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OpenSSL has an unfortunate tendency to mix per-session state error handling with per-thread error handling. This can cause problems when programs that link to libpq with OpenSSL enabled have some other use of OpenSSL; without care, one caller of OpenSSL may cause problems for the other caller. Backend code might similarly be affected, for example when a third party extension independently uses OpenSSL without taking the appropriate precautions. To fix, don't trust other users of OpenSSL to clear the per-thread error queue. Instead, clear the entire per-thread queue ahead of certain I/O operations when it appears that there might be trouble (these I/O operations mostly need to call SSL_get_error() to check for success, which relies on the queue being empty). This is slightly aggressive, but it's pretty clear that the other callers have a very dubious claim to ownership of the per-thread queue. Do this is both frontend and backend code. Finally, be more careful about clearing our own error queue, so as to not cause these problems ourself. It's possibly that control previously did not always reach SSLerrmessage(), where ERR_get_error() was supposed to be called to clear the queue's earliest code. Make sure ERR_get_error() is always called, so as to spare other users of OpenSSL the possibility of similar problems caused by libpq (as opposed to problems caused by a third party OpenSSL library like PHP's OpenSSL extension). Again, do this is both frontend and backend code. See bug #12799 and https://bugs.php.net/bug.php?id=68276 Based on patches by Dave Vitek and Peter Eisentraut. From: Peter Geoghegan <pg@bowt.ie>
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: http://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 http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.