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https://github.com/octoleo/restic.git
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05958caf6e
This is a follow-up on fb9729fdb9, which
runs the `ssh` in its own process group and selects that process group
as the foreground group. After the sftp connection is established,
restic switches back to the previous foreground process group.
This allows `ssh` to prompt for the password, but it won't receive
the interrupt signal (SIGINT, ^C) later on, because it is not in the
foreground process group any more, allowing a clean tear down.
74 lines
1.5 KiB
Go
74 lines
1.5 KiB
Go
// +build !windows
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package sftp
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import (
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"os"
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"os/exec"
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"os/signal"
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"syscall"
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"unsafe"
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"github.com/restic/restic/internal/errors"
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)
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func tcsetpgrp(fd int, pid int) error {
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_, _, errno := syscall.RawSyscall(syscall.SYS_IOCTL, uintptr(fd),
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uintptr(syscall.TIOCSPGRP), uintptr(unsafe.Pointer(&pid)))
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if errno == 0 {
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return nil
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}
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return errno
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}
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// startForeground runs cmd in the foreground, by temporarily switching to the
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// new process group created for cmd. The returned function `bg` switches back
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// to the previous process group.
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func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
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// open the TTY, we need the file descriptor
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tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0)
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if err != nil {
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return nil, errors.Wrap(err, "open TTY")
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}
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signal.Ignore(syscall.SIGTTIN)
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signal.Ignore(syscall.SIGTTOU)
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// run the command in its own process group
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cmd.SysProcAttr = &syscall.SysProcAttr{
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Setpgid: true,
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}
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// start the process
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err = cmd.Start()
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if err != nil {
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_ = tty.Close()
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return nil, errors.Wrap(err, "cmd.Start")
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}
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// move the command's process group into the foreground
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prev := syscall.Getpgrp()
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err = tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
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if err != nil {
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_ = tty.Close()
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return nil, err
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}
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bg = func() error {
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signal.Reset(syscall.SIGTTIN)
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signal.Reset(syscall.SIGTTOU)
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// reset the foreground process group
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err = tcsetpgrp(int(tty.Fd()), prev)
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if err != nil {
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_ = tty.Close()
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return err
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}
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return tty.Close()
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}
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return bg, nil
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}
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