126 lines
3.3 KiB
C
126 lines
3.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* pqsignal.c
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* reliable BSD-style signal(2) routine stolen from RWW who stole it
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* from Stevens...
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*
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/libpq/pqsignal.c,v 1.19 2001/02/10 02:31:26 tgl Exp $
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*
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* NOTES
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* This shouldn't be in libpq, but the monitor and some other
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* things need it...
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*
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* A NOTE ABOUT SIGNAL HANDLING ACROSS THE VARIOUS PLATFORMS.
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*
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* config.h defines the macro HAVE_POSIX_SIGNALS for some platforms and
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* not for others. This file and pqsignal.h use that macro to decide
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* how to handle signalling.
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*
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* signal(2) handling - this is here because it affects some of
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* the frontend commands as well as the backend server.
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*
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* Ultrix and SunOS provide BSD signal(2) semantics by default.
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*
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* SVID2 and POSIX signal(2) semantics differ from BSD signal(2)
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* semantics. We can use the POSIX sigaction(2) on systems that
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* allow us to request restartable signals (SA_RESTART).
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*
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* Some systems don't allow restartable signals at all unless we
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* link to a special BSD library.
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*
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* We devoutly hope that there aren't any systems that provide
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* neither POSIX signals nor BSD signals. The alternative
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* is to do signal-handler reinstallation, which doesn't work well
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* at all.
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* ------------------------------------------------------------------------*/
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#include "postgres.h"
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#include <signal.h>
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#include "libpq/pqsignal.h"
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/*
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* Initialize BlockSig and UnBlockSig.
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*
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* BlockSig is the set of signals to block when we are trying to block
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* signals. This includes all signals we normally expect to get, but NOT
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* signals that should never be turned off.
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*
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* UnBlockSig is the set of signals to block when we don't want to block
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* signals (is this ever nonzero??)
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*/
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void
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pqinitmask(void)
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{
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#ifdef HAVE_SIGPROCMASK
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sigemptyset(&UnBlockSig);
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sigfillset(&BlockSig);
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/*
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* Unmark those signals that should never be blocked.
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* Some of these signal names don't exist on all platforms. Most do,
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* but might as well ifdef them all for consistency...
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*/
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#ifdef SIGTRAP
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sigdelset(&BlockSig, SIGTRAP);
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#endif
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#ifdef SIGABRT
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sigdelset(&BlockSig, SIGABRT);
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#endif
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#ifdef SIGILL
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sigdelset(&BlockSig, SIGILL);
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#endif
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#ifdef SIGFPE
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sigdelset(&BlockSig, SIGFPE);
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#endif
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#ifdef SIGSEGV
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sigdelset(&BlockSig, SIGSEGV);
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#endif
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#ifdef SIGBUS
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sigdelset(&BlockSig, SIGBUS);
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#endif
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#ifdef SIGSYS
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sigdelset(&BlockSig, SIGSYS);
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#endif
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#ifdef SIGCONT
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sigdelset(&BlockSig, SIGCONT);
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#endif
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#else
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UnBlockSig = 0;
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BlockSig = sigmask(SIGHUP) | sigmask(SIGQUIT) |
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sigmask(SIGTERM) | sigmask(SIGALRM) |
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sigmask(SIGINT) | sigmask(SIGUSR1) |
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sigmask(SIGUSR2) | sigmask(SIGCHLD) |
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sigmask(SIGWINCH) | sigmask(SIGFPE);
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#endif
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}
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/*
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* Set up a signal handler
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*/
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pqsigfunc
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pqsignal(int signo, pqsigfunc func)
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{
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#if !defined(HAVE_POSIX_SIGNALS)
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return signal(signo, func);
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#else
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struct sigaction act,
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oact;
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act.sa_handler = func;
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sigemptyset(&act.sa_mask);
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act.sa_flags = 0;
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if (signo != SIGALRM)
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act.sa_flags |= SA_RESTART;
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if (sigaction(signo, &act, &oact) < 0)
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return SIG_ERR;
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return oact.sa_handler;
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#endif /* !HAVE_POSIX_SIGNALS */
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}
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