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-rw-r--r--src/basic/path-util.c1397
1 files changed, 1397 insertions, 0 deletions
diff --git a/src/basic/path-util.c b/src/basic/path-util.c
new file mode 100644
index 0000000..72c0d6b
--- /dev/null
+++ b/src/basic/path-util.c
@@ -0,0 +1,1397 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fnmatch.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "chase-symlinks.h"
+#include "extract-word.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "glob-util.h"
+#include "log.h"
+#include "macro.h"
+#include "path-util.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "time-util.h"
+
+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);
+
+ return path_join(prefix, p);
+}
+
+int safe_getcwd(char **ret) {
+ _cleanup_free_ char *cwd = NULL;
+
+ 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] != '/')
+ return -ENOMEDIUM;
+
+ if (ret)
+ *ret = TAKE_PTR(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, const char *to, char **ret) {
+ _cleanup_free_ char *result = NULL;
+ unsigned n_parents;
+ const char *f, *t;
+ int r, k;
+ char *p;
+
+ assert(from);
+ assert(to);
+ assert(ret);
+
+ /* Strips the common part, and adds ".." elements as necessary. */
+
+ if (!path_is_absolute(from) || !path_is_absolute(to))
+ return -EINVAL;
+
+ for (;;) {
+ r = path_find_first_component(&from, true, &f);
+ if (r < 0)
+ return r;
+
+ k = path_find_first_component(&to, true, &t);
+ if (k < 0)
+ return k;
+
+ if (r == 0) {
+ /* end of 'from' */
+ if (k == 0) {
+ /* from and to are equivalent. */
+ result = strdup(".");
+ if (!result)
+ return -ENOMEM;
+ } else {
+ /* 'to' is inside of 'from'. */
+ result = strdup(t);
+ if (!result)
+ return -ENOMEM;
+
+ path_simplify(result);
+
+ if (!path_is_valid(result))
+ return -EINVAL;
+ }
+
+ *ret = TAKE_PTR(result);
+ return 0;
+ }
+
+ if (r != k || !strneq(f, t, r))
+ break;
+ }
+
+ /* If we're here, then "from_dir" has one or more elements that need to
+ * be replaced with "..". */
+
+ for (n_parents = 1;; n_parents++) {
+ /* If this includes ".." we can't do a simple series of "..". */
+ r = path_find_first_component(&from, false, &f);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+ }
+
+ if (isempty(t) && n_parents * 3 > PATH_MAX)
+ /* PATH_MAX is counted *with* the trailing NUL byte */
+ return -EINVAL;
+
+ result = new(char, n_parents * 3 + !isempty(t) + strlen_ptr(t));
+ if (!result)
+ return -ENOMEM;
+
+ for (p = result; n_parents > 0; n_parents--)
+ p = mempcpy(p, "../", 3);
+
+ if (isempty(t)) {
+ /* Remove trailing slash and terminate string. */
+ *(--p) = '\0';
+ *ret = TAKE_PTR(result);
+ return 0;
+ }
+
+ strcpy(p, t);
+
+ path_simplify(result);
+
+ if (!path_is_valid(result))
+ return -EINVAL;
+
+ *ret = TAKE_PTR(result);
+ return 0;
+}
+
+int path_make_relative_parent(const char *from_child, const char *to, char **ret) {
+ _cleanup_free_ char *from = NULL;
+ int r;
+
+ assert(from_child);
+ assert(to);
+ assert(ret);
+
+ /* Similar to path_make_relative(), but provides the relative path from the parent directory of
+ * 'from_child'. This may be useful when creating relative symlink.
+ *
+ * E.g.
+ * - from = "/path/to/aaa", to = "/path/to/bbb"
+ * path_make_relative(from, to) = "../bbb"
+ * path_make_relative_parent(from, to) = "bbb"
+ *
+ * - from = "/path/to/aaa/bbb", to = "/path/to/ccc/ddd"
+ * path_make_relative(from, to) = "../../ccc/ddd"
+ * path_make_relative_parent(from, to) = "../ccc/ddd"
+ */
+
+ r = path_extract_directory(from_child, &from);
+ if (r < 0)
+ return r;
+
+ return path_make_relative(from, to, ret);
+}
+
+char* path_startswith_strv(const char *p, char **set) {
+ STRV_FOREACH(s, set) {
+ char *t;
+
+ t = path_startswith(p, *s);
+ if (t)
+ return t;
+ }
+
+ return NULL;
+}
+
+int path_strv_make_absolute_cwd(char **l) {
+ 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);
+ free_and_replace(*s, t);
+ }
+
+ return 0;
+}
+
+char** path_strv_resolve(char **l, const char *root) {
+ 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 = path_join(root, orig);
+ if (!t) {
+ enomem = true;
+ continue;
+ }
+ } else
+ t = *s;
+
+ r = chase_symlinks(t, root, 0, &u, NULL);
+ 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_full(char *path, PathSimplifyFlags flags) {
+ bool add_slash = false, keep_trailing_slash;
+ char *f = ASSERT_PTR(path);
+ int r;
+
+ /* Removes redundant inner and trailing slashes. Also removes unnecessary dots.
+ * Modifies the passed string in-place.
+ *
+ * ///foo//./bar/. becomes /foo/bar
+ * .//./foo//./bar/. becomes foo/bar
+ */
+
+ if (isempty(path))
+ return path;
+
+ keep_trailing_slash = FLAGS_SET(flags, PATH_SIMPLIFY_KEEP_TRAILING_SLASH) && endswith(path, "/");
+
+ if (path_is_absolute(path))
+ f++;
+
+ for (const char *p = f;;) {
+ const char *e;
+
+ r = path_find_first_component(&p, true, &e);
+ if (r == 0)
+ break;
+
+ if (add_slash)
+ *f++ = '/';
+
+ if (r < 0) {
+ /* if path is invalid, then refuse to simplify remaining part. */
+ memmove(f, p, strlen(p) + 1);
+ return path;
+ }
+
+ memmove(f, e, r);
+ f += r;
+
+ add_slash = true;
+ }
+
+ /* Special rule, if we stripped everything, we need a "." for the current directory. */
+ if (f == path)
+ *f++ = '.';
+
+ if (*(f-1) != '/' && keep_trailing_slash)
+ *f++ = '/';
+
+ *f = '\0';
+ return path;
+}
+
+char* path_startswith_full(const char *path, const char *prefix, bool accept_dot_dot) {
+ 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 (;;) {
+ const char *p, *q;
+ int r, k;
+
+ r = path_find_first_component(&path, accept_dot_dot, &p);
+ if (r < 0)
+ return NULL;
+
+ k = path_find_first_component(&prefix, accept_dot_dot, &q);
+ if (k < 0)
+ return NULL;
+
+ if (k == 0)
+ return (char*) (p ?: path);
+
+ if (r != k)
+ return NULL;
+
+ if (!strneq(p, q, r))
+ return NULL;
+ }
+}
+
+int path_compare(const char *a, const char *b) {
+ int r;
+
+ /* Order NULL before non-NULL */
+ r = CMP(!!a, !!b);
+ if (r != 0)
+ return r;
+
+ /* 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. */
+ r = CMP(path_is_absolute(a), path_is_absolute(b));
+ if (r != 0)
+ return r;
+
+ for (;;) {
+ const char *aa, *bb;
+ int j, k;
+
+ j = path_find_first_component(&a, true, &aa);
+ k = path_find_first_component(&b, true, &bb);
+
+ if (j < 0 || k < 0) {
+ /* When one of paths is invalid, order invalid path after valid one. */
+ r = CMP(j < 0, k < 0);
+ if (r != 0)
+ return r;
+
+ /* fallback to use strcmp() if both paths are invalid. */
+ return strcmp(a, b);
+ }
+
+ /* Order prefixes first: "/foo" before "/foo/bar" */
+ if (j == 0) {
+ if (k == 0)
+ return 0;
+ return -1;
+ }
+ if (k == 0)
+ return 1;
+
+ /* Alphabetical sort: "/foo/aaa" before "/foo/b" */
+ r = memcmp(aa, bb, MIN(j, k));
+ if (r != 0)
+ return r;
+
+ /* Sort "/foo/a" before "/foo/aaa" */
+ r = CMP(j, k);
+ if (r != 0)
+ return r;
+ }
+}
+
+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;
+}
+
+bool path_equal_filename(const char *a, const char *b) {
+ _cleanup_free_ char *a_basename = NULL, *b_basename = NULL;
+ int r;
+
+ assert(a);
+ assert(b);
+
+ r = path_extract_filename(a, &a_basename);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to parse basename of %s: %m", a);
+ return false;
+ }
+ r = path_extract_filename(b, &b_basename);
+ if (r < 0) {
+ log_debug_errno(r, "Failed to parse basename of %s: %m", b);
+ return false;
+ }
+
+ return path_equal(a_basename, b_basename);
+}
+
+char* path_extend_internal(char **x, ...) {
+ size_t sz, old_sz;
+ char *q, *nx;
+ const char *p;
+ va_list ap;
+ bool slash;
+
+ /* 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.
+ *
+ * The first argument may be an already allocated string that is extended via realloc() if
+ * non-NULL. path_extend() and path_join() are macro wrappers around this function, making use of the
+ * first parameter to distinguish the two operations.
+ *
+ * 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 = old_sz = x ? strlen_ptr(*x) : 0;
+ va_start(ap, x);
+ while ((p = va_arg(ap, char*)) != POINTER_MAX) {
+ size_t add;
+
+ if (isempty(p))
+ continue;
+
+ add = 1 + strlen(p);
+ if (sz > SIZE_MAX - add) { /* overflow check */
+ va_end(ap);
+ return NULL;
+ }
+
+ sz += add;
+ }
+ va_end(ap);
+
+ nx = realloc(x ? *x : NULL, GREEDY_ALLOC_ROUND_UP(sz+1));
+ if (!nx)
+ return NULL;
+ if (x)
+ *x = nx;
+
+ if (old_sz > 0)
+ slash = nx[old_sz-1] == '/';
+ else {
+ nx[old_sz] = 0;
+ slash = true; /* no need to generate a slash anymore */
+ }
+
+ q = nx + old_sz;
+
+ va_start(ap, x);
+ while ((p = va_arg(ap, char*)) != POINTER_MAX) {
+ if (isempty(p))
+ continue;
+
+ if (!slash && p[0] != '/')
+ *(q++) = '/';
+
+ q = stpcpy(q, p);
+ slash = endswith(p, "/");
+ }
+ va_end(ap);
+
+ return nx;
+}
+
+static int check_x_access(const char *path, int *ret_fd) {
+ _cleanup_close_ int fd = -1;
+ int r;
+
+ /* We need to use O_PATH because there may be executables for which we have only exec
+ * permissions, but not read (usually suid executables). */
+ fd = open(path, O_PATH|O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ r = fd_verify_regular(fd);
+ if (r < 0)
+ return r;
+
+ r = access_fd(fd, X_OK);
+ if (r == -ENOSYS) {
+ /* /proc is not mounted. Fallback to access(). */
+ if (access(path, X_OK) < 0)
+ return -errno;
+ } else if (r < 0)
+ return r;
+
+ if (ret_fd)
+ *ret_fd = TAKE_FD(fd);
+
+ return 0;
+}
+
+static int find_executable_impl(const char *name, const char *root, char **ret_filename, int *ret_fd) {
+ _cleanup_close_ int fd = -1;
+ _cleanup_free_ char *path_name = NULL;
+ int r;
+
+ assert(name);
+
+ /* Function chase_symlinks() is invoked only when root is not NULL, as using it regardless of
+ * root value would alter the behavior of existing callers for example: /bin/sleep would become
+ * /usr/bin/sleep when find_executables is called. Hence, this function should be invoked when
+ * needed to avoid unforeseen regression or other complicated changes. */
+ if (root) {
+ r = chase_symlinks(name,
+ root,
+ CHASE_PREFIX_ROOT,
+ &path_name,
+ /* ret_fd= */ NULL); /* prefix root to name in case full paths are not specified */
+ if (r < 0)
+ return r;
+
+ name = path_name;
+ }
+
+ r = check_x_access(name, ret_fd ? &fd : NULL);
+ if (r < 0)
+ return r;
+
+ if (ret_filename) {
+ r = path_make_absolute_cwd(name, ret_filename);
+ if (r < 0)
+ return r;
+ }
+
+ if (ret_fd)
+ *ret_fd = TAKE_FD(fd);
+
+ return 0;
+}
+
+int find_executable_full(const char *name, const char *root, char **exec_search_path, bool use_path_envvar, char **ret_filename, int *ret_fd) {
+ int last_error = -ENOENT, r = 0;
+ const char *p = NULL;
+
+ assert(name);
+
+ if (is_path(name))
+ return find_executable_impl(name, root, ret_filename, ret_fd);
+
+ if (use_path_envvar)
+ /* 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;
+
+ if (exec_search_path) {
+ STRV_FOREACH(element, exec_search_path) {
+ _cleanup_free_ char *full_path = NULL;
+
+ if (!path_is_absolute(*element))
+ continue;
+
+ full_path = path_join(*element, name);
+ if (!full_path)
+ return -ENOMEM;
+
+ r = find_executable_impl(full_path, root, ret_filename, ret_fd);
+ if (r < 0) {
+ if (r != -EACCES)
+ last_error = r;
+ continue;
+ }
+ return 0;
+ }
+ return last_error;
+ }
+
+ /* Resolve a single-component name to a full path */
+ for (;;) {
+ _cleanup_free_ char *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;
+
+ if (!path_extend(&element, name))
+ return -ENOMEM;
+
+ r = find_executable_impl(element, root, ret_filename, ret_fd);
+ if (r < 0) {
+ /* PATH entries which we don't have access to are ignored, as per tradition. */
+ if (r != -EACCES)
+ last_error = r;
+ continue;
+ }
+
+ /* Found it! */
+ return 0;
+ }
+
+ return last_error;
+}
+
+bool paths_check_timestamp(const char* const* paths, usec_t *timestamp, bool update) {
+ bool changed = false, originally_unset;
+
+ assert(timestamp);
+
+ if (!paths)
+ return false;
+
+ originally_unset = *timestamp == 0;
+
+ STRV_FOREACH(i, paths) {
+ struct stat stats;
+ usec_t u;
+
+ if (stat(*i, &stats) < 0)
+ continue;
+
+ u = timespec_load(&stats.st_mtim);
+
+ /* check first */
+ if (*timestamp >= u)
+ continue;
+
+ log_debug(originally_unset ? "Loaded timestamp for '%s'." : "Timestamp of '%s' changed.", *i);
+
+ /* update timestamp */
+ if (update) {
+ *timestamp = u;
+ changed = true;
+ } else
+ return true;
+ }
+
+ return changed;
+}
+
+static int executable_is_good(const char *executable) {
+ _cleanup_free_ char *p = NULL, *d = NULL;
+ int r;
+
+ r = find_executable(executable, &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(void) {
+ return executable_is_good("fsck");
+}
+
+int fsck_exists_for_fstype(const char *fstype) {
+ const char *checker;
+ int r;
+
+ assert(fstype);
+
+ if (streq(fstype, "auto"))
+ return -EINVAL;
+
+ r = fsck_exists();
+ if (r <= 0)
+ return r;
+
+ checker = strjoina("fsck.", fstype);
+ return executable_is_good(checker);
+}
+
+static const char* skip_slash_or_dot(const char *p) {
+ for (; !isempty(p); p++) {
+ if (*p == '/')
+ continue;
+ if (startswith(p, "./")) {
+ p++;
+ continue;
+ }
+ break;
+ }
+ return p;
+}
+
+int path_find_first_component(const char **p, bool accept_dot_dot, const char **ret) {
+ const char *q, *first, *end_first, *next;
+ size_t len;
+
+ assert(p);
+
+ /* When a path is input, then returns the pointer to the first component and its length, and
+ * move the input pointer to the next component or nul. This skips both over any '/'
+ * immediately *before* and *after* the first component before returning.
+ *
+ * Examples
+ * Input: p: "//.//aaa///bbbbb/cc"
+ * Output: p: "bbbbb///cc"
+ * ret: "aaa///bbbbb/cc"
+ * return value: 3 (== strlen("aaa"))
+ *
+ * Input: p: "aaa//"
+ * Output: p: (pointer to NUL)
+ * ret: "aaa//"
+ * return value: 3 (== strlen("aaa"))
+ *
+ * Input: p: "/", ".", ""
+ * Output: p: (pointer to NUL)
+ * ret: NULL
+ * return value: 0
+ *
+ * Input: p: NULL
+ * Output: p: NULL
+ * ret: NULL
+ * return value: 0
+ *
+ * Input: p: "(too long component)"
+ * Output: return value: -EINVAL
+ *
+ * (when accept_dot_dot is false)
+ * Input: p: "//..//aaa///bbbbb/cc"
+ * Output: return value: -EINVAL
+ */
+
+ q = *p;
+
+ first = skip_slash_or_dot(q);
+ if (isempty(first)) {
+ *p = first;
+ if (ret)
+ *ret = NULL;
+ return 0;
+ }
+ if (streq(first, ".")) {
+ *p = first + 1;
+ if (ret)
+ *ret = NULL;
+ return 0;
+ }
+
+ end_first = strchrnul(first, '/');
+ len = end_first - first;
+
+ if (len > NAME_MAX)
+ return -EINVAL;
+ if (!accept_dot_dot && len == 2 && first[0] == '.' && first[1] == '.')
+ return -EINVAL;
+
+ next = skip_slash_or_dot(end_first);
+
+ *p = next + streq(next, ".");
+ if (ret)
+ *ret = first;
+ return len;
+}
+
+static const char* skip_slash_or_dot_backward(const char *path, const char *q) {
+ assert(path);
+ assert(!q || q >= path);
+
+ for (; q; q = PTR_SUB1(q, path)) {
+ if (*q == '/')
+ continue;
+ if (q > path && strneq(q - 1, "/.", 2))
+ continue;
+ break;
+ }
+ return q;
+}
+
+int path_find_last_component(const char *path, bool accept_dot_dot, const char **next, const char **ret) {
+ const char *q, *last_end, *last_begin;
+ size_t len;
+
+ /* Similar to path_find_first_component(), but search components from the end.
+ *
+ * Examples
+ * Input: path: "//.//aaa///bbbbb/cc//././"
+ * next: NULL
+ * Output: next: "/cc//././"
+ * ret: "cc//././"
+ * return value: 2 (== strlen("cc"))
+ *
+ * Input: path: "//.//aaa///bbbbb/cc//././"
+ * next: "/cc//././"
+ * Output: next: "///bbbbb/cc//././"
+ * ret: "bbbbb/cc//././"
+ * return value: 5 (== strlen("bbbbb"))
+ *
+ * Input: path: "/", ".", "", or NULL
+ * Output: next: equivalent to path
+ * ret: NULL
+ * return value: 0
+ *
+ * Input: path: "(too long component)"
+ * Output: return value: -EINVAL
+ *
+ * (when accept_dot_dot is false)
+ * Input: path: "//..//aaa///bbbbb/cc/..//"
+ * Output: return value: -EINVAL
+ */
+
+ if (isempty(path)) {
+ if (next)
+ *next = path;
+ if (ret)
+ *ret = NULL;
+ return 0;
+ }
+
+ if (next && *next) {
+ if (*next < path || *next > path + strlen(path))
+ return -EINVAL;
+ if (*next == path) {
+ if (ret)
+ *ret = NULL;
+ return 0;
+ }
+ if (!IN_SET(**next, '\0', '/'))
+ return -EINVAL;
+ q = *next - 1;
+ } else
+ q = path + strlen(path) - 1;
+
+ q = skip_slash_or_dot_backward(path, q);
+ if (!q || /* the root directory */
+ (q == path && *q == '.')) { /* path is "." or "./" */
+ if (next)
+ *next = path;
+ if (ret)
+ *ret = NULL;
+ return 0;
+ }
+
+ last_end = q + 1;
+
+ while (q && *q != '/')
+ q = PTR_SUB1(q, path);
+
+ last_begin = q ? q + 1 : path;
+ len = last_end - last_begin;
+
+ if (len > NAME_MAX)
+ return -EINVAL;
+ if (!accept_dot_dot && len == 2 && strneq(last_begin, "..", 2))
+ return -EINVAL;
+
+ if (next) {
+ q = skip_slash_or_dot_backward(path, q);
+ *next = q ? q + 1 : path;
+ }
+
+ if (ret)
+ *ret = last_begin;
+ return len;
+}
+
+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.
+ *
+ * This always succeeds (except if you pass NULL in which case it returns NULL, too).
+ */
+
+ 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 *path, char **ret) {
+ _cleanup_free_ char *a = NULL;
+ const char *c, *next = NULL;
+ int r;
+
+ /* 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. Returns:
+ *
+ * -EINVAL → if the path is not valid
+ * -EADDRNOTAVAIL → if only a directory was specified, but no filename, i.e. the root dir
+ * itself or "." is specified
+ * -ENOMEM → no memory
+ *
+ * Returns >= 0 on success. If the input path has a trailing slash, returns O_DIRECTORY, to
+ * indicate the referenced file must be a directory.
+ *
+ * This function guarantees to return a fully valid filename, i.e. one that passes
+ * filename_is_valid() – this means "." and ".." are not accepted. */
+
+ if (!path_is_valid(path))
+ return -EINVAL;
+
+ r = path_find_last_component(path, false, &next, &c);
+ if (r < 0)
+ return r;
+ if (r == 0) /* root directory */
+ return -EADDRNOTAVAIL;
+
+ a = strndup(c, r);
+ if (!a)
+ return -ENOMEM;
+
+ *ret = TAKE_PTR(a);
+ return strlen(c) > (size_t) r ? O_DIRECTORY : 0;
+}
+
+int path_extract_directory(const char *path, char **ret) {
+ _cleanup_free_ char *a = NULL;
+ const char *c, *next = NULL;
+ int r;
+
+ /* The inverse of path_extract_filename(), i.e. returns the directory path prefix. Returns:
+ *
+ * -EINVAL → if the path is not valid
+ * -EDESTADDRREQ → if no directory was specified in the passed in path, i.e. only a filename was passed
+ * -EADDRNOTAVAIL → if the passed in parameter had no filename but did have a directory, i.e.
+ * the root dir itself or "." was specified
+ * -ENOMEM → no memory (surprise!)
+ *
+ * This function guarantees to return a fully valid path, i.e. one that passes path_is_valid().
+ */
+
+ r = path_find_last_component(path, false, &next, &c);
+ if (r < 0)
+ return r;
+ if (r == 0) /* empty or root */
+ return isempty(path) ? -EINVAL : -EADDRNOTAVAIL;
+ if (next == path) {
+ if (*path != '/') /* filename only */
+ return -EDESTADDRREQ;
+
+ a = strdup("/");
+ if (!a)
+ return -ENOMEM;
+ *ret = TAKE_PTR(a);
+ return 0;
+ }
+
+ a = strndup(path, next - path);
+ if (!a)
+ return -ENOMEM;
+
+ path_simplify(a);
+
+ if (!path_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)) /* Yes, in this context we consider "." and ".." invalid */
+ return false;
+
+ e = strchrnul(p, '/');
+ if (*e != 0)
+ return false;
+
+ if (e - p > NAME_MAX) /* NAME_MAX is counted *without* the trailing NUL byte */
+ return false;
+
+ return true;
+}
+
+bool path_is_valid_full(const char *p, bool accept_dot_dot) {
+ if (isempty(p))
+ return false;
+
+ for (const char *e = p;;) {
+ int r;
+
+ r = path_find_first_component(&e, accept_dot_dot, NULL);
+ if (r < 0)
+ return false;
+
+ if (e - p >= PATH_MAX) /* Already reached the maximum length for a path? (PATH_MAX is counted
+ * *with* the trailing NUL byte) */
+ return false;
+ if (*e == 0) /* End of string? Yay! */
+ return true;
+ }
+}
+
+bool path_is_normalized(const char *p) {
+ if (!path_is_safe(p))
+ return false;
+
+ if (streq(p, ".") || 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) {
+ assert(filename);
+
+ if (filename[0] == '.' ||
+ STR_IN_SET(filename,
+ "lost+found",
+ "aquota.user",
+ "aquota.group") ||
+ endswith(filename, "~"))
+ return true;
+
+ const char *dot = strrchr(filename, '.');
+ if (!dot)
+ 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(dot + 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 for paths that likely refer to a device, either by path in sysfs or to something in
+ * /dev. This accepts any path that starts with /dev/ or /sys/ and has something after that prefix.
+ * It does not actually resolve the path.
+ *
+ * Examples:
+ * /dev/sda, /dev/sda/foo, /sys/class, /dev/.., /sys/.., /./dev/foo → yes.
+ * /../dev/sda, /dev, /sys, /usr/path, /usr/../dev/sda → no.
+ */
+
+ const char *p = PATH_STARTSWITH_SET(ASSERT_PTR(path), "/dev/", "/sys/");
+ return !isempty(p);
+}
+
+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 those accepted by
+ * DeviceAllow= and DeviceDeny=. */
+
+ if (STARTSWITH_SET(path, "block-", "char-"))
+ return true;
+
+ return valid_device_node_path(path);
+}
+
+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 *path) {
+
+ /* 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 (isempty(path))
+ return true;
+
+ return path_equal(path, "/");
+}
+
+bool path_strv_contains(char **l, const char *path) {
+ STRV_FOREACH(i, l)
+ if (path_equal(*i, path))
+ return true;
+
+ return false;
+}
+
+bool prefixed_path_strv_contains(char **l, const char *path) {
+ STRV_FOREACH(i, l) {
+ const char *j = *i;
+
+ if (*j == '-')
+ j++;
+ if (*j == '+')
+ j++;
+ if (path_equal(j, path))
+ return true;
+ }
+
+ return false;
+}
+
+int path_glob_can_match(const char *pattern, const char *prefix, char **ret) {
+ assert(pattern);
+ assert(prefix);
+
+ for (const char *a = pattern, *b = prefix;;) {
+ _cleanup_free_ char *g = NULL, *h = NULL;
+ const char *p, *q;
+ int r, s;
+
+ r = path_find_first_component(&a, /* accept_dot_dot = */ false, &p);
+ if (r < 0)
+ return r;
+
+ s = path_find_first_component(&b, /* accept_dot_dot = */ false, &q);
+ if (s < 0)
+ return s;
+
+ if (s == 0) {
+ /* The pattern matches the prefix. */
+ if (ret) {
+ char *t;
+
+ t = path_join(prefix, p);
+ if (!t)
+ return -ENOMEM;
+
+ *ret = t;
+ }
+ return true;
+ }
+
+ if (r == 0)
+ break;
+
+ if (r == s && strneq(p, q, r))
+ continue; /* common component. Check next. */
+
+ g = strndup(p, r);
+ if (!g)
+ return -ENOMEM;
+
+ if (!string_is_glob(g))
+ break;
+
+ /* We found a glob component. Check if the glob pattern matches the prefix component. */
+
+ h = strndup(q, s);
+ if (!h)
+ return -ENOMEM;
+
+ r = fnmatch(g, h, 0);
+ if (r == FNM_NOMATCH)
+ break;
+ if (r != 0) /* Failure to process pattern? */
+ return -EINVAL;
+ }
+
+ /* The pattern does not match the prefix. */
+ if (ret)
+ *ret = NULL;
+ return false;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-26 20:27:50 +0000