pgsql: Prevent using strncpy with src == dest in TupleDescInitEntry. - Mailing list pgsql-committers

From Tom Lane
Subject pgsql: Prevent using strncpy with src == dest in TupleDescInitEntry.
Date
Msg-id E1VaxVb-0003cR-Bk@gemulon.postgresql.org
Whole thread Raw
List pgsql-committers
Prevent using strncpy with src == dest in TupleDescInitEntry.

The C and POSIX standards state that strncpy's behavior is undefined when
source and destination areas overlap.  While it remains dubious whether any
implementations really misbehave when the pointers are exactly equal, some
platforms are now starting to force the issue by complaining when an
undefined call occurs.  (In particular OS X 10.9 has been seen to dump core
here, though the exact set of circumstances needed to trigger that remain
elusive.  Similar behavior can be expected to be optional on Linux and
other platforms in the near future.)  So tweak the code to explicitly do
nothing when nothing need be done.

Back-patch to all active branches.  In HEAD, this also lets us get rid of
an exception in valgrind.supp.

Per discussion of a report from Matthias Schmitt.

Branch
------
REL9_2_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/a37f94ae4106634babe53a30a0cfc80380c12431

Modified Files
--------------
src/backend/access/common/tupdesc.c |   14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)


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