commonlib/bsd: Add strcat() and strncat() functions

An upcoming vboot feature [1] will need strcat() to be defined in
string.h. Therefore, add strcat() and strncat() to commonlib/bsd. Remove
those functions from libpayload.

[1] https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/5650810

Change-Id: If02fce0eafb4f6fa01d8bab17d87a32360f4ac83
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83765
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

payloads/libpayload/include/string.h

@@ -53,8 +53,6 @@ int strcasecmp(const char *s1, const char *s2);
 int strncasecmp(const char *s1, const char *s2, size_t maxlen);
 char *strncpy(char *d, const char *s, size_t n);
 char *strcpy(char *d, const char *s);
-char *strncat(char *d, const char *s, size_t n);
-char *strcat(char *d, const char *s);
 char *strchr(const char *s, int c);
 char *strrchr(const char *s, int c);
 char *strdup(const char *s);

payloads/libpayload/libc/string.c

@@ -152,46 +152,6 @@ char *strcpy(char *d, const char *s)
 	return strncpy(d, s, strlen(s) + 1);
 }
 
-/**
- * Concatenates two strings
- *
- * @param d The destination string.
- * @param s The source string.
- * @return A pointer to the destination string.
- */
-char *strcat(char *d, const char *s)
-{
-	char *p = d + strlen(d);
-	size_t sl = strlen(s);
-
-	for (size_t i = 0; i < sl; i++)
-		p[i] = s[i];
-
-	p[sl] = '\0';
-	return d;
-}
-
-/**
- * Concatenates two strings with a maximum length.
- *
- * @param d The destination string.
- * @param s The source string.
- * @param n Not more than n characters from s will be appended to d.
- * @return A pointer to the destination string.
- */
-char *strncat(char *d, const char *s, size_t n)
-{
-	char *p = d + strlen(d);
-	size_t sl = strlen(s);
-	size_t max = n > sl ? sl : n;
-
-	for (size_t i = 0; i < max; i++)
-		p[i] = s[i];
-
-	p[max] = '\0';
-	return d;
-}
-
 /**
  * Concatenates two strings with a maximum length.
  *

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

@@ -8,6 +8,8 @@
 
 size_t strlen(const char *src);
 size_t strnlen(const char *str, size_t maxlen);
+char *strcat(char *dst, const char *src);
+char *strncat(char *dst, const char *src, size_t n);
 
 unsigned int skip_atoi(char **ptr);
 

src/commonlib/bsd/string.c

@@ -23,6 +23,29 @@ size_t strnlen(const char *str, size_t maxlen)
 	return ptr - str - 1;
 }
 
+char *strcat(char *dst, const char *src)
+{
+	char *ptr = dst + strlen(dst);
+
+	while (*src)
+		*ptr++ = *src++;
+
+	*ptr = '\0';
+	return dst;
+}
+
+char *strncat(char *dst, const char *src, size_t n)
+{
+	char *ptr = dst + strlen(dst);
+
+	/* Not using strncpy() because '\0' may not be appended. */
+	while (n-- > 0 && *src)
+		*ptr++ = *src++;
+
+	*ptr = '\0';
+	return dst;
+}
+
 unsigned int skip_atoi(char **ptr)
 {
 	unsigned int result = 0;

tests/commonlib/bsd/string-test.c

@@ -2,6 +2,7 @@
 
 #include <commonlib/bsd/string.h>
 #include <stddef.h>
+#include <string.h>
 #include <tests/test.h>
 
 static void test_strlen(void **state)
@@ -38,6 +39,77 @@ static void test_strnlen(void **state)
 	assert_int_equal(0, strnlen("", 3));
 }
 
+static void test_strcat(void **state)
+{
+	static const char str[] = "Hello ";
+	size_t len = __builtin_strlen(str);
+	static const char src[] = "World";
+	static const char expected[] = "Hello World";
+	size_t expected_len = __builtin_strlen(expected);
+	char dst[100];
+	char *ret;
+
+	/* Empty src & dst */
+	dst[0] = '\0';
+	memset(dst + 1, 0xee, sizeof(dst) - 1);
+	ret = strcat(dst, "");
+	assert_ptr_equal(dst, ret);
+	assert_int_equal('\0', dst[0]);
+
+	/* Empty src */
+	memcpy(dst, str, len + 1);
+	memset(dst + len + 1, 0xee, sizeof(dst) - len - 1);
+	ret = strcat(dst, "");
+	assert_memory_equal(str, dst, len + 1);
+
+	/* Empty dst */
+	memset(dst, 0x0, sizeof(dst));
+	memset(dst + 1, 0xee, sizeof(dst) - 1);
+	ret = strcat(dst, src);
+	assert_ptr_equal(dst, ret);
+	assert_memory_equal(src, dst, __builtin_strlen(src) + 1);
+
+	/* Non-empty str & dst */
+	memcpy(dst, str, len + 1);
+	memset(dst + len + 1, 0xee, sizeof(dst) - len - 1);
+	ret = strcat(dst, src);
+	assert_ptr_equal(dst, ret);
+	assert_memory_equal(expected, dst, expected_len + 1);
+}
+
+static void test_strncat(void **state)
+{
+	static const char str[] = "Hello ";
+	size_t len = __builtin_strlen(str);
+	static const char src[] = "World";
+	size_t src_len = __builtin_strlen(src);
+	static const char expected[] = "Hello World";
+	size_t expected_len = __builtin_strlen(expected);
+	char dst[100];
+	char *ret;
+
+	/* n larger than src len */
+	memcpy(dst, str, len + 1);
+	memset(dst + len + 1, 0xee, sizeof(dst) - len - 1);
+	ret = strncat(dst, src, src_len + 5);
+	assert_ptr_equal(dst, ret);
+	assert_memory_equal(expected, dst, expected_len + 1);
+
+	/* n smaller than src len */
+	memcpy(dst, str, len + 1);
+	memset(dst + len + 1, 0xee, sizeof(dst) - len - 1);
+	ret = strncat(dst, src, src_len - 2);
+	assert_ptr_equal(dst, ret);
+	assert_memory_equal("Hello Wor", dst, expected_len - 2 + 1);
+
+	/* n is 0 */
+	memcpy(dst, str, len + 1);
+	memset(dst + len + 1, 0xee, sizeof(dst) - len - 1);
+	ret = strncat(dst, src, 0);
+	assert_ptr_equal(dst, ret);
+	assert_memory_equal(str, dst, len + 1);
+}
+
 static void test_skip_atoi(void **state)
 {
 	int i;
@@ -66,6 +138,8 @@ int main(void)
 	const struct CMUnitTest tests[] = {
 		cmocka_unit_test(test_strlen),
 		cmocka_unit_test(test_strnlen),
+		cmocka_unit_test(test_strcat),
+		cmocka_unit_test(test_strncat),
 		cmocka_unit_test(test_skip_atoi),
 	};