add strrchr()

lib/include/string.h

@@ -23,6 +23,7 @@ int strcmp(const char *s1, const char *s2);
 int strncmp(const char *s1, const char *s2, size_t n);
 char *strstr(const char *haystack, const char *needle);
 char *strchr(const char *s, int n);
+char *strrchr(const char *s, int n);
 void *memcpy(void *dest, const void *src, size_t n);
 void *memcpy_long(void *dest, const void *src, size_t n);
 int memcmp(const void *s1, const void *s2, size_t n);

lib/string.c

@@ -95,7 +95,20 @@ char *strchr(const char *s, int n) {
 	}
 	return NULL;
 }
-		
+
+char *
+strrchr(const char *s, int c)
+{
+	const char *last = NULL;
+
+	do {
+		if (*s == c) {
+			last = s;
+		}
+	} while (*(s++));
+
+	return (char *)last;
+} /* strrchr() */
 
 char *strstr(const char *haystack, const char *needle)
 {