protobuf/compiler/subprocess.h

0001 // Protocol Buffers - Google's data interchange format
0002 // Copyright 2008 Google Inc.  All rights reserved.
0003 //
0004 // Use of this source code is governed by a BSD-style
0005 // license that can be found in the LICENSE file or at
0006 // https://developers.google.com/open-source/licenses/bsd
0007
0008 // Author: kenton@google.com (Kenton Varda)
0009
0010 #ifndef GOOGLE_PROTOBUF_COMPILER_SUBPROCESS_H__
0011 #define GOOGLE_PROTOBUF_COMPILER_SUBPROCESS_H__
0012
0013 #ifdef _WIN32
0014 #ifndef WIN32_LEAN_AND_MEAN
0015 #define WIN32_LEAN_AND_MEAN  // right...
0016 #endif
0017 #include <windows.h>
0018 #else  // _WIN32
0019 #include <sys/types.h>
0020 #include <unistd.h>
0021 #endif  // !_WIN32
0022 #include <string>
0023
0024 #include "google/protobuf/port.h"
0025
0026 // Must be included last.
0027 #include "google/protobuf/port_def.inc"
0028
0029 namespace google {
0030 namespace protobuf {
0031
0032 class Message;
0033
0034 namespace compiler {
0035
0036 // Utility class for launching sub-processes.
0037 class PROTOC_EXPORT Subprocess {
0038  public:
0039   Subprocess();
0040   ~Subprocess();
0041
0042   enum SearchMode {
0043     SEARCH_PATH,  // Use PATH environment variable.
0044     EXACT_NAME    // Program is an exact file name; don't use the PATH.
0045   };
0046
0047   // Start the subprocess.  Currently we don't provide a way to specify
0048   // arguments as protoc plugins don't have any.
0049   void Start(const std::string& program, SearchMode search_mode);
0050
0051   // Serialize the input message and pipe it to the subprocess's stdin, then
0052   // close the pipe.  Meanwhile, read from the subprocess's stdout and parse
0053   // the data into *output.  All this is done carefully to avoid deadlocks.
0054   // Returns true if successful.  On any sort of error, returns false and sets
0055   // *error to a description of the problem.
0056   bool Communicate(const Message& input, Message* output, std::string* error);
0057
0058 #ifdef _WIN32
0059   // Given an error code, returns a human-readable error message.  This is
0060   // defined here so that CommandLineInterface can share it.
0061   static std::string Win32ErrorMessage(DWORD error_code);
0062 #endif
0063
0064  private:
0065 #ifdef _WIN32
0066   DWORD process_start_error_;
0067   HANDLE child_handle_;
0068
0069   // The file handles for our end of the child's pipes.  We close each and
0070   // set it to NULL when no longer needed.
0071   HANDLE child_stdin_;
0072   HANDLE child_stdout_;
0073
0074 #else  // _WIN32
0075   pid_t child_pid_;
0076
0077   // The file descriptors for our end of the child's pipes.  We close each and
0078   // set it to -1 when no longer needed.
0079   int child_stdin_;
0080   int child_stdout_;
0081
0082 #endif  // !_WIN32
0083 };
0084
0085 }  // namespace compiler
0086 }  // namespace protobuf
0087 }  // namespace google
0088
0089 #include "google/protobuf/port_undef.inc"
0090
0091 #endif  // GOOGLE_PROTOBUF_COMPILER_SUBPROCESS_H__