Replace --foreground with --background

Always run in foreground by default. Service manager and supervisors
expect services to run in foreground, so they can track the lifetime of
the child process. Those that don't implement their own logic to fork
daemons anyway.

For users running usbmuxd manually, running in background by default
provides a confusing experience, since it gives the impression that
usbmuxd has exited immediately.

Anyone needing to run usbmuxd in background can use the --background
option.

Author: WhyNotHugo

NEWS

@@ -34,6 +34,9 @@ Version 1.1.1
   - Unify and improve log message output
   - Improve README.md with project description, installation, contributing and
     usage sections
+  - The "--foreground" flag has been removed; usbmuxd now runs in foreground by
+    default. For the previous behaviour, use "--background" to run in
+    background instead.
 
 Version 1.1.0
 ~~~~~~~~~~~~~

README.md

@@ -103,8 +103,8 @@ The daemon also manages pairing records with iOS devices and the host in
 
 Ensure proper permissions are setup for the daemon to access the directory.
 
-For debugging purposes it is helpful to start usbmuxd using the foreground `-f`
-argument and enable verbose mode `-v` to get suitable logs.
+For debugging purposes it is helpful to enable verbose mode `-v` to get
+suitable logs.
 
 Please consult the usage information or manual page for a full documentation of
 available command line options:

docs/usbmuxd.8

@@ -32,8 +32,8 @@ Ensure proper permissions are setup for the daemon to access the directory.
 .B \-U, \-\-user USER
 Change to this user after startup (needs USB privileges).
 .TP
-.B \-f, \-\-foreground
-Do not daemonize (implies one -v).
+.B \-f, \-\-background
+Daemonize (double fork and run in background).
 .TP
 .B \-n, \-\-disable-hotplug
 Disables automatic discovery of devices on hotplug. Starting another instance
@@ -44,7 +44,7 @@ Enable "--exit" request from other instances and exit automatically if no
 device is attached.
 .TP
 .B \-u, \-\-udev
-Run in udev operation mode (implies -n and -z).
+Run in udev operation mode (implies -n, -b and -z).
 .TP
 .B \-s, \-\-systemd
 Run in systemd operation mode (implies -z and -f).

src/main.c

@@ -65,7 +65,7 @@ int no_preflight = 0;
 
 // Global state for main.c
 static int verbose = 0;
-static int foreground = 0;
+static int background = 0;
 static int drop_privileges = 0;
 static const char *drop_user = NULL;
 static int opt_disable_hotplug = 0;
@@ -504,15 +504,15 @@ static void usage()
 	printf("OPTIONS:\n");
 	printf("  -h, --help\t\tPrint this message.\n");
 	printf("  -v, --verbose\t\tBe verbose (use twice or more to increase).\n");
-	printf("  -f, --foreground\tDo not daemonize (implies one -v).\n");
+	printf("  -b, --background\tDaemonize (double fork immediately).\n");
 	printf("  -U, --user USER\tChange to this user after startup (needs USB privileges).\n");
 	printf("  -n, --disable-hotplug\tDisables automatic discovery of devices on hotplug.\n");
 	printf("                       \tStarting another instance will trigger discovery instead.\n");
 	printf("  -z, --enable-exit\tEnable \"--exit\" request from other instances and exit\n");
 	printf("                   \tautomatically if no device is attached.\n");
 	printf("  -p, --no-preflight\tDisable lockdownd preflight on new device.\n");
 #ifdef HAVE_UDEV
-	printf("  -u, --udev\t\tRun in udev operation mode (implies -n and -z).\n");
+	printf("  -u, --udev\t\tRun in udev operation mode (implies -n, -b and -z).\n");
 #endif
 #ifdef HAVE_SYSTEMD
 	printf("  -s, --systemd\t\tRun in systemd operation mode (implies -z and -f).\n");
@@ -537,7 +537,7 @@ static void parse_opts(int argc, char **argv)
 {
 	static struct option longopts[] = {
 		{"help", no_argument, NULL, 'h'},
-		{"foreground", no_argument, NULL, 'f'},
+		{"background", no_argument, NULL, 'b'},
 		{"verbose", no_argument, NULL, 'v'},
 		{"user", required_argument, NULL, 'U'},
 		{"disable-hotplug", no_argument, NULL, 'n'},
@@ -577,8 +577,8 @@ static void parse_opts(int argc, char **argv)
 		case 'h':
 			usage();
 			exit(0);
-		case 'f':
-			foreground = 1;
+		case 'b':
+			background = 1;
 			break;
 		case 'v':
 			++verbose;
@@ -597,12 +597,13 @@ static void parse_opts(int argc, char **argv)
 		case 'u':
 			opt_disable_hotplug = 1;
 			opt_enable_exit = 1;
+			background = 1;
 			break;
 #endif
 #ifdef HAVE_SYSTEMD
 		case 's':
 			opt_enable_exit = 1;
-			foreground = 1;
+			background = 0;
 			break;
 #endif
 		case 'n':
@@ -675,7 +676,7 @@ int main(int argc, char *argv[])
 	argc -= optind;
 	argv += optind;
 
-	if (!foreground && !use_logfile) {
+	if (background && !use_logfile) {
 		verbose += LL_WARNING;
 		log_enable_syslog();
 	} else {
@@ -751,7 +752,7 @@ int main(int argc, char *argv[])
 		goto terminate;
 	}
 
-	if (!foreground) {
+	if (background) {
 		if ((res = daemonize()) < 0) {
 			fprintf(stderr, "usbmuxd: FATAL: Could not daemonize!\n");
 			usbmuxd_log(LL_FATAL, "Could not daemonize!");