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Re: [bug-diffutils] [PATCH] diff: avoid possible longjmp-triggered misbe
Re: [bug-diffutils] [PATCH] diff: avoid possible longjmp-triggered misbehavior
Thu, 30 Aug 2012 07:55:51 -0700
Mozilla/5.0 (X11; Linux i686; rv:14.0) Gecko/20120714 Thunderbird/14.0
On 08/28/2012 02:08 AM, Jim Meyering wrote:
> It seems legit, but perhaps it should be complaining about "match"
> rather than "file".
I don't see why it's legit. Even if longjmp trashes
the value of 'match', the code right after the longjmp
immediately sets 'match' (there's a comment to the code
to that effect).
This bogus warning, along with the seemingly random variable
name that it mentions, may be the symptom of a deeper
problem in GCC, one that causes GCC to generate incorrect code,
so it's probably worth filing a GCC bug report.
For now I pushed this further patch into diffutils:
>From e1c27502ee286392ef2be93af752a51574930038 Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Thu, 30 Aug 2012 07:52:22 -0700
Subject: [PATCH] diff: silence GCC warning instead of slowing down
* src/dir.c (find_dir_file_pathname): Use 'IF_LINT (volatile)' to
silence the gcc warning, rather than using 'volatile', as the
warning appears to be bogus.
src/dir.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/src/dir.c b/src/dir.c
index a2f6bba..530807e 100644
@@ -323,8 +323,13 @@ dir_loop (struct comparison const *cmp, int i)
find_dir_file_pathname (char const *dir, char const *file)
+ /* The 'IF_LINT (volatile)' works around what appears to be a bug in
+ gcc 4.8.0 20120825; see
+ char const * IF_LINT (volatile) match = file;
- char const *volatile match = file;
struct dirdata dirdata;
dirdata.names = NULL;
dirdata.data = NULL;