Go to file
Thomas Munro fef8c7a0c5 Harden dsm_impl.c against unexpected EEXIST.
Previously, we trusted the OS not to report EEXIST unless we'd passed in
IPC_CREAT | IPC_EXCL or O_CREAT | O_EXCL, as appropriate.  Solaris's
shm_open() can in fact do that, causing us to crash because we didn't
ereport and then we blithely assumed the mapping was successful.

Let's treat EEXIST just like any other error, unless we're actually
trying to create a new segment.  This applies to shm_open(), where this
behavior has been seen, and also to the equivalent operations for our
sysv and mmap modes just on principle.

Based on the underlying reason for the error, namely contention on a
lock file managed by Solaris librt for each distinct name, this problem
is only likely to happen on 15 and later, because the new shared memory
stats system produces shm_open() calls for the same path from
potentially large numbers of backends concurrently during
authentication.  Earlier releases only shared memory segments between a
small number of parallel workers under one Gather node.  You could
probably hit it if you tried hard enough though, and we should have been
more defensive in the first place.  Therefore, back-patch to all
supported releases.

Per build farm animal margay.  This isn't the end of the story, though,
it just changes random crashes into random "File exists" errors; more
work needed for a green build farm.

Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGKqKrCV5xKWfh9rnm%3Do%3DDwZLTLtnsj_XpUi9g5%3DV%2B9oyg%40mail.gmail.com
2022-07-01 13:15:17 +12:00
config Pre-beta mechanical code beautification. 2022-05-12 15:17:30 -04:00
contrib CREATE INDEX: use the original userid for more ACL checks. 2022-06-25 09:07:41 -07:00
doc relnotes: update item about public schema permission change 2022-06-28 16:35:32 -04:00
src Harden dsm_impl.c against unexpected EEXIST. 2022-07-01 13:15:17 +12:00
.cirrus.yml Make upgradecheck a no-op in MSVC's vcregress.pl 2022-04-02 12:06:11 +09:00
.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
.git-blame-ignore-revs Add 82d0ffae3 to git-blame-ignore-revs. 2022-06-30 11:08:12 -04:00
.gitattributes Remove trailing whitespace from *.sgml files. 2022-04-20 11:04:49 -04:00
.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 Stamp 15beta2. 2022-06-27 16:11:56 -04:00
configure.ac Stamp 15beta2. 2022-06-27 16:11:56 -04:00
COPYRIGHT Update copyright for 2022 2022-01-07 19:04:57 -05:00
GNUmakefile.in Run tests of libpq on installcheck-world, checkprep and check-world 2022-06-03 13:15:20 +09:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Dynamically find correct installation docs in Makefile. 2022-01-19 14:48:25 +01:00
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/.