open file description locks are inherited across fork and only auto
dropped after the last fd of the file description is closed, they can be
used to synchronize between threads that open separate file descriptions
for the same file.
new in linux 3.15 commit
0d3f7a2dd2f5cf9642982515e020c1aee2cf7af6
#define O_WRONLY 01
#define O_RDWR 02
+#define F_OFD_GETLK 36
+#define F_OFD_SETLK 37
+#define F_OFD_SETLKW 38
+
#define F_DUPFD_CLOEXEC 1030
#define F_RDLCK 0