From 75aad9a85effb0da11ce8a4e317e2132395354a2 Mon Sep 17 00:00:00 2001
From: Ian Barwick <barwick@gmail.com>
Date: Wed, 30 Sep 2015 17:01:23 +0900
Subject: [PATCH] repmgr witness create --force: overwrite existing data
 directory

Per Github #82 (dimitri).
---
 check_dir.c | 50 +++++++++++++++++++++++++++++++++++++++++++++-----
 check_dir.h |  1 +
 repmgr.c    |  4 ++--
 3 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/check_dir.c b/check_dir.c
index 8038e752..6289079b 100644
--- a/check_dir.c
+++ b/check_dir.c
@@ -23,15 +23,19 @@
 #include <errno.h>
 #include <stdio.h>
 #include <string.h>
+#include <ftw.h>
 
 /* NB: postgres_fe must be included BEFORE check_dir */
 #include <libpq-fe.h>
 #include <postgres_fe.h>
-#include "check_dir.h"
 
+#include "check_dir.h"
 #include "strutil.h"
 #include "log.h"
 
+static bool _create_pg_dir(char *dir, bool force, bool for_witness);
+static int unlink_dir_callback(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf);
+
 /*
  * make sure the directory either doesn't exist or is empty
  * we use this function to check the new data directory and
@@ -244,6 +248,19 @@ is_pg_dir(char *dir)
 
 bool
 create_pg_dir(char *dir, bool force)
+{
+	return _create_pg_dir(dir, force, false);
+}
+
+bool
+create_witness_pg_dir(char *dir, bool force)
+{
+	return _create_pg_dir(dir, force, true);
+}
+
+
+static bool
+_create_pg_dir(char *dir, bool force, bool for_witness)
 {
 	bool		pg_dir = false;
 
@@ -280,12 +297,24 @@ create_pg_dir(char *dir, bool force)
 
 			pg_dir = is_pg_dir(dir);
 
-			/*
-			 * we use force to reduce the time needed to restore a node which
-			 * turn async after a failover or anything else
-			 */
+
 			if (pg_dir && force)
 			{
+
+				/*
+				 * The witness server does not store any data other than a copy of the
+				 * repmgr metadata, so in --force mode we can simply overwrite the
+				 * directory.
+				 *
+				 * For non-witness servers, we'll leave the data in place, both to reduce
+				 * the risk of unintentional data loss and to make it possible for the
+				 * data directory to be brought up-to-date with rsync.
+				 */
+				if (for_witness)
+				{
+					log_notice(_("deleting existing data directory \"%s\"\n"), dir);
+					nftw(dir, unlink_dir_callback, 64, FTW_DEPTH | FTW_PHYS);
+				}
 				/* Let it continue */
 				break;
 			}
@@ -307,3 +336,14 @@ create_pg_dir(char *dir, bool force)
 	}
 	return true;
 }
+
+static int
+unlink_dir_callback(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf)
+{
+    int rv = remove(fpath);
+
+    if (rv)
+        perror(fpath);
+
+    return rv;
+}
diff --git a/check_dir.h b/check_dir.h
index d11ec589..b3d44134 100644
--- a/check_dir.h
+++ b/check_dir.h
@@ -26,5 +26,6 @@ bool		create_dir(char *dir);
 bool		set_dir_permissions(char *dir);
 bool		is_pg_dir(char *dir);
 bool		create_pg_dir(char *dir, bool force);
+bool		create_witness_pg_dir(char *dir, bool force);
 
 #endif
diff --git a/repmgr.c b/repmgr.c
index 1e9f46cb..5b775335 100644
--- a/repmgr.c
+++ b/repmgr.c
@@ -2010,7 +2010,7 @@ do_witness_create(void)
 	masterconn = establish_db_connection_by_params(keywords, values, true);
 	if (!masterconn)
 	{
-		/* No event logging possible as we can't connect to the master */
+		/* No event logging possible here as we can't connect to the master */
 		log_err(_("unable to connect to master\n"));
 		exit(ERR_DB_CON);
 	}
@@ -2065,7 +2065,7 @@ do_witness_create(void)
 	}
 
 	/* Check this directory could be used as a PGDATA dir */
-	if (!create_pg_dir(runtime_options.dest_dir, runtime_options.force))
+	if (!create_witness_pg_dir(runtime_options.dest_dir, runtime_options.force))
 	{
 		PQExpBufferData errmsg;
 		initPQExpBuffer(&errmsg);