perl/SOURCES/perl-5.27.5-perl-132442-Fix-stack-with-do-my-sub-l-1.patch
2021-09-10 13:23:24 +00:00

106 lines
3.1 KiB
Diff
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

From 695d6585affc8f13711f013329fb4810ab89d833 Mon Sep 17 00:00:00 2001
From: Father Chrysostomos <sprout@cpan.org>
Date: Tue, 14 Nov 2017 18:55:55 -0800
Subject: [PATCH] [perl #132442] Fix stack with do {my sub l; 1}
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
A block in perl usually compiles to a leave op with an enter inside
it, followed by the statements:
leave
enter
nextstate
... expr ...
nextstate
... expr ...
If a block contains only one statement, and that statement is suffic-
iently innocuous, then the enter/leave pair to create the scope at run
time get skipped, and instead we have a simple scope op which is not
even executed:
scope
ex-nextstate
... expr ...
The nextstate in this case also gets nulled.
In the case of do { my sub l; 1 } we were getting a variation of the
latter, that looked like this:
scope
introcv
clonecv
nextstate
... expr ...
The problem here is that nextstate resets the stack, even though a new
scope has not been pushed, so we end up with all existing stack items
from the *outer* scope getting clobbered.
One can have fun with this and erase everything pushed on to the stack
so far in a given statement:
$ ./perl -le 'print join "-", 1..10, do {my sub l; ","}, 11..20'
11,12,13,14,15,16,17,18,19,20
Here I replaced the first argument to join() from within the do{}
block, after having cleared the stack.
Why was the op tree was getting muddled up like this? The my sub
declaration does not immediately add any ops to the op tree; those ops
get added when the current scope finishing compiling, since those ops
must be inserted at the beginning of the block.
I have not fully looked into the order that things happen, and why the
nextstate op does not get nulled; but it did not matter, because of
the simple fix: Treat lexical sub declarations as not innocuous by
setting the HINT_BLOCK_SCOPE flag when a lexical sub is declared.
Thus, we end up with an enter/leave pair, which creates a
proper scope.
Signed-off-by: Petr Písař <ppisar@redhat.com>
---
op.c | 2 ++
t/op/lexsub.t | 5 ++++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/op.c b/op.c
index 8fa5aad876..c617ad2a00 100644
--- a/op.c
+++ b/op.c
@@ -9243,6 +9243,8 @@ Perl_newMYSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
PERL_ARGS_ASSERT_NEWMYSUB;
+ PL_hints |= HINT_BLOCK_SCOPE;
+
/* Find the pad slot for storing the new sub.
We cannot use PL_comppad, as it is the pad owned by the new sub. We
need to look in CvOUTSIDE and find the pad belonging to the enclos-
diff --git a/t/op/lexsub.t b/t/op/lexsub.t
index 3fa17acdda..f085cd97e8 100644
--- a/t/op/lexsub.t
+++ b/t/op/lexsub.t
@@ -7,7 +7,7 @@ BEGIN {
*bar::is = *is;
*bar::like = *like;
}
-plan 149;
+plan 150;
# -------------------- our -------------------- #
@@ -957,3 +957,6 @@ like runperl(
{
my sub h; sub{my $x; sub{h}}
}
+
+is join("-", qw(aa bb), do { my sub lleexx; 123 }, qw(cc dd)),
+ "aa-bb-123-cc-dd", 'do { my sub...} in a list [perl #132442]';
--
2.13.6