commonlib/bsd: Add strlen() and strnlen() functions

Add strlen() and strnlen() to commonlib/bsd by rewriting them from
scratch, and remove the same functions from coreboot and libpayload.

Note that in the existing libpayload implementation, these functions
return 0 for NULL strings. Given that POSIX doesn't require the NULL
check and that other major libc implementations (e.g. glibc [1]) don't
seem to do that, the new functions also don't perform the NULL check.

[1] https://github.com/bminor/glibc/blob/master/sysdeps/i386/strlen.c

Change-Id: I1203ec9affabe493bd14b46662d212b08240cced
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83830
Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

tests/commonlib/bsd/string-test.c

@@ -1,24 +1,57 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <commonlib/bsd/string.h>
+#include <stddef.h>
 #include <tests/test.h>
 
-/* Used to test skip_atoi */
-struct str_with_u_val_t {
-	char *str;
-	uint32_t value;
-	uint32_t offset;
-} str_with_u_val[] = {
-	{"42aa", 42, 2},
-	{"a", 0, 0},
-	{"0", 0, 1},
-	{"4a2", 4, 1},
-};
+static void test_strlen(void **state)
+{
+	const char *str;
+
+	str = "coreboot";
+	assert_int_equal(__builtin_strlen(str), strlen(str));
+
+	str = "is\0very";
+	assert_int_equal(__builtin_strlen(str), strlen(str));
+
+	str = "nice\n";
+	assert_int_equal(__builtin_strlen(str), strlen(str));
+
+	assert_int_equal(0, strlen(""));
+}
+
+static void test_strnlen(void **state)
+{
+	/* maxlen larger than string len */
+	assert_int_equal(8, strnlen("coreboot", 100));
+
+	/* maxlen equal to string len */
+	assert_int_equal(8, strnlen("coreboot", 8));
+
+	/* maxlen smaller than string len */
+	assert_int_equal(5, strnlen("coreboot", 5));
+
+	/* maxlen is 0 */
+	assert_int_equal(0, strnlen("coreboot", 0));
+
+	/* Empty string */
+	assert_int_equal(0, strnlen("", 3));
+}
 
 static void test_skip_atoi(void **state)
 {
 	int i;
 	char *ptr, *copy;
+	const struct str_with_u_val_t {
+		char *str;
+		uint32_t value;
+		uint32_t offset;
+	} str_with_u_val[] = {
+		{"42aa", 42, 2},
+		{"a", 0, 0},
+		{"0", 0, 1},
+		{"4a2", 4, 1},
+	};
 
 	for (i = 0; i < ARRAY_SIZE(str_with_u_val); i++) {
 		ptr = str_with_u_val[i].str;
@@ -31,6 +64,8 @@ static void test_skip_atoi(void **state)
 int main(void)
 {
 	const struct CMUnitTest tests[] = {
+		cmocka_unit_test(test_strlen),
+		cmocka_unit_test(test_strnlen),
 		cmocka_unit_test(test_skip_atoi),
 	};