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From "Steve Hay" <>
Subject RE: VS2010 release builds of Apache/mod_perl crash on Vista/2008/Win7
Date Fri, 04 Feb 2011 23:45:34 GMT
William A. Rowe Jr. wrote on 2011-02-04:
> On 2/4/2011 3:49 PM, Steve Hay wrote:
>> Yes, Apache, Perl and mod_perl were all brand-new builds done one
> immediately after another on the same machine, using the same VS2010
> installation for them all.
> I presume by Apache you mean httpd as well as apr and apr-util, etc.

Yes, the full built with "nmake /f installr".

>> Also, note that the test.cpp program that I attached in my original
> post (which you've quoted the stack trace from above) is a self-
> contained standalone program, not linked to anything other than
> standard MS libraries. The functions in it are copied directly from the
> APR code with just minor renaming, macro expansion and comment removal.
> Ack.
>> Actually, there is one comment in httpd-
>> 2.2.17\srclib\apr\misc\win32\apr_app.c that sounds very pertinent:
>>  *   _dbg_malloc/realloc is used in place of the usual API, in order
>>  *   to convince the MSVCRT that it created these entities.  If we
>>  *   do not create them as _CRT_BLOCK entities, the crt will fault
>>  *   on an assert.  We are not worrying about the crt's locks here,
>>  *   since we are single threaded [so far].
>> It looks like the original environ[] was allocated by msvcr100.dll
> using something other than a function matching the HeapFree() function
> where the crash finally happens. The CRT code is trying to free the
> existing PATH in its environment before setting the new value coming
> from _putenv(), and it is that free that crashes, presumably because the
> APR re-processing of the environ entities didn't fool MSVCRT well enough?
> That makes sense, and it should be easy to make that conditional on the
> vc version.
> Now the question is where were these allocated from in MSVCR100?  Only
> a trip through
> the crt sources will help out, there.

Indeed, but looking through the VS2010 CRT source code the environment seems to be initialized
in stdenvp.c using _calloc_crt, which should match the _free_crt call in setenv.c line 211
where it all goes wrong, so I'm confused why it's crashing. The VS2008 CRT source code looks
the same in this area too.
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