ui/termstatus: extract background handling code

internal/terminal/background_unix.go

@@ -0,0 +1,24 @@
+//go:build unix
+
+package terminal
+
+import "github.com/restic/restic/internal/debug"
+
+// IsProcessBackground reports whether the current process is running in the
+// background. fd must be a file descriptor for the terminal.
+func IsProcessBackground(fd uintptr) bool {
+	bg, err := isProcessBackground(int(fd))
+	if err != nil {
+		debug.Log("Can't check if we are in the background. Using default behaviour. Error: %s\n", err.Error())
+		return false
+	}
+	return bg
+}
+
+func isProcessBackground(fd int) (bg bool, err error) {
+	pgid, err := Tcgetpgrp(fd)
+	if err != nil {
+		return false, err
+	}
+	return pgid != Getpgrp(), nil
+}

internal/terminal/background_unix_test.go

@@ -0,0 +1,22 @@
+//go:build unix
+
+package terminal
+
+import (
+	"os"
+	"testing"
+
+	rtest "github.com/restic/restic/internal/test"
+)
+
+func TestIsProcessBackground(t *testing.T) {
+	tty, err := os.Open("/dev/tty")
+	if err != nil {
+		t.Skipf("can't open terminal: %v", err)
+	}
+
+	_, err = isProcessBackground(int(tty.Fd()))
+	rtest.OK(t, err)
+
+	_ = tty.Close()
+}

internal/terminal/background_windows.go

@@ -0,0 +1,7 @@
+package terminal
+
+// IsProcessBackground reports whether the current process is running in the
+// background. Not implemented for this platform.
+func IsProcessBackground(_ uintptr) bool {
+	return false
+}

internal/terminal/foreground_unix.go

@@ -9,7 +9,6 @@ import (
 
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/errors"
-	"github.com/restic/restic/internal/ui/termstatus"
 
 	"golang.org/x/sys/unix"
 )
@@ -29,13 +28,13 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
 	}
 
 	// only move child process to foreground if restic is in the foreground
-	prev, err := termstatus.Tcgetpgrp(int(tty.Fd()))
+	prev, err := Tcgetpgrp(int(tty.Fd()))
 	if err != nil {
 		_ = tty.Close()
 		return nil, err
 	}
 
-	self := termstatus.Getpgrp()
+	self := Getpgrp()
 	if prev != self {
 		debug.Log("restic is not controlling the tty; err = %v", err)
 		if err := tty.Close(); err != nil {
@@ -56,7 +55,7 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
 	}
 
 	// move the command's process group into the foreground
-	err = termstatus.Tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
+	err = Tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
 	if err != nil {
 		_ = tty.Close()
 		return nil, err
@@ -67,7 +66,7 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
 		signal.Reset(unix.SIGTTOU)
 
 		// reset the foreground process group
-		err = termstatus.Tcsetpgrp(int(tty.Fd()), prev)
+		err = Tcsetpgrp(int(tty.Fd()), prev)
 		if err != nil {
 			_ = tty.Close()
 			return err

internal/terminal/getpgrp_solaris.go

@@ -0,0 +1,8 @@
+package terminal
+
+import "golang.org/x/sys/unix"
+
+func Getpgrp() int {
+	pid, _ := unix.Getpgrp()
+	return pid
+}

internal/terminal/getpgrp_unix.go

@@ -0,0 +1,7 @@
+//go:build unix && !solaris
+
+package terminal
+
+import "golang.org/x/sys/unix"
+
+func Getpgrp() int { return unix.Getpgrp() }

internal/terminal/tcgetpgrp_linux.go

@@ -0,0 +1,12 @@
+package terminal
+
+import "golang.org/x/sys/unix"
+
+func Tcgetpgrp(ttyfd int) (int, error) {
+	// We need to use IoctlGetUint32 here, because pid_t is 32-bit even on
+	// 64-bit Linux. IoctlGetInt doesn't work on big-endian platforms:
+	// https://github.com/golang/go/issues/45585
+	// https://github.com/golang/go/issues/60429
+	pid, err := unix.IoctlGetUint32(ttyfd, unix.TIOCGPGRP)
+	return int(pid), err
+}

internal/terminal/tcgetpgrp_unix.go

@@ -0,0 +1,9 @@
+//go:build unix && !linux
+
+package terminal
+
+import "golang.org/x/sys/unix"
+
+func Tcgetpgrp(ttyfd int) (int, error) {
+	return unix.IoctlGetInt(ttyfd, unix.TIOCGPGRP)
+}

internal/terminal/tcsetpgrp_aix.go

@@ -0,0 +1,10 @@
+package terminal
+
+import "golang.org/x/sys/unix"
+
+func Tcsetpgrp(fd int, pid int) error {
+	// The second argument to IoctlSetPointerInt has type int on AIX,
+	// but the constant overflows 64-bit int, hence the two-step cast.
+	req := uint(unix.TIOCSPGRP)
+	return unix.IoctlSetPointerInt(fd, int(req), pid)
+}

internal/terminal/tcsetpgrp_unix.go

@@ -0,0 +1,9 @@
+//go:build unix && !aix
+
+package terminal
+
+import "golang.org/x/sys/unix"
+
+func Tcsetpgrp(fd int, pid int) error {
+	return unix.IoctlSetPointerInt(fd, unix.TIOCSPGRP, pid)
+}