Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1150 insertions, 0 deletions

diff --git a/src/basic/path-util.c b/src/basic/path-util.c
new file mode 100644
index 0000000..2215173
--- /dev/null
+++ b/src/basic/path-util.c
@@ -0,0 +1,1150 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+/* When we include libgen.h because we need dirname() we immediately
+ * undefine basename() since libgen.h defines it as a macro to the
+ * POSIX version which is really broken. We prefer GNU basename(). */
+#include <libgen.h>
+#undef basename
+
+#include "alloc-util.h"
+#include "extract-word.h"
+#include "fs-util.h"
+#include "glob-util.h"
+#include "log.h"
+#include "macro.h"
+#include "missing.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "time-util.h"
+#include "utf8.h"
+
+bool path_is_absolute(const char *p) {
+        return p[0] == '/';
+}
+
+bool is_path(const char *p) {
+        return !!strchr(p, '/');
+}
+
+int path_split_and_make_absolute(const char *p, char ***ret) {
+        char **l;
+        int r;
+
+        assert(p);
+        assert(ret);
+
+        l = strv_split(p, ":");
+        if (!l)
+                return -ENOMEM;
+
+        r = path_strv_make_absolute_cwd(l);
+        if (r < 0) {
+                strv_free(l);
+                return r;
+        }
+
+        *ret = l;
+        return r;
+}
+
+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) || isempty(prefix))
+                return strdup(p);
+
+        if (endswith(prefix, "/"))
+                return strjoin(prefix, p);
+        else
+                return strjoin(prefix, "/", p);
+}
+
+int safe_getcwd(char **ret) {
+        char *cwd;
+
+        cwd = get_current_dir_name();
+        if (!cwd)
+                return negative_errno();
+
+        /* Let's make sure the directory is really absolute, to protect us from the logic behind
+         * CVE-2018-1000001 */
+        if (cwd[0] != '/') {
+                free(cwd);
+                return -ENOMEDIUM;
+        }
+
+        *ret = cwd;
+        return 0;
+}
+
+int path_make_absolute_cwd(const char *p, char **ret) {
+        char *c;
+        int r;
+
+        assert(p);
+        assert(ret);
+
+        /* Similar to path_make_absolute(), but prefixes with the
+         * current working directory. */
+
+        if (path_is_absolute(p))
+                c = strdup(p);
+        else {
+                _cleanup_free_ char *cwd = NULL;
+
+                r = safe_getcwd(&cwd);
+                if (r < 0)
+                        return r;
+
+                c = path_join(cwd, p);
+        }
+        if (!c)
+                return -ENOMEM;
+
+        *ret = c;
+        return 0;
+}
+
+int path_make_relative(const char *from_dir, const char *to_path, char **_r) {
+        char *f, *t, *r, *p;
+        unsigned n_parents = 0;
+
+        assert(from_dir);
+        assert(to_path);
+        assert(_r);
+
+        /* Strips the common part, and adds ".." elements as necessary. */
+
+        if (!path_is_absolute(from_dir) || !path_is_absolute(to_path))
+                return -EINVAL;
+
+        f = strdupa(from_dir);
+        t = strdupa(to_path);
+
+        path_simplify(f, true);
+        path_simplify(t, true);
+
+        /* Skip the common part. */
+        for (;;) {
+                size_t a, b;
+
+                f += *f == '/';
+                t += *t == '/';
+
+                if (!*f) {
+                        if (!*t)
+                                /* from_dir equals to_path. */
+                                r = strdup(".");
+                        else
+                                /* from_dir is a parent directory of to_path. */
+                                r = strdup(t);
+                        if (!r)
+                                return -ENOMEM;
+
+                        *_r = r;
+                        return 0;
+                }
+
+                if (!*t)
+                        break;
+
+                a = strcspn(f, "/");
+                b = strcspn(t, "/");
+
+                if (a != b || memcmp(f, t, a) != 0)
+                        break;
+
+                f += a;
+                t += 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 (; *f;) {
+                size_t w;
+
+                w = strcspn(f, "/");
+
+                /* If this includes ".." we can't do a simple series of "..", refuse */
+                if (w == 2 && f[0] == '.' && f[1] == '.')
+                        return -EINVAL;
+
+                /* Count number of elements */
+                n_parents++;
+
+                f += w;
+                f += *f == '/';
+        }
+
+        r = new(char, n_parents * 3 + strlen(t) + 1);
+        if (!r)
+                return -ENOMEM;
+
+        for (p = r; n_parents > 0; n_parents--)
+                p = mempcpy(p, "../", 3);
+
+        if (*t)
+                strcpy(p, t);
+        else
+                /* Remove trailing slash */
+                *(--p) = 0;
+
+        *_r = r;
+        return 0;
+}
+
+int path_strv_make_absolute_cwd(char **l) {
+        char **s;
+        int r;
+
+        /* 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;
+
+                r = path_make_absolute_cwd(*s, &t);
+                if (r < 0)
+                        return r;
+
+                path_simplify(t, false);
+                free_and_replace(*s, t);
+        }
+
+        return 0;
+}
+
+char **path_strv_resolve(char **l, const char *root) {
+        char **s;
+        unsigned k = 0;
+        bool enomem = false;
+        int r;
+
+        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) {
+                _cleanup_free_ char *orig = NULL;
+                char *t, *u;
+
+                if (!path_is_absolute(*s)) {
+                        free(*s);
+                        continue;
+                }
+
+                if (root) {
+                        orig = *s;
+                        t = prefix_root(root, orig);
+                        if (!t) {
+                                enomem = true;
+                                continue;
+                        }
+                } else
+                        t = *s;
+
+                r = chase_symlinks(t, root, 0, &u);
+                if (r == -ENOENT) {
+                        if (root) {
+                                u = TAKE_PTR(orig);
+                                free(t);
+                        } else
+                                u = t;
+                } else if (r < 0) {
+                        free(t);
+
+                        if (r == -ENOMEM)
+                                enomem = true;
+
+                        continue;
+                } else if (root) {
+                        char *x;
+
+                        free(t);
+                        x = path_startswith(u, root);
+                        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_and_replace(u, orig);
+                        }
+                } else
+                        free(t);
+
+                l[k++] = u;
+        }
+
+        l[k] = NULL;
+
+        if (enomem)
+                return NULL;
+
+        return l;
+}
+
+char **path_strv_resolve_uniq(char **l, const char *root) {
+
+        if (strv_isempty(l))
+                return l;
+
+        if (!path_strv_resolve(l, root))
+                return NULL;
+
+        return strv_uniq(l);
+}
+
+char *path_simplify(char *path, bool kill_dots) {
+        char *f, *t;
+        bool slash = false, ignore_slash = false, absolute;
+
+        assert(path);
+
+        /* Removes redundant inner and trailing slashes. Also removes unnecessary dots
+         * if kill_dots is true. Modifies the passed string in-place.
+         *
+         * ///foo//./bar/.   becomes /foo/./bar/.      (if kill_dots is false)
+         * ///foo//./bar/.   becomes /foo/bar          (if kill_dots is true)
+         * .//./foo//./bar/. becomes ././foo/./bar/.   (if kill_dots is false)
+         * .//./foo//./bar/. becomes foo/bar           (if kill_dots is true)
+         */
+
+        if (isempty(path))
+                return path;
+
+        absolute = path_is_absolute(path);
+
+        f = path;
+        if (kill_dots && *f == '.' && IN_SET(f[1], 0, '/')) {
+                ignore_slash = true;
+                f++;
+        }
+
+        for (t = path; *f; f++) {
+
+                if (*f == '/') {
+                        slash = true;
+                        continue;
+                }
+
+                if (slash) {
+                        if (kill_dots && *f == '.' && IN_SET(f[1], 0, '/'))
+                                continue;
+
+                        slash = false;
+                        if (ignore_slash)
+                                ignore_slash = false;
+                        else
+                                *(t++) = '/';
+                }
+
+                *(t++) = *f;
+        }
+
+        /* Special rule, if we stripped everything, we either need a "/" (for the root directory)
+         * or "." for the current directory */
+        if (t == path) {
+                if (absolute)
+                        *(t++) = '/';
+                else
+                        *(t++) = '.';
+        }
+
+        *t = 0;
+        return path;
+}
+
+char* path_startswith(const char *path, const char *prefix) {
+        assert(path);
+        assert(prefix);
+
+        /* Returns a pointer to the start of the first component after the parts matched by
+         * the prefix, iff
+         * - both paths are absolute or both paths are relative,
+         * and
+         * - each component in prefix in turn matches a component in path at the same position.
+         * An empty string will be returned when the prefix and path are equivalent.
+         *
+         * Returns NULL otherwise.
+         */
+
+        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 absolute 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 != 0)
+                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 != 0)
+                        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 != 0)
+                        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, int flags) {
+        return path_equal(a, b) || files_same(a, b, flags) > 0;
+}
+
+char* path_join_internal(const char *first, ...) {
+        char *joined, *q;
+        const char *p;
+        va_list ap;
+        bool slash;
+        size_t sz;
+
+        /* Joins all listed strings until the sentinel and places a "/" between them unless the strings end/begin
+         * already with one so that it is unnecessary. Note that slashes which are already duplicate won't be
+         * removed. The string returned is hence always equal to or longer than the sum of the lengths of each
+         * individual string.
+         *
+         * Note: any listed empty string is simply skipped. This can be useful for concatenating strings of which some
+         * are optional.
+         *
+         * Examples:
+         *
+         * path_join("foo", "bar") → "foo/bar"
+         * path_join("foo/", "bar") → "foo/bar"
+         * path_join("", "foo", "", "bar", "") → "foo/bar" */
+
+        sz = strlen_ptr(first);
+        va_start(ap, first);
+        while ((p = va_arg(ap, char*)) != (const char*) -1)
+                if (!isempty(p))
+                        sz += 1 + strlen(p);
+        va_end(ap);
+
+        joined = new(char, sz + 1);
+        if (!joined)
+                return NULL;
+
+        if (!isempty(first)) {
+                q = stpcpy(joined, first);
+                slash = endswith(first, "/");
+        } else {
+                /* Skip empty items */
+                joined[0] = 0;
+                q = joined;
+                slash = true; /* no need to generate a slash anymore */
+        }
+
+        va_start(ap, first);
+        while ((p = va_arg(ap, char*)) != (const char*) -1) {
+                if (isempty(p))
+                        continue;
+
+                if (!slash && p[0] != '/')
+                        *(q++) = '/';
+
+                q = stpcpy(q, p);
+                slash = endswith(p, "/");
+        }
+        va_end(ap);
+
+        return joined;
+}
+
+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);
+                if (!j)
+                        return -ENOMEM;
+
+                if (access(j, X_OK) >= 0) {
+                        /* Found it! */
+
+                        if (ret) {
+                                *ret = path_simplify(j, false);
+                                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)
+                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_IN_SET(d, "true"
+                               "/bin/true",
+                               "/usr/bin/true",
+                               "/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 (empty_or_root(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_simplify(p, false);
+        if (suppress_root && empty_or_root(p))
+                p = mfree(p);
+
+        free_and_replace(*arg, p);
+
+        return 0;
+}
+
+char* dirname_malloc(const char *path) {
+        char *d, *dir, *dir2;
+
+        assert(path);
+
+        d = strdup(path);
+        if (!d)
+                return NULL;
+
+        dir = dirname(d);
+        assert(dir);
+
+        if (dir == d)
+                return d;
+
+        dir2 = strdup(dir);
+        free(d);
+
+        return dir2;
+}
+
+const char *last_path_component(const char *path) {
+
+        /* Finds the last component of the path, preserving the optional trailing slash that signifies a directory.
+         *
+         *    a/b/c → c
+         *    a/b/c/ → c/
+         *    x → x
+         *    x/ → x/
+         *    /y → y
+         *    /y/ → y/
+         *    / → /
+         *    // → /
+         *    /foo/a → a
+         *    /foo/a/ → a/
+         *
+         *    Also, the empty string is mapped to itself.
+         *
+         * This is different than basename(), which returns "" when a trailing slash is present.
+         */
+
+        unsigned l, k;
+
+        if (!path)
+                return NULL;
+
+        l = k = strlen(path);
+        if (l == 0) /* special case — an empty string */
+                return path;
+
+        while (k > 0 && path[k-1] == '/')
+                k--;
+
+        if (k == 0) /* the root directory */
+                return path + l - 1;
+
+        while (k > 0 && path[k-1] != '/')
+                k--;
+
+        return path + k;
+}
+
+int path_extract_filename(const char *p, char **ret) {
+        _cleanup_free_ char *a = NULL;
+        const char *c, *e = NULL, *q;
+
+        /* Extracts the filename part (i.e. right-most component) from a path, i.e. string that passes
+         * filename_is_valid(). A wrapper around last_path_component(), but eats up trailing slashes. */
+
+        if (!p)
+                return -EINVAL;
+
+        c = last_path_component(p);
+
+        for (q = c; *q != 0; q++)
+                if (*q != '/')
+                        e = q + 1;
+
+        if (!e) /* no valid character? */
+                return -EINVAL;
+
+        a = strndup(c, e - c);
+        if (!a)
+                return -ENOMEM;
+
+        if (!filename_is_valid(a))
+                return -EINVAL;
+
+        *ret = TAKE_PTR(a);
+
+        return 0;
+}
+
+bool filename_is_valid(const char *p) {
+        const char *e;
+
+        if (isempty(p))
+                return false;
+
+        if (dot_or_dot_dot(p))
+                return false;
+
+        e = strchrnul(p, '/');
+        if (*e != 0)
+                return false;
+
+        if (e - p > FILENAME_MAX) /* FILENAME_MAX is counted *without* the trailing NUL byte */
+                return false;
+
+        return true;
+}
+
+bool path_is_valid(const char *p) {
+
+        if (isempty(p))
+                return false;
+
+        if (strlen(p) >= PATH_MAX) /* PATH_MAX is counted *with* the trailing NUL byte */
+                return false;
+
+        return true;
+}
+
+bool path_is_normalized(const char *p) {
+
+        if (!path_is_valid(p))
+                return false;
+
+        if (dot_or_dot_dot(p))
+                return false;
+
+        if (startswith(p, "../") || endswith(p, "/..") || strstr(p, "/../"))
+                return false;
+
+        if (startswith(p, "./") || endswith(p, "/.") || strstr(p, "/./"))
+                return false;
+
+        if (strstr(p, "//"))
+                return false;
+
+        return true;
+}
+
+char *file_in_same_dir(const char *path, const char *filename) {
+        char *e, *ret;
+        size_t k;
+
+        assert(path);
+        assert(filename);
+
+        /* This removes the last component of path and appends
+         * filename, unless the latter is absolute anyway or the
+         * former isn't */
+
+        if (path_is_absolute(filename))
+                return strdup(filename);
+
+        e = strrchr(path, '/');
+        if (!e)
+                return strdup(filename);
+
+        k = strlen(filename);
+        ret = new(char, (e + 1 - path) + k + 1);
+        if (!ret)
+                return NULL;
+
+        memcpy(mempcpy(ret, path, e + 1 - path), filename, k + 1);
+        return ret;
+}
+
+bool hidden_or_backup_file(const char *filename) {
+        const char *p;
+
+        assert(filename);
+
+        if (filename[0] == '.' ||
+            streq(filename, "lost+found") ||
+            streq(filename, "aquota.user") ||
+            streq(filename, "aquota.group") ||
+            endswith(filename, "~"))
+                return true;
+
+        p = strrchr(filename, '.');
+        if (!p)
+                return false;
+
+        /* Please, let's not add more entries to the list below. If external projects think it's a good idea to come up
+         * with always new suffixes and that everybody else should just adjust to that, then it really should be on
+         * them. Hence, in future, let's not add any more entries. Instead, let's ask those packages to instead adopt
+         * one of the generic suffixes/prefixes for hidden files or backups, possibly augmented with an additional
+         * string. Specifically: there's now:
+         *
+         *    The generic suffixes "~" and ".bak" for backup files
+         *    The generic prefix "." for hidden files
+         *
+         * Thus, if a new package manager "foopkg" wants its own set of ".foopkg-new", ".foopkg-old", ".foopkg-dist"
+         * or so registered, let's refuse that and ask them to use ".foopkg.new", ".foopkg.old" or ".foopkg~" instead.
+         */
+
+        return STR_IN_SET(p + 1,
+                          "rpmnew",
+                          "rpmsave",
+                          "rpmorig",
+                          "dpkg-old",
+                          "dpkg-new",
+                          "dpkg-tmp",
+                          "dpkg-dist",
+                          "dpkg-bak",
+                          "dpkg-backup",
+                          "dpkg-remove",
+                          "ucf-new",
+                          "ucf-old",
+                          "ucf-dist",
+                          "swp",
+                          "bak",
+                          "old",
+                          "new");
+}
+
+bool is_device_path(const char *path) {
+
+        /* Returns true on paths that likely refer to a device, either by path in sysfs or to something in /dev */
+
+        return PATH_STARTSWITH_SET(path, "/dev/", "/sys/");
+}
+
+bool valid_device_node_path(const char *path) {
+
+        /* Some superficial checks whether the specified path is a valid device node path, all without looking at the
+         * actual device node. */
+
+        if (!PATH_STARTSWITH_SET(path, "/dev/", "/run/systemd/inaccessible/"))
+                return false;
+
+        if (endswith(path, "/")) /* can't be a device node if it ends in a slash */
+                return false;
+
+        return path_is_normalized(path);
+}
+
+bool valid_device_allow_pattern(const char *path) {
+        assert(path);
+
+        /* Like valid_device_node_path(), but also allows full-subsystem expressions, like DeviceAllow= and DeviceDeny=
+         * accept it */
+
+        if (STARTSWITH_SET(path, "block-", "char-"))
+                return true;
+
+        return valid_device_node_path(path);
+}
+
+int systemd_installation_has_version(const char *root, unsigned minimal_version) {
+        const char *pattern;
+        int r;
+
+        /* Try to guess if systemd installation is later than the specified version. This
+         * is hacky and likely to yield false negatives, particularly if the installation
+         * is non-standard. False positives should be relatively rare.
+         */
+
+        NULSTR_FOREACH(pattern,
+                       /* /lib works for systems without usr-merge, and for systems with a sane
+                        * usr-merge, where /lib is a symlink to /usr/lib. /usr/lib is necessary
+                        * for Gentoo which does a merge without making /lib a symlink.
+                        */
+                       "lib/systemd/libsystemd-shared-*.so\0"
+                       "lib64/systemd/libsystemd-shared-*.so\0"
+                       "usr/lib/systemd/libsystemd-shared-*.so\0"
+                       "usr/lib64/systemd/libsystemd-shared-*.so\0") {
+
+                _cleanup_strv_free_ char **names = NULL;
+                _cleanup_free_ char *path = NULL;
+                char *c, **name;
+
+                path = prefix_root(root, pattern);
+                if (!path)
+                        return -ENOMEM;
+
+                r = glob_extend(&names, path);
+                if (r == -ENOENT)
+                        continue;
+                if (r < 0)
+                        return r;
+
+                assert_se(c = endswith(path, "*.so"));
+                *c = '\0'; /* truncate the glob part */
+
+                STRV_FOREACH(name, names) {
+                        /* This is most likely to run only once, hence let's not optimize anything. */
+                        char *t, *t2;
+                        unsigned version;
+
+                        t = startswith(*name, path);
+                        if (!t)
+                                continue;
+
+                        t2 = endswith(t, ".so");
+                        if (!t2)
+                                continue;
+
+                        t2[0] = '\0'; /* truncate the suffix */
+
+                        r = safe_atou(t, &version);
+                        if (r < 0) {
+                                log_debug_errno(r, "Found libsystemd shared at \"%s.so\", but failed to parse version: %m", *name);
+                                continue;
+                        }
+
+                        log_debug("Found libsystemd shared at \"%s.so\", version %u (%s).",
+                                  *name, version,
+                                  version >= minimal_version ? "OK" : "too old");
+                        if (version >= minimal_version)
+                                return true;
+                }
+        }
+
+        return false;
+}
+
+bool dot_or_dot_dot(const char *path) {
+        if (!path)
+                return false;
+        if (path[0] != '.')
+                return false;
+        if (path[1] == 0)
+                return true;
+        if (path[1] != '.')
+                return false;
+
+        return path[2] == 0;
+}
+
+bool empty_or_root(const char *root) {
+
+        /* For operations relative to some root directory, returns true if the specified root directory is redundant,
+         * i.e. either / or NULL or the empty string or any equivalent. */
+
+        if (!root)
+                return true;
+
+        return root[strspn(root, "/")] == 0;
+}
+
+int path_simplify_and_warn(
+                char *path,
+                unsigned flag,
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *lvalue) {
+
+        bool absolute, fatal = flag & PATH_CHECK_FATAL;
+
+        assert(!FLAGS_SET(flag, PATH_CHECK_ABSOLUTE | PATH_CHECK_RELATIVE));
+
+        if (!utf8_is_valid(path)) {
+                log_syntax_invalid_utf8(unit, LOG_ERR, filename, line, path);
+                return -EINVAL;
+        }
+
+        if (flag & (PATH_CHECK_ABSOLUTE | PATH_CHECK_RELATIVE)) {
+                absolute = path_is_absolute(path);
+
+                if (!absolute && (flag & PATH_CHECK_ABSOLUTE)) {
+                        log_syntax(unit, LOG_ERR, filename, line, 0,
+                                   "%s= path is not absolute%s: %s",
+                                   lvalue, fatal ? "" : ", ignoring", path);
+                        return -EINVAL;
+                }
+
+                if (absolute && (flag & PATH_CHECK_RELATIVE)) {
+                        log_syntax(unit, LOG_ERR, filename, line, 0,
+                                   "%s= path is absolute%s: %s",
+                                   lvalue, fatal ? "" : ", ignoring", path);
+                        return -EINVAL;
+                }
+        }
+
+        path_simplify(path, true);
+
+        if (!path_is_normalized(path)) {
+                log_syntax(unit, LOG_ERR, filename, line, 0,
+                           "%s= path is not normalized%s: %s",
+                           lvalue, fatal ? "" : ", ignoring", path);
+                return -EINVAL;
+        }
+
+        if (!path_is_valid(path)) {
+                log_syntax(unit, LOG_ERR, filename, line, 0,
+                           "%s= path has invalid length (%zu bytes)%s.",
+                           lvalue, strlen(path), fatal ? "" : ", ignoring");
+                return -EINVAL;
+        }
+
+        return 0;
+}