bug#24703: Store references in 8-byte chunks in compiled code

[Ludovic Courtès]

Leo Famulari <address@hidden> skribis:

> On Mon, Oct 17, 2016 at 11:36:57PM -0400, Mark H Weaver wrote:
>> I've been investigating another approach: to enhance our scanner and
>> grafter to handle these 8-byte-chunked references.  I believe it is
>> feasible, but only if we abandon the ability to change the file names of
>> grafts outside of the hash.  The reason is that the hash portion of
>> store references are surrounded by enough other known characters on both
>> sides that the hash portion is almost always contained entirely within
>> 8-byte chunks.
>> 
>> To be continued...
>
> Any progress?

I built GCC 5.3 with the patch I posted just to notice that it had no
effect (according to ‘ltrace’ it never goes through the
getenv("NIX_STORE") call that the patch adds.)

I plan to investigate further Real Soon.

> If not, I think we should start making a list of packages affected by
> the bug in order to prepare a -fno-builtin-strcpy branch.

Yeah it would be nice to identify these packages.

I’d prefer the GCC patch over -fno-builtin-strcpy because the latter is
hacky and potentially misses the issue when it occurs with other
builtins.

Either way, we’ll have to rebuild a lot of things.

Ludo’.