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Fix shutdown hang when restic is started as background job

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restic uses a cleanup hook to ensure that it restores the terminal
configuration to a sane state, when restic is interrupted while reading
a password from the terminal. However, this causes a problem, when
restic runs in a background job, as reconfiguring a terminal will cause
a SIGTTOU to be sent to restic pausing it. Therefore, restic seems to
hang on shutdown when it was running in the background.

This commit changes the behavior to only restore the terminal
configuration if restic was interrupted while reading a password from
the terminal. As reading a password from the terminal requires that
restic is in the foreground, this should avoid restic getting stopped.

Fixes #2298
Issue introduced in #402
This commit is contained in:
Michael Eischer 2020-04-12 18:46:22 +02:00
parent 5a7c27ddb6
commit 1a1c572bac
1 changed files with 17 additions and 2 deletions
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19
cmd/restic/global.go
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@ -85,6 +85,8 @@ var globalOptions = GlobalOptions{
stderr: os.Stderr, stderr: os.Stderr,
} }
var isReadingPassword bool
func init() { func init() {
var cancel context.CancelFunc var cancel context.CancelFunc
globalOptions.ctx, cancel = context.WithCancel(context.Background()) globalOptions.ctx, cancel = context.WithCancel(context.Background())
@ -146,7 +148,10 @@ func stdoutTerminalWidth() int {
} }
// restoreTerminal installs a cleanup handler that restores the previous // restoreTerminal installs a cleanup handler that restores the previous
// terminal state on exit. // terminal state on exit. This handler is only intended to restore the
// terminal configuration if restic exits after receiving a signal. A regular
// program execution must revert changes to the terminal configuration itself.
// The terminal configuration is only restored while reading a password.
func restoreTerminal() { func restoreTerminal() {
if !stdoutIsTerminal() { if !stdoutIsTerminal() {
return return
@ -160,9 +165,17 @@ func restoreTerminal() {
} }
AddCleanupHandler(func() error { AddCleanupHandler(func() error {
// Restoring the terminal configuration while restic runs in the
// background, causes restic to get stopped on unix systems with
// a SIGTTOU signal. Thus only restore the terminal settings if
// they might have been modified, which is the case while reading
// a password.
if !isReadingPassword {
return nil
}
err := checkErrno(terminal.Restore(fd, state)) err := checkErrno(terminal.Restore(fd, state))
if err != nil { if err != nil {
fmt.Fprintf(os.Stderr, "unable to get restore terminal state: %#+v\n", err) fmt.Fprintf(os.Stderr, "unable to restore terminal state: %v\n", err)
} }
return err return err
}) })
@ -302,7 +315,9 @@ func readPassword(in io.Reader) (password string, err error) {
// password. // password.
func readPasswordTerminal(in *os.File, out io.Writer, prompt string) (password string, err error) { func readPasswordTerminal(in *os.File, out io.Writer, prompt string) (password string, err error) {
fmt.Fprint(out, prompt) fmt.Fprint(out, prompt)
isReadingPassword = true
buf, err := terminal.ReadPassword(int(in.Fd())) buf, err := terminal.ReadPassword(int(in.Fd()))
isReadingPassword = false
fmt.Fprintln(out) fmt.Fprintln(out)
if err != nil { if err != nil {
return "", errors.Wrap(err, "ReadPassword") return "", errors.Wrap(err, "ReadPassword")