Re: Patch: Fix OS X PowerPC support

[Bruno Haible]

Sevan Janiyan wrote:
> On 10/11/2023 02:41, Sevan Janiyan wrote:
> > On 09/11/2023 23:48, Bruno Haible wrote:
> >> The patch tests MAC_OS_X_VERSION_MIN_REQUIRED in one place and
> >> MAC_OS_X_VERSION_MAX_ALLOWED in the other place. What if someone compiles
> >> for a range that includes both 10.4 and 10.5? That is,
> >>    MAC_OS_X_VERSION_MIN_REQUIRED is MAC_OS_X_VERSION_10_4
> >> and
> >>    MAC_OS_X_VERSION_MAX_ALLOWED is MAC_OS_X_VERSION_10_5 or larger.
> >> Then your patch will not define SIGSEGV_FAULT_STACKPOINTER.
> > 
> > You would be doing that on 10.5 or 10.6 and passing 
> > -mmacosx-version-min=10.4.
> > 
> > If I go about it backbackwards with ./configure 
> > CFLAGS=-mmacosx-version-min=10.5, on 10.4, build breaks with
> > sigsegv.c: In function ‘sigsegv_handler’:
> > sigsegv.c:1044: error: ‘struct mcontext’ has no member named ‘__ss’
> > 
> > 
> > On a 10.5 system, if I run ./configure CFLAGS=-mmacosx-version-min=10.4 
> > and attempt the build, everything builds & runs ok.
> > Copying the resulting binaries to 10.4 system,
> > test-sigsegv-catch-segv1 & 2 run fine.
> > 
> > test-sigsegv-catch-stackoverflow1 & 2 fail to run though, since 
> > sigaltstack variable types were changed in 10.5. I had to sidestep calls 
> > to setrlimit in the test .c files as that was the initial breakage, but 
> > not relevant to the issue.
> > 
> > test-sigsegv-catch-stackoverflow1:
> > dyld: lazy symbol binding failed: Symbol not found: _sigaltstack$UNIX2003
> >    Referenced from: /Users/sevan/./test-sigsegv-catch-stackoverflow2
> >    Expected in: /usr/lib/libSystem.B.dylib
> > 
> > dyld: Symbol not found: _sigaltstack$UNIX2003
> >    Referenced from: /Users/sevan/./test-sigsegv-catch-stackoverflow2
> >    Expected in: /usr/lib/libSystem.B.dylib
> > 
> > Trace/BPT trap
> > 
> > test-sigsegv-catch-stackoverflow2:
> > dyld: lazy symbol binding failed: Symbol not found: _sigaltstack$UNIX2003
> >    Referenced from: /Users/sevan/./test-sigsegv-catch-stackoverflow1
> >    Expected in: /usr/lib/libSystem.B.dylib
> > 
> > dyld: Symbol not found: _sigaltstack$UNIX2003
> >    Referenced from: /Users/sevan/./test-sigsegv-catch-stackoverflow1
> >    Expected in: /usr/lib/libSystem.B.dylib
> > 
> > Trace/BPT trap
> 
> How should we proceed?

I can't find the time to think through the detailed results that you listed.
I hope you can do that.

But in summary, my point was "the patch is odd, because it uses MIN in one
place and MAX in the other place" and I guessed "it will not work for a range
that includes both 10.4 and 10.5". Your answer is "this will not work anyway",
right? Did I understand it right?

If so, can you change your patch so that
  1) it is symmetric w.r.t. to MIN and MAX,
and/or
  2) it at least compiles for a range that includes both 10.4 and 10.5,
     and ideally works on 10.5? I think that would be the best behaviour
     for MacPorts/Homebrew/Fink/etc.

Bruno