Re: [Nmh-workers] GCC 8 pre-releases have escaped...

[Bakul Shah]

On Sat, 10 Feb 2018 17:05:37 +0000 Ralph Corderoy <address@hidden> wrote:
Ralph Corderoy writes:
> 
> I built nmh git here with gc 7.6.0-1 by `cheating' with Makefile.
> 
>     AM_CFLAGS = -Dmalloc=GC_malloc -Dfree=GC_free -Drealloc=GC_realloc
>     AM_LDFLAGS = -lgc
> 
> It works!  Well, simpler programs work.  scan(1) SEGVs, ditto folder(1).

I did the same here (on FreeBSD amd64) and it too crashed.

Looking a bit deeper, I see that in mf.c:258 strdup() is
called and strdup() uses system malloc(), not GC_malloc().

So I added malloc/realloc/free in sbr/util.c, which call their
corresponding GC_ versions and verified that strdup() does
indeed call GC_malloc(). Now scan goes further but then fails
at sbr/mts.c:342 where getpwuid() is called -- which in turn
calls nsdispatch() and eventually some internal routine calls
GC_free and dies. To debug this I'd have to recompile libgc
with different flags usuch as REDIRECT_MALLOC and link to
libgc before libc. May be in future.

But this is GC, right? We don't need no stinking free()! So I 
redefined it to be

    void free(void*) {}

And the programs I tried worked fine. Running best scan time
for 200K messages, scan+gc takes 13.5 seconds while the
regular scan 7.4 seconds. Looking top, the GC version takes
27MB while the nonGC version 22MB.