src/write_manifest.cc

// Copyright 2024 The Bazel 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.

#include <stdio.h>
#include <stdlib.h>

#ifdef _WIN32

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#include <string>

// Writes a new app manifest to a Windows executable.
int wmain(int argc, wchar_t *argv[]) {
  if (argc != 2) {
    fwprintf(stderr, L"Usage: %ls <filename>\n", argv[0]);
    return 1;
  }

  std::string new_manifest;
  char buf[4096];
  size_t n;
  while ((n = fread(buf, 1, sizeof(buf), stdin)) > 0) {
    new_manifest.append(buf, n);
  }

  HANDLE update_handle = BeginUpdateResourceW(argv[1], false);
  if (!update_handle) {
    fwprintf(stderr, L"Error opening file %ls for update: %d\n", argv[1],
             GetLastError());
    return 1;
  }
  if (!UpdateResourceA(update_handle, RT_MANIFEST, MAKEINTRESOURCE(1),
                       MAKELANGID(LANG_NEUTRAL, SUBLANG_NEUTRAL),
                       const_cast<char *>(new_manifest.c_str()),
                       new_manifest.size())) {
    fwprintf(stderr, L"Error updating resource: %d\n", GetLastError());
    return 1;
  }
  if (!EndUpdateResourceW(update_handle, false)) {
    fwprintf(stderr, L"Error finalizing update: %d\n", GetLastError());
    return 1;
  }

  return 0;
}

#else  // !_WIN32

// Updating the app manifest requires the UpdateResource Windows API, so this
// is a no-op when cross-compiling for Windows from a non-Windows host.
// TODO: Patch app manifests when cross-compiling from a non-Windows host.
int main(int argc, char* argv[]) {
  if (argc != 2) {
    fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
    return 1;
  }
  // Drain the manifest from stdin so that the writer doesn't get a SIGPIPE.
  char buf[4096];
  while (fread(buf, 1, sizeof(buf), stdin) > 0) {
  }
  fprintf(stderr,
          "WARNING: not patching the app manifest of %s: only supported when "
          "building on Windows\n",
          argv[1]);
  return 0;
}

#endif  // _WIN32