3 files changed, 55 insertions, 0 deletions

diff --git a/common/path.c b/common/path.c
index d3d881d..a2ba6ec 100644
--- a/common/path.c
+++ b/common/path.c
@@ -262,3 +262,39 @@ p11_path_build (const char *path,
 	built[at] = '\0';
 	return built;
 }
+
+char *
+p11_path_parent (const char *path)
+{
+	const char *e;
+	char *parent;
+	bool had = false;
+
+	return_val_if_fail (path != NULL, NULL);
+
+	/* Find the end of the last component */
+	e = path + strlen (path);
+	while (e != path && is_path_component_or_null (*e))
+		e--;
+
+	/* Find the beginning of the last component */
+	while (e != path && !is_path_component_or_null (*e)) {
+		had = true;
+		e--;
+	}
+
+	/* Find the end of the last component */
+	while (e != path && is_path_component_or_null (*e))
+		e--;
+
+	if (e == path) {
+		if (!had)
+			return NULL;
+		parent = strdup ("/");
+	} else {
+		parent = strndup (path, (e - path) + 1);
+	}
+
+	return_val_if_fail (parent != NULL, NULL);
+	return parent;
+}
diff --git a/common/path.h b/common/path.h
index a518008..1fce607 100644
--- a/common/path.h
+++ b/common/path.h
@@ -59,4 +59,6 @@ char *       p11_path_build     (const char *path,
 
 bool         p11_path_absolute  (const char *path);
 
+char *       p11_path_parent    (const char *path);
+
 #endif /* P11_PATH_H__ */
diff --git a/common/tests/test-path.c b/common/tests/test-path.c
index f1bccbd..ec2c200 100644
--- a/common/tests/test-path.c
+++ b/common/tests/test-path.c
@@ -173,6 +173,22 @@ test_absolute (void)
 #endif
 }
 
+static void
+test_parent (void)
+{
+	check_equals_and_free ("/", p11_path_parent ("/root"));
+	check_equals_and_free ("/", p11_path_parent ("/root/"));
+	check_equals_and_free ("/", p11_path_parent ("/root//"));
+	check_equals_and_free ("/root", p11_path_parent ("/root/second"));
+	check_equals_and_free ("/root", p11_path_parent ("/root//second"));
+	check_equals_and_free ("/root", p11_path_parent ("/root//second//"));
+	check_equals_and_free ("/root", p11_path_parent ("/root///second"));
+	check_equals_and_free ("/root/second", p11_path_parent ("/root/second/test.file"));
+	assert_ptr_eq (NULL, p11_path_parent ("/"));
+	assert_ptr_eq (NULL, p11_path_parent ("//"));
+	assert_ptr_eq (NULL, p11_path_parent (""));
+}
+
 int
 main (int argc,
       char *argv[])
@@ -181,6 +197,7 @@ main (int argc,
 	p11_test (test_build, "/path/build");
 	p11_test (test_expand, "/path/expand");
 	p11_test (test_absolute, "/path/absolute");
+	p11_test (test_parent, "/path/parent");
 
 	return p11_test_run (argc, argv);
 }