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Tom Lane 48d67fd897 Fix race condition in psql \e's detection of file modification.
psql's editing commands decide whether the user has edited the file
by checking for change of modification timestamp.  This is probably
fine for a pre-existing file, but with a temporary file that is
created within the command, it's possible for a fast typist to
save-and-exit in less than the one-second granularity of stat(2)
timestamps.  On Windows FAT filesystems the granularity is even
worse, 2 seconds, making the race a bit easier to hit.

To fix, try to set the temp file's mod time to be two seconds ago.
It's unlikely this would fail, but then again the race condition
itself is unlikely, so just ignore any error.

Also, we might as well check the file size as well as its mod time.

While this is a difficult bug to hit, it still seems worth
back-patching, to ensure that users' edits aren't lost.

Laurenz Albe, per gripe from Jacob Champion; based on fix suggestions
from Jacob and myself

Discussion: https://postgr.es/m/0ba3f2a658bac6546d9934ab6ba63a805d46a49b.camel@cybertec.at
2021-03-12 12:20:15 -05:00
config Update copyright for 2021 2021-01-02 13:06:25 -05:00
contrib Revert changes for SSL compression in libpq 2021-03-10 09:35:42 +09:00
doc Forbid marking an identity column as nullable. 2021-03-12 11:08:42 -05:00
src Fix race condition in psql \e's detection of file modification. 2021-03-12 12:20:15 -05:00
.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 Remove configure-time probe for DocBook DTD. 2020-11-30 15:24:13 -05:00
configure Add missing pthread_barrier_t. 2021-03-10 17:44:04 +13:00
configure.ac Add missing pthread_barrier_t. 2021-03-10 17:44:04 +13:00
COPYRIGHT Update copyright for 2021 2021-01-02 13:06:25 -05:00
GNUmakefile.in Make install-tests target work with vpath builds 2020-05-31 18:33:00 -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/.