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/*-------------------------------------------------------------------------
*
* pqsignal.c
* reliable BSD-style signal(2) routine stolen from RWW who stole it
* from Stevens...
*
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/port/pqsignal.c
*
* A NOTE ABOUT SIGNAL HANDLING ACROSS THE VARIOUS PLATFORMS.
*
* pg_config.h defines the macro HAVE_POSIX_SIGNALS for some platforms and
* not for others. We use that here to decide how to handle signalling.
*
* Ultrix and SunOS provide BSD signal(2) semantics by default.
*
* SVID2 and POSIX signal(2) semantics differ from BSD signal(2)
* semantics. We can use the POSIX sigaction(2) on systems that
* allow us to request restartable signals (SA_RESTART).
*
* Some systems don't allow restartable signals at all unless we
* link to a special BSD library.
*
* We devoutly hope that there aren't any Unix-oid systems that provide
* neither POSIX signals nor BSD signals. The alternative is to do
* signal-handler reinstallation, which doesn't work well at all.
*
* Windows, of course, is resolutely in a class by itself. In the backend,
* we don't use this file at all; src/backend/port/win32/signal.c provides
* pqsignal() for the backend environment. Frontend programs can use
* this version of pqsignal() if they wish, but beware that Windows
* requires signal-handler reinstallation, because indeed it provides
* neither POSIX signals nor BSD signals :-(
* ------------------------------------------------------------------------
*/
#include "c.h"
#include <signal.h>
#if !defined(WIN32) || defined(FRONTEND)
/*
* Set up a signal handler for signal "signo"
*
* Returns the previous handler.
*/
pqsigfunc
pqsignal(int signo, pqsigfunc func)
{
#if !defined(HAVE_POSIX_SIGNALS)
return signal(signo, func);
#else
struct sigaction act,
oact;
act.sa_handler = func;
sigemptyset(&act.sa_mask);
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;
#endif /* !HAVE_POSIX_SIGNALS */
}
#endif /* !defined(WIN32) || defined(FRONTEND) */
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