Re: REPOST: InitDB Failure on install

From: "Magnus Hagander" <mha(at)sollentuna(dot)net>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>, <pgsql-hackers-win32(at)postgresql(dot)org>
Subject: Re: REPOST: InitDB Failure on install
Date: 2004-08-16 20:49:28
Message-ID: 6BCB9D8A16AC4241919521715F4D8BCE4569CA@algol.sollentuna.se
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>>>> (BTW, there was some discussion around this point while
>you were gone.
>>>> Dunno if you've caught up on the list traffic yet.)
>
>> Ok. I think I'm caught up now, and I don't find anything directly
>> related to this. Could be because there was so much mail
>that I skimmed
>> some of it a bit too quickly... Could you provide me with a pointer?
>
>It took some digging, but here is the thread I had in mind:
>http://archives.postgresql.org/pgsql-hackers-win32/2004-08/msg00047.php
>http://archives.postgresql.org/pgsql-hackers-win32/2004-08/msg00050.php
>
>Life does get simpler if we can just do "errno = GetLastError()" but
>I strongly suspect we're gonna end up wanting to do some mapping.

Arrgh. I did see that one, just didn't connect. I guess the brain gets
mushy after about 2500 mails.. Sorry about that one.

Looking around a bit on the net, I see tons and tons of examples of
people just doing the "errno=GetLastError()" codepath. And I find no
evidence anywhere that this should not be safe. For winsock, look at for
example
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winsock
/winsock/error_codes_errno_h_errno_and_wsagetlasterror_2.asp which
states "For compatibility with BSD, an application may choose to include
a line of the form: #define errno WSAGetLastError". And
WSAGetLastError() is equivalent to GetLastError() in any windows these
days.

Based on this, I think we're quite safe doing errno=GetLastError() in
any places where we need it.

What we might need to do is change the useful_strerror() function to use
the FormatMessage function for all messages on win32, and not as now is
done just for winsock functions. I'm not 100% sure this is needed - it's
possible it handles all the standard messages and just not winsock. But
it should not report *incorrect* error messages, it would just not know
the text for the error message.

In order to be future safe we ight want to do something like put a macro
in win32.h doing
#define Win32ErrorToErrno(i) i
and then use
errno=Win32ErrorToErrno(GetLastError())

In case we ever need a mapping, we can just change that macro into a
function call, without needing to revisit all the code. Not sure if it's
worth it, though?

//Magnus

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