From 1a1c572bacbfa422f4aa18b4abc9a0fb8c98559e Mon Sep 17 00:00:00 2001
From: Michael Eischer <michael.eischer@fau.de>
Date: Sun, 12 Apr 2020 18:46:22 +0200
Subject: [PATCH 1/2] Fix shutdown hang when restic is started as background
 job

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
---
 cmd/restic/global.go | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/cmd/restic/global.go b/cmd/restic/global.go
index 2c4d1fccd..4eb73d2bf 100644
--- a/cmd/restic/global.go
+++ b/cmd/restic/global.go
@@ -85,6 +85,8 @@ var globalOptions = GlobalOptions{
 	stderr: os.Stderr,
 }
 
+var isReadingPassword bool
+
 func init() {
 	var cancel context.CancelFunc
 	globalOptions.ctx, cancel = context.WithCancel(context.Background())
@@ -146,7 +148,10 @@ func stdoutTerminalWidth() int {
 }
 
 // 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() {
 	if !stdoutIsTerminal() {
 		return
@@ -160,9 +165,17 @@ func restoreTerminal() {
 	}
 
 	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))
 		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
 	})
@@ -302,7 +315,9 @@ func readPassword(in io.Reader) (password string, err error) {
 // password.
 func readPasswordTerminal(in *os.File, out io.Writer, prompt string) (password string, err error) {
 	fmt.Fprint(out, prompt)
+	isReadingPassword = true
 	buf, err := terminal.ReadPassword(int(in.Fd()))
+	isReadingPassword = false
 	fmt.Fprintln(out)
 	if err != nil {
 		return "", errors.Wrap(err, "ReadPassword")

From 4a400f94bb3362002776660ad7e07c886d850c58 Mon Sep 17 00:00:00 2001
From: Michael Eischer <michael.eischer@fau.de>
Date: Sun, 12 Apr 2020 19:24:23 +0200
Subject: [PATCH 2/2] Add changelog

---
 changelog/unreleased/issue-2298 | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 changelog/unreleased/issue-2298

diff --git a/changelog/unreleased/issue-2298 b/changelog/unreleased/issue-2298
new file mode 100644
index 000000000..5da1f108f
--- /dev/null
+++ b/changelog/unreleased/issue-2298
@@ -0,0 +1,8 @@
+Bugfix: Do not hang when run as a background job
+
+Restic did hang on exit while restoring the terminal configuration when it was
+started as a background job, for example using `restic ... &`. This has been
+fixed by only restoring the terminal configuration when restic is interrupted
+while reading a password from the terminal.
+
+https://github.com/restic/restic/issues/2298