From 138903616a122dbfe57b313577a571b10d667191 Mon Sep 17 00:00:00 2001
From: psbob <178673413+psbob@users.noreply.github.com>
Date: Fri, 25 Apr 2025 10:32:24 +0100
Subject: [PATCH 1/2] Update Windows ReadFile and WriteFile to recognise Access
 Denied error when a read or write is attempted on a disconnected virtual com
 port

---
 lib/std/os/windows.zig | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/std/os/windows.zig b/lib/std/os/windows.zig
index 5a9296e889bd..d5437c5e6a58 100644
--- a/lib/std/os/windows.zig
+++ b/lib/std/os/windows.zig
@@ -602,6 +602,8 @@ pub const ReadFileError = error{
     OperationAborted,
     /// Unable to read file due to lock.
     LockViolation,
+    /// Unable to read from disconnected virtual com port
+    AccessDenied,
     Unexpected,
 };
 
@@ -634,6 +636,7 @@ pub fn ReadFile(in_hFile: HANDLE, buffer: []u8, offset: ?u64) ReadFileError!usiz
                 .HANDLE_EOF => return 0,
                 .NETNAME_DELETED => return error.ConnectionResetByPeer,
                 .LOCK_VIOLATION => return error.LockViolation,
+                .ACCESS_DENIED => return error.AccessDenied,
                 else => |err| return unexpectedError(err),
             }
         }
@@ -651,6 +654,8 @@ pub const WriteFileError = error{
     LockViolation,
     /// The specified network name is no longer available.
     ConnectionResetByPeer,
+    /// Unable to write to disconnected virtual com port
+    AccessDenied,
     Unexpected,
 };
 
@@ -687,6 +692,7 @@ pub fn WriteFile(
             .INVALID_HANDLE => return error.NotOpenForWriting,
             .LOCK_VIOLATION => return error.LockViolation,
             .NETNAME_DELETED => return error.ConnectionResetByPeer,
+            .ACCESS_DENIED => return error.AccessDenied,
             else => |err| return unexpectedError(err),
         }
     }

From f7f958c5dcc36ef394844f05238dd78ed1935bd6 Mon Sep 17 00:00:00 2001
From: psbob <178673413+psbob@users.noreply.github.com>
Date: Sat, 26 Apr 2025 08:29:21 +0100
Subject: [PATCH 2/2] Updated ReadFile and WriteFile error set comments

---
 lib/std/os/windows.zig | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/std/os/windows.zig b/lib/std/os/windows.zig
index d5437c5e6a58..e24617645a36 100644
--- a/lib/std/os/windows.zig
+++ b/lib/std/os/windows.zig
@@ -602,7 +602,8 @@ pub const ReadFileError = error{
     OperationAborted,
     /// Unable to read file due to lock.
     LockViolation,
-    /// Unable to read from disconnected virtual com port
+    /// Known to be possible when:
+    /// - Unable to read from disconnected virtual com port (Windows)
     AccessDenied,
     Unexpected,
 };
@@ -654,7 +655,8 @@ pub const WriteFileError = error{
     LockViolation,
     /// The specified network name is no longer available.
     ConnectionResetByPeer,
-    /// Unable to write to disconnected virtual com port
+    /// Known to be possible when:
+    /// - Unable to write to disconnected virtual com port (Windows)
     AccessDenied,
     Unexpected,
 };