path-util.c revision 0c6ea3a4e2ac3f350dcb58e8f08bb74b030cd624
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010-2012 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 <assert.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <signal.h>
#include <stdio.h>
#include <fcntl.h>
#include <dirent.h>
#include <sys/statvfs.h>
#include "macro.h"
#include "util.h"
#include "log.h"
#include "strv.h"
#include "path-util.h"
#include "missing.h"
bool path_is_absolute(const char *p) {
return p[0] == '/';
}
bool is_path(const char *p) {
return !!strchr(p, '/');
}
int path_get_parent(const char *path, char **_r) {
const char *e, *a = NULL, *b = NULL, *p;
char *r;
bool slash = false;
assert(path);
assert(_r);
if (!*path)
return -EINVAL;
for (e = path; *e; e++) {
if (!slash && *e == '/') {
a = b;
b = e;
slash = true;
} else if (slash && *e != '/')
slash = false;
}
if (*(e-1) == '/')
p = a;
else
p = b;
if (!p)
return -EINVAL;
if (p == path)
r = strdup("/");
else
r = strndup(path, p-path);
if (!r)
return -ENOMEM;
*_r = r;
return 0;
}
char **path_split_and_make_absolute(const char *p) {
char **l;
assert(p);
l = strv_split(p, ":");
if (!l)
return NULL;
if (!path_strv_make_absolute_cwd(l)) {
strv_free(l);
return NULL;
}
return l;
}
char *path_make_absolute(const char *p, const char *prefix) {
assert(p);
/* Makes every item in the list an absolute path by prepending
* the prefix, if specified and necessary */
if (path_is_absolute(p) || !prefix)
return strdup(p);
return strjoin(prefix, "/", p, NULL);
}
char *path_make_absolute_cwd(const char *p) {
_cleanup_free_ char *cwd = NULL;
assert(p);
/* Similar to path_make_absolute(), but prefixes with the
* current working directory. */
if (path_is_absolute(p))
return strdup(p);
cwd = get_current_dir_name();
if (!cwd)
return NULL;
return path_make_absolute(p, cwd);
}
int path_make_relative(const char *from_dir, const char *to_path, char **_r) {
char *r, *p;
unsigned n_parents;
assert(from_dir);
assert(to_path);
assert(_r);
/* Strips the common part, and adds ".." elements as necessary. */
if (!path_is_absolute(from_dir))
return -EINVAL;
if (!path_is_absolute(to_path))
return -EINVAL;
/* Skip the common part. */
for (;;) {
size_t a;
size_t b;
from_dir += strspn(from_dir, "/");
to_path += strspn(to_path, "/");
if (!*from_dir) {
if (!*to_path)
/* from_dir equals to_path. */
r = strdup(".");
else
/* from_dir is a parent directory of to_path. */
r = strdup(to_path);
if (!r)
return -ENOMEM;
path_kill_slashes(r);
*_r = r;
return 0;
}
if (!*to_path)
break;
a = strcspn(from_dir, "/");
b = strcspn(to_path, "/");
if (a != b)
break;
if (memcmp(from_dir, to_path, a) != 0)
break;
from_dir += a;
to_path += b;
}
/* If we're here, then "from_dir" has one or more elements that need to
* be replaced with "..". */
/* Count the number of necessary ".." elements. */
for (n_parents = 0;;) {
from_dir += strspn(from_dir, "/");
if (!*from_dir)
break;
from_dir += strcspn(from_dir, "/");
n_parents++;
}
r = malloc(n_parents * 3 + strlen(to_path) + 1);
if (!r)
return -ENOMEM;
for (p = r; n_parents > 0; n_parents--, p += 3)
memcpy(p, "../", 3);
strcpy(p, to_path);
path_kill_slashes(r);
*_r = r;
return 0;
}
char **path_strv_make_absolute_cwd(char **l) {
char **s;
/* Goes through every item in the string list and makes it
* absolute. This works in place and won't rollback any
* changes on failure. */
STRV_FOREACH(s, l) {
char *t;
t = path_make_absolute_cwd(*s);
if (!t)
return NULL;
free(*s);
*s = t;
}
return l;
}
char **path_strv_resolve(char **l, const char *prefix) {
char **s;
unsigned k = 0;
bool enomem = false;
if (strv_isempty(l))
return l;
/* Goes through every item in the string list and canonicalize
* the path. This works in place and won't rollback any
* changes on failure. */
STRV_FOREACH(s, l) {
char *t, *u;
_cleanup_free_ char *orig = NULL;
if (!path_is_absolute(*s)) {
free(*s);
continue;
}
if (prefix) {
orig = *s;
t = strappend(prefix, orig);
if (!t) {
enomem = true;
continue;
}
} else
t = *s;
errno = 0;
u = canonicalize_file_name(t);
if (!u) {
if (errno == ENOENT) {
if (prefix) {
u = orig;
orig = NULL;
free(t);
} else
u = t;
} else {
free(t);
if (errno == ENOMEM || errno == 0)
enomem = true;
continue;
}
} else if (prefix) {
char *x;
free(t);
x = path_startswith(u, prefix);
if (x) {
/* restore the slash if it was lost */
if (!startswith(x, "/"))
*(--x) = '/';
t = strdup(x);
free(u);
if (!t) {
enomem = true;
continue;
}
u = t;
} else {
/* canonicalized path goes outside of
* prefix, keep the original path instead */
u = orig;
orig = NULL;
}
} else
free(t);
l[k++] = u;
}
l[k] = NULL;
if (enomem)
return NULL;
return l;
}
char **path_strv_resolve_uniq(char **l, const char *prefix) {
if (strv_isempty(l))
return l;
if (!path_strv_resolve(l, prefix))
return NULL;
return strv_uniq(l);
}
char *path_kill_slashes(char *path) {
char *f, *t;
bool slash = false;
/* Removes redundant inner and trailing slashes. Modifies the
* passed string in-place.
*
* ///foo///bar/ becomes /foo/bar
*/
for (f = path, t = path; *f; f++) {
if (*f == '/') {
slash = true;
continue;
}
if (slash) {
slash = false;
*(t++) = '/';
}
*(t++) = *f;
}
/* Special rule, if we are talking of the root directory, a
trailing slash is good */
if (t == path && slash)
*(t++) = '/';
*t = 0;
return path;
}
char* path_startswith(const char *path, const char *prefix) {
assert(path);
assert(prefix);
if ((path[0] == '/') != (prefix[0] == '/'))
return NULL;
for (;;) {
size_t a, b;
path += strspn(path, "/");
prefix += strspn(prefix, "/");
if (*prefix == 0)
return (char*) path;
if (*path == 0)
return NULL;
a = strcspn(path, "/");
b = strcspn(prefix, "/");
if (a != b)
return NULL;
if (memcmp(path, prefix, a) != 0)
return NULL;
path += a;
prefix += b;
}
}
bool path_equal(const char *a, const char *b) {
assert(a);
assert(b);
if ((a[0] == '/') != (b[0] == '/'))
return false;
for (;;) {
size_t j, k;
a += strspn(a, "/");
b += strspn(b, "/");
if (*a == 0 && *b == 0)
return true;
if (*a == 0 || *b == 0)
return false;
j = strcspn(a, "/");
k = strcspn(b, "/");
if (j != k)
return false;
if (memcmp(a, b, j) != 0)
return false;
a += j;
b += k;
}
}
char* path_join(const char *root, const char *path, const char *rest) {
assert(path);
if (!isempty(root))
return strjoin(root, "/",
path[0] == '/' ? path+1 : path,
rest ? "/" : NULL,
rest && rest[0] == '/' ? rest+1 : rest,
NULL);
else
return strjoin(path,
rest ? "/" : NULL,
rest && rest[0] == '/' ? rest+1 : rest,
NULL);
}
int path_is_mount_point(const char *t, bool allow_symlink) {
union file_handle_union h = {
.handle.handle_bytes = MAX_HANDLE_SZ
};
int mount_id, mount_id_parent;
_cleanup_free_ char *parent = NULL;
struct stat a, b;
int r;
/* We are not actually interested in the file handles, but
* name_to_handle_at() also passes us the mount ID, hence use
* it but throw the handle away */
if (path_equal(t, "/"))
return 1;
r = name_to_handle_at(AT_FDCWD, t, &h.handle, &mount_id, allow_symlink ? AT_SYMLINK_FOLLOW : 0);
if (r < 0) {
if (IN_SET(errno, ENOSYS, EOPNOTSUPP))
/* This kernel or file system does not support
* name_to_handle_at(), hence fallback to the
* traditional stat() logic */
goto fallback;
if (errno == ENOENT)
return 0;
return -errno;
}
r = path_get_parent(t, &parent);
if (r < 0)
return r;
h.handle.handle_bytes = MAX_HANDLE_SZ;
r = name_to_handle_at(AT_FDCWD, parent, &h.handle, &mount_id_parent, 0);
if (r < 0) {
/* The parent can't do name_to_handle_at() but the
* directory we are interested in can? If so, it must
* be a mount point */
if (errno == EOPNOTSUPP)
return 1;
return -errno;
}
return mount_id != mount_id_parent;
fallback:
if (allow_symlink)
r = stat(t, &a);
else
r = lstat(t, &a);
if (r < 0) {
if (errno == ENOENT)
return 0;
return -errno;
}
r = path_get_parent(t, &parent);
if (r < 0)
return r;
r = lstat(parent, &b);
if (r < 0)
return -errno;
return a.st_dev != b.st_dev;
}
int path_is_read_only_fs(const char *path) {
struct statvfs st;
assert(path);
if (statvfs(path, &st) < 0)
return -errno;
return !!(st.f_flag & ST_RDONLY);
}
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 = strappenda(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 = strappenda(path, "/etc/os-release");
r = access(p, F_OK);
return r >= 0;
}
int find_binary(const char *name, char **filename) {
assert(name);
if (is_path(name)) {
if (access(name, X_OK) < 0)
return -errno;
if (filename) {
char *p;
p = path_make_absolute_cwd(name);
if (!p)
return -ENOMEM;
*filename = p;
}
return 0;
} else {
const char *path;
char *state, *w;
size_t l;
/**
* Plain getenv, not secure_getenv, because we want
* to actually allow the user to pick the binary.
*/
path = getenv("PATH");
if (!path)
path = DEFAULT_PATH;
FOREACH_WORD_SEPARATOR(w, l, path, ":", state) {
_cleanup_free_ char *p = NULL;
if (asprintf(&p, "%.*s/%s", (int) l, w, name) < 0)
return -ENOMEM;
if (access(p, X_OK) < 0)
continue;
if (filename) {
*filename = path_kill_slashes(p);
p = NULL;
}
return 0;
}
return -ENOENT;
}
}
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;
}
int fsck_exists(const char *fstype) {
_cleanup_free_ char *p = NULL, *d = NULL;
const char *checker;
int r;
checker = strappenda("fsck.", fstype);
r = find_binary(checker, &p);
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 >= 0 &&
(path_equal(d, "/bin/true") ||
path_equal(d, "/usr/bin/true") ||
path_equal(d, "/dev/null")))
return -ENOENT;
return 0;
}