utils: Provide a path_absolute() function to check path for non-relativeness

The usually used trivial '/' check won't work on Windows platforms.

src/libstrongswan/tests/suites/test_utils.c

@@ -508,52 +508,54 @@ START_TEST(test_strreplace)
 END_TEST
 
 /*******************************************************************************
- * path_dirname/basename
+ * path_dirname/basename/absolute
  */
 
 static struct {
 	char *path;
 	char *dir;
 	char *base;
+	bool absolute;
 } path_data[] = {
-	{NULL, ".", "."},
-	{"", ".", "."},
-	{".", ".", "."},
-	{"..", ".", ".."},
+	{NULL, ".", ".", FALSE},
+	{"", ".", ".", FALSE},
+	{".", ".", ".", FALSE},
+	{"..", ".", "..", FALSE},
 #ifdef WIN32
-	{"C:\\", "C:\\", "C:\\"},
-	{"C:\\\\", "C:\\", "C:\\"},
-	{"foo", ".", "foo"},
-	{"f\\", ".", "f"},
-	{"foo\\", ".", "foo"},
-	{"foo\\\\", ".", "foo"},
-	{"C:\\f", "C:\\", "f"},
-	{"C:\\f\\", "\\", "f"},
-	{"C:\\foo", "C:\\", "foo"},
-	{"C:\\foo\\", "C:\\", "foo"},
-	{"foo\\bar", "foo", "bar"},
-	{"foo\\\\bar", "foo", "bar"},
-	{"C:\\foo\\bar", "C:\\foo", "bar"},
-	{"C:\\foo\\bar\\", "C:\\foo", "bar"},
-	{"C:\\foo\\bar\\baz", "C:\\foo\\bar", "baz"},
-	{"\\foo\\bar", "\\foo", "bar"},
+	{"C:\\", "C:", "C:", TRUE},
+	{"X:\\\\", "X:", "X:", TRUE},
+	{"foo", ".", "foo", FALSE},
+	{"f\\", ".", "f", FALSE},
+	{"foo\\", ".", "foo", FALSE},
+	{"foo\\\\", ".", "foo", FALSE},
+	{"d:\\f", "d:", "f", TRUE},
+	{"C:\\f\\", "C:", "f", TRUE},
+	{"C:\\foo", "C:", "foo", TRUE},
+	{"C:\\foo\\", "C:", "foo", TRUE},
+	{"foo\\bar", "foo", "bar", FALSE},
+	{"foo\\\\bar", "foo", "bar", FALSE},
+	{"C:\\foo\\bar", "C:\\foo", "bar", TRUE},
+	{"C:\\foo\\bar\\", "C:\\foo", "bar", TRUE},
+	{"C:\\foo\\bar\\baz", "C:\\foo\\bar", "baz", TRUE},
+	{"\\foo\\bar", "\\foo", "bar", FALSE},
+	{"\\\\foo\\bar", "\\\\foo", "bar", TRUE},
 #else /* !WIN32 */
-	{"/", "/", "/"},
-	{"//", "/", "/"},
-	{"foo", ".", "foo"},
-	{"f/", ".", "f"},
-	{"foo/", ".", "foo"},
-	{"foo//", ".", "foo"},
-	{"/f", "/", "f"},
-	{"/f/", "/", "f"},
-	{"/foo", "/", "foo"},
-	{"/foo/", "/", "foo"},
-	{"//foo/", "/", "foo"},
-	{"foo/bar", "foo", "bar"},
-	{"foo//bar", "foo", "bar"},
-	{"/foo/bar", "/foo", "bar"},
-	{"/foo/bar/", "/foo", "bar"},
-	{"/foo/bar/baz", "/foo/bar", "baz"},
+	{"/", "/", "/", TRUE},
+	{"//", "/", "/", TRUE},
+	{"foo", ".", "foo", FALSE},
+	{"f/", ".", "f", FALSE},
+	{"foo/", ".", "foo", FALSE},
+	{"foo//", ".", "foo", FALSE},
+	{"/f", "/", "f", TRUE},
+	{"/f/", "/", "f", TRUE},
+	{"/foo", "/", "foo", TRUE},
+	{"/foo/", "/", "foo", TRUE},
+	{"//foo/", "/", "foo", TRUE},
+	{"foo/bar", "foo", "bar", FALSE},
+	{"foo//bar", "foo", "bar", FALSE},
+	{"/foo/bar", "/foo", "bar", TRUE},
+	{"/foo/bar/", "/foo", "bar", TRUE},
+	{"/foo/bar/baz", "/foo/bar", "baz", TRUE},
 #endif
 };
 
@@ -577,6 +579,12 @@ START_TEST(test_path_basename)
 }
 END_TEST
 
+START_TEST(test_path_absolute)
+{
+	ck_assert(path_data[_i].absolute == path_absolute(path_data[_i].path));
+}
+END_TEST
+
 /*******************************************************************************
  * time_printf_hook
  */
@@ -744,11 +752,18 @@ Suite *utils_suite_create()
 	tcase_add_loop_test(tc, test_strreplace, 0, countof(strreplace_data));
 	suite_add_tcase(s, tc);
 
-	tc = tcase_create("path_dirname/basename");
+	tc = tcase_create("path_dirname");
 	tcase_add_loop_test(tc, test_path_dirname, 0, countof(path_data));
+	suite_add_tcase(s, tc);
+
+	tc = tcase_create("path_basename");
 	tcase_add_loop_test(tc, test_path_basename, 0, countof(path_data));
 	suite_add_tcase(s, tc);
 
+	tc = tcase_create("path_absolute");
+	tcase_add_loop_test(tc, test_path_absolute, 0, countof(path_data));
+	suite_add_tcase(s, tc);
+
 	tc = tcase_create("printf_hooks");
 	tcase_add_loop_test(tc, test_time_printf_hook, 0, countof(time_data));
 	tcase_add_loop_test(tc, test_time_delta_printf_hook, 0, countof(time_delta_data));

src/libstrongswan/utils/utils.c

@@ -288,6 +288,33 @@ char* path_basename(const char *path)
 	return trail ? strndup(pos, trail - pos) : strdup(pos);
 }
 
+/**
+ * Described in header.
+ */
+bool path_absolute(const char *path)
+{
+	if (!path)
+	{
+		return FALSE;
+	}
+#ifdef WIN32
+	if (strpfx(path, "\\\\"))
+	{	/* UNC */
+		return TRUE;
+	}
+	if (strlen(path) && isalpha(path[0]) && path[1] == ':')
+	{	/* drive letter */
+		return TRUE;
+	}
+#else /* !WIN32 */
+	if (path[0] == DIRECTORY_SEPARATOR[0])
+	{
+		return TRUE;
+	}
+#endif
+	return FALSE;
+}
+
 /**
  * Described in header.
  */

src/libstrongswan/utils/utils.h

@@ -568,6 +568,14 @@ char *path_dirname(const char *path);
  */
 char *path_basename(const char *path);
 
+/**
+ * Check if a given path is absolute.
+ *
+ * @param path		path to check
+ * @return			TRUE if absolute, FALSE if relative
+ */
+bool path_absolute(const char *path);
+
 /**
  * Creates a directory and all required parent directories.
  *