first commit

src/lock.c

@@ -0,0 +1,17 @@
+#include "lock.h"
+#include "paths.h"
+#include "util.h"
+#include <fcntl.h>
+#include <unistd.h>
+
+lock_st lock() {
+  if (exists(mc_lock_path))
+    return ALREADY_LOCKED;
+  if (creat(mc_lock_path, 0600) == -1)
+    return LOCK_ERROR;
+  return LOCK_SUCCESS;
+}
+
+void unlock() {
+  unlink(mc_lock_path);
+}