Subject: pgsql: Fix gai_strerror() thread-safety on Windows.

From: Thomas Munro <[email-masked]>
Date: Sun, 11 Feb 2024 22:18:00 +0000

Fix gai_strerror() thread-safety on Windows.

Commit 5579388d removed code that supplied a fallback implementation of
getaddrinfo(), which was dead code on modern systems.  One tiny piece of
the removed code was still doing something useful on Windows, though:
that OS's own gai_strerror()/gai_strerrorA() function returns a pointer
to a static buffer that it overwrites each time, so it's not
thread-safe.  In rare circumstances, a multi-threaded client program
could get an incorrect or corrupted error message.

Restore the replacement gai_strerror() function, though now that it's
only for Windows we can put it into a win32-specific file and cut it
down to the errors that Windows documents.  The error messages here are
taken from FreeBSD, because Windows' own messages seemed too verbose.

Back-patch to 16.

Reviewed-by: Kyotaro Horiguchi <[email-masked]>
Discussion: https://postgr.es/m/CA%2BhUKGKz%2BF9d2PTiXwfYV7qJw%2BWg2jzACgSDgPizUw7UG%3Di58A%40mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/65f438471b769f6b9706a386028f81df065d0a25

Modified Files
--------------
configure                           |  6 +++++
configure.ac                        |  1 +
src/include/port/win32/sys/socket.h |  8 +++++++
src/port/meson.build                |  1 +
src/port/win32gai_strerror.c        | 45 +++++++++++++++++++++++++++++++++++++
5 files changed, 61 insertions(+)