Re: Extend win32 error codes to errno mapping in win32error.c

On Tue, Sep 27, 2022 at 03:23:04PM +0530, Bharath Rupireddy wrote:
> The failure occurs in dosmaperr() in win32error.c due to an unmapped
> errno for win32 error code. The error code 123 i.e. ERROR_INVALID_NAME
> says "The file name, directory name, or volume label syntax is
> incorrect." [2], the closest errno mapping would be ENOENT. I quickly
> looked around for the other win32 error codes [2] that don't have
> mapping.

> I filtered out some common error codes such as
> ERROR_OUTOFMEMORY, ERROR_HANDLE_DISK_FULL, ERROR_INSUFFICIENT_BUFFER,
> ERROR_NOACCESS. There may be many more, but these seemed common IMO.
>
> Having a right errno mapping always helps recognize the errors correctly.

One important thing, in my opinion, when it comes to updating this
table, is that it could be better to report the original error number
if errno can be somewhat confusing for the mapping. It is also less
interesting to increase the size of the table for errors that cannot
be reached, or related to system calls we don't use.

ERROR_INVALID_NAME => ENOENT
Yeah, this mapping looks fine.

ERROR_HANDLE_DISK_FULL => ENOSPC
This one maps to various Setup*Error(), as well as
GetDiskFreeSpaceEx(). The former is not interesting, but I can buy
the case of the former for extension code (I've played with that in
the past on WIN32, actually).

ERROR_OUTOFMEMORY => ENOMEM
ERROR_NOACCESS => EACCES
ERROR_INSUFFICIENT_BUFFER => EINVAL
Hmm. I have looked at our WIN32 system calls and the upstream docs,
but these do not seem to be reachable in our code.
--
Michael