Re: [ANNOUNCEMENT] TEST RELEASE: Cygwin 2.10.0-0.1

[Ken Brown <kbrown@cornell.edu>]

On 1/24/2018 7:16 PM, Yaakov Selkowitz wrote:
> On 2018-01-24 13:25, Ken Brown wrote:
>> On 1/20/2018 6:49 PM, Ken Brown wrote:
>>> On 1/20/2018 7:23 AM, Ken Brown wrote:
>>>> On 1/19/2018 10:27 PM, Ken Brown wrote:
>>>>> Here's another issue that's come up with _FORTIFY_SOURCE.  One of the
>>>>> emacs source files, fileio.c, makes use of a pointer to readlinkat.
>>>>> When _FORTIFY_SOURCE > 0, this leads to an "undefined reference to
>>>>> `__ssp_protected_readlinkat'" linking error.  Does this sound like
>>>>> something that will be fixed with the new gcc release?
>>>>
>>>> I got to this sooner than expected:
>>>>
>>>> $ cat ssp_test.c
>>>> #define  _FORTIFY_SOURCE 1
>>>> #include <unistd.h>
>>>> void foo (ssize_t (*preadlinkat) (int, char const *, char *, size_t));
>>>>
>>>> void baz ()
>>>> {
>>>>     foo (readlinkat);
>>>> }
>>
>> The following patch seems to fix the problem:
>>
>> -#define __ssp_inline extern __inline__ __attribute__((__always_inline__, __gnu_inline__))
>> +#define __ssp_inline extern __inline__ __attribute__((__always_inline__))
> 
> No, that would have other consequences:
> 
> https://gcc.gnu.org/onlinedocs/gcc/Inline.html
> 
>> I arrived at this by comparing Cygwin's ssp.h with NetBSD's, on which
>> Cygwin's was based, and I noticed that NetBSD didn't use __gnu_inline__.
> 
> The BSDs also stuck with GCC 4.2 due to licensing reasons, so you can't
> always compare.
> 
>> Yaakov, is there a reason that Cygwin needs __gnu_inline__?
> 
> Because the semantics of inline changed in GCC 4.3.
> 
>> It apparently prevents fortified functions from being used as function pointers.
> 
> I am currently testing the following, which seems to match glibc in this
> detail:
> 
> --- a/newlib/libc/include/ssp/ssp.h
> +++ b/newlib/libc/include/ssp/ssp.h
> @@ -51,7 +51,6 @@
>                  __chk_fail()
>   #define __ssp_decl(rtype, fun, args) \
>   rtype __ssp_real_(fun) args __asm__(__ASMNAME(#fun)); \
> -__ssp_inline rtype fun args __asm__(__ASMNAME("__ssp_protected_" #fun)); \
>   __ssp_inline rtype fun args
>   #define __ssp_redirect_raw(rtype, fun, args, call, cond, bos) \
>   __ssp_decl(rtype, fun, args) \

Works for me.

Ken


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