helper/wrappedstreams: get original console input/output on Windows

Fixes #10266

panicwrap was using Extrafiles to get the original standard streams for
`terraform console`. This doesn't work on Windows. Instead, we must use
the Win32 APIs to get the exact handles.

helper/wrappedstreams/streams.go

@@ -38,10 +38,15 @@ func Stderr() *os.File {
 	return stderr
 }
 
-// These are the wrapped streams. There doesn't appear to be a negative
-// impact of opening these files even if the file descriptor doesn't exist.
+// These are the wrapped standard streams. These are setup by the
+// platform specific code in initPlatform.
 var (
-	wrappedStdin  = os.NewFile(uintptr(3), "stdin")
-	wrappedStdout = os.NewFile(uintptr(4), "stdout")
-	wrappedStderr = os.NewFile(uintptr(5), "stderr")
+	wrappedStdin  *os.File
+	wrappedStdout *os.File
+	wrappedStderr *os.File
 )
+
+func init() {
+	// Initialize the platform-specific code
+	initPlatform()
+}

helper/wrappedstreams/streams_other.go

@@ -0,0 +1,10 @@
+// +build !windows
+
+package wrappedstreams
+
+func initPlatform() {
+	// The standard streams are passed in via extra file descriptors.
+	wrappedStdin = os.NewFile(uintptr(3), "stdin")
+	wrappedStdout = os.NewFile(uintptr(4), "stdout")
+	wrappedStderr = os.NewFile(uintptr(5), "stderr")
+}

helper/wrappedstreams/streams_windows.go

@@ -0,0 +1,52 @@
+// +build windows
+
+package wrappedstreams
+
+import (
+	"log"
+	"os"
+	"syscall"
+)
+
+func initPlatform() {
+	wrappedStdin = openConsole("CONIN$", os.Stdin)
+	wrappedStdout = openConsole("CONOUT$", os.Stdout)
+	wrappedStderr = wrappedStdout
+}
+
+// openConsole opens a console handle, using a backup if it fails.
+// This is used to get the exact console handle instead of the redirected
+// handles from panicwrap.
+func openConsole(name string, backup *os.File) *os.File {
+	// Convert to UTF16
+	path, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		log.Printf("[ERROR] wrappedstreams: %s", err)
+		return backup
+	}
+
+	// Determine the share mode
+	var shareMode uint32
+	switch name {
+	case "CONIN$":
+		shareMode = syscall.FILE_SHARE_READ
+	case "CONOUT$":
+		shareMode = syscall.FILE_SHARE_WRITE
+	}
+
+	// Get the file
+	h, err := syscall.CreateFile(
+		path,
+		syscall.GENERIC_READ|syscall.GENERIC_WRITE,
+		shareMode,
+		nil,
+		syscall.OPEN_EXISTING,
+		0, 0)
+	if err != nil {
+		log.Printf("[ERROR] wrappedstreams: %s", err)
+		return backup
+	}
+
+	// Create the Go file
+	return os.NewFile(uintptr(h), name)
+}

vendor/vendor.json

@@ -1915,10 +1915,10 @@
 			"revision": "314aad379a39f6ad5bcca278e6757d9abbb3a52e"
 		},
 		{
-			"checksumSHA1": "wqU8bs9c+xm0f07t6ajQFWYS+rE=",
+			"checksumSHA1": "kTntIB9SdU1NsCqKwDkUr99qaj0=",
 			"path": "github.com/mitchellh/panicwrap",
-			"revision": "168f3680ad986108df63bae07da2978f51c4ac8e",
-			"revisionTime": "2016-11-14T06:37:33Z"
+			"revision": "fde185d0dfb5ecac6e6b201e8855da798ebcd76f",
+			"revisionTime": "2016-11-21T18:34:54Z"
 		},
 		{
 			"path": "github.com/mitchellh/prefixedio",