cmd/go/internal/doc: ignore SIGINT and SIGQUIT

Just like we do in cmd/doc when we start pkgsite, ignore SIGINT (and
SIGQUIT on unix) when we start cmd/doc so that it's handled by cmd/doc
(if pkgsite is not started, and before it is started) or pkgsite, if it
is started. Also exit with the exit status of the command, rather than
using base.Errorf so that we don't print an extra error message to the
terminal.

For #68106

Change-Id: If968e88b95031761432d13dc47c5febe3391945d
Reviewed-on: https://go-review.googlesource.com/c/go/+/675076
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Auto-Submit: Michael Matloob <matloob@google.com>

src/cmd/go/internal/base/base.go

@@ -191,20 +191,28 @@ func GetExitStatus() int {
 // connected to the go command's own stdout and stderr.
 // If the command fails, Run reports the error using Errorf.
 func Run(cmdargs ...any) {
+	if err := RunErr(cmdargs...); err != nil {
+		Errorf("%v", err)
+	}
+}
+
+// Run runs the command, with stdout and stderr
+// connected to the go command's own stdout and stderr.
+// If the command fails, RunErr returns the error, which
+// may be an *exec.ExitError.
+func RunErr(cmdargs ...any) error {
 	cmdline := str.StringList(cmdargs...)
 	if cfg.BuildN || cfg.BuildX {
 		fmt.Printf("%s\n", strings.Join(cmdline, " "))
 		if cfg.BuildN {
-			return
+			return nil
 		}
 	}
 
 	cmd := exec.Command(cmdline[0], cmdline[1:]...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
-	if err := cmd.Run(); err != nil {
-		Errorf("%v", err)
-	}
+	return cmd.Run()
 }
 
 // RunStdin is like run but connects Stdin. It retries if it encounters an ETXTBSY.

src/cmd/go/internal/doc/doc.go

@@ -9,6 +9,9 @@ import (
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
 	"context"
+	"errors"
+	"os"
+	"os/exec"
 	"path/filepath"
 )
 
@@ -131,5 +134,13 @@ Flags:
 }
 
 func runDoc(ctx context.Context, cmd *base.Command, args []string) {
-	base.Run(cfg.BuildToolexec, filepath.Join(cfg.GOROOTbin, "go"), "tool", "doc", args)
+	base.StartSigHandlers()
+	err := base.RunErr(cfg.BuildToolexec, filepath.Join(cfg.GOROOTbin, "go"), "tool", "doc", args)
+	if err != nil {
+		var ee *exec.ExitError
+		if errors.As(err, &ee) {
+			os.Exit(ee.ExitCode())
+		}
+		base.Error(err)
+	}
 }