Add CloseStdinAndStdout()

util/posix/close_stdio.cc

Index: util/posix/close_stdio.cc
diff --git a/util/posix/close_stdio.cc b/util/posix/close_stdio.cc
new file mode 100644
index 0000000000000000000000000000000000000000..8ff59d0af31a2029541b52edcca66acba29ff949
--- /dev/null
+++ b/util/posix/close_stdio.cc
@@ -0,0 +1,52 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/posix/close_stdio.h"
+
+#include <fcntl.h>
+#include <paths.h>
+#include <unistd.h>
+
+#include "base/basictypes.h"
+#include "base/files/scoped_file.h"
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+
+namespace crashpad {
+
+namespace {
+
+void CloseStdioStream(int desired_fd, int oflag) {
+  base::ScopedFD fd(HANDLE_EINTR(open(_PATH_DEVNULL, oflag)));
+  if (fd == desired_fd) {
+    // Weird, but play along.
+    ignore_result(fd.release());
+  } else {
+    PCHECK(fd.get() >= 0) << "open";
+    PCHECK(HANDLE_EINTR(dup2(fd.get(), desired_fd)) != -1) << "dup2";
+    fd.reset();
+  }
+}
+
+}  // namespace
+
+void CloseStdinAndStdout() {
+  // Open /dev/null for stdin and stdout separately, so that it can be opened
+  // with the correct mode each time. This ensures that attempts to write to
+  // stdin or read from stdout fail with EBADF.
+  CloseStdioStream(STDIN_FILENO, O_RDONLY);
+  CloseStdioStream(STDOUT_FILENO, O_WRONLY);
+}
+
+}  // namespace crashpad