From 053bea810096f410d3b03ade7ef761da05565a45 Mon Sep 17 00:00:00 2001
From: Florian Forster <octo@noris.net>
Date: Thu, 11 Nov 2010 16:56:32 +0100
Subject: [PATCH] unixsock plugin: Implement the "DeleteSocket" option.

---
 src/collectd.conf.in  |  1 +
 src/collectd.conf.pod |  7 +++++++
 src/unixsock.c        | 30 ++++++++++++++++++++++++++++--
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/collectd.conf.in b/src/collectd.conf.in
index 42addd27..e194d142 100644
--- a/src/collectd.conf.in
+++ b/src/collectd.conf.in
@@ -913,6 +913,7 @@
 #	SocketFile "@prefix@/var/run/@PACKAGE_NAME@-unixsock"
 #	SocketGroup "collectd"
 #	SocketPerms "0660"
+#	DeleteSocket false
 #</Plugin>
 
 #<Plugin uuid>
diff --git a/src/collectd.conf.pod b/src/collectd.conf.pod
index 1da35982..1c31d97f 100644
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -4558,6 +4558,13 @@ Change the file permissions of the UNIX-socket after it has been created. The
 permissions must be given as a numeric, octal value as you would pass to
 L<chmod(1)>. Defaults to B<0770>.
 
+=item B<DeleteSocket> B<false>|B<true>
+
+If set to B<true>, delete the socket file before calling L<bind(2)>, if a file
+with the given name already exists. If I<collectd> crashes a socket file may be
+left over, preventing the daemon from opening a new socket when restarted.
+Since this is potentially dangerous, this defaults to B<false>.
+
 =back
 
 =head2 Plugin C<uuid>
diff --git a/src/unixsock.c b/src/unixsock.c
index 0b897482..6de13956 100644
--- a/src/unixsock.c
+++ b/src/unixsock.c
@@ -54,7 +54,8 @@ static const char *config_keys[] =
 {
 	"SocketFile",
 	"SocketGroup",
-	"SocketPerms"
+	"SocketPerms",
+	"DeleteSocket"
 };
 static int config_keys_num = STATIC_ARRAY_SIZE (config_keys);
 
@@ -65,6 +66,7 @@ static int   sock_fd    = -1;
 static char *sock_file  = NULL;
 static char *sock_group = NULL;
 static int   sock_perms = S_IRWXU | S_IRWXG;
+static _Bool delete_socket = 0;
 
 static pthread_t listen_thread = (pthread_t) 0;
 
@@ -89,10 +91,27 @@ static int us_open_socket (void)
 	sa.sun_family = AF_UNIX;
 	sstrncpy (sa.sun_path, (sock_file != NULL) ? sock_file : US_DEFAULT_PATH,
 			sizeof (sa.sun_path));
-	/* unlink (sa.sun_path); */
 
 	DEBUG ("unixsock plugin: socket path = %s", sa.sun_path);
 
+	if (delete_socket)
+	{
+		errno = 0;
+		status = unlink (sa.sun_path);
+		if ((status != 0) && (errno != ENOENT))
+		{
+			char errbuf[1024];
+			WARNING ("unixsock plugin: Deleting socket file \"%s\" failed: %s",
+					sa.sun_path,
+					sstrerror (errno, errbuf, sizeof (errbuf)));
+		}
+		else if (status == 0)
+		{
+			INFO ("unixsock plugin: Successfully deleted socket file \"%s\".",
+					sa.sun_path);
+		}
+	}
+
 	status = bind (sock_fd, (struct sockaddr *) &sa, sizeof (sa));
 	if (status != 0)
 	{
@@ -392,6 +411,13 @@ static int us_config (const char *key, const char *val)
 	{
 		sock_perms = (int) strtol (val, NULL, 8);
 	}
+	else if (strcasecmp (key, "DeleteSocket") == 0)
+	{
+		if (IS_TRUE (val))
+			delete_socket = 1;
+		else
+			delete_socket = 0;
+	}
 	else
 	{
 		return (-1);
-- 
2.11.0