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Here's a patch for Versions 1 and 2 that fixes the following bug:

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When you try to do any UPDATE of the catalog class pg_class, such as
to change ownership of a class, the backend crashes.

This is really two serial bugs: 1) there is a hardcoded copy of the
schema of pg_class in the postgres program, and it doesn't match the
actual class that initdb creates in the database; 2) Parts of postgres
determine whether to pass an attribute value by value or by reference
based on the attbyval attribute of the attribute in class
pg_attribute.  Other parts of postgres have it hardcoded.  For the
relacl[] attribute in class pg_class, attbyval does not match the
hardcoded expectation.

The fix is to correct the hardcoded schema for pg_attribute and to
change the fetchatt macro so it ignores attbyval for all variable
length attributes.  The fix also adds a bunch of logic documentation and
extends genbki.sh so it allows source files to contain such documentation.

--
Bryan Henderson                                    Phone 408-227-6803
San Jose, California
This commit is contained in:
Marc G. Fournier
1996-08-21 04:25:49 +00:00
parent 93ad36fdc2
commit 5e773a4f70
4 changed files with 96 additions and 46 deletions
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16
src/backend/access/tupmacs.h
View File

@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: tupmacs.h,v 1.1.1.1 1996/07/09 06:21:09 scrappy Exp $
* $Id: tupmacs.h,v 1.2 1996/08/21 04:25:37 scrappy Exp $
*
*-------------------------------------------------------------------------
*/
@@ -22,6 +22,12 @@
* given a AttributeTupleForm and a pointer into a tuple's data
* area, return the correct value or pointer.
*
* We return a 4 byte (char *) value in all cases. If the attribute has
* "byval" false or has variable length, we return the same pointer
* into the tuple data area that we're passed. Otherwise, we return
* the 1, 2, or 4 bytes pointed to by it, properly extended to 4
* bytes, depending on the length of the attribute.
*
* note that T must already be properly LONGALIGN/SHORTALIGN'd for
* this to work correctly.
*
@@ -30,9 +36,15 @@
* sign-extension may get weird if you use an integer type that
* isn't the same size as (char *) for the first cast. (on the other
* hand, it's safe to use another type for the (foo *)(T).)
*
* attbyval seems to be fairly redundant. We have to return a pointer if
* the value is longer than 4 bytes or has variable length; returning the
* value would be useless. In fact, for at least the variable length case,
* the caller assumes we return a pointer regardless of attbyval.
* I would eliminate attbyval altogether, but I don't know how. -BRYANH.
*/
#define fetchatt(A, T) \
((*(A))->attbyval \
((*(A))->attbyval && (*(A))->attlen != -1 \
? ((*(A))->attlen > sizeof(int16) \
? (char *) (long) *((int32 *)(T)) \
: ((*(A))->attlen < sizeof(int16) \