[485589] Close stdin etc. when daemonised.

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=485589

ChangeLog.txt

@@ -5,6 +5,7 @@ Broker:
  mount point. This is only affects brokers where the mount_point option is in
  use. Closes #487178.
 - Fix detection of broken connections on Windows. Closes #485143.
+- Close stdin etc. when daemonised. Closes #485589.
 
 Client library:
 - mosq->want_write should be cleared immediately before a call to SSL_write,

src/mosquitto.c

@@ -21,6 +21,7 @@ and the Eclipse Distribution License is available at
 # define _BSD_SOURCE
 # include <unistd.h>
 # include <grp.h>
+# include <assert.h>
 #endif
 
 #ifndef WIN32
@@ -175,6 +176,35 @@ void handle_sigusr1(int signal)
 #endif
 }
 
+void mosquitto__daemonise(void)
+{
+#ifndef WIN32
+ char err[256];
+ pid_t pid;
+
+ pid = fork();
+ if(pid < 0){
+ strerror_r(errno, err, 256);
+ _mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error in fork: %s", err);
+ exit(1);
+ }
+ if(pid > 0){
+ exit(0);
+ }
+ if(setsid() < 0){
+ strerror_r(errno, err, 256);
+ _mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error in setsid: %s", err);
+ exit(1);
+ }
+
+ assert(freopen("/dev/null", "r", stdin));
+ assert(freopen("/dev/null", "w", stdout));
+ assert(freopen("/dev/null", "w", stderr));
+#else
+ _mosquitto_log_printf(NULL, MOSQ_LOG_WARNING, "Warning: Can't start in daemon mode in Windows.");
+#endif
+}
+
 /* Signal handler for SIGUSR2 - vacuum the db. */
 void handle_sigusr2(int signal)
 {
@@ -197,7 +227,6 @@ int main(int argc, char *argv[])
 #ifdef WIN32
  SYSTEMTIME st;
 #else
- char err[256];
  struct timeval tv;
 #endif
  struct mosquitto *ctxt, *ctxt_tmp;
@@ -236,20 +265,7 @@ int main(int argc, char *argv[])
  int_db.config = &config;
 
  if(config.daemon){
-#ifndef WIN32
- switch(fork()){
- case 0:
- break;
- case -1:
- strerror_r(errno, err, 256);
- _mosquitto_log_printf(NULL, MOSQ_LOG_ERR, "Error in fork: %s", err);
- return 1;
- default:
- return MOSQ_ERR_SUCCESS;
- }
-#else
- _mosquitto_log_printf(NULL, MOSQ_LOG_WARNING, "Warning: Can't start in daemon mode in Windows.");
-#endif
+ mosquitto__daemonise();
  }
 
  if(config.daemon && config.pid_file){