From f06984707de8055534826d6716fb3f220b63d95a Mon Sep 17 00:00:00 2001
From: Alex 'AdUser' Z <ad_user@runbox.com>
Date: Tue, 15 Mar 2016 22:20:40 +1000
Subject: [PATCH] * readable file locking errors

---
 src/main.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/main.c b/src/main.c
index 387cd3b..7a309f8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -184,7 +184,10 @@ int main(int argc, char *argv[]) {
     FILE *pidfile = NULL;
     if ((pidfile = fopen(opts.pidfile_path, "w")) != NULL) {
       if (flock(fileno(pidfile), LOCK_EX | LOCK_NB) != 0) {
-        f2b_log_msg(log_error, "can't lock pidfile: %s", strerror(errno));
+        const char *err = (errno == EWOULDBLOCK)
+          ? "another instance already running"
+          : strerror(errno);
+        f2b_log_msg(log_error, "can't lock pidfile: %s", err);
         exit(EXIT_FAILURE);
       }
       fprintf(pidfile, "%d\n", getpid());