Re: [RFC/PATCH] ignore memcmp() overreading in bsearch() callback

Jeff King [off-list ref] writes:

On Mon, Jan 14, 2013 at 03:36:21PM -0800, Junio C Hamano wrote:

quoted

It appears that memcmp() uses the usual "one word at a time"
comparison and triggers valgrind in a callback of bsearch() used in
the refname search.  I can easily trigger problems in any script
with test_commit (e.g. "sh t0101-at-syntax.sh --valgrind -i -v")
without this suppression.

Out of curiosity, what platform do you see this on? I can't reproduce on
glibc.

    Debian GNU/Linux 6.0.6 (squeeze), on Linux 2.6.32-5-amd64.
    libc-bin              2.11.3-4
    valgrind-3.6.0.SVN-Debian
    gcc                   4:4.4.5-1

quoted

diff --git a/t/valgrind/default.supp b/t/valgrind/default.supp
index 0a6724f..032332f 100644
--- a/t/valgrind/default.supp
+++ b/t/valgrind/default.supp

@@ -49,3 +49,11 @@
 	Memcheck:Addr4
 	fun:copy_ref
 }
+
+{
+	ignore-memcmp-reading-too-much-in-bsearch-callback
+	Memcheck:Addr4
+	fun:ref_entry_cmp_sslice
+	fun:bsearch
+	fun:search_ref_dir
+}

Given that it is valgrind-clean on my platform, and reading the code I
don't see any problems, I think it probably is a false positive, and
this suppression makes sense.

Thanks for a sanity check.