Add CloseStdinAndStdout()

util/posix/close_stdio.h

+// 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.
+
+#ifndef CRASHPAD_UTIL_POSIX_CLOSE_STDIO_H_
+#define CRASHPAD_UTIL_POSIX_CLOSE_STDIO_H_
+
+namespace crashpad {
+
+//! \brief Closes `stdin` and `stdout` by opening `/dev/null` over them.
+//!
+//! It is normally inadvisable to `close()` the three standard input/output
+//! streams, because they occupy special file descriptors. Closing them outright
+//! could result in their file descriptors being reused. This causes problems
+//! for library code (including the standard library) that expects these file
+//! descriptors to have special meaning.
+//!
+//! This function discards the standard input and standard output streams by
+//! opening `/dev/null` and assigning it to their file descriptors, closing
+//! whatever had been at those file descriptors previously.
+//!
+//! `stderr`, the standard error stream, is not closed. It is often useful to
+//! retain the ability to send diagnostic messages to the standard error stream.
+//!
+//! \note This function can only maintain its guarantees in a single-threaded
+//!     process, or in situations where the caller has control of all threads in
+//!     the process.
+void CloseStdinAndStdout();
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_POSIX_CLOSE_STDIO_H_