better detect cygwin i/o

arangosh/Shell/ConsoleFeature.cpp

@@ -120,7 +120,7 @@ void ConsoleFeature::collectOptions(std::shared_ptr<ProgramOptions> options) {
 
 void ConsoleFeature::prepare() {
 #if _WIN32
-  if (getenv("SHELL") != nullptr) {
+  if (_is_cyg_tty (STDOUT_FILENO) || getenv("SHELL") != nullptr) {
     _cygwinShell = true;
   }
 #endif

lib/Basics/win-utils.cpp

@@ -653,3 +653,51 @@ _cyg_isatty (int fd)
   errno = EINVAL;
   return 0;
 }
+
+// Detect cygwin ssh / terminals
+int
+_is_cyg_tty (int fd)
+{
+  // detect standard windows ttys:
+  if (_isatty (fd)) {
+    return 0;
+  }
+  
+  HANDLE fh;
+
+  char  buff[sizeof(FILE_NAME_INFO) + sizeof(WCHAR)*MAX_PATH];
+  FILE_NAME_INFO *FileInformation = (FILE_NAME_INFO*) buff;
+
+  /* get the HANDLE for the filedescriptor. */
+  fh = (HANDLE) _get_osfhandle (fd);
+  if (!fh || fh == INVALID_HANDLE_VALUE) {
+    return 0;
+  }
+
+  /* Cygwin consoles are pipes. If its not, no reason to continue: */
+  if (GetFileType (fh) != FILE_TYPE_PIPE) {
+    return 0;
+  }
+
+  if (!GetFileInformationByHandleEx(fh, FileNameInfo,
+                                    FileInformation, sizeof(buff))) {
+    return 0;
+  }
+
+  // we expect something along the lines of: \cygwin-0eb90a57d5759b7b-pty3-to-master?? - if we find it its a tty.
+  PWCHAR cp = (PWCHAR) FileInformation->FileName;
+  if (!wcsncmp (cp, L"\\cygwin-", 8)
+      && !wcsncmp (cp + 24, L"-pty", 4)) {
+    cp = wcschr (cp + 28, '-');
+    if (!cp) {
+      return 0;
+    }
+
+    if (!wcsncmp (cp, L"-from-master", sizeof("-from-master") - 1) ||
+        !wcsncmp (cp, L"-to-master", sizeof("-to-master") -1)) {
+      return 1;
+    }
+  }
+  errno = EINVAL;
+  return 0;
+}

lib/Basics/win-utils.h

@@ -141,4 +141,9 @@ void TRI_WindowsEmergencyLog(char const* func, char const* file, int line,
 ////////////////////////////////////////////////////////////////////////////////
 int _cyg_isatty (int fd);
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief detects whether an FD is connected to a cygwin-tty.
+////////////////////////////////////////////////////////////////////////////////
+int _is_cyg_tty (int fd);
+
 #endif