Fix panic in fwrite

src/header/stdio/mod.rs

@@ -562,11 +562,14 @@ pub unsafe extern "C" fn funlockfile(file: *mut FILE) {
 pub unsafe extern "C" fn fwrite(
     ptr: *const c_void,
     size: size_t,
-    count: size_t,
+    nitems: size_t,
     stream: *mut FILE,
 ) -> size_t {
+    if size == 0 || nitems == 0 {
+        return 0
+    }
     let mut stream = (*stream).lock();
-    let buf = slice::from_raw_parts_mut(ptr as *mut u8, size as usize * count as usize);
+    let buf = slice::from_raw_parts_mut(ptr as *mut u8, size as usize * nitems as usize);
     let mut written = 0;
     while written < buf.len() {
         match stream.write(&mut buf[written..]) {