[dart:io] Adds Platform.ansiSupported

runtime/bin/platform_win.cc

Index: runtime/bin/platform_win.cc
diff --git a/runtime/bin/platform_win.cc b/runtime/bin/platform_win.cc
index 71a274346d439320e45cbe43a029e26a2cf21091..e34d515963d8bc9cf69a58c1e10f44c3d9b583a7 100644
--- a/runtime/bin/platform_win.cc
+++ b/runtime/bin/platform_win.cc
@@ -46,6 +46,7 @@ class PlatformWin {
   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
@@ -61,50 +62,89 @@ class PlatformWin {
 
   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,
@@ -120,9 +160,9 @@ class 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();
@@ -219,6 +259,11 @@ const char* Platform::ResolveExecutablePath() {
 }
 
 
+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;