syscall: export Tc{get,set}pgrp for testing

Provide appropriate implementations of Tc{get,set}pgrp and export
these for use in the TestForeground* tests in exec_unix_test.go.
This avoids calling ioctl via syscall.Syscall on BSDs.

Fixes #59667
Updates #63900

Change-Id: Ice4dcedae1f0931c026bddf33043d3864a52d44e
Reviewed-on: https://go-review.googlesource.com/c/go/+/572155
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: David Chase <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Joel Sing <[email protected]>

src/syscall/exec_aix_test.go

@@ -34,4 +34,13 @@ func Getpgrp() (pgrp int) {
 	return
 }
 
-var IoctlPtr = ioctlPtr
+func Tcgetpgrp(fd int) (pgid int32, err error) {
+	if errno := ioctlPtr(uintptr(fd), TIOCGPGRP, unsafe.Pointer(&pgid)); errno != 0 {
+		return -1, errno
+	}
+	return pgid, nil
+}
+
+func Tcsetpgrp(fd int, pgid int32) (err error) {
+	return ioctlPtr(uintptr(fd), TIOCSPGRP, unsafe.Pointer(&pgid))
+}

src/syscall/exec_solaris_test.go

@@ -34,4 +34,13 @@ func Getpgrp() (pgrp int) {
 	return
 }
 
-var IoctlPtr = ioctlPtr
+func Tcgetpgrp(fd int) (pgid int32, err error) {
+	if errno := ioctlPtr(uintptr(fd), TIOCGPGRP, unsafe.Pointer(&pgid)); errno != 0 {
+		return -1, errno
+	}
+	return pgid, nil
+}
+
+func Tcsetpgrp(fd int, pgid int32) (err error) {
+	return ioctlPtr(uintptr(fd), TIOCSPGRP, unsafe.Pointer(&pgid))
+}

src/syscall/exec_unix_test.go

@@ -19,7 +19,6 @@ import (
 	"syscall"
 	"testing"
 	"time"
-	"unsafe"
 )
 
 type command struct {
@@ -176,15 +175,12 @@ func TestForeground(t *testing.T) {
 	}
 	defer tty.Close()
 
-	// This should really be pid_t, however _C_int (aka int32) is generally
-	// equivalent.
-	fpgrp := int32(0)
+	ttyFD := int(tty.Fd())
 
-	errno := syscall.IoctlPtr(tty.Fd(), syscall.TIOCGPGRP, unsafe.Pointer(&fpgrp))
-	if errno != 0 {
-		t.Fatalf("TIOCGPGRP failed with error code: %s", errno)
+	fpgrp, err := syscall.Tcgetpgrp(ttyFD)
+	if err != nil {
+		t.Fatalf("Tcgetpgrp failed: %v", err)
 	}
-
 	if fpgrp == 0 {
 		t.Fatalf("Foreground process group is zero")
 	}
@@ -194,7 +190,7 @@ func TestForeground(t *testing.T) {
 	cmd := create(t)
 
 	cmd.proc.SysProcAttr = &syscall.SysProcAttr{
-		Ctty:       int(tty.Fd()),
+		Ctty:       ttyFD,
 		Foreground: true,
 	}
 	cmd.Start()
@@ -217,7 +213,7 @@ func TestForeground(t *testing.T) {
 
 	// This call fails on darwin/arm64. The failure doesn't matter, though.
 	// This is just best effort.
-	syscall.IoctlPtr(tty.Fd(), syscall.TIOCSPGRP, unsafe.Pointer(&fpgrp))
+	syscall.Tcsetpgrp(ttyFD, fpgrp)
 }
 
 func TestForegroundSignal(t *testing.T) {
@@ -227,22 +223,19 @@ func TestForegroundSignal(t *testing.T) {
 	}
 	defer tty.Close()
 
-	// This should really be pid_t, however _C_int (aka int32) is generally
-	// equivalent.
-	fpgrp := int32(0)
+	ttyFD := int(tty.Fd())
 
-	errno := syscall.IoctlPtr(tty.Fd(), syscall.TIOCGPGRP, unsafe.Pointer(&fpgrp))
-	if errno != 0 {
-		t.Fatalf("TIOCGPGRP failed with error code: %s", errno)
+	fpgrp, err := syscall.Tcgetpgrp(ttyFD)
+	if err != nil {
+		t.Fatalf("Tcgetpgrp failed: %v", err)
 	}
-
 	if fpgrp == 0 {
 		t.Fatalf("Foreground process group is zero")
 	}
 
 	defer func() {
 		signal.Ignore(syscall.SIGTTIN, syscall.SIGTTOU)
-		syscall.IoctlPtr(tty.Fd(), syscall.TIOCSPGRP, unsafe.Pointer(&fpgrp))
+		syscall.Tcsetpgrp(ttyFD, fpgrp)
 		signal.Reset()
 	}()
 
@@ -256,7 +249,7 @@ func TestForegroundSignal(t *testing.T) {
 
 	go func() {
 		cmd.proc.SysProcAttr = &syscall.SysProcAttr{
-			Ctty:       int(tty.Fd()),
+			Ctty:       ttyFD,
 			Foreground: true,
 		}
 		cmd.Start()

src/syscall/export_bsd_test.go

@@ -0,0 +1,25 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build darwin || dragonfly || freebsd || netbsd || openbsd
+
+package syscall
+
+import (
+	"unsafe"
+)
+
+// pgid should really be pid_t, however _C_int (aka int32) is generally
+// equivalent.
+
+func Tcgetpgrp(fd int) (pgid int32, err error) {
+	if err := ioctlPtr(fd, TIOCGPGRP, unsafe.Pointer(&pgid)); err != nil {
+		return -1, err
+	}
+	return pgid, nil
+}
+
+func Tcsetpgrp(fd int, pgid int32) (err error) {
+	return ioctlPtr(fd, TIOCSPGRP, unsafe.Pointer(&pgid))
+}

src/syscall/export_linux_test.go

@@ -4,6 +4,10 @@
 
 package syscall
 
+import (
+	"unsafe"
+)
+
 var (
 	RawSyscallNoError = rawSyscallNoError
 	ForceClone3       = &forceClone3
@@ -12,3 +16,19 @@ var (
 const (
 	Sys_GETEUID = sys_GETEUID
 )
+
+func Tcgetpgrp(fd int) (pgid int32, err error) {
+	_, _, errno := Syscall6(SYS_IOCTL, uintptr(fd), uintptr(TIOCGPGRP), uintptr(unsafe.Pointer(&pgid)), 0, 0, 0)
+	if errno != 0 {
+		return -1, errno
+	}
+	return pgid, nil
+}
+
+func Tcsetpgrp(fd int, pgid int32) (err error) {
+	_, _, errno := Syscall6(SYS_IOCTL, uintptr(fd), uintptr(TIOCSPGRP), uintptr(unsafe.Pointer(&pgid)), 0, 0, 0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}