From: David Mitchell <davem@iabyn.com>
Date: Thu, 19 May 2016 11:03:48 +0000 (+0100)
Subject: su_uplevel: populate lower stack frames properly
X-Git-Tag: rt112246^2~13
X-Git-Url: http://git.vpit.fr/?a=commitdiff_plain;h=5736d907ca8e5e47a4c2c70564014c8b4ec4f1aa;p=perl%2Fmodules%2FScope-Upper.git

su_uplevel: populate lower stack frames properly

When creating a temporary new argument stack, su_uplevel() copies most of
the old stack to a new one. This isn't really needed, as the new stack
will be abandoned before it ever pops back to that level.  But it *is*
needed when debugging code prints out the stack, as in for example,
'perl -Dstv'.

However, the code didn't actually copy the old stack: it copied garbage
instead, since it was using PL_curstack rather than AvARRAY(PL_curstack)
as the address of of the old stack. Which was causing 'perl -Dstv' to
SEGV.

This commit fixes that.
---

diff --git a/Upper.xs b/Upper.xs
index f6e678d..f7698d8 100644
--- a/Upper.xs
+++ b/Upper.xs
@@ -1984,7 +1984,7 @@ static I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
   * target context, plus the forthcoming arguments. */
  new_mark = cx->blk_oldsp;
  av_extend(si->si_stack, new_mark + 1 + args + 1);
- Copy(PL_curstack, AvARRAY(si->si_stack), new_mark + 1, SV *);
+ Copy(AvARRAY(PL_curstack), AvARRAY(si->si_stack), new_mark + 1, SV *);
  AvFILLp(si->si_stack) = new_mark;
  SU_POISON(AvARRAY(si->si_stack) + new_mark + 1, args + 1, SV *);