From ab8b57ff54a160bf61a0bcfa008c956804e651c4 Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Sun, 3 Feb 2019 20:46:23 +0000
Subject: [PATCH] Allow broker to always restart on Windows when using
 `log_dest file`.

Closes #1080. Thanks to lcouz.
---
 ChangeLog.txt   |  2 ++
 lib/util_mosq.c | 17 ++++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/ChangeLog.txt b/ChangeLog.txt
index f17e68a0..e72b9211 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -30,6 +30,8 @@ Broker:
 - Handle mismatched handshakes (e.g. QoS1 PUBLISH with QoS2 reply) properly.
 - Fix spaces not being allowed in the bridge remote_username option. Closes
   #1131.
+- Allow broker to always restart on Windows when using `log_dest file`. Closes
+  #1080.
 
 Library:
 - Fix TLS connections not working over SOCKS.
diff --git a/lib/util_mosq.c b/lib/util_mosq.c
index 72666872..350d1ccc 100644
--- a/lib/util_mosq.c
+++ b/lib/util_mosq.c
@@ -404,6 +404,21 @@ FILE *mosquitto__fopen(const char *path, const char *mode, bool restrict_read)
 			char username[UNLEN + 1];
 			int ulen = UNLEN;
 			SECURITY_DESCRIPTOR sd;
+			DWORD dwCreationDisposition;
+
+			switch(mode[0]){
+				case 'a':
+					dwCreationDisposition = OPEN_ALWAYS;
+					break;
+				case 'r':
+					dwCreationDisposition = OPEN_EXISTING;
+					break;
+				case 'w':
+					dwCreationDisposition = CREATE_ALWAYS;
+					break;
+				default:
+					return NULL;
+			}
 
 			GetUserName(username, &ulen);
 			if (!InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION)) {
@@ -424,7 +439,7 @@ FILE *mosquitto__fopen(const char *path, const char *mode, bool restrict_read)
 
 			hfile = CreateFile(buf, GENERIC_READ | GENERIC_WRITE, 0,
 				&sec,
-				CREATE_NEW,
+				dwCreationDisposition,
 				FILE_ATTRIBUTE_NORMAL,
 				NULL);