restic/internal/backend/util/foreground_unix.go

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//go:build !aix && !solaris && !windows
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// +build !aix,!solaris,!windows
package util
import (
"os"
"os/exec"
"os/signal"
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"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"golang.org/x/sys/unix"
)
func tcsetpgrp(fd int, pid int) error {
// IoctlSetPointerInt silently casts to int32 internally,
// so this assumes pid fits in 31 bits.
return unix.IoctlSetPointerInt(fd, unix.TIOCSPGRP, pid)
}
func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
// open the TTY, we need the file descriptor
tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0)
if err != nil {
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debug.Log("unable to open tty: %v", err)
bg = func() error {
return nil
}
return bg, cmd.Start()
}
signal.Ignore(unix.SIGTTIN)
signal.Ignore(unix.SIGTTOU)
// run the command in its own process group
cmd.SysProcAttr = &unix.SysProcAttr{
Setpgid: true,
}
// start the process
err = cmd.Start()
if err != nil {
_ = tty.Close()
return nil, errors.Wrap(err, "cmd.Start")
}
// move the command's process group into the foreground
prev := unix.Getpgrp()
err = tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
if err != nil {
_ = tty.Close()
return nil, err
}
bg = func() error {
signal.Reset(unix.SIGTTIN)
signal.Reset(unix.SIGTTOU)
// reset the foreground process group
err = tcsetpgrp(int(tty.Fd()), prev)
if err != nil {
_ = tty.Close()
return err
}
return tty.Close()
}
return bg, nil
}