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Heikki Linnakangas ffd080d94f libpq: Extend "read pending" check from SSL to GSS
An extra check for pending bytes in the SSL layer has been part of
pqReadReady() for a very long time (79ff2e96d). But when GSS transport
encryption was added, it didn't receive the same treatment. (As
79ff2e96d notes, "The bug that I fixed in this patch is exceptionally
hard to reproduce reliably.")

Without that check, it's possible to hit a hang in gssencmode, if the
server splits a large libpq message such that the final message in a
streamed response is part of the same wrapped token as the split
message:

    DataRowDataRowDataRowDataRowDataRowData
    -- token boundary --
    RowDataRowCommandCompleteReadyForQuery

If the split message takes up enough memory to nearly fill libpq's
receive buffer, libpq may return from pqReadData() before the later
messages are pulled out of the PqGSSRecvBuffer. Without additional
socket activity from the server, pqReadReady() (via pqSocketCheck())
will never again return true, hanging the connection.

Pull the pending-bytes check into the pqsecure API layer, where both
SSL and GSS now implement it.

Note that this does not fix the root problem! Third party clients of
libpq have no way to call pqsecure_read_is_pending() in their own
polling. This just brings the GSS implementation up to par with the
existing SSL workaround; a broader fix is left to a subsequent commit.

In preparation for the broader fix, this patch already changes the
*_read_pending() functions to return the number of bytes in the buffer
rather than just a boolean. The current callers don't need that, but
the subsequent fix will.

Author: Jacob Champion <jacob.champion@enterprisedb.com>
Discussion: https://postgr.es/m/CAOYmi%2BmpymrgZ76Jre2dx_PwRniS9YZojwH0rZnTuiGHCsj0rA%40mail.gmail.com
Backpatch-through: 14
2026-07-07 18:45:34 +03:00
.github ci: Improve ccache handling 2026-06-08 15:26:47 -04:00
config Update config.guess and config.sub 2026-04-09 11:26:14 +02:00
contrib postgres_fdw: Report ANALYZE to pgstats after importing statistics. 2026-07-07 18:40:00 +09:00
doc doc: Add reference to CREATE PROCEDURE on CREATE FUNCTION 2026-07-07 15:55:24 +02:00
src libpq: Extend "read pending" check from SSL to GSS 2026-07-07 18:45:34 +03:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Update .editorconfig and .gitattributes for postgresql.conf.sample. 2025-11-18 10:28:36 -06:00
.git-blame-ignore-revs Add commit fdad19e1cf to .git-blame-ignore-revs. 2026-07-03 14:05:21 +05:30
.gitattributes Update .editorconfig and .gitattributes for postgresql.conf.sample. 2025-11-18 10:28:36 -06:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
.mailmap Add a Git .mailmap file 2024-11-05 13:56:02 +01:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Stamp HEAD as 20devel. 2026-06-29 16:29:11 -04:00
configure.ac Stamp HEAD as 20devel. 2026-06-29 16:29:11 -04:00
COPYRIGHT Update copyright for 2026 2026-01-01 13:24:10 -05:00
GNUmakefile.in Allow selecting the git revision to be packaged by "make dist". 2024-05-03 11:08:50 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Restore AIX support. 2026-02-23 13:34:22 -05:00
meson.build Stamp HEAD as 20devel. 2026-06-29 16:29:11 -04:00
meson_options.txt Revert "Add built-in fuzzing harnesses for security testing." 2026-04-10 09:53:58 -04:00
README.md Revise the style of a paragraph in README.md. 2024-03-21 10:16:41 -05:00

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.

Copyright and license information can be found in the file COPYRIGHT.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.

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