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Date: Mon, 10 Apr 2006 13:38:50 -0400
From: Christopher Faylor <cgf-no-personal-reply-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Cygwin backwards compatibility break with WinMain and GetCommandLine  (was Re: WinMain() not getting cl...)
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On Mon, Apr 10, 2006 at 09:48:10AM -0400, Igor Peshansky wrote:
>On Sun, 9 Apr 2006, Christopher Faylor wrote:
>
>> On Tue, Apr 04, 2006 at 11:44:47AM -0700, David Rothenberger wrote:
>> >WinMain() in a program compiled with cygwin1.dll is no longer
>> >getting passed the command-line from bash correctly with the
>> >20060403 snapshot. It works fine with the 20060329 snapshot.
>> >
>> >This is the same problem mentioned in
>> ><http://cygwin.com/ml/cygwin/2005-09/msg00298.html>.
>> >
>> >The same test case is attached here again (winCmdLine.c). I compile
>> >it with "gcc -o winCmdLine winCmdLine.c" (note no -mno-cygwin).
>>
>> This is due to recent changes which cause cygwin to stop filling out the
>> command-line for cygwin1.dll using programs.  We did this to fix the
>> "long command line" problem.
>>
>> There is a crude workaround for the problem which reinstates the
>> previous cygwin behavior but I really would rather not go that way.  It
>> would be nice if, just this once, we could make cygwin a little faster
>> at the expense of programs which are using a non-linux-like interface.
>>
>> So, I'm thinking that if you want your WinMain or GetCommandLine using
>> program to work with Cygwin 1.5.20 then you'll have to relink it.  I
>> realize that this is a major departure from previous stated goal of
>> maintaining backwards compatibility but we've already broken that once
>> in recent memory with the case of pure Windows environment variables so
>> I think we probably will just take the logical next step and break
>> things for WinMain and GetCommandLine as well.
>>
>> If there are a lot of programs out there which are using WinMain or
>> GetCommandLine then I guess we'll hear about it.  Otherwise, unless
>> someone can convince me that this is a bad idea, Cygwin will start
>> carrying a GetCommandLine substitute which regenerates the command line
>> from the argv list.  I have something ready to go in my sandbox now
>> but I thought I'd hold off doing this in case someone had a valid
>> objection to this approach.
>
>One argument against doing this is that people will now have to build and
>distribute 2 versions of each such program -- one that works on 1.5.20,
>and one that works on all previous versions of Cygwin.  However, I think
>there *is* a way of writing the program so that it will work on both
>versions, by using something like the following (untested) function:

This is not a problem.  GetCommandLine won't live in cygwin1.dll.  It
will live in libcygwin.a.  So, once linked, the binary will work with
any version of cygwin.

cgf

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