src/stdio_redirection.h

// Copyright 2023 Google Inc. 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 NINJA_STDIO_REDIRECTION_H_
#define NINJA_STDIO_REDIRECTION_H_

#include <stdio.h>

#include <string>

#include "ipc_handle.h"

/// Multiple classes related to redirecting stdio streams.

/// A class used to manage redirection of stdin/stdout/stderr
/// between two processes, using an IpcHandle for communication.
///
/// IMPORTANT: THIS DOES NOT WORK ON WINDOWS. Due to Win32
/// technical limitations (i.e. DuplicateHandle() will always
/// fail to duplicate console handlers from another process,
/// which happens during ReceiveStandardDescriptors).
///
/// Usage is:
///   1) Create instance, passing a reference to the handle.
///
///   2) On the client, call SendStandardDescriptors() to send
///      standard descriptors to the server. This does not change
///      the current process.
///
///   3) On the server, call ReceiveStandardDescriptors() to
///      receive them from the handle, and modify the process'
///      current standard descriptors to use them.
///
///   4) The destructor will restore the previous standard
///      descriptors, in the case where ReceiveStandardDescriptors()
///      was called.
///
class StdioRedirector {
 public:
  StdioRedirector(IpcHandle& connection);
  ~StdioRedirector();

  bool SendStandardDescriptors(std::string* err);
  bool ReceiveStandardDescriptors(std::string* err);

 protected:
  IpcHandle& connection_;
  IpcHandle old_stdin_;
  IpcHandle old_stdout_;
  IpcHandle old_stderr_;
};

#endif  // NINJA_STDIO_REDIRECTION_H_