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Tom Lane 6e9ffcf13a Harden TAP tests that intentionally corrupt page checksums.
The previous method for doing that was to write zeroes into a
predetermined set of page locations.  However, there's a roughly
1-in-64K chance that the existing checksum will match by chance,
and yesterday several buildfarm animals started to reproducibly
see that, resulting in test failures because no checksum mismatch
was reported.

Since the checksum includes the page LSN, test success depends on
the length of the installation's WAL history, which is affected by
(at least) the initial catalog contents, the set of locales installed
on the system, and the length of the pathname of the test directory.
Sooner or later we were going to hit a chance match, and today is
that day.

Harden these tests by specifically inverting the checksum field and
leaving all else alone, thereby guaranteeing that the checksum is
incorrect.

In passing, fix places that were using seek() to set up for syswrite(),
a combination that the Perl docs very explicitly warn against.  We've
probably escaped problems because no regular buffered I/O is done on
these filehandles; but if it ever breaks, we wouldn't deserve or get
much sympathy.

Although we've only seen problems in HEAD, now that we recognize the
environmental dependencies it seems like it might be just a matter
of time until someone manages to hit this in back-branch testing.
Hence, back-patch to v11 where we started doing this kind of test.

Discussion: https://postgr.es/m/3192026.1648185780@sss.pgh.pa.us
2022-03-25 14:23:26 -04:00
config Suppress warning about stack_base_ptr with late-model GCC. 2022-02-17 22:45:34 -05:00
contrib Fix default signature length for gist_ltree_ops 2022-03-16 11:41:34 +03:00
doc Doc: fix our example systemd script. 2022-03-20 12:39:53 -04:00
src Harden TAP tests that intentionally corrupt page checksums. 2022-03-25 14:23:26 -04:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.gitattributes gitattributes: Add new file 2019-11-12 08:13:55 +01:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
aclocal.m4 Probe $PROVE not $PERL while checking for modules needed by TAP tests. 2021-11-22 12:54:52 -05:00
configure configure: check for dlsym instead of dlopen. 2022-03-23 12:43:40 -07:00
configure.in configure: check for dlsym instead of dlopen. 2022-03-23 12:43:40 -07:00
COPYRIGHT Update copyright for 2022 2022-01-07 19:04:56 -05:00
GNUmakefile.in add missing tag from commit b8c4261e5e 2021-07-01 15:40:42 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Don't unset MAKEFLAGS in non-GNU Makefile. 2019-06-25 09:36:21 +12:00
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00

PostgreSQL Database Management System
=====================================

This directory contains the source code distribution of the PostgreSQL
database management system.

PostgreSQL is an advanced object-relational database management system
that supports an extended subset of the SQL standard, including
transactions, foreign keys, subqueries, triggers, user-defined types
and functions.  This distribution also contains C language bindings.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download/

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.