subprocess.cc | Explore in Territory

// Protocol Buffers - Google's data interchange format
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// Author: [email protected] (Kenton Varda)

#include <google/protobuf/compiler/subprocess.h>

#include <algorithm>
#include <cstring>
#include <iostream>

#ifndef _WIN32
#include <errno.h>
#include <signal.h>
#include <sys/select.h>
#include <sys/wait.h>
#endif

#include <google/protobuf/stubs/logging.h>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/stubs/substitute.h>
#include <google/protobuf/message.h>
#include <google/protobuf/io/io_win32.h>

namespace google {
namespace protobuf {
namespace compiler {

namespace {
char* portable_strdup(const char* s) { … }
}  // namespace

#ifdef _WIN32

static void CloseHandleOrDie(HANDLE handle) {
  if (!CloseHandle(handle)) {
    GOOGLE_LOG(FATAL) << "CloseHandle: "
                      << Subprocess::Win32ErrorMessage(GetLastError());
  }
}

Subprocess::Subprocess()
    : process_start_error_(ERROR_SUCCESS),
      child_handle_(nullptr),
      child_stdin_(nullptr),
      child_stdout_(nullptr) {}

Subprocess::~Subprocess() {
  if (child_stdin_ != nullptr) {
    CloseHandleOrDie(child_stdin_);
  }
  if (child_stdout_ != nullptr) {
    CloseHandleOrDie(child_stdout_);
  }
}

void Subprocess::Start(const std::string& program, SearchMode search_mode) {
  // Create the pipes.
  HANDLE stdin_pipe_read;
  HANDLE stdin_pipe_write;
  HANDLE stdout_pipe_read;
  HANDLE stdout_pipe_write;

  if (!CreatePipe(&stdin_pipe_read, &stdin_pipe_write, nullptr, 0)) {
    GOOGLE_LOG(FATAL) << "CreatePipe: " << Win32ErrorMessage(GetLastError());
  }
  if (!CreatePipe(&stdout_pipe_read, &stdout_pipe_write, nullptr, 0)) {
    GOOGLE_LOG(FATAL) << "CreatePipe: " << Win32ErrorMessage(GetLastError());
  }

  // Make child side of the pipes inheritable.
  if (!SetHandleInformation(stdin_pipe_read, HANDLE_FLAG_INHERIT,
                            HANDLE_FLAG_INHERIT)) {
    GOOGLE_LOG(FATAL) << "SetHandleInformation: "
                      << Win32ErrorMessage(GetLastError());
  }
  if (!SetHandleInformation(stdout_pipe_write, HANDLE_FLAG_INHERIT,
                            HANDLE_FLAG_INHERIT)) {
    GOOGLE_LOG(FATAL) << "SetHandleInformation: "
                      << Win32ErrorMessage(GetLastError());
  }

  // Setup STARTUPINFO to redirect handles.
  STARTUPINFOW startup_info;
  ZeroMemory(&startup_info, sizeof(startup_info));
  startup_info.cb = sizeof(startup_info);
  startup_info.dwFlags = STARTF_USESTDHANDLES;
  startup_info.hStdInput = stdin_pipe_read;
  startup_info.hStdOutput = stdout_pipe_write;
  startup_info.hStdError = GetStdHandle(STD_ERROR_HANDLE);

  if (startup_info.hStdError == INVALID_HANDLE_VALUE) {
    GOOGLE_LOG(FATAL) << "GetStdHandle: " << Win32ErrorMessage(GetLastError());
  }

  // get wide string version of program as the path may contain non-ascii characters
  std::wstring wprogram;
  if (!io::win32::strings::utf8_to_wcs(program.c_str(), &wprogram)) {
    GOOGLE_LOG(FATAL) << "utf8_to_wcs: " << Win32ErrorMessage(GetLastError());
  }

  // Invoking cmd.exe allows for '.bat' files from the path as well as '.exe'.
  std::string command_line = "cmd.exe /c \"" + program + "\"";

  // get wide string version of command line as the path may contain non-ascii characters
  std::wstring wcommand_line;
  if (!io::win32::strings::utf8_to_wcs(command_line.c_str(), &wcommand_line)) {
    GOOGLE_LOG(FATAL) << "utf8_to_wcs: " << Win32ErrorMessage(GetLastError());
  }

  // Using a malloc'ed string because CreateProcess() can mutate its second
  // parameter.
  wchar_t *wcommand_line_copy = _wcsdup(wcommand_line.c_str());

  // Create the process.
  PROCESS_INFORMATION process_info;

  if (CreateProcessW((search_mode == SEARCH_PATH) ? nullptr : wprogram.c_str(),
                     (search_mode == SEARCH_PATH) ? wcommand_line_copy : NULL,
                     nullptr,  // process security attributes
                     nullptr,  // thread security attributes
                     TRUE,     // inherit handles?
                     0,        // obscure creation flags
                     nullptr,  // environment (inherit from parent)
                     nullptr,  // current directory (inherit from parent)
                     &startup_info, &process_info)) {
    child_handle_ = process_info.hProcess;
    CloseHandleOrDie(process_info.hThread);
    child_stdin_ = stdin_pipe_write;
    child_stdout_ = stdout_pipe_read;
  } else {
    process_start_error_ = GetLastError();
    CloseHandleOrDie(stdin_pipe_write);
    CloseHandleOrDie(stdout_pipe_read);
  }

  CloseHandleOrDie(stdin_pipe_read);
  CloseHandleOrDie(stdout_pipe_write);
  free(wcommand_line_copy);
}

bool Subprocess::Communicate(const Message& input, Message* output,
                             std::string* error) {
  if (process_start_error_ != ERROR_SUCCESS) {
    *error = Win32ErrorMessage(process_start_error_);
    return false;
  }

  GOOGLE_CHECK(child_handle_ != nullptr) << "Must call Start() first.";

  std::string input_data;
  if (!input.SerializeToString(&input_data)) {
    *error = "Failed to serialize request.";
    return false;
  }
  std::string output_data;

  int input_pos = 0;

  while (child_stdout_ != nullptr) {
    HANDLE handles[2];
    int handle_count = 0;

    if (child_stdin_ != nullptr) {
      handles[handle_count++] = child_stdin_;
    }
    if (child_stdout_ != nullptr) {
      handles[handle_count++] = child_stdout_;
    }

    DWORD wait_result =
        WaitForMultipleObjects(handle_count, handles, FALSE, INFINITE);

    HANDLE signaled_handle = nullptr;
    if (wait_result >= WAIT_OBJECT_0 &&
        wait_result < WAIT_OBJECT_0 + handle_count) {
      signaled_handle = handles[wait_result - WAIT_OBJECT_0];
    } else if (wait_result == WAIT_FAILED) {
      GOOGLE_LOG(FATAL) << "WaitForMultipleObjects: "
                        << Win32ErrorMessage(GetLastError());
    } else {
      GOOGLE_LOG(FATAL) << "WaitForMultipleObjects: Unexpected return code: "
                        << wait_result;
    }

    if (signaled_handle == child_stdin_) {
      DWORD n;
      if (!WriteFile(child_stdin_, input_data.data() + input_pos,
                     input_data.size() - input_pos, &n, nullptr)) {
        // Child closed pipe.  Presumably it will report an error later.
        // Pretend we're done for now.
        input_pos = input_data.size();
      } else {
        input_pos += n;
      }

      if (input_pos == input_data.size()) {
        // We're done writing.  Close.
        CloseHandleOrDie(child_stdin_);
        child_stdin_ = nullptr;
      }
    } else if (signaled_handle == child_stdout_) {
      char buffer[4096];
      DWORD n;

      if (!ReadFile(child_stdout_, buffer, sizeof(buffer), &n, nullptr)) {
        // We're done reading.  Close.
        CloseHandleOrDie(child_stdout_);
        child_stdout_ = nullptr;
      } else {
        output_data.append(buffer, n);
      }
    }
  }

  if (child_stdin_ != nullptr) {
    // Child did not finish reading input before it closed the output.
    // Presumably it exited with an error.
    CloseHandleOrDie(child_stdin_);
    child_stdin_ = nullptr;
  }

  DWORD wait_result = WaitForSingleObject(child_handle_, INFINITE);

  if (wait_result == WAIT_FAILED) {
    GOOGLE_LOG(FATAL) << "WaitForSingleObject: "
                      << Win32ErrorMessage(GetLastError());
  } else if (wait_result != WAIT_OBJECT_0) {
    GOOGLE_LOG(FATAL) << "WaitForSingleObject: Unexpected return code: "
                      << wait_result;
  }

  DWORD exit_code;
  if (!GetExitCodeProcess(child_handle_, &exit_code)) {
    GOOGLE_LOG(FATAL) << "GetExitCodeProcess: "
                      << Win32ErrorMessage(GetLastError());
  }

  CloseHandleOrDie(child_handle_);
  child_handle_ = nullptr;

  if (exit_code != 0) {
    *error = strings::Substitute("Plugin failed with status code $0.", exit_code);
    return false;
  }

  if (!output->ParseFromString(output_data)) {
    *error = "Plugin output is unparseable: " + CEscape(output_data);
    return false;
  }

  return true;
}

std::string Subprocess::Win32ErrorMessage(DWORD error_code) {
  char* message;

  // WTF?
  FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
                     FORMAT_MESSAGE_IGNORE_INSERTS,
                 nullptr, error_code,
                 MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
                 (LPSTR)&message,  // NOT A BUG!
                 0, nullptr);

  std::string result = message;
  LocalFree(message);
  return result;
}

// ===================================================================

#else  // _WIN32

Subprocess::Subprocess()
    : … { … }

Subprocess::~Subprocess() { … }

void Subprocess::Start(const std::string& program, SearchMode search_mode) { … }

bool Subprocess::Communicate(const Message& input, Message* output,
                             std::string* error) { … }

#endif  // !_WIN32

}  // namespace compiler
}  // namespace protobuf
}  // namespace google
chromium/third_party/protobuf/src/google/protobuf/compiler/subprocess.cc
