static bool Execute()

in lib/llvm/Support/Windows/Program.inc [152:315]

• 125 lines of code
• 24 McCabe index (conditional complexity)

static bool Execute(ProcessInfo &PI, StringRef Program,
                    ArrayRef<StringRef> Args, Optional<ArrayRef<StringRef>> Env,
                    ArrayRef<Optional<StringRef>> Redirects,
                    unsigned MemoryLimit, std::string *ErrMsg) {
  if (!sys::fs::can_execute(Program)) {
    if (ErrMsg)
      *ErrMsg = "program not executable";
    return false;
  }

  // can_execute may succeed by looking at Program + ".exe". CreateProcessW
  // will implicitly add the .exe if we provide a command line without an
  // executable path, but since we use an explicit executable, we have to add
  // ".exe" ourselves.
  SmallString<64> ProgramStorage;
  if (!sys::fs::exists(Program))
    Program = Twine(Program + ".exe").toStringRef(ProgramStorage);

  // Windows wants a command line, not an array of args, to pass to the new
  // process.  We have to concatenate them all, while quoting the args that
  // have embedded spaces (or are empty).
  std::string Command = flattenWindowsCommandLine(Args);

  // The pointer to the environment block for the new process.
  std::vector<wchar_t> EnvBlock;

  if (Env) {
    // An environment block consists of a null-terminated block of
    // null-terminated strings. Convert the array of environment variables to
    // an environment block by concatenating them.
    for (const auto E : *Env) {
      SmallVector<wchar_t, MAX_PATH> EnvString;
      if (std::error_code ec = windows::UTF8ToUTF16(E, EnvString)) {
        SetLastError(ec.value());
        MakeErrMsg(ErrMsg, "Unable to convert environment variable to UTF-16");
        return false;
      }

      EnvBlock.insert(EnvBlock.end(), EnvString.begin(), EnvString.end());
      EnvBlock.push_back(0);
    }
    EnvBlock.push_back(0);
  }

  // Create a child process.
  STARTUPINFOW si;
  memset(&si, 0, sizeof(si));
  si.cb = sizeof(si);
  si.hStdInput = INVALID_HANDLE_VALUE;
  si.hStdOutput = INVALID_HANDLE_VALUE;
  si.hStdError = INVALID_HANDLE_VALUE;

  if (!Redirects.empty()) {
    si.dwFlags = STARTF_USESTDHANDLES;

    si.hStdInput = RedirectIO(Redirects[0], 0, ErrMsg);
    if (si.hStdInput == INVALID_HANDLE_VALUE) {
      MakeErrMsg(ErrMsg, "can't redirect stdin");
      return false;
    }
    si.hStdOutput = RedirectIO(Redirects[1], 1, ErrMsg);
    if (si.hStdOutput == INVALID_HANDLE_VALUE) {
      CloseHandle(si.hStdInput);
      MakeErrMsg(ErrMsg, "can't redirect stdout");
      return false;
    }
    if (Redirects[1] && Redirects[2] && *Redirects[1] == *Redirects[2]) {
      // If stdout and stderr should go to the same place, redirect stderr
      // to the handle already open for stdout.
      if (!DuplicateHandle(GetCurrentProcess(), si.hStdOutput,
                           GetCurrentProcess(), &si.hStdError,
                           0, TRUE, DUPLICATE_SAME_ACCESS)) {
        CloseHandle(si.hStdInput);
        CloseHandle(si.hStdOutput);
        MakeErrMsg(ErrMsg, "can't dup stderr to stdout");
        return false;
      }
    } else {
      // Just redirect stderr
      si.hStdError = RedirectIO(Redirects[2], 2, ErrMsg);
      if (si.hStdError == INVALID_HANDLE_VALUE) {
        CloseHandle(si.hStdInput);
        CloseHandle(si.hStdOutput);
        MakeErrMsg(ErrMsg, "can't redirect stderr");
        return false;
      }
    }
  }

  PROCESS_INFORMATION pi;
  memset(&pi, 0, sizeof(pi));

  fflush(stdout);
  fflush(stderr);

  SmallVector<wchar_t, MAX_PATH> ProgramUtf16;
  if (std::error_code ec = path::widenPath(Program, ProgramUtf16)) {
    SetLastError(ec.value());
    MakeErrMsg(ErrMsg,
               std::string("Unable to convert application name to UTF-16"));
    return false;
  }

  SmallVector<wchar_t, MAX_PATH> CommandUtf16;
  if (std::error_code ec = windows::UTF8ToUTF16(Command, CommandUtf16)) {
    SetLastError(ec.value());
    MakeErrMsg(ErrMsg,
               std::string("Unable to convert command-line to UTF-16"));
    return false;
  }

  BOOL rc = CreateProcessW(ProgramUtf16.data(), CommandUtf16.data(), 0, 0,
                           TRUE, CREATE_UNICODE_ENVIRONMENT,
                           EnvBlock.empty() ? 0 : EnvBlock.data(), 0, &si,
                           &pi);
  DWORD err = GetLastError();

  // Regardless of whether the process got created or not, we are done with
  // the handles we created for it to inherit.
  CloseHandle(si.hStdInput);
  CloseHandle(si.hStdOutput);
  CloseHandle(si.hStdError);

  // Now return an error if the process didn't get created.
  if (!rc) {
    SetLastError(err);
    MakeErrMsg(ErrMsg, std::string("Couldn't execute program '") +
               Program.str() + "'");
    return false;
  }

  PI.Pid = pi.dwProcessId;
  PI.Process = pi.hProcess;

  // Make sure these get closed no matter what.
  ScopedCommonHandle hThread(pi.hThread);

  // Assign the process to a job if a memory limit is defined.
  ScopedJobHandle hJob;
  if (MemoryLimit != 0) {
    hJob = CreateJobObjectW(0, 0);
    bool success = false;
    if (hJob) {
      JOBOBJECT_EXTENDED_LIMIT_INFORMATION jeli;
      memset(&jeli, 0, sizeof(jeli));
      jeli.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_PROCESS_MEMORY;
      jeli.ProcessMemoryLimit = uintptr_t(MemoryLimit) * 1048576;
      if (SetInformationJobObject(hJob, JobObjectExtendedLimitInformation,
                                  &jeli, sizeof(jeli))) {
        if (AssignProcessToJobObject(hJob, pi.hProcess))
          success = true;
      }
    }
    if (!success) {
      SetLastError(GetLastError());
      MakeErrMsg(ErrMsg, std::string("Unable to set memory limit"));
      TerminateProcess(pi.hProcess, 1);
      WaitForSingleObject(pi.hProcess, INFINITE);
      return false;
    }
  }

  return true;
}