path: Add p11_path_prefix() function

Checks if a wellformed path is identical to or a prefix
of another path.

3 files changed, 33 insertions, 0 deletions

diff --git a/common/path.c b/common/path.c
index a2ba6ec..8362765 100644
--- a/common/path.c
+++ b/common/path.c
@@ -298,3 +298,20 @@ p11_path_parent (const char *path)
 	return_val_if_fail (parent != NULL, NULL);
 	return parent;
 }
+
+bool
+p11_path_prefix (const char *string,
+                 const char *prefix)
+{
+	int a, b;
+
+	return_val_if_fail (string != NULL, false);
+	return_val_if_fail (prefix != NULL, false);
+
+	a = strlen (string);
+	b = strlen (prefix);
+
+	return a > b &&
+	       strncmp (string, prefix, b) == 0 &&
+	       is_path_component_or_null (string[b]);
+}
diff --git a/common/path.h b/common/path.h
index 1fce607..cd135cb 100644
--- a/common/path.h
+++ b/common/path.h
@@ -61,4 +61,7 @@ bool         p11_path_absolute  (const char *path);
 
 char *       p11_path_parent    (const char *path);
 
+bool         p11_path_prefix    (const char *string,
+                                 const char *prefix);
+
 #endif /* P11_PATH_H__ */
diff --git a/common/tests/test-path.c b/common/tests/test-path.c
index ec2c200..1671381 100644
--- a/common/tests/test-path.c
+++ b/common/tests/test-path.c
@@ -189,6 +189,18 @@ test_parent (void)
 	assert_ptr_eq (NULL, p11_path_parent (""));
 }
 
+static void
+test_prefix (void)
+{
+	assert (p11_path_prefix ("/test/second", "/test"));
+	assert (!p11_path_prefix ("/test", "/test"));
+	assert (!p11_path_prefix ("/different/prefix", "/test"));
+	assert (!p11_path_prefix ("/te", "/test"));
+	assert (!p11_path_prefix ("/test", "/test/blah"));
+	assert (p11_path_prefix ("/test/other/second", "/test"));
+	assert (p11_path_prefix ("/test//other//second", "/test"));
+}
+
 int
 main (int argc,
       char *argv[])
@@ -198,6 +210,7 @@ main (int argc,
 	p11_test (test_expand, "/path/expand");
 	p11_test (test_absolute, "/path/absolute");
 	p11_test (test_parent, "/path/parent");
+	p11_test (test_prefix, "/path/prefix");
 
 	return p11_test_run (argc, argv);
 }