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