Update Dup test to check that duplicated handles have the same seek offset

Author: CraftSpider

tests/pass-dep/shims/windows-fs.rs

@@ -2,9 +2,9 @@
 //@compile-flags: -Zmiri-disable-isolation
 #![allow(nonstandard_style)]
 
-use std::io::{ErrorKind, Read, Write};
+use std::io::{ErrorKind, Read, Seek, SeekFrom, Write};
 use std::os::windows::ffi::OsStrExt;
-use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle};
+use std::os::windows::io::{AsRawHandle, FromRawHandle};
 use std::path::Path;
 use std::{fs, mem, ptr};
 
@@ -277,7 +277,13 @@ unsafe fn test_file_read_write() {
 
 unsafe fn test_dup_handle() {
     let temp = utils::tmp().join("test_dup.txt");
-    let first_handle = fs::File::create(&temp).unwrap().into_raw_handle();
+
+    let mut file1 = fs::File::options().read(true).write(true).create(true).open(&temp).unwrap();
+
+    file1.write_all(b"Hello, World!\n").unwrap();
+    file1.seek(SeekFrom::Start(0)).unwrap();
+
+    let first_handle = file1.as_raw_handle();
 
     let cur_proc = GetCurrentProcess();
     let mut second_handle = mem::zeroed();
@@ -291,11 +297,15 @@ unsafe fn test_dup_handle() {
         DUPLICATE_SAME_ACCESS,
     );
     assert!(res != 0);
-    let mut file = fs::File::from_raw_handle(second_handle);
-    file.write(b"Test").unwrap();
-    // Duplicated permissions, so reading fails on the second file
-    let err = file.read(&mut [0]).unwrap_err();
-    assert_eq!(err.kind(), ErrorKind::PermissionDenied, "I/O Error wrong kind: {:?}", err);
+
+    let mut buf1 = [0; 5];
+    file1.read(&mut buf1).unwrap();
+    assert_eq!(&buf1, b"Hello");
+
+    let mut file2 = fs::File::from_raw_handle(second_handle);
+    let mut buf2 = [0; 5];
+    file2.read(&mut buf2).unwrap();
+    assert_eq!(&buf2, b", Wor");
 }
 
 unsafe fn test_file_seek() {