cmd/go/internal/tool: only forward SIGHUP, SIGINT, SIGQUIT, and SIGTERM

These are the signals that are likely to be sent to go tool by other
programs. This means we won't forward SIGTSTP, SIGTTIN, SIGTTOU. Doing
so was breaking expected behavior in a terminal.

Fixes #76173

Change-Id: I018808e8ecf59e4e111f353968d83b856a6a6964
Reviewed-on: https://go-review.googlesource.com/c/go/+/763060
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

4 files changed, 43 insertions, 1 deletions

diff --git a/src/cmd/go/internal/tool/signal.go b/src/cmd/go/internal/tool/signal.go
new file mode 100644
index 0000000000..a6525c8d68
--- /dev/null
+++ b/src/cmd/go/internal/tool/signal.go
@@ -0,0 +1,14 @@
+// Copyright 2026 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 !plan9 && !js
+
+package tool
+
+import (
+	"os"
+	"syscall"
+)
+
+var signalsToForward = []os.Signal{syscall.SIGHUP, os.Interrupt, syscall.SIGQUIT, syscall.SIGTERM}
diff --git a/src/cmd/go/internal/tool/signal_js.go b/src/cmd/go/internal/tool/signal_js.go
new file mode 100644
index 0000000000..064f88ffb2
--- /dev/null
+++ b/src/cmd/go/internal/tool/signal_js.go
@@ -0,0 +1,14 @@
+// Copyright 2026 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 js
+
+package tool
+
+import (
+	"os"
+	"syscall"
+)
+
+var signalsToForward = []os.Signal{os.Interrupt, syscall.SIGQUIT, syscall.SIGTERM}
diff --git a/src/cmd/go/internal/tool/signal_plan9.go b/src/cmd/go/internal/tool/signal_plan9.go
new file mode 100644
index 0000000000..45fa878a68
--- /dev/null
+++ b/src/cmd/go/internal/tool/signal_plan9.go
@@ -0,0 +1,14 @@
+// Copyright 2012 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 plan9
+
+package tool
+
+import (
+	"os"
+	"syscall"
+)
+
+var signalsToForward = []os.Signal{syscall.SIGHUP, os.Interrupt, syscall.SIGTERM}
diff --git a/src/cmd/go/internal/tool/tool.go b/src/cmd/go/internal/tool/tool.go
index a84b2e8ccb..094c5b719b 100644
--- a/src/cmd/go/internal/tool/tool.go
+++ b/src/cmd/go/internal/tool/tool.go
@@ -403,7 +403,7 @@ func runBuiltTool(toolName string, env, cmdline []string) error {
 	err := toolCmd.Start()
 	if err == nil {
 		c := make(chan os.Signal, 100)
-		signal.Notify(c)
+		signal.Notify(c, signalsToForward...)
 		go func() {
 			for sig := range c {
 				toolCmd.Process.Signal(sig)