internal/testpty: move from os/signal/internal/pty

We're going to use this for another test, so make it more accessible.

Preparation for #37486.

Change-Id: If194cc4244c4b9e1b1f253759b813555b39ad67e
Reviewed-on: https://go-review.googlesource.com/c/go/+/449502
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

3 files changed, 102 insertions, 0 deletions

diff --git a/src/internal/testpty/pty.go b/src/internal/testpty/pty.go
new file mode 100644
index 0000000000..88a47cf85f
--- /dev/null
+++ b/src/internal/testpty/pty.go
@@ -0,0 +1,36 @@
+// Copyright 2017 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 ((aix || dragonfly || freebsd || (linux && !android) || netbsd || openbsd) && cgo) || darwin
+
+// Package testpty is a simple pseudo-terminal package for Unix systems,
+// implemented by calling C functions via cgo.
+package testpty
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+type PtyError struct {
+	FuncName    string
+	ErrorString string
+	Errno       syscall.Errno
+}
+
+func ptyError(name string, err error) *PtyError {
+	return &PtyError{name, err.Error(), err.(syscall.Errno)}
+}
+
+func (e *PtyError) Error() string {
+	return fmt.Sprintf("%s: %s", e.FuncName, e.ErrorString)
+}
+
+func (e *PtyError) Unwrap() error { return e.Errno }
+
+// Open returns a control pty and the name of the linked process tty.
+func Open() (pty *os.File, processTTY string, err error) {
+	return open()
+}
diff --git a/src/internal/testpty/pty_cgo.go b/src/internal/testpty/pty_cgo.go
new file mode 100644
index 0000000000..1db6a925af
--- /dev/null
+++ b/src/internal/testpty/pty_cgo.go
@@ -0,0 +1,34 @@
+// Copyright 2017 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 cgo && (aix || dragonfly || freebsd || (linux && !android) || netbsd || openbsd)
+
+package testpty
+
+/*
+#define _XOPEN_SOURCE 600
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+*/
+import "C"
+
+import "os"
+
+func open() (pty *os.File, processTTY string, err error) {
+	m, err := C.posix_openpt(C.O_RDWR)
+	if err != nil {
+		return nil, "", ptyError("posix_openpt", err)
+	}
+	if _, err := C.grantpt(m); err != nil {
+		C.close(m)
+		return nil, "", ptyError("grantpt", err)
+	}
+	if _, err := C.unlockpt(m); err != nil {
+		C.close(m)
+		return nil, "", ptyError("unlockpt", err)
+	}
+	processTTY = C.GoString(C.ptsname(m))
+	return os.NewFile(uintptr(m), "pty"), processTTY, nil
+}
diff --git a/src/internal/testpty/pty_darwin.go b/src/internal/testpty/pty_darwin.go
new file mode 100644
index 0000000000..f29517c0e2
--- /dev/null
+++ b/src/internal/testpty/pty_darwin.go
@@ -0,0 +1,32 @@
+// Copyright 2017 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.
+
+package testpty
+
+import (
+	"internal/syscall/unix"
+	"os"
+	"syscall"
+)
+
+func open() (pty *os.File, processTTY string, err error) {
+	m, err := unix.PosixOpenpt(syscall.O_RDWR)
+	if err != nil {
+		return nil, "", ptyError("posix_openpt", err)
+	}
+	if err := unix.Grantpt(m); err != nil {
+		syscall.Close(m)
+		return nil, "", ptyError("grantpt", err)
+	}
+	if err := unix.Unlockpt(m); err != nil {
+		syscall.Close(m)
+		return nil, "", ptyError("unlockpt", err)
+	}
+	processTTY, err = unix.Ptsname(m)
+	if err != nil {
+		syscall.Close(m)
+		return nil, "", ptyError("ptsname", err)
+	}
+	return os.NewFile(uintptr(m), "pty"), processTTY, nil
+}