Bug 1736459 - Handle null RawHandles in winapi-util. r=xpcom-reviewers,nika

This works around a regression in rust 1.56's libstd.

Differential Revision: https://phabricator.services.mozilla.com/D129571

Cargo.lock

@@ -5777,8 +5777,6 @@ checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 [[package]]
 name = "winapi-util"
 version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
 dependencies = [
  "winapi",
 ]

Cargo.toml

@@ -110,3 +110,7 @@ path = "third_party/rust/mio"
 
 [patch.crates-io.prost-derive]
 path = "third_party/rust/prost-derive"
+
+# Patched to work around https://github.com/rust-lang/rust/issues/88576
+[patch.crates-io.winapi-util]
+path = "third_party/rust/winapi-util"

third_party/rust/winapi-util/src/win.rs

@@ -101,13 +101,16 @@ struct HandleRefInner(Option<File>);
 
 impl Drop for HandleRefInner {
     fn drop(&mut self) {
-        self.0.take().unwrap().into_raw_handle();
+        self.0.take().map(|f| f.into_raw_handle());
     }
 }
 
 impl AsRawHandle for HandleRef {
     fn as_raw_handle(&self) -> RawHandle {
-        self.as_file().as_raw_handle()
+        match (self.0).0.as_ref() {
+            Some(f) => f.as_raw_handle(),
+            None => std::ptr::null_mut(),
+        }
     }
 }
 
@@ -159,17 +162,11 @@ impl HandleRef {
     /// is a valid handle. The caller must ensure this is true before invoking
     /// this constructor.
     pub unsafe fn from_raw_handle(handle: RawHandle) -> HandleRef {
-        HandleRef(HandleRefInner(Some(File::from_raw_handle(handle))))
-    }
-
-    /// Return this handle as a standard `File` reference.
-    pub fn as_file(&self) -> &File {
-        (self.0).0.as_ref().unwrap()
-    }
-
-    /// Return this handle as a standard `File` mutable reference.
-    pub fn as_file_mut(&mut self) -> &mut File {
-        (self.0).0.as_mut().unwrap()
+        HandleRef(HandleRefInner(if handle.is_null() {
+            None
+        } else {
+            Some(File::from_raw_handle(handle))
+        }))
     }
 }