lib: unic: Implement strcat

Also fix-up the strncpy func.

Signed-off-by: Ivaylo Ivanov <ivo.ivanov.ivanov1@gmail.com>

lib/unic/string.c

@@ -99,24 +99,21 @@ char *strcpy(char *s1, const char *s2)
 	return rc;
 }
 
-char *strncpy(char *s1, const char *s2, size_t n)
+
+char *strncpy(char *d, char *s, long n)
 {
-	char *rc = s1;
-
-	while (n && (*s1++ = *s2++)) {
-		/* Cannot do "n--" in the conditional as size_t is unsigned and we have
-		   to check it again for >0 in the next loop below, so we must not risk
-		   underflow.
-		*/
-		--n;
+	int len = strlen(s);
+	if (len > n)
+		len = n;
+	memcpy(d, s, len);
+	memset(d + len, 0, n - len);
+	return d;
 }
 
-	/* Checking against 1 as we missed the last --n in the loop above. */
-	while (n-- > 1) {
-		*s1++ = '\0';
-	}
-
-	return rc;
+char *strcat(char *d, char *s)
+{
+	strcpy(d + strlen(d), s);
+	return d;
 }
 
 int strcmp(const char *s1, const char *s2)

lib/unic/string.h

@@ -16,7 +16,8 @@
 int memcmp (const void *s1, const void *s2, size_t n);
 void *memchr (const void *s, int c, size_t n);
 char *strcpy (char *s1, const char *s2);
-char *strncpy (char *s1, const char *s2, size_t n);
+char *strncpy (char *d, char *s, long n);
+char *strcat (char *d, char *s);
 int strcmp (const char *s1, const char *s2);
 int strncmp (const char *s1, const char *s2, size_t n);
 size_t strlen (const char *s);