Merge pull request #5493 from greatroar/ioctl

backend,termstatus: Unify foreground/background detection

internal/backend/util/foreground_sysv.go

@@ -1,28 +0,0 @@
-//go:build aix || solaris
-// +build aix solaris
-
-package util
-
-import (
-	"os/exec"
-	"syscall"
-
-	"github.com/restic/restic/internal/errors"
-)
-
-func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
-	// run the command in its own process group so that SIGINT
-	// is not sent to it.
-	cmd.SysProcAttr = &syscall.SysProcAttr{
-		Setpgid: true,
-	}
-
-	// start the process
-	err = cmd.Start()
-	if err != nil {
-		return nil, errors.Wrap(err, "cmd.Start")
-	}
-
-	bg = func() error { return nil }
-	return bg, nil
-}

internal/backend/util/foreground_unix.go

@@ -1,5 +1,4 @@
-//go:build !aix && !solaris && !windows
+//go:build unix
-// +build !aix,!solaris,!windows
 
 package util
 
@@ -10,20 +9,11 @@ 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"
 )
 
-func tcgetpgrp(fd int) (int, error) {
-	return unix.IoctlGetInt(fd, unix.TIOCGPGRP)
-}
-
-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) {
 	// run the command in its own process group
 	// this ensures that sending ctrl-c to restic will not immediately stop the backend process.
@@ -39,15 +29,15 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
 	}
 
 	// only move child process to foreground if restic is in the foreground
-	prev, err := tcgetpgrp(int(tty.Fd()))
+	prev, err := termstatus.Tcgetpgrp(int(tty.Fd()))
 	if err != nil {
 		_ = tty.Close()
 		return nil, err
 	}
 
-	self := unix.Getpgrp()
+	self := termstatus.Getpgrp()
 	if prev != self {
-		debug.Log("restic is not controlling the tty")
+		debug.Log("restic is not controlling the tty; err = %v", err)
 		if err := tty.Close(); err != nil {
 			return nil, err
 		}
@@ -66,7 +56,7 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
 	}
 
 	// move the command's process group into the foreground
-	err = tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
+	err = termstatus.Tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
 	if err != nil {
 		_ = tty.Close()
 		return nil, err
@@ -77,7 +67,7 @@ func startForeground(cmd *exec.Cmd) (bg func() error, err error) {
 		signal.Reset(unix.SIGTTOU)
 
 		// reset the foreground process group
-		err = tcsetpgrp(int(tty.Fd()), prev)
+		err = termstatus.Tcsetpgrp(int(tty.Fd()), prev)
 		if err != nil {
 			_ = tty.Close()
 			return err

internal/ui/termstatus/background_linux.go

@@ -1,27 +0,0 @@
-package termstatus
-
-import (
-	"github.com/restic/restic/internal/debug"
-
-	"golang.org/x/sys/unix"
-)
-
-// 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(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 uintptr) (bool, 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(int(fd), unix.TIOCGPGRP)
-	return int(pid) != unix.Getpgrp(), err
-}

internal/ui/termstatus/background_unix.go

@@ -0,0 +1,24 @@
+//go:build unix
+
+package termstatus
+
+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/ui/termstatus/background_unix_test.go

@@ -1,3 +1,5 @@
+//go:build unix
+
 package termstatus
 
 import (
@@ -13,7 +15,7 @@ func TestIsProcessBackground(t *testing.T) {
 		t.Skipf("can't open terminal: %v", err)
 	}
 
-	_, err = isProcessBackground(tty.Fd())
+	_, err = isProcessBackground(int(tty.Fd()))
 	rtest.OK(t, err)
 
 	_ = tty.Close()

internal/ui/termstatus/background_windows.go

@@ -1,6 +1,3 @@
-//go:build !linux
-// +build !linux
-
 package termstatus
 
 // IsProcessBackground reports whether the current process is running in the

internal/ui/termstatus/getpgrp_solaris.go

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

internal/ui/termstatus/getpgrp_unix.go

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

internal/ui/termstatus/tcgetpgrp_linux.go

@@ -0,0 +1,12 @@
+package termstatus
+
+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/ui/termstatus/tcgetpgrp_unix.go

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

internal/ui/termstatus/tcsetpgrp_aix.go

@@ -0,0 +1,10 @@
+package termstatus
+
+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/ui/termstatus/tcsetpgrp_unix.go

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