Add a "native_support" service.

services/native_support/make_pty_pair.cc

Index: services/native_support/make_pty_pair.cc
diff --git a/services/native_support/make_pty_pair.cc b/services/native_support/make_pty_pair.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2af21f5216e7f79526a47e2f2b5d61fca1a5e36b
--- /dev/null
+++ b/services/native_support/make_pty_pair.cc
@@ -0,0 +1,65 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "services/native_support/make_pty_pair.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+
+namespace native_support {
+
+bool MakePtyPair(base::ScopedFD* master_fd,
+                 base::ScopedFD* slave_fd,
+                 int* errno_value) {
+  DCHECK(master_fd);
+  DCHECK(!master_fd->is_valid());  // Not very wrong, but unlikely.
+  DCHECK(slave_fd);
+  DCHECK(!slave_fd->is_valid());  // Not very wrong, but unlikely.
+  DCHECK(errno_value);
+
+  // TODO(vtl): |getpt()| is a glibc extension.
+  base::ScopedFD master(getpt());
+  if (!master.is_valid()) {
+    *errno_value = errno;
+    PLOG(ERROR) << "getpt()";
+    return false;
+  }
+
+  if (grantpt(master.get()) < 0) {
+    *errno_value = errno;
+    PLOG(ERROR) << "grantpt()";
+    return false;
+  }
+
+  if (unlockpt(master.get()) < 0) {
+    *errno_value = errno;
+    PLOG(ERROR) << "unlockpt()";
+    return false;
+  }
+
+  const char* name = ptsname(master.get());
+  if (!name) {
+    *errno_value = errno;
+    PLOG(ERROR) << "ptsname()";
+    return false;
+  }
+
+  base::ScopedFD slave(HANDLE_EINTR(open(name, O_RDWR)));
+  if (!slave.is_valid()) {
+    *errno_value = errno;
+    PLOG(ERROR) << "open()";
+    return false;
+  }
+
+  *master_fd = master.Pass();
+  *slave_fd = slave.Pass();
+  return true;
+}
+
+}  // namespace native_support