PARI/GP Bug report logs - #1237
undefined behaviour in pari_init_parser

Package: pari; Maintainer for pari is Aurel Page <aurel.page@normalesup.org>; Source for pari is src:pari.

Reported by: Julian Taylor <jtaylor.debian@googlemail.com>

Date: Wed, 31 Aug 2011 15:33:08 UTC

Severity: normal

Done: Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>

Bug is archived. No further changes may be made.

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Subject: Bug#1237: undefined behaviour in pari_init_parser
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From: Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>
To: Julian Taylor <jtaylor.debian@googlemail.com>,
	1237@pari.math.u-bordeaux.fr
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On Mon, Sep 19, 2011 at 11:23:59PM +0200, Julian Taylor wrote:
> On 09/18/2011 11:47 PM, Bill Allombert wrote:
> >>
> >> unfortunately it still fails with the same issue in my qemu armel chroot
> >> on ubuntu oneiric which has pretty much the same gcc version as debian
> >> (4.6-9ubuntu3).
> >> I don't understand why.
> > 
> > Can you check with the debugger whether it is not a different instance of the same
> > issue ? The function pari_init_parser has a similar issue.
> > 
> > Cheers,
> > Bill.
> 
> doing the same thing for pari_init_parser does fix the problem in my
> armel emulation but one must mess with the pari_tree variable which
> probably breaks api.
> Maybe some header restructuring + a macro can retain it.
> See attached patch which should not break api but it does break abi and
> is really ugly :/

Yes, this breaks the ABI. What you can do instead is leverage the fact that
s_node is static, so only this file can change pari_tree.
So you can create a 

static THREAD struct
{
  node * n;
  pari_stack s;
} tree;

and set pari_tree = tree.n before calling optimizenode() in pari_compile_str.

But probably a simpler and more robust fix would be to stop inlining stack_init
by moving it to a regular C file that preferably do not use it.

Cheers,
Bill.

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Bill Allombert <allomber@math.u-bordeaux.fr>. Last modified: Sat Aug 26 17:15:14 2023; Machine Name: pari

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