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In commit 1f39a1c06 I made PQisBusy consider conn->write_failed, but that is now looking like complete brain fade. In the first place, the logic is quite wrong: it ought to be like "and not" rather than "or". This meant that once we'd gotten into a write_failed state, PQisBusy would always return true, probably causing the calling application to iterate its loop until PQconsumeInput returns a hard failure thanks to connection loss. That's not what we want: the intended behavior is to return an error PGresult, which the application probably has much cleaner support for. But in the second place, checking write_failed here seems like the wrong thing anyway. The idea of the write_failed mechanism is to postpone handling of a write failure until we've read all we can from the server; so that flag should not interfere with input-processing behavior. (Compare 7247e243a.) What we *should* check for is status = CONNECTION_BAD, ie, socket already closed. (Most places that close the socket don't touch asyncStatus, but they do reset status.) This primarily ensures that if PQisBusy() returns true then there is an open socket, which is assumed by several call sites in our own code, and probably other applications too. While at it, fix a nearby thinko in libpq's my_sock_write: we should only consult errno for res < 0, not res == 0. This is harmless since pqsecure_raw_write would force errno to zero in such a case, but it still could confuse readers. Noted by Andres Freund. Backpatch to v12 where 1f39a1c06 came in. Discussion: https://postgr.es/m/20220211011025.ek7exh6owpzjyudn@alap3.anarazel.de
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/.