chase: replace path_prefix_root_cwd() with chaseat_prefix_root()

The function path_prefix_root_cwd() was introduced for prefixing the
result from chaseat() with root, but
- it is named slightly generic,
- the logic is different from what chase() does.

This makes the name more explanative and specific for the result of the
chaseat(), and make the logic consistent with chase().

Fixes https://github.com/systemd/systemd/pull/27199#issuecomment-1511387731.

Follow-up for #27199.

5 files changed, 35 insertions, 31 deletions

diff --git a/src/basic/chase.c b/src/basic/chase.c
index 96b59e7845..373252b645 100644
--- a/src/basic/chase.c
+++ b/src/basic/chase.c
@@ -583,6 +583,37 @@ int chase(const char *path, const char *root, ChaseFlags flags, char **ret_path,
         return r;
 }
 
+int chaseat_prefix_root(const char *path, const char *root, char **ret) {
+        char *q;
+        int r;
+
+        assert(path);
+        assert(ret);
+
+        /* This is mostly for prefixing the result of chaseat(). */
+
+        if (!path_is_absolute(path)) {
+                _cleanup_free_ char *root_abs = NULL;
+
+                /* If the dir_fd points to the root directory, chaseat() always returns an absolute path. */
+                assert(!empty_or_root(root));
+
+                r = path_make_absolute_cwd(root, &root_abs);
+                if (r < 0)
+                        return r;
+
+                root = path_simplify(root_abs);
+
+                q = path_join(root, path + (path[0] == '.' && IN_SET(path[1], '/', '\0')));
+        } else
+                q = strdup(path);
+        if (!q)
+                return -ENOMEM;
+
+        *ret = q;
+        return 0;
+}
+
 int chase_and_open(const char *path, const char *root, ChaseFlags chase_flags, int open_flags, char **ret_path) {
         _cleanup_close_ int path_fd = -EBADF;
         _cleanup_free_ char *p = NULL, *fname = NULL;
diff --git a/src/basic/chase.h b/src/basic/chase.h
index 40121f7d70..f37e836822 100644
--- a/src/basic/chase.h
+++ b/src/basic/chase.h
@@ -42,6 +42,8 @@ bool unsafe_transition(const struct stat *a, const struct stat *b);
 
 int chase(const char *path_with_prefix, const char *root, ChaseFlags chase_flags, char **ret_path, int *ret_fd);
 
+int chaseat_prefix_root(const char *path, const char *root, char **ret);
+
 int chase_and_open(const char *path, const char *root, ChaseFlags chase_flags, int open_flags, char **ret_path);
 int chase_and_opendir(const char *path, const char *root, ChaseFlags chase_flags, char **ret_path, DIR **ret_dir);
 int chase_and_stat(const char *path, const char *root, ChaseFlags chase_flags, char **ret_path, struct stat *ret_stat);
diff --git a/src/basic/os-util.c b/src/basic/os-util.c
index dd8faf2376..5d06e20871 100644
--- a/src/basic/os-util.c
+++ b/src/basic/os-util.c
@@ -155,7 +155,7 @@ int open_os_release(const char *root, char **ret_path, int *ret_fd) {
                 return r;
 
         if (ret_path) {
-                r = path_prefix_root_cwd(p, root, ret_path);
+                r = chaseat_prefix_root(p, root, ret_path);
                 if (r < 0)
                         return r;
         }
@@ -292,7 +292,7 @@ int open_extension_release(
                 return r;
 
         if (ret_path) {
-                r = path_prefix_root_cwd(p, root, ret_path);
+                r = chaseat_prefix_root(p, root, ret_path);
                 if (r < 0)
                         return r;
         }
diff --git a/src/basic/path-util.c b/src/basic/path-util.c
index fa2e26789f..0b0f0da760 100644
--- a/src/basic/path-util.c
+++ b/src/basic/path-util.c
@@ -100,34 +100,6 @@ int path_make_absolute_cwd(const char *p, char **ret) {
         return 0;
 }
 
-int path_prefix_root_cwd(const char *p, const char *root, char **ret) {
-        _cleanup_free_ char *root_abs = NULL;
-        char *c;
-        int r;
-
-        assert(p);
-        assert(ret);
-
-        /* Unlike path_make_absolute(), this always prefixes root path if specified.
-         * The root path is always simplified, but the provided path will not.
-         * This is useful for prefixing the result of chaseat(). */
-
-        if (empty_or_root(root))
-                return path_make_absolute_cwd(p, ret);
-
-        r = path_make_absolute_cwd(root, &root_abs);
-        if (r < 0)
-                return r;
-
-        path_simplify(root_abs);
-        c = path_join(root_abs, 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;
diff --git a/src/basic/path-util.h b/src/basic/path-util.h
index a0af9de674..7843599816 100644
--- a/src/basic/path-util.h
+++ b/src/basic/path-util.h
@@ -60,7 +60,6 @@ int path_split_and_make_absolute(const char *p, char ***ret);
 char* path_make_absolute(const char *p, const char *prefix);
 int safe_getcwd(char **ret);
 int path_make_absolute_cwd(const char *p, char **ret);
-int path_prefix_root_cwd(const char *p, const char *root, char **ret);
 int path_make_relative(const char *from, const char *to, char **ret);
 int path_make_relative_parent(const char *from_child, const char *to, char **ret);
 char *path_startswith_full(const char *path, const char *prefix, bool accept_dot_dot) _pure_;