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pgsql: Clean up a number of bogosities around pltcl's handling of the

From: tgl(at)postgresql(dot)org (Tom Lane)
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Clean up a number of bogosities around pltcl's handling of the
Date: 2008-06-17 00:52:49
Message-ID: 20080617005249.B89F5754595@cvs.postgresql.org (view raw or flat)
Thread:
Lists: pgsql-committers
Log Message:
-----------
Clean up a number of bogosities around pltcl's handling of the Tcl "result":

1. Directly reading interp->result is deprecated in Tcl 8.0 and later;
you're supposed to use Tcl_GetStringResult.  This code finally broke with
Tcl 8.5, because Tcl_GetVar can now have side-effects on interp->result even
though it preserves the logical state of the result.  (There's arguably a
Tcl issue here, because Tcl_GetVar could invalidate the pointer result of a
just-preceding Tcl_GetStringResult, but I doubt the Tcl guys will see it as
a bug.)

2. We were being sloppy about the encoding of the result: some places would
push database-encoding data into the Tcl result, which should not happen,
and we were assuming that any error result coming back from Tcl was in the
database encoding, which is not a good assumption.

3. There were a lot of calls of Tcl_SetResult that uselessly specified
TCL_VOLATILE for constant strings.  This is only a minor performance issue,
but I fixed it in passing since I had to look at all the calls anyway.

#2 is a live bug regardless of which Tcl version you are interested in,
so back-patch even to branches that are unlikely to be used with Tcl 8.5.
I went back as far as 8.0, which is as far as the patch applied easily;
7.4 was using a different error processing scheme that has got its own
problems :-(

Tags:
----
REL8_3_STABLE

Modified Files:
--------------
    pgsql/src/pl/tcl:
        pltcl.c (r1.117 -> r1.117.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/tcl/pltcl.c?r1=1.117&r2=1.117.2.1)

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