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return NULL;
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a = strcspn(path, "/");
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b = strcspn(prefix, "/");
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if (a != b)
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return NULL;
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if (memcmp(path, prefix, a) != 0)
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return NULL;
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path += a;
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prefix += b;
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}
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}
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int path_compare(const char *a, const char *b) {
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int d;
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assert(a);
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assert(b);
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/* A relative path and an abolute path must not compare as equal.
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* Which one is sorted before the other does not really matter.
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* Here a relative path is ordered before an absolute path. */
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d = (a[0] == '/') - (b[0] == '/');
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if (d != 0)
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return d;
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for (;;) {
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size_t j, k;
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a += strspn(a, "/");
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b += strspn(b, "/");
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if (*a == 0 && *b == 0)
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return 0;
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/* Order prefixes first: "/foo" before "/foo/bar" */
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if (*a == 0)
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return -1;
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if (*b == 0)
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return 1;
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j = strcspn(a, "/");
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k = strcspn(b, "/");
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/* Alphabetical sort: "/foo/aaa" before "/foo/b" */
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d = memcmp(a, b, MIN(j, k));
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if (d != 0)
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return (d > 0) - (d < 0); /* sign of d */
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/* Sort "/foo/a" before "/foo/aaa" */
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d = (j > k) - (j < k); /* sign of (j - k) */
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if (d != 0)
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return d;
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a += j;
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b += k;
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}
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}
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bool path_equal(const char *a, const char *b) {
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return path_compare(a, b) == 0;
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}
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bool path_equal_or_files_same(const char *a, const char *b) {
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return path_equal(a, b) || files_same(a, b) > 0;
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}
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char* path_join(const char *root, const char *path, const char *rest) {
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assert(path);
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if (!isempty(root))
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return strjoin(root, endswith(root, "/") ? "" : "/",
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path[0] == '/' ? path+1 : path,
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rest ? (endswith(path, "/") ? "" : "/") : NULL,
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rest && rest[0] == '/' ? rest+1 : rest,
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NULL);
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else
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return strjoin(path,
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rest ? (endswith(path, "/") ? "" : "/") : NULL,
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rest && rest[0] == '/' ? rest+1 : rest,
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NULL);
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}
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static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *mnt_id) {
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char path[strlen("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)];
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_cleanup_free_ char *fdinfo = NULL;
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_cleanup_close_ int subfd = -1;
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char *p;
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int r;
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if ((flags & AT_EMPTY_PATH) && isempty(filename))
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xsprintf(path, "/proc/self/fdinfo/%i", fd);
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else {
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subfd = openat(fd, filename, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_PATH);
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if (subfd < 0)
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return -errno;
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xsprintf(path, "/proc/self/fdinfo/%i", subfd);
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}
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r = read_full_file(path, &fdinfo, NULL);
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if (r == -ENOENT) /* The fdinfo directory is a relatively new addition */
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return -EOPNOTSUPP;
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if (r < 0)
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return -errno;
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p = startswith(fdinfo, "mnt_id:");
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if (!p) {
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p = strstr(fdinfo, "\nmnt_id:");
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if (!p) /* The mnt_id field is a relatively new addition */
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return -EOPNOTSUPP;
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p += 8;
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}
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p += strspn(p, WHITESPACE);
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p[strcspn(p, WHITESPACE)] = 0;
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return safe_atoi(p, mnt_id);
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}
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int fd_is_mount_point(int fd, const char *filename, int flags) {
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union file_handle_union h = FILE_HANDLE_INIT, h_parent = FILE_HANDLE_INIT;
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int mount_id = -1, mount_id_parent = -1;
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bool nosupp = false, check_st_dev = true;
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struct stat a, b;
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int r;
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assert(fd >= 0);
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assert(filename);
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/* First we will try the name_to_handle_at() syscall, which
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* tells us the mount id and an opaque file "handle". It is
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* not supported everywhere though (kernel compile-time
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* option, not all file systems are hooked up). If it works
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* the mount id is usually good enough to tell us whether
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* something is a mount point.
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*
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* If that didn't work we will try to read the mount id from
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* /proc/self/fdinfo/<fd>. This is almost as good as
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* name_to_handle_at(), however, does not return the
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* opaque file handle. The opaque file handle is pretty useful
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* to detect the root directory, which we should always
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* consider a mount point. Hence we use this only as
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* fallback. Exporting the mnt_id in fdinfo is a pretty recent
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* kernel addition.
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*
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* As last fallback we do traditional fstat() based st_dev
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* comparisons. This is how things were traditionally done,
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* but unionfs breaks breaks this since it exposes file
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* systems with a variety of st_dev reported. Also, btrfs
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* subvolumes have different st_dev, even though they aren't
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* real mounts of their own. */
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r = name_to_handle_at(fd, filename, &h.handle, &mount_id, flags);
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if (r < 0) {
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if (errno == ENOSYS)
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/* This kernel does not support name_to_handle_at()
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* fall back to simpler logic. */
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goto fallback_fdinfo;
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else if (errno == EOPNOTSUPP)
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/* This kernel or file system does not support
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* name_to_handle_at(), hence let's see if the
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* upper fs supports it (in which case it is a
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* mount point), otherwise fallback to the
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* traditional stat() logic */
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nosupp = true;
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else
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return -errno;
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}
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r = name_to_handle_at(fd, "", &h_parent.handle, &mount_id_parent, AT_EMPTY_PATH);
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if (r < 0) {
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if (errno == EOPNOTSUPP) {
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if (nosupp)
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/* Neither parent nor child do name_to_handle_at()?
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We have no choice but to fall back. */
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goto fallback_fdinfo;
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else
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/* The parent can't do name_to_handle_at() but the
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* directory we are interested in can?
|
|
* If so, it must be a mount point. */
|
|
return 1;
|
|
} else
|
|
return -errno;
|
|
}
|
|
|
|
/* The parent can do name_to_handle_at() but the
|
|
* directory we are interested in can't? If so, it
|
|
* must be a mount point. */
|
|
if (nosupp)
|
|
return 1;
|
|
|
|
/* If the file handle for the directory we are
|
|
* interested in and its parent are identical, we
|
|
* assume this is the root directory, which is a mount
|
|
* point. */
|
|
|
|
if (h.handle.handle_bytes == h_parent.handle.handle_bytes &&
|
|
h.handle.handle_type == h_parent.handle.handle_type &&
|
|
memcmp(h.handle.f_handle, h_parent.handle.f_handle, h.handle.handle_bytes) == 0)
|
|
return 1;
|
|
|
|
return mount_id != mount_id_parent;
|
|
|
|
fallback_fdinfo:
|
|
r = fd_fdinfo_mnt_id(fd, filename, flags, &mount_id);
|
|
if (r == -EOPNOTSUPP)
|
|
goto fallback_fstat;
|
|
if (r < 0)
|
|
return r;
|
|
|
|
r = fd_fdinfo_mnt_id(fd, "", AT_EMPTY_PATH, &mount_id_parent);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (mount_id != mount_id_parent)
|
|
return 1;
|
|
|
|
/* Hmm, so, the mount ids are the same. This leaves one
|
|
* special case though for the root file system. For that,
|
|
* let's see if the parent directory has the same inode as we
|
|
* are interested in. Hence, let's also do fstat() checks now,
|
|
* too, but avoid the st_dev comparisons, since they aren't
|
|
* that useful on unionfs mounts. */
|
|
check_st_dev = false;
|
|
|
|
fallback_fstat:
|
|
/* yay for fstatat() taking a different set of flags than the other
|
|
* _at() above */
|
|
if (flags & AT_SYMLINK_FOLLOW)
|
|
flags &= ~AT_SYMLINK_FOLLOW;
|
|
else
|
|
flags |= AT_SYMLINK_NOFOLLOW;
|
|
if (fstatat(fd, filename, &a, flags) < 0)
|
|
return -errno;
|
|
|
|
if (fstatat(fd, "", &b, AT_EMPTY_PATH) < 0)
|
|
return -errno;
|
|
|
|
/* A directory with same device and inode as its parent? Must
|
|
* be the root directory */
|
|
if (a.st_dev == b.st_dev &&
|
|
a.st_ino == b.st_ino)
|
|
return 1;
|
|
|
|
return check_st_dev && (a.st_dev != b.st_dev);
|
|
}
|
|
|
|
/* flags can be AT_SYMLINK_FOLLOW or 0 */
|
|
int path_is_mount_point(const char *t, int flags) {
|
|
_cleanup_close_ int fd = -1;
|
|
_cleanup_free_ char *canonical = NULL, *parent = NULL;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
if (path_equal(t, "/"))
|
|
return 1;
|
|
|
|
/* we need to resolve symlinks manually, we can't just rely on
|
|
* fd_is_mount_point() to do that for us; if we have a structure like
|
|
* /bin -> /usr/bin/ and /usr is a mount point, then the parent that we
|
|
* look at needs to be /usr, not /. */
|
|
if (flags & AT_SYMLINK_FOLLOW) {
|
|
canonical = canonicalize_file_name(t);
|
|
if (!canonical)
|
|
return -errno;
|
|
|
|
t = canonical;
|
|
}
|
|
|
|
r = path_get_parent(t, &parent);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
fd = openat(AT_FDCWD, parent, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_PATH);
|
|
if (fd < 0)
|
|
return -errno;
|
|
|
|
return fd_is_mount_point(fd, basename(t), flags);
|
|
}
|
|
|
|
int path_is_read_only_fs(const char *path) {
|
|
struct statvfs st;
|
|
|
|
assert(path);
|
|
|
|
if (statvfs(path, &st) < 0)
|
|
return -errno;
|
|
|
|
if (st.f_flag & ST_RDONLY)
|
|
return true;
|
|
|
|
/* On NFS, statvfs() might not reflect whether we can actually
|
|
* write to the remote share. Let's try again with
|
|
* access(W_OK) which is more reliable, at least sometimes. */
|
|
if (access(path, W_OK) < 0 && errno == EROFS)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
int path_is_os_tree(const char *path) {
|
|
char *p;
|
|
int r;
|
|
|
|
/* We use /usr/lib/os-release as flag file if something is an OS */
|
|
p = strjoina(path, "/usr/lib/os-release");
|
|
r = access(p, F_OK);
|
|
if (r >= 0)
|
|
return 1;
|
|
|
|
/* Also check for the old location in /etc, just in case. */
|
|
p = strjoina(path, "/etc/os-release");
|
|
r = access(p, F_OK);
|
|
|
|
return r >= 0;
|
|
}
|
|
|
|
int find_binary(const char *name, char **ret) {
|
|
int last_error, r;
|
|
const char *p;
|
|
|
|
assert(name);
|
|
|
|
if (is_path(name)) {
|
|
if (access(name, X_OK) < 0)
|
|
return -errno;
|
|
|
|
if (ret) {
|
|
r = path_make_absolute_cwd(name, ret);
|
|
if (r < 0)
|
|
return r;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Plain getenv, not secure_getenv, because we want
|
|
* to actually allow the user to pick the binary.
|
|
*/
|
|
p = getenv("PATH");
|
|
if (!p)
|
|
p = DEFAULT_PATH;
|
|
|
|
last_error = -ENOENT;
|
|
|
|
for (;;) {
|
|
_cleanup_free_ char *j = NULL, *element = NULL;
|
|
|
|
r = extract_first_word(&p, &element, ":", EXTRACT_RELAX|EXTRACT_DONT_COALESCE_SEPARATORS);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
break;
|
|
|
|
if (!path_is_absolute(element))
|
|
continue;
|
|
|
|
j = strjoin(element, "/", name, NULL);
|
|
if (!j)
|
|
return -ENOMEM;
|
|
|
|
if (access(j, X_OK) >= 0) {
|
|
/* Found it! */
|
|
|
|
if (ret) {
|
|
*ret = path_kill_slashes(j);
|
|
j = NULL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
last_error = -errno;
|
|
}
|
|
|
|
return last_error;
|
|
}
|
|
|
|
bool paths_check_timestamp(const char* const* paths, usec_t *timestamp, bool update) {
|
|
bool changed = false;
|
|
const char* const* i;
|
|
|
|
assert(timestamp);
|
|
|
|
if (paths == NULL)
|
|
return false;
|
|
|
|
STRV_FOREACH(i, paths) {
|
|
struct stat stats;
|
|
usec_t u;
|
|
|
|
if (stat(*i, &stats) < 0)
|
|
continue;
|
|
|
|
u = timespec_load(&stats.st_mtim);
|
|
|
|
/* first check */
|
|
if (*timestamp >= u)
|
|
continue;
|
|
|
|
log_debug("timestamp of '%s' changed", *i);
|
|
|
|
/* update timestamp */
|
|
if (update) {
|
|
*timestamp = u;
|
|
changed = true;
|
|
} else
|
|
return true;
|
|
}
|
|
|
|
return changed;
|
|
}
|
|
|
|
static int binary_is_good(const char *binary) {
|
|
_cleanup_free_ char *p = NULL, *d = NULL;
|
|
int r;
|
|
|
|
r = find_binary(binary, &p);
|
|
if (r == -ENOENT)
|
|
return 0;
|
|
if (r < 0)
|
|
return r;
|
|
|
|
/* An fsck that is linked to /bin/true is a non-existent
|
|
* fsck */
|
|
|
|
r = readlink_malloc(p, &d);
|
|
if (r == -EINVAL) /* not a symlink */
|
|
return 1;
|
|
if (r < 0)
|
|
return r;
|
|
|
|
return !path_equal(d, "true") &&
|
|
!path_equal(d, "/bin/true") &&
|
|
!path_equal(d, "/usr/bin/true") &&
|
|
!path_equal(d, "/dev/null");
|
|
}
|
|
|
|
int fsck_exists(const char *fstype) {
|
|
const char *checker;
|
|
|
|
assert(fstype);
|
|
|
|
if (streq(fstype, "auto"))
|
|
return -EINVAL;
|
|
|
|
checker = strjoina("fsck.", fstype);
|
|
return binary_is_good(checker);
|
|
}
|
|
|
|
int mkfs_exists(const char *fstype) {
|
|
const char *mkfs;
|
|
|
|
assert(fstype);
|
|
|
|
if (streq(fstype, "auto"))
|
|
return -EINVAL;
|
|
|
|
mkfs = strjoina("mkfs.", fstype);
|
|
return binary_is_good(mkfs);
|
|
}
|
|
|
|
char *prefix_root(const char *root, const char *path) {
|
|
char *n, *p;
|
|
size_t l;
|
|
|
|
/* If root is passed, prefixes path with it. Otherwise returns
|
|
* it as is. */
|
|
|
|
assert(path);
|
|
|
|
/* First, drop duplicate prefixing slashes from the path */
|
|
while (path[0] == '/' && path[1] == '/')
|
|
path++;
|
|
|
|
if (isempty(root) || path_equal(root, "/"))
|
|
return strdup(path);
|
|
|
|
l = strlen(root) + 1 + strlen(path) + 1;
|
|
|
|
n = new(char, l);
|
|
if (!n)
|
|
return NULL;
|
|
|
|
p = stpcpy(n, root);
|
|
|
|
while (p > n && p[-1] == '/')
|
|
p--;
|
|
|
|
if (path[0] != '/')
|
|
*(p++) = '/';
|
|
|
|
strcpy(p, path);
|
|
return n;
|
|
}
|
|
|
|
int parse_path_argument_and_warn(const char *path, bool suppress_root, char **arg) {
|
|
char *p;
|
|
int r;
|
|
|
|
/*
|
|
* This function is intended to be used in command line
|
|
* parsers, to handle paths that are passed in. It makes the
|
|
* path absolute, and reduces it to NULL if omitted or
|
|
* root (the latter optionally).
|
|
*
|
|
* NOTE THAT THIS WILL FREE THE PREVIOUS ARGUMENT POINTER ON
|
|
* SUCCESS! Hence, do not pass in uninitialized pointers.
|
|
*/
|
|
|
|
if (isempty(path)) {
|
|
*arg = mfree(*arg);
|
|
return 0;
|
|
}
|
|
|
|
r = path_make_absolute_cwd(path, &p);
|
|
if (r < 0)
|
|
return log_error_errno(r, "Failed to parse path \"%s\" and make it absolute: %m", path);
|
|
|
|
path_kill_slashes(p);
|
|
if (suppress_root && path_equal(p, "/"))
|
|
p = mfree(p);
|
|
|
|
free(*arg);
|
|
*arg = p;
|
|
return 0;
|
|
}
|