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>

payloads/libpayload/include/string.h

@@ -47,8 +47,6 @@ int memcmp(const void *s1, const void *s2, size_t len);
  * @defgroup string String functions
  * @{
  */
-size_t strnlen(const char *str, size_t maxlen);
-size_t strlen(const char *str);
 int strcmp(const char *s1, const char *s2);
 int strncmp(const char *s1, const char *s2, size_t maxlen);
 int strcasecmp(const char *s1, const char *s2);

payloads/libpayload/libc/string.c

@@ -35,50 +35,6 @@
 #include <limits.h>
 #include <errno.h>
 
-/**
- * Calculate the length of a fixed-size string.
- *
- * @param str The input string.
- * @param maxlen Return at most maxlen characters as length of the string.
- * @return The length of the string, not including the final NUL character.
- * 	   The maximum length returned is maxlen.
- */
-size_t strnlen(const char *str, size_t maxlen)
-{
-	size_t len = 0;
-
-	/* NULL and empty strings have length 0. */
-	if (!str)
-		return 0;
-
-	/* Loop until we find a NUL character, or maxlen is reached. */
-	while ((*str++ != '\0') && (len < maxlen))
-		len++;
-
-	return len;
-}
-
-/**
- * Calculate the length of a string.
- *
- * @param str The input string.
- * @return The length of the string, not including the final NUL character.
- */
-size_t strlen(const char *str)
-{
-	size_t len = 0;
-
-	/* NULL and empty strings have length 0. */
-	if (!str)
-		return 0;
-
-	/* Loop until we find a NUL character. */
-	while (*str++ != '\0')
-		len++;
-
-	return len;
-}
-
 /**
  * Compare two strings.
  *

src/commonlib/bsd/include/commonlib/bsd/string.h

@@ -3,8 +3,12 @@
 #ifndef _COMMONLIB_BSD_STRING_H_
 #define _COMMONLIB_BSD_STRING_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
+size_t strlen(const char *src);
+size_t strnlen(const char *str, size_t maxlen);
+
 unsigned int skip_atoi(char **ptr);
 
 #endif  /* _COMMONLIB_BSD_STRING_H_ */

src/commonlib/bsd/string.c

@@ -2,6 +2,26 @@
 
 #include <commonlib/bsd/string.h>
 #include <ctype.h>
+#include <stddef.h>
+
+size_t strlen(const char *str)
+{
+	const char *ptr = str;
+
+	while (*ptr++)
+		;
+	return ptr - str - 1;
+}
+
+size_t strnlen(const char *str, size_t maxlen)
+{
+	const char *ptr = str;
+	const char *end = str + maxlen + 1;
+
+	while (*ptr++ && ptr < end)
+		;
+	return ptr - str - 1;
+}
 
 unsigned int skip_atoi(char **ptr)
 {

src/include/string.h

@@ -13,8 +13,6 @@ int memcmp(const void *s1, const void *s2, size_t n);
 void *memchr(const void *s, int c, size_t n);
 char *strdup(const char *s);
 char *strconcat(const char *s1, const char *s2);
-size_t strnlen(const char *src, size_t max);
-size_t strlen(const char *src);
 char *strchr(const char *s, int c);
 char *strncpy(char *to, const char *from, size_t count);
 char *strcpy(char *dst, const char *src);

src/lib/string.c

@@ -33,22 +33,6 @@ char *strconcat(const char *s1, const char *s2)
 	return d;
 }
 
-size_t strnlen(const char *src, size_t max)
-{
-	size_t i = 0;
-	while ((*src++) && (i < max))
-		i++;
-	return i;
-}
-
-size_t strlen(const char *src)
-{
-	size_t i = 0;
-	while (*src++)
-		i++;
-	return i;
-}
-
 char *strchr(const char *s, int c)
 {
 	do {

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),
 	};
 

tests/lib/string-test.c

@@ -23,12 +23,6 @@ struct string_pairs_t {
 	{"", ""},
 };
 
-const char *strings[] = {
-	"coreboot",
-	"is\0very",
-	"nice\n"
-};
-
 /* Used to test atol */
 struct str_with_l_val_t {
 	char *str;
@@ -76,26 +70,6 @@ static void test_strconcat(void **state)
 	}
 }
 
-static void test_strnlen(void **state)
-{
-	int i, n = 5;
-	size_t str_len, limited_len;
-
-	for (i = 0; i < ARRAY_SIZE(strings); i++) {
-		str_len = __builtin_strlen(strings[i]);
-		limited_len = MIN(n, str_len);
-		assert_int_equal(limited_len, strnlen(strings[i], n));
-	}
-}
-
-static void test_strlen(void **state)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(strings); i++)
-		assert_int_equal(__builtin_strlen(strings[i]), strlen(strings[i]));
-}
-
 static void test_strchr(void **state)
 {
 	char str[] = "Abracadabra!\n";
@@ -227,8 +201,6 @@ int main(void)
 	const struct CMUnitTest tests[] = {
 		cmocka_unit_test(test_strdup),
 		cmocka_unit_test(test_strconcat),
-		cmocka_unit_test(test_strnlen),
-		cmocka_unit_test(test_strlen),
 		cmocka_unit_test(test_strchr),
 		cmocka_unit_test(test_strrchr),
 		cmocka_unit_test(test_strncpy),