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Re: [PATCH, libstdc++] Make empty std::string storage readonly
On 08/28/2012 08:12 PM, Jonathan Wakely wrote:
> On 28 August 2012 18:27, Michael Haubenwallner wrote:
>>>
>>> Does it actually produce a segfault? I suppose it might on some
>>> platforms, but not all, so I'm not sure it's worth changing.
>>
>> It does segfault here on (32bit each):
>> i686-pc-linux-gnu
>> ia64-hp-hpux11.31
>> i386-pc-solaris2.10
>> sparc-sun-solaris2.10
>> powerpc-ibm-aix5.3.0.0
>> powerpc-ibm-aix6.1.0.0
>> powerpc-ibm-aix7.1.0.0
>>
>> It does not segfault here on:
>> hppa2.0n-hp-hpux11.31
>> i586-pc-interix5.2
>> i586-pc-winnt5.2 (using MSVC)
>>
>> Maybe it could be made segfault on hppa2.0n-hp-hpux11.31 too using some linker flag,
>> but that's a deprecated platform anyway.
>>
>> As long as the major development platform (Linux) does segfault, it feels worth
>> changing - especially as string.clear() to write the '\0' back again won't help
>> as quick'n dirty workaround since gcc-4.4.4 any more.
>
> Hmm, I tested it on x86_64-unknown-linux-gnu without getting a
> segfault - but I might have messed up my test.
Using this patch on my x86_64 Gentoo Linux Desktop with gcc-4.7.1 does segfault
as expected - when I make sure the correct libstdc++ is used at runtime,
having the '_S_empty_rep_storage' symbol in the .rodata section rather than .bss.
/haubi/