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Re: [PATCH] setup.exe SEGV on WinXP/Pro

On Fri, Aug 09, 2013 at 11:01:32AM -0500, Thrall, Bryan wrote:
>Christopher Faylor wrote on 2013-08-09:
>> On Fri, Aug 09, 2013 at 11:07:26AM +0200, Corinna Vinschen wrote:
>>> On Aug  8 20:34, Achim Gratz wrote:
>>>> I've been having sporadic SEGV on WinXP/Pro just after the MD5 of a
>>>> package was checked that used to clear up after a reboot.  Today,
>with a
>>>> freshly built setup.exe this failure was now entirely reproduceable.
>>>> I've fixed it by reimplementing the string formatting for the MD5
>>>> using C++ stream functions.
>>>>> From 677e2e89d1e4046c967dd1759ac53116f6643bd9 Mon Sep 17
>> 00:00:00 2001
>>>> From: Achim Gratz <Stromeko@Stromeko.DE>
>>>> Date: Thu, 8 Aug 2013 20:23:31 +0200
>>>> Subject: [PATCH] fix SEGV on WinXP/Pro
>>>>     * csu_util/ (MD5Sum::operator std::string() const):
>>>>     Reimplement using stringstream to avoid a SEGV on WinXP/Pro.
>>> Patch applied.
>>>> -  return std::string(hexdigest);
>>>     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>> I'm wondering if that was the problem.  This expression constructs a
>>> std:string and then immediately destructs it since the scope is
>>> to the end of the function (which the return statement is all about).
>>> Reading the value of this object in the parent function is basically
>>> luck, isn't it?
>> Sheesh.  Yes, that looks like the problem.  But doesn't the new code
>> pretty much the same thing?
>> +  std::ostringstream hexdigest;
>> +  return hexdigest.str();
>According to this:
>Returning the object should be ok because it is copied before leaving
>the function scope; returning a reference or pointer to the object is
>where you get into problems.

Thanks for clarifying.  Isn't that what the original code did too then?


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