utils: add a trunkname() function to extract the trunk of a filename

/path/to/foo.bar returns "foo"

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/util-strings.c

@@ -155,3 +155,34 @@ strv_join(char **strv, const char *joiner)
 
 	return str;
 }
+
+/**
+ * Similar to basename() but returns the trunk only without the (last)
+ * trailing suffix, so that:
+ *
+ * - foo.c returns foo
+ * - foo.a.b returns foo.a
+ * - foo returns foo
+ * - foo/ returns ""
+ *
+ * @return an allocated string representing the trunk name of the file
+ */
+char *
+trunkname(const char *filename)
+{
+	/* See basename(3), there are two versions and they depend on
+	 * whether libgen.h is included. We can't be sure which basename()
+	 * applies here, so let's play it safe and assume it's the POSIX
+	 * one. */
+	char *tmp = strdup(filename);
+	char *base = basename(tmp);
+	char *suffix;
+	char *trunk;
+
+	if ((suffix = rindex(base, '.')))
+	    *suffix = '\0';
+
+	trunk = strdup(base);
+	free(tmp);
+	return trunk;
+}

src/util-strings.h

@@ -391,3 +391,6 @@ strstartswith(const char *str, const char *prefix)
 
 	return prefixlen > 0 ? strneq(str, prefix, strlen(prefix)) : false;
 }
+
+char *
+trunkname(const char *filename);

test/test-utils.c

@@ -1292,6 +1292,32 @@ START_TEST(strneq_test)
 }
 END_TEST
 
+START_TEST(trunkname_test)
+{
+	struct test {
+		const char *path;
+		const char *expected;
+	} tests[] = {
+		{ "foo.c", "foo" },
+		{ "/path/to/foo.h", "foo" },
+		{ "../bar.foo", "bar" },
+		{ "./bar.foo.baz", "bar.foo" },
+		{ "./", "" },
+		{ "/", "" },
+		{ "/bar/", "" },
+		{ "/bar", "bar" },
+		{ "", "" },
+	};
+	struct test *t;
+
+	ARRAY_FOR_EACH(tests, t) {
+		char *result = trunkname(t->path);
+		ck_assert_str_eq(result, t->expected);
+		free(result);
+	}
+}
+END_TEST
+
 static Suite *
 litest_utils_suite(void)
 {
@@ -1335,6 +1361,7 @@ litest_utils_suite(void)
 	tcase_add_test(tc, strverscmp_test);
 	tcase_add_test(tc, streq_test);
 	tcase_add_test(tc, strneq_test);
+	tcase_add_test(tc, trunkname_test);
 
 	suite_add_tcase(s, tc);