Handle SIGTERM in pg_receivewal and pg_recvlogical

In pg_receivewal, compressed output is only flushed on clean exits.  The
reason to support SIGTERM as well as SIGINT (which is currently handled)
is that pg_receivewal might well be running as a daemon, and systemd's
default KillSignal is SIGTERM.

Since pg_recvlogical is also supposed to run as a daemon, teach it about
SIGTERM as well and update the documentation to match.  While in there,
change pg_receivewal's time_to_stop to be sig_atomic_t like it is in
pg_recvlogical.

Author: Christoph Berg <myon@debian.org>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/Yvo/5No5S0c4EFMj@msg.df7cb.de

Author: danielgustafsson

doc/src/sgml/ref/pg_receivewal.sgml

@@ -118,8 +118,9 @@ PostgreSQL documentation
 
   <para>
    In the absence of fatal errors, <application>pg_receivewal</application>
-   will run until terminated by the <systemitem>SIGINT</systemitem> signal
-   (<keycombo action="simul"><keycap>Control</keycap><keycap>C</keycap></keycombo>).
+   will run until terminated by the <systemitem>SIGINT</systemitem>
+   (<keycombo action="simul"><keycap>Control</keycap><keycap>C</keycap></keycombo>)
+   or <systemitem>SIGTERM</systemitem> signal.
   </para>
  </refsect1>
 
@@ -457,7 +458,8 @@ PostgreSQL documentation
 
   <para>
    <application>pg_receivewal</application> will exit with status 0 when
-   terminated by the <systemitem>SIGINT</systemitem> signal.  (That is the
+   terminated by the <systemitem>SIGINT</systemitem> or
+   <systemitem>SIGTERM</systemitem> signal.  (That is the
    normal way to end it.  Hence it is not an error.)  For fatal errors or
    other signals, the exit status will be nonzero.
   </para>

doc/src/sgml/ref/pg_recvlogical.sgml

@@ -46,6 +46,13 @@ PostgreSQL documentation
     a slot without consuming it, use
    <link linkend="functions-replication"><function>pg_logical_slot_peek_changes</function></link>.
   </para>
+
+  <para>
+   In the absence of fatal errors, <application>pg_recvlogical</application>
+   will run until terminated by the <systemitem>SIGINT</systemitem>
+   (<keycombo action="simul"><keycap>Control</keycap><keycap>C</keycap></keycombo>)
+   or <systemitem>SIGTERM</systemitem> signal.
+  </para>
  </refsect1>
 
  <refsect1>
@@ -407,6 +414,17 @@ PostgreSQL documentation
    </para>
  </refsect1>
 
+ <refsect1>
+  <title>Exit Status</title>
+  <para>
+   <application>pg_recvlogical</application> will exit with status 0 when
+   terminated by the <systemitem>SIGINT</systemitem> or
+   <systemitem>SIGTERM</systemitem> signal.  (That is the
+   normal way to end it.  Hence it is not an error.)  For fatal errors or
+   other signals, the exit status will be nonzero.
+  </para>
+ </refsect1>
+
  <refsect1>
   <title>Environment</title>
 

src/bin/pg_basebackup/pg_receivewal.c

@@ -45,7 +45,7 @@ static int	verbose = 0;
 static int	compresslevel = 0;
 static int	noloop = 0;
 static int	standby_message_timeout = 10 * 1000;	/* 10 sec = default */
-static volatile bool time_to_stop = false;
+static volatile sig_atomic_t time_to_stop = false;
 static bool do_create_slot = false;
 static bool slot_exists_ok = false;
 static bool do_drop_slot = false;
@@ -673,13 +673,13 @@ StreamLog(void)
 }
 
 /*
- * When sigint is called, just tell the system to exit at the next possible
- * moment.
+ * When SIGINT/SIGTERM are caught, just tell the system to exit at the next
+ * possible moment.
  */
 #ifndef WIN32
 
 static void
-sigint_handler(int signum)
+sigexit_handler(int signum)
 {
 	time_to_stop = true;
 }
@@ -905,7 +905,8 @@ main(int argc, char **argv)
 	 * if one is needed, in GetConnection.)
 	 */
 #ifndef WIN32
-	pqsignal(SIGINT, sigint_handler);
+	pqsignal(SIGINT, sigexit_handler);
+	pqsignal(SIGTERM, sigexit_handler);
 #endif
 
 	/*

src/bin/pg_basebackup/pg_recvlogical.c

@@ -650,11 +650,11 @@ StreamLogicalLog(void)
 #ifndef WIN32
 
 /*
- * When sigint is called, just tell the system to exit at the next possible
- * moment.
+ * When SIGINT/SIGTERM are caught, just tell the system to exit at the next
+ * possible moment.
  */
 static void
-sigint_handler(int signum)
+sigexit_handler(int signum)
 {
 	time_to_abort = true;
 }
@@ -922,7 +922,8 @@ main(int argc, char **argv)
 	 * if one is needed, in GetConnection.)
 	 */
 #ifndef WIN32
-	pqsignal(SIGINT, sigint_handler);
+	pqsignal(SIGINT, sigexit_handler);
+	pqsignal(SIGTERM, sigexit_handler);
 	pqsignal(SIGHUP, sighup_handler);
 #endif