Add memrchr()

src/header/string/mod.rs

@@ -107,6 +107,20 @@ pub unsafe extern "C" fn memmove(s1: *mut c_void, s2: *const c_void, n: size_t)
     s1
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn memrchr(
+    haystack: *const c_void,
+    needle: c_int,
+    len: size_t,
+) -> *mut c_void {
+    let haystack = slice::from_raw_parts(haystack as *const u8, len as usize);
+
+    match memchr::memrchr(needle as u8, haystack) {
+        Some(index) => haystack[index..].as_ptr() as *mut c_void,
+        None => ptr::null_mut(),
+    }
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn memset(s: *mut c_void, c: c_int, n: size_t) -> *mut c_void {
     for i in 0..n {