From 78d551ec7e5151dceee2d182a8f258fdc4b59554 Mon Sep 17 00:00:00 2001
From: Michael Banck <mbanck@debian.org>
Date: Thu, 28 Mar 2019 10:57:11 +0100
Subject: [PATCH 2/2] Support toggling of pg_checksums progress reporting via
 SIGUSR1.

This feature does not work on Windows.

Author: Bernd Helmle, Michael Banck
Reviewed-by: Fabien Coelho, Alvaro Herrera, Michael Paquier, Kyotaro HORIGUCHI
---
 doc/src/sgml/ref/pg_checksums.sgml  |  4 ++-
 src/bin/pg_checksums/pg_checksums.c | 51 +++++++++++++++++++++++++++----------
 2 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/doc/src/sgml/ref/pg_checksums.sgml b/doc/src/sgml/ref/pg_checksums.sgml
index 0934426e58..9f5cbc79ff 100644
--- a/doc/src/sgml/ref/pg_checksums.sgml
+++ b/doc/src/sgml/ref/pg_checksums.sgml
@@ -141,7 +141,9 @@ PostgreSQL documentation
       <listitem>
        <para>
         Enable progress reporting. Turning this on will deliver a progress
-        report while checking or enabling checksums.
+        report while checking or enabling checksums. Sending the
+        <systemitem>SIGUSR1</systemitem> signal will toggle progress reporting
+        on or off during the verification run (not available on Windows).
        </para>
       </listitem>
      </varlistentry>
diff --git a/src/bin/pg_checksums/pg_checksums.c b/src/bin/pg_checksums/pg_checksums.c
index d09cf8068d..bc7f29c3c4 100644
--- a/src/bin/pg_checksums/pg_checksums.c
+++ b/src/bin/pg_checksums/pg_checksums.c
@@ -15,6 +15,7 @@
 #include "postgres_fe.h"
 
 #include <dirent.h>
+#include <signal.h>
 #include <time.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -109,6 +110,23 @@ static const char *const skip[] = {
 	NULL,
 };
 
+static void
+toggle_progress_report(int signum)
+{
+
+	/* we handle SIGUSR1 only, and toggle the value of show_progress */
+	if (signum == SIGUSR1)
+	{
+		/*
+		 * Skip to the next line in order to avoid overwriting half of
+		 * the progress report line with the final output.
+		 */
+		if (show_progress && isatty(fileno(stderr)))
+			fprintf(stderr, "\n");
+		show_progress = !show_progress;
+	}
+}
+
 /*
  * Report current progress status. Parts borrowed from
  * PostgreSQLs' src/bin/pg_basebackup.c
@@ -529,23 +547,28 @@ main(int argc, char *argv[])
 		exit(1);
 	}
 
+#ifndef WIN32
 	/*
-	 * If progress status information is requested, we need to scan the
-	 * directory tree(s) twice, once to get the idea how much data we need to
-	 * scan and finally to do the real legwork.
+	 * Assign SIGUSR1 signal handler to toggle progress status information
 	 */
-	if (show_progress)
-	{
-		total_size = scan_directory(DataDir, "global", true);
-		total_size += scan_directory(DataDir, "base", true);
-		total_size += scan_directory(DataDir, "pg_tblspc", true);
+	pqsignal(SIGUSR1, toggle_progress_report);
+#endif
 
-		/*
-		 * Remember start time. Required to calculate the current speed in
-		 * report_progress().
-		 */
-		INSTR_TIME_SET_CURRENT(scan_started);
-	}
+	/*
+	 * As progress status information may be requested even after start of
+	 * operation, we need to scan the directory tree(s) twice, once to get
+	 * the idea how much data we need to scan and finally to do the real
+	 * legwork.
+	 */
+	total_size = scan_directory(DataDir, "global", true);
+	total_size += scan_directory(DataDir, "base", true);
+	total_size += scan_directory(DataDir, "pg_tblspc", true);
+
+	/*
+	 * Remember start time. Required to calculate the current speed in
+	 * report_progress()
+	 */
+	INSTR_TIME_SET_CURRENT(scan_started);
 
 	if (ControlFile->data_checksum_version == 0 &&
 		mode == PG_MODE_DISABLE)
-- 
2.11.0