From 06a367c382d0a3595238eff2e777222dbc91911b Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 10 Oct 2019 14:24:56 -0400 Subject: [PATCH] Put back pqsignal() as an exported libpq symbol. This reverts commit f7ab80285. Per discussion, we can't remove an exported symbol without a SONAME bump, which we don't want to do. In particular that breaks usage of current libpq.so with pre-9.3 versions of psql etc, which need libpq to export pqsignal(). As noted in that commit message, exporting the symbol from libpgport.a won't work reliably; but actually we don't want to export src/port's implementation anyway. Any pre-9.3 client is going to be expecting the definition that pqsignal() had before 9.3, which was that it didn't set SA_RESTART for SIGALRM. Hence, put back pqsignal() in a separate source file in src/interfaces/libpq, and give it the old semantics. Back-patch to v12. Discussion: https://postgr.es/m/E1g5vmT-0003K1-6S@gemulon.postgresql.org --- src/interfaces/libpq/Makefile | 2 +- src/interfaces/libpq/exports.txt | 2 +- src/interfaces/libpq/legacy-pqsignal.c | 57 ++++++++++++++++++++++++++ 3 files changed, 59 insertions(+), 2 deletions(-) create mode 100644 src/interfaces/libpq/legacy-pqsignal.c diff --git a/src/interfaces/libpq/Makefile b/src/interfaces/libpq/Makefile index c734965d63..4b0a8c719d 100644 --- a/src/interfaces/libpq/Makefile +++ b/src/interfaces/libpq/Makefile @@ -29,7 +29,7 @@ endif OBJS= fe-auth.o fe-auth-scram.o fe-connect.o fe-exec.o fe-misc.o fe-print.o fe-lobj.o \ fe-protocol2.o fe-protocol3.o pqexpbuffer.o fe-secure.o \ - libpq-events.o + legacy-pqsignal.o libpq-events.o # src/backend/utils/mb OBJS += encnames.o wchar.o diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt index 7c808e5215..ccec59919b 100644 --- a/src/interfaces/libpq/exports.txt +++ b/src/interfaces/libpq/exports.txt @@ -116,7 +116,7 @@ PQserverVersion 113 PQgetssl 114 pg_char_to_encoding 115 pg_valid_server_encoding 116 -# pqsignal 117 # no longer exported, see libpgport instead +pqsignal 117 PQprepare 118 PQsendPrepare 119 PQgetCancel 120 diff --git a/src/interfaces/libpq/legacy-pqsignal.c b/src/interfaces/libpq/legacy-pqsignal.c new file mode 100644 index 0000000000..a56fbbce8e --- /dev/null +++ b/src/interfaces/libpq/legacy-pqsignal.c @@ -0,0 +1,57 @@ +/*------------------------------------------------------------------------- + * + * legacy-pqsignal.c + * reliable BSD-style signal(2) routine stolen from RWW who stole it + * from Stevens... + * + * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/interfaces/libpq/legacy-pqsignal.c + * + *------------------------------------------------------------------------- + */ +#include "postgres_fe.h" + +#include + + +/* + * This version of pqsignal() exists only because pre-9.3 releases + * of libpq exported pqsignal(), and some old client programs still + * depend on that. (Since 9.3, clients are supposed to get it from + * libpgport instead.) + * + * Because it is only intended for backwards compatibility, we freeze it + * with the semantics it had in 9.2; in particular, this has different + * behavior for SIGALRM than the version in src/port/pqsignal.c. + * + * libpq itself uses this only for SIGPIPE (and even then, only in + * non-ENABLE_THREAD_SAFETY builds), so the incompatibility isn't + * troublesome for internal references. + */ +pqsigfunc +pqsignal(int signo, pqsigfunc func) +{ +#ifndef WIN32 + struct sigaction act, + oact; + + act.sa_handler = func; + sigemptyset(&act.sa_mask); + act.sa_flags = 0; + if (signo != SIGALRM) + act.sa_flags |= SA_RESTART; +#ifdef SA_NOCLDSTOP + if (signo == SIGCHLD) + act.sa_flags |= SA_NOCLDSTOP; +#endif + if (sigaction(signo, &act, &oact) < 0) + return SIG_ERR; + return oact.sa_handler; +#else /* WIN32 */ + return signal(signo, func); +#endif +}