From eba38e7977c3e8a0c75e60448183aee8ed6c8c7e Mon Sep 17 00:00:00 2001
From: Michal Sojka <michal.sojka@cvut.cz>
Date: Fri, 15 Dec 2017 12:51:54 +0100
Subject: [PATCH] Make liblockdev optional and use flock

---
 Makefile       | 3 +++
 debian/control | 2 +-
 sterm.c        | 9 +++++++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 5aada56..f7d0b4d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,8 @@
 CFLAGS = -O2 -Wall -g
+
+ifneq ($(findstring HAVE_LOCKDEV,$(CFLAGS)),)
 LDLIBS = -llockdev
+endif
 
 PREFIX ?= /usr/local
 INSTALL ?= install
diff --git a/debian/control b/debian/control
index d99eebd..de83d26 100644
--- a/debian/control
+++ b/debian/control
@@ -2,7 +2,7 @@ Source: sterm
 Section: comm
 Priority: optional
 Maintainer: Michal Sojka <sojkam1@fel.cvut.cz>
-Build-Depends: debhelper (>= 9), liblockdev1-dev
+Build-Depends: debhelper (>= 9)
 Standards-Version: 3.9.5
 Homepage: https://rtime.felk.cvut.cz/gitweb/sojka/sterm.git
 Vcs-Git: git://rtime.felk.cvut.cz/sojka/sterm.git
diff --git a/sterm.c b/sterm.c
index ea86573..6ecb117 100644
--- a/sterm.c
+++ b/sterm.c
@@ -44,7 +44,10 @@
 #include <stdbool.h>
 #include <string.h>
 #include <signal.h>
+#ifdef HAVE_LOCKDEV
 #include <lockdev.h>
+#endif
+#include <sys/file.h>
 #include <errno.h>
 
 #define STRINGIFY(val) #val
@@ -74,10 +77,12 @@ void restore_stdin_term()
 	tcsetattr(0, TCSANOW, &stdin_tio_backup);
 }
 
+#ifdef HAVE_LOCKDEV
 void unlock()
 {
 	dev_unlock(dev, getpid());
 }
+#endif
 
 void sighandler(int arg)
 {
@@ -266,6 +271,7 @@ int main(int argc, char *argv[])
 	signal(SIGTERM, sighandler);
 	signal(SIGHUP, sighandler);
 
+#ifdef HAVE_LOCKDEV
 	pid_t pid = dev_lock(dev);
 	if (pid > 0) {
 		fprintf(stderr, "%s is used by PID %d\n", dev, pid);
@@ -280,6 +286,7 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 	atexit(unlock);
+#endif
 
 	/* O_NONBLOCK is needed to not wait for the CDC signal. See tty_ioctl(4). */
 	if ((fd = open(dev, O_RDWR|O_NOCTTY|O_NONBLOCK)) < 0) {
@@ -290,6 +297,8 @@ int main(int argc, char *argv[])
 	int n = fcntl(fd, F_GETFL, 0);
         fcntl(fd, F_SETFL, n & ~O_NDELAY);
 
+	flock(fd, LOCK_EX);
+
 	if (isatty(fd)) {
 		CHECK(ioctl(fd, TIOCEXCL, NULL));
 
-- 
2.39.2