v2-0002-Make-error-hint-from-bind-failure-more-accurate.patch

From 49d48efe4cc4af558b06c474a0bec22316f4bf55 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 22 Oct 2020 08:47:52 +0200
Subject: [PATCH v2 2/2] Make error hint from bind() failure more accurate

The hint "Is another postmaster already running ..." should only be
printed for errors that are really about something else already using
the address.  In other cases it is misleading.

Discussion: https://www.postgresql.org/message-id/flat/6dee8574-b0ad-fc49-9c8c-2edc796f0033@2ndquadrant.com
---
 src/backend/libpq/pqcomm.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index 84568508c5..b8be7de70e 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -530,18 +530,21 @@ StreamServerPort(int family, const char *hostName, unsigned short portNumber,
 		err = bind(fd, addr->ai_addr, addr->ai_addrlen);
 		if (err < 0)
 		{
+			int			saved_errno = errno;
+
 			ereport(LOG,
 					(errcode_for_socket_access(),
 			/* 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.",
-							 (int) portNumber, service) :
-					 errhint("Is another postmaster already running on port %d?"
-							 " If not, wait a few seconds and retry.",
-							 (int) portNumber)));
+					 saved_errno == EADDRINUSE ?
+					 (IS_AF_UNIX(addr->ai_family) ?
+					  errhint("Is another postmaster already running on port %d?"
+							  " If not, remove socket file \"%s\" and retry.",
+							  (int) portNumber, service) :
+					  errhint("Is another postmaster already running on port %d?"
+							  " If not, wait a few seconds and retry.",
+							  (int) portNumber)) : 0));
 			closesocket(fd);
 			continue;
 		}
-- 
2.28.0