Magnus Hagander wrote:
> On Thu, Feb 3, 2011 at 04:40, Bruce Momjian <bruce@momjian.us> wrote:
> > I am seeing the following compiler warning for the past few days:
> >
> > ? ? ? ?basebackup.c:213: warning: variable `ptr' might be clobbered by
> > ? ? ? ?`longjmp' or `vfork'
> >
> > and I see this comment in the file:
> >
> > ? ? ? ?/*
> > ? ? ? ? * Actually do a base backup for the specified tablespaces.
> > ? ? ? ? *
> > ? ? ? ? * This is split out mainly to avoid complaints about "variable might be
> > ? ? ? ? * clobbered by longjmp" from stupider versions of gcc.
> > ? ? ? ? */
> >
> > Seems that isn't working as expected. ?I am using:
> >
> > ? ? ? ?gcc version 2.95.3 20010315 (release)
> >
> > with -O1.
>
> This is the same warning Tom fixed earlier. I have no idea what
> actually causes it :(
>
> I think it's somehow caused by the PG_ENSURE_ERROR_CLEANUP stuff.
> Does it go away if you break everything inside the if
> (opt->includewal) into it's own function? (Or at least everything
> except the pq_putemptymessage() call, because moving that would make
> the code very confusing)
I added the attached C comment so we know why the warning is generated.
We can remove it later if we want, but I want to have it if we get
reports about 9.1 problems.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index b5cda50..d94b61f 100644
*** a/src/backend/replication/basebackup.c
--- b/src/backend/replication/basebackup.c
*************** perform_base_backup(basebackup_options *
*** 217,222 ****
--- 217,228 ----
ptr.xlogid = logid;
ptr.xrecoff = logseg * XLogSegSize + TAR_SEND_SIZE * i;
+ /*
+ * Some old compilers, e.g. 2.95.3/x86, think that passing
+ * a struct in the same function as a longjump might clobber
+ * a variable. bjm 2011-02-04
+ * http://lists.apple.com/archives/xcode-users/2003/Dec//msg00051.html
+ */
XLogRead(buf, ptr, TAR_SEND_SIZE);
if (pq_putmessage('d', buf, TAR_SEND_SIZE))
ereport(ERROR,