This is the mail archive of the cygwin-apps mailing list for the Cygwin project.
Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|
Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |
Other format: | [Raw text] |
On Aug 9 12:55, Christopher Faylor wrote: > 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 > >digest > >>>> 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.cc (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 > >limited > >>> 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 > >do > >> pretty much the same thing? > >> > >> + std::ostringstream hexdigest; > >> + return hexdigest.str(); > > > >According to this: > > > >http://stackoverflow.com/questions/275214/scope-and-return-values-in-c > > > >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? Not quite. ostringstream::str returns string, the string constructor implicitely returns string&. It's sometimes tricky to wrap the brain around the differences as far as the scope is concerned. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
Attachment:
pgp7gpXQ4imWl.pgp
Description: PGP signature
Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|
Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |