Ken Brown kbrown@cornell.edu
Sat Jan 20 03:27:00 GMT 2018

On 1/18/2018 6:28 PM, Ken Brown wrote:
> On 1/18/2018 4:30 PM, Yaakov Selkowitz wrote:
>> On 2018-01-18 08:35, Ken Brown wrote:
>>> On 1/17/2018 5:29 PM, Ken Brown wrote:
>>>> Do we need a new gcc release to go along with the recent ssp changes?
>>> The following commit message seems to answer my question:
>>>      Note that this does require building gcc with --disable-libssp and
>>>      gcc_cv_libc_provides_ssp=yes.
>> Correct.
>>> Are there plans to coordinate the release of Cygwin 2.10.0 with a new
>>> gcc release?  In the meantime, I guess package maintainers have to build
>>> with -U_FORTIFY_SOURCE in order to test building with Cygwin 2.10.0.  Or
>>> am I missing something?
>> -D_FORTIFY_SOURCE is not the default, so simply omitting it is
>> sufficient.
> I was talking about building projects in which _FORTIFY_SOURCE is 
> defined by default.  That happens, for instance, in the gnulib 
> subdirectory of the emacs tree, so it may affect other projects that use 
> gnulib also.
>> You could also just delete
>> /usr/lib/gcc/*-pc-cygwin/6.4.0/include/ssp, since we won't need it
>> anymore and it wasn't even being used properly in the first place.
> That's a simpler workaround than what I was doing.  Thanks.

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. 
[More precisely, the file uses an external function foo() with a 
parameter 'bar' that's a pointer to a function; foo is called in 
fileio.c with bar = 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 realize I haven't given you full details, but it might be a few days 
until I have a chance to extract an STC for this issue, so I thought I'd 
give it a shot.

If you can't answer the question based on the information above, I'll 
make an STC as soon as I can.


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