From 282b6d00abf5cebece6f94c796a4ed807a0176db Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 21 Nov 2021 14:13:35 -0500
Subject: [PATCH] pg_receivewal, pg_recvlogical: allow canceling initial
 password prompt.

Previously it was impossible to terminate these programs via control-C
while they were prompting for a password.  We can fix that trivially
for their initial password prompts, by moving setup of the SIGINT
handler from just before to just after their initial GetConnection()
calls.

This fix doesn't permit escaping out of later re-prompts, but those
should be exceedingly rare, since the user's password or the server's
authentication setup would have to have changed meanwhile.  We
considered applying a fix similar to commit 46d665bc2, but that
seemed more complicated than it'd be worth.  Moreover, this way is
back-patchable, which that wasn't.

The misbehavior exists in all supported versions, so back-patch to all.

Tom Lane and Nathan Bossart

Discussion: https://postgr.es/m/747443.1635536754@sss.pgh.pa.us
---
 src/bin/pg_basebackup/pg_receivewal.c  | 12 ++++++++----
 src/bin/pg_basebackup/pg_recvlogical.c | 23 ++++++++++++-----------
 2 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/src/bin/pg_basebackup/pg_receivewal.c b/src/bin/pg_basebackup/pg_receivewal.c
index 23cf5f8ec7..4b1439be90 100644
--- a/src/bin/pg_basebackup/pg_receivewal.c
+++ b/src/bin/pg_basebackup/pg_receivewal.c
@@ -917,10 +917,6 @@ main(int argc, char **argv)
 		close_destination_dir(dir, basedir);
 	}
 
-#ifndef WIN32
-	pqsignal(SIGINT, sigint_handler);
-#endif
-
 	/*
 	 * Obtain a connection before doing anything.
 	 */
@@ -930,6 +926,14 @@ main(int argc, char **argv)
 		exit(1);
 	atexit(disconnect_atexit);
 
+	/*
+	 * Trap signals.  (Don't do this until after the initial password prompt,
+	 * if one is needed, in GetConnection.)
+	 */
+#ifndef WIN32
+	pqsignal(SIGINT, sigint_handler);
+#endif
+
 	/*
 	 * Run IDENTIFY_SYSTEM to make sure we've successfully have established a
 	 * replication connection and haven't connected using a database specific
diff --git a/src/bin/pg_basebackup/pg_recvlogical.c b/src/bin/pg_basebackup/pg_recvlogical.c
index f235d6fecf..13319cf0d3 100644
--- a/src/bin/pg_basebackup/pg_recvlogical.c
+++ b/src/bin/pg_basebackup/pg_recvlogical.c
@@ -216,8 +216,6 @@ StreamLogicalLog(void)
 	output_written_lsn = InvalidXLogRecPtr;
 	output_fsync_lsn = InvalidXLogRecPtr;
 
-	query = createPQExpBuffer();
-
 	/*
 	 * Connect in replication mode to the server
 	 */
@@ -236,6 +234,7 @@ StreamLogicalLog(void)
 					replication_slot);
 
 	/* Initiate the replication stream at specified location */
+	query = createPQExpBuffer();
 	appendPQExpBuffer(query, "START_REPLICATION SLOT \"%s\" LOGICAL %X/%X",
 					  replication_slot, LSN_FORMAT_ARGS(startpos));
 
@@ -932,16 +931,9 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
-
-#ifndef WIN32
-	pqsignal(SIGINT, sigint_handler);
-	pqsignal(SIGHUP, sighup_handler);
-#endif
-
 	/*
-	 * Obtain a connection to server. This is not really necessary but it
-	 * helps to get more precise error messages about authentication, required
-	 * GUC parameters and such.
+	 * Obtain a connection to server.  Notably, if we need a password, we want
+	 * to collect it from the user immediately.
 	 */
 	conn = GetConnection();
 	if (!conn)
@@ -949,6 +941,15 @@ main(int argc, char **argv)
 		exit(1);
 	atexit(disconnect_atexit);
 
+	/*
+	 * Trap signals.  (Don't do this until after the initial password prompt,
+	 * if one is needed, in GetConnection.)
+	 */
+#ifndef WIN32
+	pqsignal(SIGINT, sigint_handler);
+	pqsignal(SIGHUP, sighup_handler);
+#endif
+
 	/*
 	 * Run IDENTIFY_SYSTEM to make sure we connected using a database specific
 	 * replication connection.