Improve postmaster's logging of listen socket creation.

When one of the kernel calls in the socket()/bind()/listen() sequence
fails, include the specific address we're trying to bind to in the log
message.  This greatly eases debugging of network misconfigurations.

Also, after successfully setting up a listen socket, report its address
in the log, to ease verification that the expected addresses were bound.
There was some debate about whether to print this message at LOG level or
only DEBUG1, but the majority of votes were for the former.

Discussion: https://postgr.es/m/9564.1489091245@sss.pgh.pa.us

doc/src/sgml/runtime.sgml

@@ -464,9 +464,9 @@ su - postgres -c "/usr/local/pgsql/bin/pg_ctl start -l logfile -D /usr/local/pgs
 
     <para>
 <screen>
-LOG:  could not bind IPv4 socket: Address already in use
+LOG:  could not bind IPv4 address "127.0.0.1": Address already in use
 HINT:  Is another postmaster already running on port 5432? If not, wait a few seconds and retry.
-FATAL:  could not create TCP/IP listen socket
+FATAL:  could not create any TCP/IP sockets
 </screen>
      This usually means just what it suggests: you tried to start
      another server on the same port where one is already running.
@@ -476,9 +476,9 @@ FATAL:  could not create TCP/IP listen socket
      on a reserved port number might draw something like:
 <screen>
 $ <userinput>postgres -p 666</userinput>
-LOG:  could not bind IPv4 socket: Permission denied
+LOG:  could not bind IPv4 address "127.0.0.1": Permission denied
 HINT:  Is another postmaster already running on port 666? If not, wait a few seconds and retry.
-FATAL:  could not create TCP/IP listen socket
+FATAL:  could not create any TCP/IP sockets
 </screen>
     </para>
 

src/backend/libpq/pqcomm.c

@@ -319,6 +319,8 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 	char		portNumberStr[32];
 	const char *familyDesc;
 	char		familyDescBuf[64];
+	const char *addrDesc;
+	char		addrBuf[NI_MAXHOST];
 	char	   *service;
 	struct addrinfo *addrs = NULL,
 			   *addr;
@@ -407,7 +409,7 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 			break;
 		}
 
-		/* set up family name for possible error messages */
+		/* set up address family name for log messages */
 		switch (addr->ai_family)
 		{
 			case AF_INET:
@@ -431,13 +433,28 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 				break;
 		}
 
+		/* set up text form of address for log messages */
+#ifdef HAVE_UNIX_SOCKETS
+		if (addr->ai_family == AF_UNIX)
+			addrDesc = unixSocketPath;
+		else
+#endif
+		{
+			pg_getnameinfo_all((const struct sockaddr_storage *) addr->ai_addr,
+							   addr->ai_addrlen,
+							   addrBuf, sizeof(addrBuf),
+							   NULL, 0,
+							   NI_NUMERICHOST);
+			addrDesc = addrBuf;
+		}
+
 		if ((fd = socket(addr->ai_family, SOCK_STREAM, 0)) == PGINVALID_SOCKET)
 		{
 			ereport(LOG,
 					(errcode_for_socket_access(),
-			/* translator: %s is IPv4, IPv6, or Unix */
-					 errmsg("could not create %s socket: %m",
-							familyDesc)));
+			/* translator: first %s is IPv4, IPv6, or Unix */
+				  errmsg("could not create %s socket for address \"%s\": %m",
+						 familyDesc, addrDesc)));
 			continue;
 		}
 
@@ -461,7 +478,9 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 			{
 				ereport(LOG,
 						(errcode_for_socket_access(),
-						 errmsg("setsockopt(SO_REUSEADDR) failed: %m")));
+				/* translator: first %s is IPv4, IPv6, or Unix */
+						 errmsg("setsockopt(SO_REUSEADDR) failed for %s address \"%s\": %m",
+								familyDesc, addrDesc)));
 				closesocket(fd);
 				continue;
 			}
@@ -476,7 +495,9 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 			{
 				ereport(LOG,
 						(errcode_for_socket_access(),
-						 errmsg("setsockopt(IPV6_V6ONLY) failed: %m")));
+				/* translator: first %s is IPv4, IPv6, or Unix */
+						 errmsg("setsockopt(IPV6_V6ONLY) failed for %s address \"%s\": %m",
+								familyDesc, addrDesc)));
 				closesocket(fd);
 				continue;
 			}
@@ -494,9 +515,9 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 		{
 			ereport(LOG,
 					(errcode_for_socket_access(),
-			/* translator: %s is IPv4, IPv6, or Unix */
-					 errmsg("could not bind %s socket: %m",
-							familyDesc),
+			/* translator: first %s is IPv4, IPv6, or Unix */
+					 errmsg("could not bind %s address \"%s\": %m",
+							familyDesc, addrDesc),
 					 (IS_AF_UNIX(addr->ai_family)) ?
 				  errhint("Is another postmaster already running on port %d?"
 						  " If not, remove socket file \"%s\" and retry.",
@@ -533,12 +554,18 @@ StreamServerPort(int family, char *hostName, unsigned short portNumber,
 		{
 			ereport(LOG,
 					(errcode_for_socket_access(),
-			/* translator: %s is IPv4, IPv6, or Unix */
-					 errmsg("could not listen on %s socket: %m",
-							familyDesc)));
+			/* translator: first %s is IPv4, IPv6, or Unix */
+					 errmsg("could not listen on %s address \"%s\": %m",
+							familyDesc, addrDesc)));
 			closesocket(fd);
 			continue;
 		}
+
+		ereport(LOG,
+		/* translator: first %s is IPv4, IPv6, or Unix */
+				(errmsg("listening on %s address \"%s\"",
+						familyDesc, addrDesc)));
+
 		ListenSocket[listen_index] = fd;
 		added++;
 	}