Crate win_error_codes 

The numbers Windows reports failure in, as types.

Windows reports a failure as a number, and which number space it is in is not in the number. A DWORD from GetLastError is one; a LONG from a registry call is the same space in a signed carrier; an HRESULT is another, signed and carrying severity and facility bits; and an NTSTATUS is a third, signed, with a two-bit severity and a facility of its own. Crates here each kept a bare u32 or wrote a Win32Error of their own, and the two that did disagreed about what to do with a code of 2^31 or more – which exist: the virtdisk errors are WIN32_ERRORs such as ERROR_VIRTDISK_NOT_VIRTUAL_DISK, 3225026581.

This crate gives each number space its own type, so a code is never a bare integer whose space the reader has to guess, and so the conversion to and from std::io::Error is written once and is exact for every code.

The decisions behind it are in the crate’s DESIGN-NOTES.md. The types carry what Windows said and nothing else: no code is mapped onto a friendlier taxonomy, and no named constants are defined here, because windows-sys has them.

The numbers and their conversions build on every target. The bridge to std::io::Error is cfg(windows), because off Windows a raw OS error is an errno and reading one as a Win32 code would be a wrong answer and not a missing feature.

Structs

HResult

An HRESULT, the signed code COM and much of the Windows API report in.

LStatus

A Win32 error code in a signed carrier: the LONG that LSTATUS is, which the registry calls (RegOpenKeyExW and the rest) return.

NtStatus

An NTSTATUS, the signed status the native API and the drivers beneath it report in.

Win32Error

A Win32 error code, exactly as Windows produced it.

Enums

NtSeverity

How bad an NTSTATUS is, from its top two bits.