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-rw-r--r--src/basic/path-util.c853
1 files changed, 853 insertions, 0 deletions
diff --git a/src/basic/path-util.c b/src/basic/path-util.c
new file mode 100644
index 0000000000..537705446a
--- /dev/null
+++ b/src/basic/path-util.c
@@ -0,0 +1,853 @@
+/*-*- 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 <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/statvfs.h>
+
+#include "macro.h"
+#include "util.h"
+#include "log.h"
+#include "strv.h"
+#include "path-util.h"
+#include "missing.h"
+#include "fileio.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 strjoin(cwd, "/", p, NULL);
+}
+
+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 */
+ free(u);
+ 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;
+ }
+}
+
+int path_compare(const char *a, const char *b) {
+ int d;
+
+ assert(a);
+ assert(b);
+
+ /* A relative path and an abolute path must not compare as equal.
+ * Which one is sorted before the other does not really matter.
+ * Here a relative path is ordered before an absolute path. */
+ d = (a[0] == '/') - (b[0] == '/');
+ if (d)
+ return d;
+
+ for (;;) {
+ size_t j, k;
+
+ a += strspn(a, "/");
+ b += strspn(b, "/");
+
+ if (*a == 0 && *b == 0)
+ return 0;
+
+ /* Order prefixes first: "/foo" before "/foo/bar" */
+ if (*a == 0)
+ return -1;
+ if (*b == 0)
+ return 1;
+
+ j = strcspn(a, "/");
+ k = strcspn(b, "/");
+
+ /* Alphabetical sort: "/foo/aaa" before "/foo/b" */
+ d = memcmp(a, b, MIN(j, k));
+ if (d)
+ return (d > 0) - (d < 0); /* sign of d */
+
+ /* Sort "/foo/a" before "/foo/aaa" */
+ d = (j > k) - (j < k); /* sign of (j - k) */
+ if (d)
+ return d;
+
+ a += j;
+ b += k;
+ }
+}
+
+bool path_equal(const char *a, const char *b) {
+ return path_compare(a, b) == 0;
+}
+
+bool path_equal_or_files_same(const char *a, const char *b) {
+ return path_equal(a, b) || files_same(a, b) > 0;
+}
+
+char* path_join(const char *root, const char *path, const char *rest) {
+ assert(path);
+
+ if (!isempty(root))
+ return strjoin(root, endswith(root, "/") ? "" : "/",
+ path[0] == '/' ? path+1 : path,
+ rest ? (endswith(path, "/") ? "" : "/") : NULL,
+ rest && rest[0] == '/' ? rest+1 : rest,
+ NULL);
+ else
+ return strjoin(path,
+ rest ? (endswith(path, "/") ? "" : "/") : NULL,
+ rest && rest[0] == '/' ? rest+1 : rest,
+ NULL);
+}
+
+static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *mnt_id) {
+ char path[strlen("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)];
+ _cleanup_free_ char *fdinfo = NULL;
+ _cleanup_close_ int subfd = -1;
+ char *p;
+ int r;
+
+ if ((flags & AT_EMPTY_PATH) && isempty(filename))
+ xsprintf(path, "/proc/self/fdinfo/%i", fd);
+ else {
+ subfd = openat(fd, filename, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_PATH);
+ if (subfd < 0)
+ return -errno;
+
+ xsprintf(path, "/proc/self/fdinfo/%i", subfd);
+ }
+
+ r = read_full_file(path, &fdinfo, NULL);
+ if (r == -ENOENT) /* The fdinfo directory is a relatively new addition */
+ return -EOPNOTSUPP;
+ if (r < 0)
+ return -errno;
+
+ p = startswith(fdinfo, "mnt_id:");
+ if (!p) {
+ p = strstr(fdinfo, "\nmnt_id:");
+ if (!p) /* The mnt_id field is a relatively new addition */
+ return -EOPNOTSUPP;
+
+ p += 8;
+ }
+
+ p += strspn(p, WHITESPACE);
+ p[strcspn(p, WHITESPACE)] = 0;
+
+ return safe_atoi(p, mnt_id);
+}
+
+int fd_is_mount_point(int fd, const char *filename, int flags) {
+ union file_handle_union h = FILE_HANDLE_INIT, h_parent = FILE_HANDLE_INIT;
+ int mount_id = -1, mount_id_parent = -1;
+ bool nosupp = false, check_st_dev = true;
+ struct stat a, b;
+ int r;
+
+ assert(fd >= 0);
+ assert(filename);
+
+ /* First we will try the name_to_handle_at() syscall, which
+ * tells us the mount id and an opaque file "handle". It is
+ * not supported everywhere though (kernel compile-time
+ * option, not all file systems are hooked up). If it works
+ * the mount id is usually good enough to tell us whether
+ * something is a mount point.
+ *
+ * If that didn't work we will try to read the mount id from
+ * /proc/self/fdinfo/<fd>. This is almost as good as
+ * name_to_handle_at(), however, does not return the the
+ * opaque file handle. The opaque file handle is pretty useful
+ * to detect the root directory, which we should always
+ * consider a mount point. Hence we use this only as
+ * fallback. Exporting the mnt_id in fdinfo is a pretty recent
+ * kernel addition.
+ *
+ * As last fallback we do traditional fstat() based st_dev
+ * comparisons. This is how things were traditionally done,
+ * but unionfs breaks breaks this since it exposes file
+ * systems with a variety of st_dev reported. Also, btrfs
+ * subvolumes have different st_dev, even though they aren't
+ * real mounts of their own. */
+
+ r = name_to_handle_at(fd, filename, &h.handle, &mount_id, flags);
+ if (r < 0) {
+ if (errno == ENOSYS)
+ /* This kernel does not support name_to_handle_at()
+ * fall back to simpler logic. */
+ goto fallback_fdinfo;
+ else if (errno == EOPNOTSUPP)
+ /* This kernel or file system does not support
+ * name_to_handle_at(), hence let's see if the
+ * upper fs supports it (in which case it is a
+ * mount point), otherwise fallback to the
+ * traditional stat() logic */
+ nosupp = true;
+ else
+ return -errno;
+ }
+
+ r = name_to_handle_at(fd, "", &h_parent.handle, &mount_id_parent, AT_EMPTY_PATH);
+ if (r < 0) {
+ if (errno == EOPNOTSUPP) {
+ if (nosupp)
+ /* Neither parent nor child do name_to_handle_at()?
+ We have no choice but to fall back. */
+ goto fallback_fdinfo;
+ else
+ /* 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. */
+ 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;
+ }
+
+ r = path_get_parent(canonical ?: 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(canonical ?: 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, bool local, char **filename) {
+ assert(name);
+
+ if (is_path(name)) {
+ if (local && 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;
+ const char *word, *state;
+ 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(word, l, path, ":", state) {
+ _cleanup_free_ char *p = NULL;
+
+ if (asprintf(&p, "%.*s/%s", (int) l, word, 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 = strjoina("fsck.", fstype);
+
+ r = find_binary(checker, true, &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;
+}
+
+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;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-15 05:01:36 +0000