package ensurefds012 // Package ensurefds012 ensures that file descriptors 0,1,2 are open. It opens // multiple copies of /dev/null as required. // The Go stdlib as well as the gocryptfs code rely on the fact that // fds 0,1,2 are always open. // // Use like this: // // import _ "github.com/rfjakob/gocryptfs/internal/ensurefds012" // // The import line MUST be in the alphabitcally first source code file of // package main! // // You can test if it works as expected by inserting a long sleep into main, // startings gocryptfs with all fds closed like this, // // $ ./gocryptfs 0<&- 1>&- 2>&- // // and then checking the open fds. It should look like this: // // $ ls -l /proc/$(pgrep gocryptfs)/fd // total 0 // lrwx------. 1 jakob jakob 64 Jan 5 15:54 0 -> /dev/null // lrwx------. 1 jakob jakob 64 Jan 5 15:54 1 -> /dev/null // lrwx------. 1 jakob jakob 64 Jan 5 15:54 2 -> /dev/null // l-wx------. 1 jakob jakob 64 Jan 5 15:54 3 -> /dev/null // lrwx------. 1 jakob jakob 64 Jan 5 15:54 4 -> 'anon_inode:[eventpoll]' // // See https://github.com/rfjakob/gocryptfs/issues/320 for details. import ( "os" "syscall" "github.com/rfjakob/gocryptfs/internal/exitcodes" ) func init() { fd, err := syscall.Open("/dev/null", syscall.O_RDWR, 0) if err != nil { os.Exit(exitcodes.DevNull) } for fd <= 2 { fd, err = syscall.Dup(fd) if err != nil { os.Exit(exitcodes.DevNull) } } // Close excess fd (usually fd 3) syscall.Close(fd) }