[dart:io] Adds Platform.ansiSupported

runtime/bin/platform_win.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/platform.h"
 
 #include <crtdbg.h>
@@ skipping 28 matching lines @@
 const char* Platform::executable_name_ = NULL;
 char* Platform::resolved_executable_name_ = NULL;
 int Platform::script_index_ = 1;
 char** Platform::argv_ = NULL;
 
 class PlatformWin {
  public:
   static void InitOnce() {
     platform_win_mutex_ = new Mutex();
     saved_output_cp_ = -1;
+    saved_input_cp_ = -1;
     // Set up a no-op handler so that CRT functions return an error instead of
     // hitting an assertion failure.
     // See: https://msdn.microsoft.com/en-us/library/a9yf33zb.aspx
     _set_invalid_parameter_handler(InvalidParameterHandler);
     // Disable the message box for assertions in the CRT in Debug builds.
     // See: https://msdn.microsoft.com/en-us/library/1y71x448.aspx
     _CrtSetReportMode(_CRT_ASSERT, 0);
     // Disable dialog boxes for "critical" errors or when OpenFile cannot find
     // the requested file. See:
     // See: https://msdn.microsoft.com/en-us/library/windows/desktop/ms680621(v=vs.85).aspx
     SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX);
   }
 
   static void SaveAndConfigureConsole() {
     MutexLocker ml(platform_win_mutex_);
+    // Set both the input and output code pages to UTF8.
     ASSERT(saved_output_cp_ == -1);
+    ASSERT(saved_input_cp_ == -1);
     saved_output_cp_ = GetConsoleOutputCP();
+    saved_input_cp_ = GetConsoleCP();
     SetConsoleOutputCP(CP_UTF8);
+    SetConsoleCP(CP_UTF8);
 
+    ansi_supported_ = true;
     HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
-    if ((out != INVALID_HANDLE_VALUE) &&
-        GetConsoleMode(out, &saved_console_out_mode_)) {
-      const DWORD request =
-          saved_console_out_mode_ | ENABLE_VIRTUAL_TERMINAL_PROCESSING;
-      SetConsoleMode(out, request);
+    DWORD out_mode;
+    if ((out != INVALID_HANDLE_VALUE) && GetConsoleMode(out, &out_mode)) {
+      const DWORD request = out_mode | ENABLE_VIRTUAL_TERMINAL_PROCESSING;
+      ansi_supported_ = ansi_supported_ && SetConsoleMode(out, request);
+    } else {
+      ansi_supported_ = false;
     }
 
     HANDLE in = GetStdHandle(STD_INPUT_HANDLE);
-    if ((in != INVALID_HANDLE_VALUE) &&
-        GetConsoleMode(in, &saved_console_in_mode_)) {
-      const DWORD request =
-          saved_console_in_mode_ | ENABLE_VIRTUAL_TERMINAL_INPUT;
-      SetConsoleMode(in, request);
+    DWORD in_mode;
+    if ((in != INVALID_HANDLE_VALUE) && GetConsoleMode(in, &in_mode)) {
+      const DWORD request = in_mode | ENABLE_VIRTUAL_TERMINAL_INPUT;
+      ansi_supported_ = ansi_supported_ && SetConsoleMode(in, request);
+    } else {
+      ansi_supported_ = false;

[sortie, 2017/03/16 11:39:08]

This looks like escape codes are considered unsupported if the input is not a
terminal, but support for escape codes only has to do with the console output. I
could imagine redirecting a file as input or using a pipe into a dart program
and still expect color output. There is no support for STD_ERROR_HANDLE here
either. The terminalness of the standard output and standard error are in
principle distinct and Platform should probably expose a different bool for
whether each of those support escape sequences.

     }
   }
 
   static void RestoreConsole() {
     MutexLocker ml(platform_win_mutex_);
+
+    // STD_OUTPUT_HANDLE and STD_INPUT_HANDLE may have been closed or
+    // redirected. Therefore, we explicitly open the CONOUT$ and CONIN$
+    // devices, so that we can be sure that we are really unsetting
+    // ENABLE_VIRTUAL_TERMINAL_PROCESSING and ENABLE_VIRTUAL_TERMINAL_INPUT
+    // respectively.
+    HANDLE out;
+    {
+      Utf8ToWideScope conin("CONOUT$");
+      out = CreateFileW(conin.wide(), GENERIC_READ | GENERIC_WRITE,
+                        FILE_SHARE_READ, 0, OPEN_EXISTING, 0, 0);
+      if (out != INVALID_HANDLE_VALUE) {
+        SetStdHandle(STD_OUTPUT_HANDLE, out);
+      }
+    }
+    DWORD out_mode;
+    if ((out != INVALID_HANDLE_VALUE) && GetConsoleMode(out, &out_mode)) {
+      DWORD request = out_mode & ~ENABLE_VIRTUAL_TERMINAL_INPUT;
+      SetConsoleMode(out, request);
+    }
+
+    HANDLE in;
+    {
+      Utf8ToWideScope conin("CONIN$");
+      in = CreateFileW(conin.wide(), GENERIC_READ | GENERIC_WRITE,
+                       FILE_SHARE_READ, 0, OPEN_EXISTING, 0, 0);
+      if (in != INVALID_HANDLE_VALUE) {
+        SetStdHandle(STD_INPUT_HANDLE, in);
+      }
+    }
+    DWORD in_mode;
+    if ((in != INVALID_HANDLE_VALUE) && GetConsoleMode(in, &in_mode)) {
+      DWORD request = in_mode & ~ENABLE_VIRTUAL_TERMINAL_INPUT;
+      SetConsoleMode(in, request);
+    }
+
     if (saved_output_cp_ != -1) {
       SetConsoleOutputCP(saved_output_cp_);
       saved_output_cp_ = -1;
     }
-    HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
-    if (out != INVALID_HANDLE_VALUE) {
-      SetConsoleMode(out, saved_console_out_mode_);
-      saved_console_out_mode_ = 0;
-    }
-    HANDLE in = GetStdHandle(STD_INPUT_HANDLE);
-    if (in != INVALID_HANDLE_VALUE) {
-      SetConsoleMode(in, saved_console_in_mode_);
-      saved_console_in_mode_ = 0;
+    if (saved_input_cp_ != -1) {
+      SetConsoleCP(saved_input_cp_);
+      saved_input_cp_ = -1;
     }
   }
 
+  static bool ansi_supported() { return ansi_supported_; }
+
  private:
   static Mutex* platform_win_mutex_;
   static int saved_output_cp_;
-  static DWORD saved_console_out_mode_;
-  static DWORD saved_console_in_mode_;
+  static int saved_input_cp_;
+  static bool ansi_supported_;
 
   static void InvalidParameterHandler(const wchar_t* expression,
                                       const wchar_t* function,
                                       const wchar_t* file,
                                       unsigned int line,
                                       uintptr_t reserved) {
     // Doing nothing here means that the CRT call that invoked it will
     // return an error code and/or set errno.
   }
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(PlatformWin);
 };
 
 int PlatformWin::saved_output_cp_ = -1;
-DWORD PlatformWin::saved_console_out_mode_ = 0;
-DWORD PlatformWin::saved_console_in_mode_ = 0;
+int PlatformWin::saved_input_cp_ = -1;
 Mutex* PlatformWin::platform_win_mutex_ = NULL;
+bool PlatformWin::ansi_supported_ = false;
 
 bool Platform::Initialize() {
   PlatformWin::InitOnce();
   PlatformWin::SaveAndConfigureConsole();
   return true;
 }
 
 
 int Platform::NumberOfProcessors() {
   SYSTEM_INFO info;
@@ skipping 76 matching lines @@
   if (GetLastError() != ERROR_SUCCESS) {
     return NULL;
   }
   char* path = StringUtilsWin::WideToUtf8(tmp_buffer);
   // Return the canonical path as the returned path might contain symlinks.
   const char* canon_path = File::GetCanonicalPath(path);
   return canon_path;
 }
 
 
+bool Platform::AnsiSupported() {
+  return PlatformWin::ansi_supported();
+}
+
+
 void Platform::Exit(int exit_code) {
   // TODO(zra): Remove once VM shuts down cleanly.
   ::dart::private_flag_windows_run_tls_destructors = false;
   // Restore the console's output code page
   PlatformWin::RestoreConsole();
   // On Windows we use ExitProcess so that threads can't clobber the exit_code.
   // See: https://code.google.com/p/nativeclient/issues/detail?id=2870
   ::ExitProcess(exit_code);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)