147 lines
3.6 KiB
C
147 lines
3.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* pqsignal.c
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* Backend signal(2) support (see also src/port/pqsignal.c)
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*
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* Portions Copyright (c) 1996-2019, 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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* src/backend/libpq/pqsignal.c
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*
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* ------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "libpq/pqsignal.h"
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/* Global variables */
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sigset_t UnBlockSig,
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BlockSig,
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StartupBlockSig;
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/*
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* Initialize BlockSig, UnBlockSig, and StartupBlockSig.
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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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* StartupBlockSig is the set of signals to block during startup packet
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* collection; it's essentially BlockSig minus SIGTERM, SIGQUIT, SIGALRM.
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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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sigemptyset(&UnBlockSig);
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/* First set all signals, then clear some. */
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sigfillset(&BlockSig);
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sigfillset(&StartupBlockSig);
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/*
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* Unmark those signals that should never be blocked. Some of these signal
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* names don't exist on all platforms. Most do, but might as well ifdef
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* 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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sigdelset(&StartupBlockSig, SIGTRAP);
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#endif
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#ifdef SIGABRT
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sigdelset(&BlockSig, SIGABRT);
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sigdelset(&StartupBlockSig, SIGABRT);
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#endif
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#ifdef SIGILL
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sigdelset(&BlockSig, SIGILL);
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sigdelset(&StartupBlockSig, SIGILL);
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#endif
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#ifdef SIGFPE
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sigdelset(&BlockSig, SIGFPE);
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sigdelset(&StartupBlockSig, SIGFPE);
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#endif
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#ifdef SIGSEGV
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sigdelset(&BlockSig, SIGSEGV);
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sigdelset(&StartupBlockSig, SIGSEGV);
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#endif
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#ifdef SIGBUS
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sigdelset(&BlockSig, SIGBUS);
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sigdelset(&StartupBlockSig, SIGBUS);
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#endif
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#ifdef SIGSYS
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sigdelset(&BlockSig, SIGSYS);
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sigdelset(&StartupBlockSig, SIGSYS);
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#endif
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#ifdef SIGCONT
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sigdelset(&BlockSig, SIGCONT);
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sigdelset(&StartupBlockSig, SIGCONT);
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#endif
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/* Signals unique to startup */
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#ifdef SIGQUIT
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sigdelset(&StartupBlockSig, SIGQUIT);
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#endif
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#ifdef SIGTERM
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sigdelset(&StartupBlockSig, SIGTERM);
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#endif
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#ifdef SIGALRM
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sigdelset(&StartupBlockSig, SIGALRM);
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#endif
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}
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/*
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* Set up a postmaster signal handler for signal "signo"
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*
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* Returns the previous handler.
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*
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* This is used only in the postmaster, which has its own odd approach to
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* signal handling. For signals with handlers, we block all signals for the
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* duration of signal handler execution. We also do not set the SA_RESTART
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* flag; this should be safe given the tiny range of code in which the
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* postmaster ever unblocks signals.
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*
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* pqinitmask() must have been invoked previously.
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*
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* On Windows, this function is just an alias for pqsignal()
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* (and note that it's calling the code in src/backend/port/win32/signal.c,
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* not src/port/pqsignal.c). On that platform, the postmaster's signal
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* handlers still have to block signals for themselves.
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*/
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pqsigfunc
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pqsignal_pm(int signo, pqsigfunc func)
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{
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#ifndef WIN32
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struct sigaction act,
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oact;
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act.sa_handler = func;
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if (func == SIG_IGN || func == SIG_DFL)
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{
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/* in these cases, act the same as pqsignal() */
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sigemptyset(&act.sa_mask);
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act.sa_flags = SA_RESTART;
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}
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else
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{
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act.sa_mask = BlockSig;
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act.sa_flags = 0;
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}
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#ifdef SA_NOCLDSTOP
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if (signo == SIGCHLD)
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act.sa_flags |= SA_NOCLDSTOP;
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#endif
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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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#else /* WIN32 */
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return pqsignal(signo, func);
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#endif
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}
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