1 files changed, 148 insertions, 0 deletions
diff --git a/src/backend/libpq/pqsignal.c b/src/backend/libpq/pqsignal.c
new file mode 100644
index 0000000..26ed671
--- /dev/null
+++ b/src/backend/libpq/pqsignal.c
@@ -0,0 +1,148 @@
+/*-------------------------------------------------------------------------
+ *
+ * pqsignal.c
+ *	  Backend signal(2) support (see also src/port/pqsignal.c)
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/libpq/pqsignal.c
+ *
+ * ------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "libpq/pqsignal.h"
+
+
+/* Global variables */
+sigset_t	UnBlockSig,
+			BlockSig,
+			StartupBlockSig;
+
+
+/*
+ * Initialize BlockSig, UnBlockSig, and StartupBlockSig.
+ *
+ * BlockSig is the set of signals to block when we are trying to block
+ * signals.  This includes all signals we normally expect to get, but NOT
+ * signals that should never be turned off.
+ *
+ * StartupBlockSig is the set of signals to block during startup packet
+ * collection; it's essentially BlockSig minus SIGTERM, SIGQUIT, SIGALRM.
+ *
+ * UnBlockSig is the set of signals to block when we don't want to block
+ * signals.
+ */
+void
+pqinitmask(void)
+{
+	sigemptyset(&UnBlockSig);
+
+	/* Note: InitializeLatchSupport() modifies UnBlockSig. */
+
+	/* First set all signals, then clear some. */
+	sigfillset(&BlockSig);
+	sigfillset(&StartupBlockSig);
+
+	/*
+	 * Unmark those signals that should never be blocked. Some of these signal
+	 * names don't exist on all platforms.  Most do, but might as well ifdef
+	 * them all for consistency...
+	 */
+#ifdef SIGTRAP
+	sigdelset(&BlockSig, SIGTRAP);
+	sigdelset(&StartupBlockSig, SIGTRAP);
+#endif
+#ifdef SIGABRT
+	sigdelset(&BlockSig, SIGABRT);
+	sigdelset(&StartupBlockSig, SIGABRT);
+#endif
+#ifdef SIGILL
+	sigdelset(&BlockSig, SIGILL);
+	sigdelset(&StartupBlockSig, SIGILL);
+#endif
+#ifdef SIGFPE
+	sigdelset(&BlockSig, SIGFPE);
+	sigdelset(&StartupBlockSig, SIGFPE);
+#endif
+#ifdef SIGSEGV
+	sigdelset(&BlockSig, SIGSEGV);
+	sigdelset(&StartupBlockSig, SIGSEGV);
+#endif
+#ifdef SIGBUS
+	sigdelset(&BlockSig, SIGBUS);
+	sigdelset(&StartupBlockSig, SIGBUS);
+#endif
+#ifdef SIGSYS
+	sigdelset(&BlockSig, SIGSYS);
+	sigdelset(&StartupBlockSig, SIGSYS);
+#endif
+#ifdef SIGCONT
+	sigdelset(&BlockSig, SIGCONT);
+	sigdelset(&StartupBlockSig, SIGCONT);
+#endif
+
+/* Signals unique to startup */
+#ifdef SIGQUIT
+	sigdelset(&StartupBlockSig, SIGQUIT);
+#endif
+#ifdef SIGTERM
+	sigdelset(&StartupBlockSig, SIGTERM);
+#endif
+#ifdef SIGALRM
+	sigdelset(&StartupBlockSig, SIGALRM);
+#endif
+}
+
+/*
+ * Set up a postmaster signal handler for signal "signo"
+ *
+ * Returns the previous handler.
+ *
+ * This is used only in the postmaster, which has its own odd approach to
+ * signal handling.  For signals with handlers, we block all signals for the
+ * duration of signal handler execution.  We also do not set the SA_RESTART
+ * flag; this should be safe given the tiny range of code in which the
+ * postmaster ever unblocks signals.
+ *
+ * pqinitmask() must have been invoked previously.
+ *
+ * On Windows, this function is just an alias for pqsignal()
+ * (and note that it's calling the code in src/backend/port/win32/signal.c,
+ * not src/port/pqsignal.c).  On that platform, the postmaster's signal
+ * handlers still have to block signals for themselves.
+ */
+pqsigfunc
+pqsignal_pm(int signo, pqsigfunc func)
+{
+#ifndef WIN32
+	struct sigaction act,
+				oact;
+
+	act.sa_handler = func;
+	if (func == SIG_IGN || func == SIG_DFL)
+	{
+		/* in these cases, act the same as pqsignal() */
+		sigemptyset(&act.sa_mask);
+		act.sa_flags = SA_RESTART;
+	}
+	else
+	{
+		act.sa_mask = BlockSig;
+		act.sa_flags = 0;
+	}
+#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 pqsignal(signo, func);
+#endif
+}