add multiple instance warning if the device is busy.

2 files changed, 3 insertions, 2 deletions

diff --git a/TODO b/TODO
index 1255a25..2d1f969 100644
--- a/TODO
+++ b/TODO
@@ -1,7 +1,6 @@
 - actual realtime scheduling (maybe). sched(7).
 - use a log file instead of stderr, so we can have error/warning messages
   after detaching from the tty.
-- find out what happens if we try to run a 2nd instance.
 - print our /dev/input/event* node name, if possible.
 - options to set the virtual device name and vendor/product IDs.
 - much as I hate systemd, get someone to write a systemd unit.
@@ -10,3 +9,4 @@
   that means another instance is already running... so either exit
   or pass a command to it (like "marsond -K" would kill an existing
   instance).
+- 'make install' should install README and TODO.
diff --git a/marsond.c b/marsond.c
index f872baf..b94883b 100644
--- a/marsond.c
+++ b/marsond.c
@@ -235,6 +235,8 @@ int main(int argc, char **argv) {
 	if(ioctl(infd, EVIOCGRAB, 1) >= 0) {
 		debug("grabbed %s", keyboard_dev);
 	} else {
+		if(errno == EBUSY)
+			warn("is an instance of %s already running?", self);
 		die("failed to grab %s: %s", keyboard_dev, strerror(errno));
 	}
 
@@ -272,7 +274,6 @@ int main(int argc, char **argv) {
 		die("UI_DEV_CREATE failed: %s", strerror(errno));
 	}
 
-
 	/* this must be done while still running as root... */
 	if(foreground) {
 		lock_memory();