summaryrefslogtreecommitdiff
path: root/onlineupdate/source/update/common/updatehelper.cxx
blob: c10ea8d580d4f9a6784be3f81fd4dd36144b71a5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifdef _WIN32
#include <windows.h>

// Needed for CreateToolhelp32Snapshot
#include <tlhelp32.h>
#ifndef ONLY_SERVICE_LAUNCHING

#include <stdio.h>
#include "shlobj.h"
#include "updatehelper.h"
#include "uachelper.h"
#include "pathhash.h"
#include "mozilla/UniquePtr.h"

// Needed for PathAppendW
#include <shlwapi.h>

using mozilla::MakeUnique;
using mozilla::UniquePtr;

BOOL PathAppendSafe(LPWSTR base, LPCWSTR extra);

/**
 * Obtains the path of a file in the same directory as the specified file.
 *
 * @param  destinationBuffer A buffer of size MAX_PATH + 1 to store the result.
 * @param  siblingFIlePath   The path of another file in the same directory
 * @param  newFileName       The filename of another file in the same directory
 * @return TRUE if successful
 */
BOOL
PathGetSiblingFilePath(LPWSTR destinationBuffer,
                       LPCWSTR siblingFilePath,
                       LPCWSTR newFileName)
{
  if (wcslen(siblingFilePath) >= MAX_PATH) {
    return FALSE;
  }

  wcsncpy(destinationBuffer, siblingFilePath, MAX_PATH);
  if (!PathRemoveFileSpecW(destinationBuffer)) {
    return FALSE;
  }

  if (wcslen(destinationBuffer) + wcslen(newFileName) >= MAX_PATH) {
    return FALSE;
  }

  return PathAppendSafe(destinationBuffer, newFileName);
}

/**
 * Launch the post update application as the specified user (helper.exe).
 * It takes in the path of the callback application to calculate the path
 * of helper.exe.  For service updates this is called from both the system
 * account and the current user account.
 *
 * @param  installationDir The path to the callback application binary.
 * @param  updateInfoDir   The directory where update info is stored.
 * @param  forceSync       If true even if the ini file specifies async, the
 *                         process will wait for termination of PostUpdate.
 * @param  userToken       The user token to run as, if nullptr the current
 *                         user will be used.
 * @return TRUE if there was no error starting the process.
 */
BOOL
LaunchWinPostProcess(const WCHAR *installationDir,
                     const WCHAR *updateInfoDir,
                     bool forceSync,
                     HANDLE userToken)
{
  WCHAR workingDirectory[MAX_PATH + 1] = { L'\0' };
  wcsncpy(workingDirectory, installationDir, MAX_PATH);

  // Launch helper.exe to perform post processing (e.g. registry and log file
  // modifications) for the update.
  WCHAR inifile[MAX_PATH + 1] = { L'\0' };
  wcsncpy(inifile, installationDir, MAX_PATH);
  if (!PathAppendSafe(inifile, L"updater.ini")) {
    return FALSE;
  }

  WCHAR exefile[MAX_PATH + 1];
  WCHAR exearg[MAX_PATH + 1];
  WCHAR exeasync[10];
  bool async = true;
  if (!GetPrivateProfileStringW(L"PostUpdateWin", L"ExeRelPath", nullptr,
                                exefile, MAX_PATH + 1, inifile)) {
    return FALSE;
  }

  if (!GetPrivateProfileStringW(L"PostUpdateWin", L"ExeArg", nullptr, exearg,
                                MAX_PATH + 1, inifile)) {
    return FALSE;
  }

  if (!GetPrivateProfileStringW(L"PostUpdateWin", L"ExeAsync", L"TRUE",
                                exeasync,
                                sizeof(exeasync)/sizeof(exeasync[0]),
                                inifile)) {
    return FALSE;
  }

  WCHAR exefullpath[MAX_PATH + 1] = { L'\0' };
  wcsncpy(exefullpath, installationDir, MAX_PATH);
  if (!PathAppendSafe(exefullpath, exefile)) {
    return false;
  }

  WCHAR dlogFile[MAX_PATH + 1];
  if (!PathGetSiblingFilePath(dlogFile, exefullpath, L"uninstall.update")) {
    return FALSE;
  }

  WCHAR slogFile[MAX_PATH + 1] = { L'\0' };
  wcsncpy(slogFile, updateInfoDir, MAX_PATH);
  if (!PathAppendSafe(slogFile, L"update.log")) {
    return FALSE;
  }

  WCHAR dummyArg[14] = { L'\0' };
  wcsncpy(dummyArg, L"argv0ignored ", sizeof(dummyArg) / sizeof(dummyArg[0]) - 1);

  size_t len = wcslen(exearg) + wcslen(dummyArg);
  WCHAR *cmdline = (WCHAR *) malloc((len + 1) * sizeof(WCHAR));
  if (!cmdline) {
    return FALSE;
  }

  wcsncpy(cmdline, dummyArg, len);
  wcscat(cmdline, exearg);

  if (forceSync ||
      !_wcsnicmp(exeasync, L"false", 6) ||
      !_wcsnicmp(exeasync, L"0", 2)) {
    async = false;
  }

  // We want to launch the post update helper app to update the Windows
  // registry even if there is a failure with removing the uninstall.update
  // file or copying the update.log file.
  CopyFileW(slogFile, dlogFile, false);

  STARTUPINFOW si = {sizeof(si), 0};
  si.lpDesktop = L"";
  PROCESS_INFORMATION pi = {0};

  bool ok;
  if (userToken) {
    ok = CreateProcessAsUserW(userToken,
                              exefullpath,
                              cmdline,
                              nullptr,  // no special security attributes
                              nullptr,  // no special thread attributes
                              false,    // don't inherit filehandles
                              0,        // No special process creation flags
                              nullptr,  // inherit my environment
                              workingDirectory,
                              &si,
                              &pi);
  } else {
    ok = CreateProcessW(exefullpath,
                        cmdline,
                        nullptr,  // no special security attributes
                        nullptr,  // no special thread attributes
                        false,    // don't inherit filehandles
                        0,        // No special process creation flags
                        nullptr,  // inherit my environment
                        workingDirectory,
                        &si,
                        &pi);
  }
  free(cmdline);
  if (ok) {
    if (!async)
      WaitForSingleObject(pi.hProcess, INFINITE);
    CloseHandle(pi.hProcess);
    CloseHandle(pi.hThread);
  }
  return ok;
}

/**
 * Starts the upgrade process for update of the service if it is
 * already installed.
 *
 * @param  installDir the installation directory where
 *         maintenanceservice_installer.exe is located.
 * @return TRUE if successful
 */
BOOL
StartServiceUpdate(LPCWSTR installDir)
{
  // Get a handle to the local computer SCM database
  SC_HANDLE manager = OpenSCManager(nullptr, nullptr,
                                    SC_MANAGER_ALL_ACCESS);
  if (!manager) {
    return FALSE;
  }

  // Open the service
  SC_HANDLE svc = OpenServiceW(manager, SVC_NAME,
                               SERVICE_ALL_ACCESS);
  if (!svc) {
    CloseServiceHandle(manager);
    return FALSE;
  }

  // If we reach here, then the service is installed, so
  // proceed with upgrading it.

  CloseServiceHandle(manager);

  // The service exists and we opened it, get the config bytes needed
  DWORD bytesNeeded;
  if (!QueryServiceConfigW(svc, nullptr, 0, &bytesNeeded) &&
      GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
    CloseServiceHandle(svc);
    return FALSE;
  }

  // Get the service config information, in particular we want the binary
  // path of the service.
  UniquePtr<char[]> serviceConfigBuffer = MakeUnique<char[]>(bytesNeeded);
  if (!QueryServiceConfigW(svc,
      reinterpret_cast<QUERY_SERVICE_CONFIGW*>(serviceConfigBuffer.get()),
      bytesNeeded, &bytesNeeded)) {
    CloseServiceHandle(svc);
    return FALSE;
  }

  CloseServiceHandle(svc);

  QUERY_SERVICE_CONFIGW &serviceConfig =
    *reinterpret_cast<QUERY_SERVICE_CONFIGW*>(serviceConfigBuffer.get());

  PathUnquoteSpacesW(serviceConfig.lpBinaryPathName);

  // Obtain the temp path of the maintenance service binary
  WCHAR tmpService[MAX_PATH + 1] = { L'\0' };
  if (!PathGetSiblingFilePath(tmpService, serviceConfig.lpBinaryPathName,
                              L"maintenanceservice_tmp.exe")) {
    return FALSE;
  }

  // Get the new maintenance service path from the install dir
  WCHAR newMaintServicePath[MAX_PATH + 1] = { L'\0' };
  wcsncpy(newMaintServicePath, installDir, MAX_PATH);
  PathAppendSafe(newMaintServicePath,
                 L"maintenanceservice.exe");

  // Copy the temp file in alongside the maintenace service.
  // This is a requirement for maintenance service upgrades.
  if (!CopyFileW(newMaintServicePath, tmpService, FALSE)) {
    return FALSE;
  }

  // Start the upgrade comparison process
  STARTUPINFOW si = {0};
  si.cb = sizeof(STARTUPINFOW);
  // No particular desktop because no UI
  si.lpDesktop = L"";
  PROCESS_INFORMATION pi = {0};
  WCHAR cmdLine[64] = { '\0' };
  wcsncpy(cmdLine, L"dummyparam.exe upgrade",
          sizeof(cmdLine) / sizeof(cmdLine[0]) - 1);
  BOOL svcUpdateProcessStarted = CreateProcessW(tmpService,
                                                cmdLine,
                                                nullptr, nullptr, FALSE,
                                                0,
                                                nullptr, installDir, &si, &pi);
  if (svcUpdateProcessStarted) {
    CloseHandle(pi.hProcess);
    CloseHandle(pi.hThread);
  }
  return svcUpdateProcessStarted;
}

#endif

/**
 * Executes a maintenance service command
 *
 * @param  argc    The total number of arguments in argv
 * @param  argv    An array of null terminated strings to pass to the service,
 * @return ERROR_SUCCESS if the service command was started.
 *         Less than 16000, a windows system error code from StartServiceW
 *         More than 20000, 20000 + the last state of the service constant if
 *         the last state is something other than stopped.
 *         17001 if the SCM could not be opened
 *         17002 if the service could not be opened
*/
DWORD
StartServiceCommand(int argc, LPCWSTR* argv)
{
  DWORD lastState = WaitForServiceStop(SVC_NAME, 5);
  if (lastState != SERVICE_STOPPED) {
    return 20000 + lastState;
  }

  // Get a handle to the SCM database.
  SC_HANDLE serviceManager = OpenSCManager(nullptr, nullptr,
                                           SC_MANAGER_CONNECT |
                                           SC_MANAGER_ENUMERATE_SERVICE);
  if (!serviceManager)  {
    return 17001;
  }

  // Get a handle to the service.
  SC_HANDLE service = OpenServiceW(serviceManager,
                                   SVC_NAME,
                                   SERVICE_START);
  if (!service) {
    CloseServiceHandle(serviceManager);
    return 17002;
  }

  // Wait at most 5 seconds trying to start the service in case of errors
  // like ERROR_SERVICE_DATABASE_LOCKED or ERROR_SERVICE_REQUEST_TIMEOUT.
  const DWORD maxWaitMS = 5000;
  DWORD currentWaitMS = 0;
  DWORD lastError = ERROR_SUCCESS;
  while (currentWaitMS < maxWaitMS) {
    BOOL result = StartServiceW(service, argc, argv);
    if (result) {
      lastError = ERROR_SUCCESS;
      break;
    } else {
      lastError = GetLastError();
    }
    Sleep(100);
    currentWaitMS += 100;
  }
  CloseServiceHandle(service);
  CloseServiceHandle(serviceManager);
  return lastError;
}

#ifndef ONLY_SERVICE_LAUNCHING

/**
 * Launch a service initiated action for a software update with the
 * specified arguments.
 *
 * @param  exePath The path of the executable to run
 * @param  argc    The total number of arguments in argv
 * @param  argv    An array of null terminated strings to pass to the exePath,
 *                 argv[0] must be the path to the updater.exe
 * @return ERROR_SUCCESS if successful
 */
DWORD
LaunchServiceSoftwareUpdateCommand(int argc, LPCWSTR* argv)
{
  // The service command is the same as the updater.exe command line except
  // it has 2 extra args: 1) The Path to updater.exe, and 2) the command
  // being executed which is "software-update"
  LPCWSTR *updaterServiceArgv = new LPCWSTR[argc + 2];
  updaterServiceArgv[0] = L"MozillaMaintenance";
  updaterServiceArgv[1] = L"software-update";

  for (int i = 0; i < argc; ++i) {
    updaterServiceArgv[i + 2] = argv[i];
  }

  // Execute the service command by starting the service with
  // the passed in arguments.
  DWORD ret = StartServiceCommand(argc + 2, updaterServiceArgv);
  delete[] updaterServiceArgv;
  return ret;
}

/**
 * Joins a base directory path with a filename.
 *
 * @param  base  The base directory path of size MAX_PATH + 1
 * @param  extra The filename to append
 * @return TRUE if the file name was successful appended to base
 */
BOOL
PathAppendSafe(LPWSTR base, LPCWSTR extra)
{
  if (wcslen(base) + wcslen(extra) >= MAX_PATH) {
    return FALSE;
  }

  return PathAppendW(base, extra);
}

/**
 * Sets update.status to pending so that the next startup will not use
 * the service and instead will attempt an update the with a UAC prompt.
 *
 * @param  updateDirPath The path of the update directory
 * @return TRUE if successful
 */
BOOL
WriteStatusPending(LPCWSTR updateDirPath)
{
  WCHAR updateStatusFilePath[MAX_PATH + 1] = { L'\0' };
  wcsncpy(updateStatusFilePath, updateDirPath, MAX_PATH);
  if (!PathAppendSafe(updateStatusFilePath, L"update.status")) {
    return FALSE;
  }

  const char pending[] = "pending";
  HANDLE statusFile = CreateFileW(updateStatusFilePath, GENERIC_WRITE, 0,
                                  nullptr, CREATE_ALWAYS, 0, nullptr);
  if (statusFile == INVALID_HANDLE_VALUE) {
    return FALSE;
  }

  DWORD wrote;
  BOOL ok = WriteFile(statusFile, pending,
                      sizeof(pending) - 1, &wrote, nullptr);
  CloseHandle(statusFile);
  return ok && (wrote == sizeof(pending) - 1);
}

/**
 * Sets update.status to a specific failure code
 *
 * @param  updateDirPath The path of the update directory
 * @return TRUE if successful
 */
BOOL
WriteStatusFailure(LPCWSTR updateDirPath, int errorCode)
{
  WCHAR updateStatusFilePath[MAX_PATH + 1] = { L'\0' };
  wcsncpy(updateStatusFilePath, updateDirPath, MAX_PATH);
  if (!PathAppendSafe(updateStatusFilePath, L"update.status")) {
    return FALSE;
  }

  HANDLE statusFile = CreateFileW(updateStatusFilePath, GENERIC_WRITE, 0,
                                  nullptr, CREATE_ALWAYS, 0, nullptr);
  if (statusFile == INVALID_HANDLE_VALUE) {
    return FALSE;
  }
  char failure[32];
  sprintf(failure, "failed: %d", errorCode);

  DWORD toWrite = strlen(failure);
  DWORD wrote;
  BOOL ok = WriteFile(statusFile, failure,
                      toWrite, &wrote, nullptr);
  CloseHandle(statusFile);
  return ok && wrote == toWrite;
}

#endif

/**
 * Waits for a service to enter a stopped state.
 * This function does not stop the service, it just blocks until the service
 * is stopped.
 *
 * @param  serviceName     The service to wait for.
 * @param  maxWaitSeconds  The maximum number of seconds to wait
 * @return state of the service after a timeout or when stopped.
 *         A value of 255 is returned for an error. Typical values are:
 *         SERVICE_STOPPED 0x00000001
 *         SERVICE_START_PENDING 0x00000002
 *         SERVICE_STOP_PENDING 0x00000003
 *         SERVICE_RUNNING 0x00000004
 *         SERVICE_CONTINUE_PENDING 0x00000005
 *         SERVICE_PAUSE_PENDING 0x00000006
 *         SERVICE_PAUSED 0x00000007
 *         last status not set 0x000000CF
 *         Could no query status 0x000000DF
 *         Could not open service, access denied 0x000000EB
 *         Could not open service, invalid handle 0x000000EC
 *         Could not open service, invalid name 0x000000ED
 *         Could not open service, does not exist 0x000000EE
 *         Could not open service, other error 0x000000EF
 *         Could not open SCM, access denied 0x000000FD
 *         Could not open SCM, database does not exist 0x000000FE;
 *         Could not open SCM, other error 0x000000FF;
 * Note: The strange choice of error codes above SERVICE_PAUSED are chosen
 * in case Windows comes out with other service stats higher than 7, they
 * would likely call it 8 and above.  JS code that uses this in TestAUSHelper
 * only handles values up to 255 so that's why we don't use GetLastError
 * directly.
 */
DWORD
WaitForServiceStop(LPCWSTR serviceName, DWORD maxWaitSeconds)
{
  // 0x000000CF is defined above to be not set
  DWORD lastServiceState = 0x000000CF;

  // Get a handle to the SCM database.
  SC_HANDLE serviceManager = OpenSCManager(nullptr, nullptr,
                                           SC_MANAGER_CONNECT |
                                           SC_MANAGER_ENUMERATE_SERVICE);
  if (!serviceManager)  {
    DWORD lastError = GetLastError();
    switch(lastError) {
    case ERROR_ACCESS_DENIED:
      return 0x000000FD;
    case ERROR_DATABASE_DOES_NOT_EXIST:
      return 0x000000FE;
    default:
      return 0x000000FF;
    }
  }

  // Get a handle to the service.
  SC_HANDLE service = OpenServiceW(serviceManager,
                                   serviceName,
                                   SERVICE_QUERY_STATUS);
  if (!service) {
    DWORD lastError = GetLastError();
    CloseServiceHandle(serviceManager);
    switch(lastError) {
    case ERROR_ACCESS_DENIED:
      return 0x000000EB;
    case ERROR_INVALID_HANDLE:
      return 0x000000EC;
    case ERROR_INVALID_NAME:
      return 0x000000ED;
    case ERROR_SERVICE_DOES_NOT_EXIST:
      return 0x000000EE;
    default:
      return 0x000000EF;
    }
  }

  DWORD currentWaitMS = 0;
  SERVICE_STATUS_PROCESS ssp;
  ssp.dwCurrentState = lastServiceState;
  while (currentWaitMS < maxWaitSeconds * 1000) {
    DWORD bytesNeeded;
    if (!QueryServiceStatusEx(service, SC_STATUS_PROCESS_INFO, (LPBYTE)&ssp,
                              sizeof(SERVICE_STATUS_PROCESS), &bytesNeeded)) {
      DWORD lastError = GetLastError();
      switch (lastError) {
      case ERROR_INVALID_HANDLE:
        ssp.dwCurrentState = 0x000000D9;
        break;
      case ERROR_ACCESS_DENIED:
        ssp.dwCurrentState = 0x000000DA;
        break;
      case ERROR_INSUFFICIENT_BUFFER:
        ssp.dwCurrentState = 0x000000DB;
        break;
      case ERROR_INVALID_PARAMETER:
        ssp.dwCurrentState = 0x000000DC;
        break;
      case ERROR_INVALID_LEVEL:
        ssp.dwCurrentState = 0x000000DD;
        break;
      case ERROR_SHUTDOWN_IN_PROGRESS:
        ssp.dwCurrentState = 0x000000DE;
        break;
      // These 3 errors can occur when the service is not yet stopped but
      // it is stopping.
      case ERROR_INVALID_SERVICE_CONTROL:
      case ERROR_SERVICE_CANNOT_ACCEPT_CTRL:
      case ERROR_SERVICE_NOT_ACTIVE:
        currentWaitMS += 50;
        Sleep(50);
        continue;
      default:
        ssp.dwCurrentState = 0x000000DF;
      }

      // We couldn't query the status so just break out
      break;
    }

    // The service is already in use.
    if (ssp.dwCurrentState == SERVICE_STOPPED) {
      break;
    }
    currentWaitMS += 50;
    Sleep(50);
  }

  lastServiceState = ssp.dwCurrentState;
  CloseServiceHandle(service);
  CloseServiceHandle(serviceManager);
  return lastServiceState;
}

#ifndef ONLY_SERVICE_LAUNCHING

/**
 * Determines if there is at least one process running for the specified
 * application. A match will be found across any session for any user.
 *
 * @param process The process to check for existence
 * @return ERROR_NOT_FOUND if the process was not found
 *         ERROR_SUCCESS if the process was found and there were no errors
 *         Other Win32 system error code for other errors
**/
DWORD
IsProcessRunning(LPCWSTR filename)
{
  // Take a snapshot of all processes in the system.
  HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
  if (INVALID_HANDLE_VALUE == snapshot) {
    return GetLastError();
  }

  PROCESSENTRY32W processEntry;
  processEntry.dwSize = sizeof(PROCESSENTRY32W);
  if (!Process32FirstW(snapshot, &processEntry)) {
    DWORD lastError = GetLastError();
    CloseHandle(snapshot);
    return lastError;
  }

  do {
    if (wcsicmp(filename, processEntry.szExeFile) == 0) {
      CloseHandle(snapshot);
      return ERROR_SUCCESS;
    }
  } while (Process32NextW(snapshot, &processEntry));
  CloseHandle(snapshot);
  return ERROR_NOT_FOUND;
}

/**
 * Waits for the specified application to exit.
 *
 * @param filename   The application to wait for.
 * @param maxSeconds The maximum amount of seconds to wait for all
 *                   instances of the application to exit.
 * @return  ERROR_SUCCESS if no instances of the application exist
 *          WAIT_TIMEOUT if the process is still running after maxSeconds.
 *          Any other Win32 system error code.
*/
DWORD
WaitForProcessExit(LPCWSTR filename, DWORD maxSeconds)
{
  DWORD applicationRunningError = WAIT_TIMEOUT;
  for(DWORD i = 0; i < maxSeconds; i++) {
    DWORD applicationRunningError = IsProcessRunning(filename);
    if (ERROR_NOT_FOUND == applicationRunningError) {
      return ERROR_SUCCESS;
    }
    Sleep(1000);
  }

  if (ERROR_SUCCESS == applicationRunningError) {
    return WAIT_TIMEOUT;
  }

  return applicationRunningError;
}

/**
 *  Determines if the fallback key exists or not
 *
 *  @return TRUE if the fallback key exists and there was no error checking
*/
BOOL
DoesFallbackKeyExist()
{
  HKEY testOnlyFallbackKey;
  if (RegOpenKeyExW(HKEY_LOCAL_MACHINE,
                    TEST_ONLY_FALLBACK_KEY_PATH, 0,
                    KEY_READ | KEY_WOW64_64KEY,
                    &testOnlyFallbackKey) != ERROR_SUCCESS) {
    return FALSE;
  }

  RegCloseKey(testOnlyFallbackKey);
  return TRUE;
}

#endif

/**
 * Determines if the file system for the specified file handle is local
 * @param file path to check the filesystem type for, must be at most MAX_PATH
 * @param isLocal out parameter which will hold TRUE if the drive is local
 * @return TRUE if the call succeeded
*/
BOOL
IsLocalFile(LPCWSTR file, BOOL &isLocal)
{
  WCHAR rootPath[MAX_PATH + 1] = { L'\0' };
  if (wcslen(file) > MAX_PATH) {
    return FALSE;
  }

  wcsncpy(rootPath, file, MAX_PATH);
  PathStripToRootW(rootPath);
  isLocal = GetDriveTypeW(rootPath) == DRIVE_FIXED;
  return TRUE;
}


/**
 * Determines the DWORD value of a registry key value
 *
 * @param key       The base key to where the value name exists
 * @param valueName The name of the value
 * @param retValue  Out parameter which will hold the value
 * @return TRUE on success
*/
static BOOL
GetDWORDValue(HKEY key, LPCWSTR valueName, DWORD &retValue)
{
  DWORD regDWORDValueSize = sizeof(DWORD);
  LONG retCode = RegQueryValueExW(key, valueName, 0, nullptr,
                                  reinterpret_cast<LPBYTE>(&retValue),
                                  &regDWORDValueSize);
  return ERROR_SUCCESS == retCode;
}

/**
 * Determines if the the system's elevation type allows
 * unprompted elevation.
 *
 * @param isUnpromptedElevation Out parameter which specifies if unprompted
 *                              elevation is allowed.
 * @return TRUE if the user can actually elevate and the value was obtained
 *         successfully.
*/
BOOL
IsUnpromptedElevation(BOOL &isUnpromptedElevation)
{
  if (!UACHelper::CanUserElevate()) {
    return FALSE;
  }

  LPCWSTR UACBaseRegKey =
    L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System";
  HKEY baseKey;
  LONG retCode = RegOpenKeyExW(HKEY_LOCAL_MACHINE,
                               UACBaseRegKey, 0,
                               KEY_READ, &baseKey);
  if (retCode != ERROR_SUCCESS) {
    return FALSE;
  }

  DWORD consent, secureDesktop;
  BOOL success = GetDWORDValue(baseKey, L"ConsentPromptBehaviorAdmin",
                               consent);
  success = success &&
            GetDWORDValue(baseKey, L"PromptOnSecureDesktop", secureDesktop);
  isUnpromptedElevation = !consent && !secureDesktop;

  RegCloseKey(baseKey);
  return success;
}
#endif