libgocryptfs/gocryptfs_main/sendsig.go

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package main
import (
"syscall"
"bytes"
"fmt"
"os"
"io/ioutil"
)
// cmdline looks like this: /bin/bash \0 /path/to/gocryptfs \0 --zerokey \0 ...
const (
WRAPPER_PREFIX = "/bin/bash\000"
WRAPPER_CONTAINS = "gocryptfs\000"
)
// Send USR1 to the "gocryptfs" wrapper shell script. This notifies it that the
// mounting has completed sucessfully.
//
// Checks /proc/$PPID/cmdline to make sure we do not kill an unrelated process.
func sendSig() {
ppid := os.Getppid()
fn := fmt.Sprintf("/proc/%d/cmdline", ppid)
cmdline, err := ioutil.ReadFile(fn)
if err != nil {
fmt.Printf("sendSig: ReadFile: %v\n", err)
return
}
if bytes.HasPrefix(cmdline, []byte(WRAPPER_PREFIX)) && bytes.Contains(cmdline, []byte(WRAPPER_CONTAINS)) {
p, err := os.FindProcess(ppid)
if err != nil {
fmt.Printf("sendSig: FindProcess: %v\n", err)
return
}
err = p.Signal(syscall.SIGUSR1)
if err != nil {
fmt.Printf("sendSig: Signal: %v\n", err)
}
} else {
fmt.Printf("Not running under the gocryptfs wrapper - will not daemonize\n")
}
}