xref: /reactos/dll/shellext/shellbtrfs/main.cpp (revision 08d10098) 
1 /* Copyright (c) Mark Harmstone 2016-17
2  *
3  * This file is part of WinBtrfs.
4  *
5  * WinBtrfs is free software: you can redistribute it and/or modify
6  * it under the terms of the GNU Lesser General Public Licence as published by
7  * the Free Software Foundation, either version 3 of the Licence, or
8  * (at your option) any later version.
9  *
10  * WinBtrfs is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU Lesser General Public Licence for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public Licence
16  * along with WinBtrfs.  If not, see <http://www.gnu.org/licenses/>. */
17 
18 #include "shellext.h"
19 #include <windows.h>
20 #include <commctrl.h>
21 #include <strsafe.h>
22 #include <stddef.h>
23 #include <stdexcept>
24 #include "factory.h"
25 #include "resource.h"
26 
27 static const GUID CLSID_ShellBtrfsIconHandler = { 0x2690b74f, 0xf353, 0x422d, { 0xbb, 0x12, 0x40, 0x15, 0x81, 0xee, 0xf8, 0xf0 } };
28 static const GUID CLSID_ShellBtrfsContextMenu = { 0x2690b74f, 0xf353, 0x422d, { 0xbb, 0x12, 0x40, 0x15, 0x81, 0xee, 0xf8, 0xf1 } };
29 static const GUID CLSID_ShellBtrfsPropSheet = { 0x2690b74f, 0xf353, 0x422d, { 0xbb, 0x12, 0x40, 0x15, 0x81, 0xee, 0xf8, 0xf2 } };
30 static const GUID CLSID_ShellBtrfsVolPropSheet = { 0x2690b74f, 0xf353, 0x422d, { 0xbb, 0x12, 0x40, 0x15, 0x81, 0xee, 0xf8, 0xf3 } };
31 
32 #define COM_DESCRIPTION_ICON_HANDLER L"WinBtrfs shell extension (icon handler)"
33 #define COM_DESCRIPTION_CONTEXT_MENU L"WinBtrfs shell extension (context menu)"
34 #define COM_DESCRIPTION_PROP_SHEET L"WinBtrfs shell extension (property sheet)"
35 #define COM_DESCRIPTION_VOL_PROP_SHEET L"WinBtrfs shell extension (volume property sheet)"
36 #define ICON_OVERLAY_NAME L"WinBtrfs"
37 
38 typedef enum _PROCESS_DPI_AWARENESS {
39     PROCESS_DPI_UNAWARE,
40     PROCESS_SYSTEM_DPI_AWARE,
41     PROCESS_PER_MONITOR_DPI_AWARE
42 } PROCESS_DPI_AWARENESS;
43 
44 typedef ULONG (WINAPI *_RtlNtStatusToDosError)(NTSTATUS Status);
45 typedef HRESULT (WINAPI *_SetProcessDpiAwareness)(PROCESS_DPI_AWARENESS value);
46 
47 HMODULE module;
48 LONG objs_loaded = 0;
49 
50 void set_dpi_aware() {
51     _SetProcessDpiAwareness SetProcessDpiAwareness;
52     HMODULE shcore = LoadLibraryW(L"shcore.dll");
53 
54     if (!shcore)
55         return;
56 
57     SetProcessDpiAwareness = (_SetProcessDpiAwareness)GetProcAddress(shcore, "SetProcessDpiAwareness");
58 
59     if (!SetProcessDpiAwareness)
60         return;
61 
62     SetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE);
63 }
64 
65 void format_size(uint64_t size, wstring& s, bool show_bytes) {
66     wstring t, bytes, kb, nb;
67     WCHAR nb2[255];
68     ULONG sr;
69     float f;
70     NUMBERFMTW fmt;
71     WCHAR dec[2], thou[4], grouping[64], *c;
72 #ifdef __REACTOS__
73     WCHAR buffer[64];
74 #endif
75 
76 #ifndef __REACTOS__
77     nb = to_wstring(size);
78 #else
79     swprintf(buffer, L"%I64d", size);
80     nb = wstring(buffer);
81 #endif
82 
83     GetLocaleInfoW(LOCALE_USER_DEFAULT, LOCALE_STHOUSAND, thou, sizeof(thou) / sizeof(WCHAR));
84 
85     dec[0] = '.'; dec[1] = 0; // not used, but silences gcc warning
86 
87     fmt.NumDigits = 0;
88     fmt.LeadingZero = 1;
89     fmt.lpDecimalSep = dec;
90     fmt.lpThousandSep = thou;
91     fmt.NegativeOrder = 0;
92 
93     // Grouping code copied from dlls/shlwapi/string.c in Wine - thank you
94 
95     fmt.Grouping = 0;
96     GetLocaleInfoW(LOCALE_USER_DEFAULT, LOCALE_SGROUPING, grouping, sizeof(grouping) / sizeof(WCHAR));
97 
98     c = grouping;
99     while (*c) {
100         if (*c >= '0' && *c < '9') {
101             fmt.Grouping *= 10;
102             fmt.Grouping += *c - '0';
103         }
104 
105         c++;
106     }
107 
108     if (fmt.Grouping % 10 == 0)
109         fmt.Grouping /= 10;
110     else
111         fmt.Grouping *= 10;
112 
113     GetNumberFormatW(LOCALE_USER_DEFAULT, 0, nb.c_str(), &fmt, nb2, sizeof(nb2) / sizeof(WCHAR));
114 
115     if (size < 1024) {
116         if (!load_string(module, size == 1 ? IDS_SIZE_BYTE : IDS_SIZE_BYTES, t))
117             throw last_error(GetLastError());
118 
119         wstring_sprintf(s, t, nb2);
120         return;
121     }
122 
123     if (show_bytes) {
124         if (!load_string(module, IDS_SIZE_BYTES, t))
125             throw last_error(GetLastError());
126 
127         wstring_sprintf(bytes, t, nb2);
128     }
129 
130     if (size >= 1152921504606846976) {
131         sr = IDS_SIZE_EB;
132         f = (float)size / 1152921504606846976.0f;
133     } else if (size >= 1125899906842624) {
134         sr = IDS_SIZE_PB;
135         f = (float)size / 1125899906842624.0f;
136     } else if (size >= 1099511627776) {
137         sr = IDS_SIZE_TB;
138         f = (float)size / 1099511627776.0f;
139     } else if (size >= 1073741824) {
140         sr = IDS_SIZE_GB;
141         f = (float)size / 1073741824.0f;
142     } else if (size >= 1048576) {
143         sr = IDS_SIZE_MB;
144         f = (float)size / 1048576.0f;
145     } else {
146         sr = IDS_SIZE_KB;
147         f = (float)size / 1024.0f;
148     }
149 
150     if (!load_string(module, sr, t))
151         throw last_error(GetLastError());
152 
153     if (show_bytes) {
154         wstring_sprintf(kb, t, f);
155 
156         if (!load_string(module, IDS_SIZE_LARGE, t))
157             throw last_error(GetLastError());
158 
159         wstring_sprintf(s, t, kb.c_str(), bytes.c_str());
160     } else
161         wstring_sprintf(s, t, f);
162 }
163 
164 wstring format_message(ULONG last_error) {
165     WCHAR* buf;
166     wstring s;
167 
168     if (FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
169         last_error, 0, (WCHAR*)&buf, 0, nullptr) == 0) {
170         return L"(error retrieving message)";
171     }
172 
173     s = buf;
174 
175     LocalFree(buf);
176 
177     // remove trailing newline
178     while (s.length() > 0 && (s.substr(s.length() - 1, 1) == L"\r" || s.substr(s.length() - 1, 1) == L"\n"))
179         s = s.substr(0, s.length() - 1);
180 
181     return s;
182 }
183 
184 wstring format_ntstatus(NTSTATUS Status) {
185     _RtlNtStatusToDosError RtlNtStatusToDosError;
186     wstring s;
187     HMODULE ntdll = LoadLibraryW(L"ntdll.dll");
188 
189     if (!ntdll)
190         return L"(error loading ntdll.dll)";
191 
192     RtlNtStatusToDosError = (_RtlNtStatusToDosError)GetProcAddress(ntdll, "RtlNtStatusToDosError");
193 
194     if (!RtlNtStatusToDosError) {
195         FreeLibrary(ntdll);
196         return L"(error loading RtlNtStatusToDosError)";
197     }
198 
199     s = format_message(RtlNtStatusToDosError(Status));
200 
201     FreeLibrary(ntdll);
202 
203     return s;
204 }
205 
206 bool load_string(HMODULE module, UINT id, wstring& s) {
207     int len;
208     LPWSTR retstr = nullptr;
209 
210     len = LoadStringW(module, id, (LPWSTR)&retstr, 0);
211 
212     if (len == 0)
213         return false;
214 
215     s = wstring(retstr, len);
216 
217     return true;
218 }
219 
220 #ifdef _MSC_VER
221 #pragma warning(push)
222 #pragma warning(disable: 4996)
223 #endif
224 
225 void wstring_sprintf(wstring& s, wstring fmt, ...) {
226     int len;
227     va_list args;
228 
229     va_start(args, fmt);
230     len = _vsnwprintf(nullptr, 0, fmt.c_str(), args);
231 
232     if (len == 0)
233         s = L"";
234     else {
235         s.resize(len);
236         _vsnwprintf((wchar_t*)s.c_str(), len, fmt.c_str(), args);
237     }
238 
239     va_end(args);
240 }
241 
242 #ifdef _MSC_VER
243 #pragma warning(pop)
244 #endif
245 
246 STDAPI DllCanUnloadNow(void) {
247     return objs_loaded == 0 ? S_OK : S_FALSE;
248 }
249 
250 STDAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, LPVOID* ppv) {
251     if (rclsid == CLSID_ShellBtrfsIconHandler) {
252         Factory* fact = new Factory;
253         if (!fact)
254             return E_OUTOFMEMORY;
255         else {
256             fact->type = FactoryIconHandler;
257 
258             return fact->QueryInterface(riid, ppv);
259         }
260     } else if (rclsid == CLSID_ShellBtrfsContextMenu) {
261         Factory* fact = new Factory;
262         if (!fact)
263             return E_OUTOFMEMORY;
264         else {
265             fact->type = FactoryContextMenu;
266 
267             return fact->QueryInterface(riid, ppv);
268         }
269     } else if (rclsid == CLSID_ShellBtrfsPropSheet) {
270         Factory* fact = new Factory;
271         if (!fact)
272             return E_OUTOFMEMORY;
273         else {
274             fact->type = FactoryPropSheet;
275 
276             return fact->QueryInterface(riid, ppv);
277         }
278     } else if (rclsid == CLSID_ShellBtrfsVolPropSheet) {
279         Factory* fact = new Factory;
280         if (!fact)
281             return E_OUTOFMEMORY;
282         else {
283             fact->type = FactoryVolPropSheet;
284 
285             return fact->QueryInterface(riid, ppv);
286         }
287     }
288 
289     return CLASS_E_CLASSNOTAVAILABLE;
290 }
291 
292 static void write_reg_key(HKEY root, const wstring& keyname, const WCHAR* val, const wstring& data) {
293     LONG l;
294     HKEY hk;
295     DWORD dispos;
296 
297     l = RegCreateKeyExW(root, keyname.c_str(), 0, nullptr, 0, KEY_ALL_ACCESS, nullptr, &hk, &dispos);
298     if (l != ERROR_SUCCESS)
299         throw string_error(IDS_REGCREATEKEY_FAILED, l);
300 
301     l = RegSetValueExW(hk, val, 0, REG_SZ, (const BYTE*)data.c_str(), (DWORD)((data.length() + 1) * sizeof(WCHAR)));
302     if (l != ERROR_SUCCESS)
303         throw string_error(IDS_REGSETVALUEEX_FAILED, l);
304 
305     l = RegCloseKey(hk);
306     if (l != ERROR_SUCCESS)
307         throw string_error(IDS_REGCLOSEKEY_FAILED, l);
308 }
309 
310 static void register_clsid(const GUID clsid, const WCHAR* description) {
311     WCHAR* clsidstring;
312     wstring inproc, clsidkeyname;
313     WCHAR dllpath[MAX_PATH];
314 
315     StringFromCLSID(clsid, &clsidstring);
316 
317     try {
318 #ifndef __REACTOS__
319         inproc = L"CLSID\\"s + clsidstring + L"\\InprocServer32"s;
320         clsidkeyname = L"CLSID\\"s + clsidstring;
321 #else
322         inproc = wstring(L"CLSID\\") + clsidstring + wstring(L"\\InprocServer32");
323         clsidkeyname = wstring(L"CLSID\\") + clsidstring;
324 #endif
325 
326         write_reg_key(HKEY_CLASSES_ROOT, clsidkeyname, nullptr, description);
327 
328         GetModuleFileNameW(module, dllpath, sizeof(dllpath) / sizeof(WCHAR));
329 
330         write_reg_key(HKEY_CLASSES_ROOT, inproc, nullptr, dllpath);
331 
332         write_reg_key(HKEY_CLASSES_ROOT, inproc, L"ThreadingModel", L"Apartment");
333     } catch (...) {
334         CoTaskMemFree(clsidstring);
335         throw;
336     }
337 
338     CoTaskMemFree(clsidstring);
339 }
340 
341 // implementation of RegDeleteTreeW, only available from Vista on
342 static void reg_delete_tree(HKEY hkey, const wstring& keyname) {
343     HKEY k;
344     LSTATUS ret;
345 
346     ret = RegOpenKeyExW(hkey, keyname.c_str(), 0, KEY_READ, &k);
347 
348     if (ret != ERROR_SUCCESS)
349         throw last_error(ret);
350 
351     try {
352         WCHAR* buf;
353         ULONG bufsize;
354 
355         ret = RegQueryInfoKeyW(k, nullptr, nullptr, nullptr, nullptr, &bufsize, nullptr,
356                                nullptr, nullptr, nullptr, nullptr, nullptr);
357         if (ret != ERROR_SUCCESS)
358             throw last_error(ret);
359 
360         bufsize++;
361         buf = new WCHAR[bufsize];
362 
363         try {
364             do {
365                 ULONG size = bufsize;
366 
367                 ret = RegEnumKeyExW(k, 0, buf, &size, nullptr, nullptr, nullptr, nullptr);
368 
369                 if (ret == ERROR_NO_MORE_ITEMS)
370                     break;
371                 else if (ret != ERROR_SUCCESS)
372                     throw last_error(ret);
373 
374                 reg_delete_tree(k, buf);
375             } while (true);
376 
377             ret = RegDeleteKeyW(hkey, keyname.c_str());
378             if (ret != ERROR_SUCCESS)
379                 throw last_error(ret);
380         } catch (...) {
381             delete[] buf;
382             throw;
383         }
384 
385         delete[] buf;
386     } catch (...) {
387         RegCloseKey(k);
388         throw;
389     }
390 
391     RegCloseKey(k);
392 }
393 
394 static void unregister_clsid(const GUID clsid) {
395     WCHAR* clsidstring;
396 
397     StringFromCLSID(clsid, &clsidstring);
398 
399     try {
400 #ifndef __REACTOS__
401         reg_delete_tree(HKEY_CLASSES_ROOT, L"CLSID\\"s + clsidstring);
402 #else
403         wstring path = wstring(L"CLSID\\") + clsidstring;
404         reg_delete_tree(HKEY_CLASSES_ROOT, path);
405 #endif
406     } catch (...) {
407         CoTaskMemFree(clsidstring);
408         throw;
409     }
410 
411     CoTaskMemFree(clsidstring);
412 }
413 
414 static void reg_icon_overlay(const GUID clsid, const wstring& name) {
415     WCHAR* clsidstring;
416 
417     StringFromCLSID(clsid, &clsidstring);
418 
419     try {
420 #ifndef __REACTOS__
421         wstring path = L"Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ShellIconOverlayIdentifiers\\"s + name;
422 #else
423         wstring path = wstring(L"Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ShellIconOverlayIdentifiers\\") + name;
424 #endif
425 
426         write_reg_key(HKEY_LOCAL_MACHINE, path, nullptr, clsidstring);
427     } catch (...) {
428         CoTaskMemFree(clsidstring);
429         throw;
430     }
431 
432     CoTaskMemFree(clsidstring);
433 }
434 
435 static void unreg_icon_overlay(const wstring& name) {
436 #ifndef __REACTOS__
437     reg_delete_tree(HKEY_LOCAL_MACHINE, L"Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ShellIconOverlayIdentifiers\\"s + name);
438 #else
439     wstring path = wstring(L"Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\ShellIconOverlayIdentifiers\\") + name;
440     reg_delete_tree(HKEY_LOCAL_MACHINE, path);
441 #endif
442 }
443 
444 static void reg_context_menu_handler(const GUID clsid, const wstring& filetype, const wstring& name) {
445     WCHAR* clsidstring;
446 
447     StringFromCLSID(clsid, &clsidstring);
448 
449     try {
450 #ifndef __REACTOS__
451         wstring path = filetype + L"\\ShellEx\\ContextMenuHandlers\\"s + name;
452 #else
453         wstring path = filetype + wstring(L"\\ShellEx\\ContextMenuHandlers\\") + name;
454 #endif
455 
456         write_reg_key(HKEY_CLASSES_ROOT, path, nullptr, clsidstring);
457     } catch (...) {
458         CoTaskMemFree(clsidstring);
459         throw;
460     }
461 }
462 
463 static void unreg_context_menu_handler(const wstring& filetype, const wstring& name) {
464 #ifndef __REACTOS__
465     reg_delete_tree(HKEY_CLASSES_ROOT, filetype + L"\\ShellEx\\ContextMenuHandlers\\"s + name);
466 #else
467     wstring path = filetype + wstring(L"\\ShellEx\\ContextMenuHandlers\\") + name;
468     reg_delete_tree(HKEY_CLASSES_ROOT, path);
469 #endif
470 }
471 
472 static void reg_prop_sheet_handler(const GUID clsid, const wstring& filetype, const wstring& name) {
473     WCHAR* clsidstring;
474 
475     StringFromCLSID(clsid, &clsidstring);
476 
477     try {
478 #ifndef __REACTOS__
479         wstring path = filetype + L"\\ShellEx\\PropertySheetHandlers\\"s + name;
480 #else
481         wstring path = filetype + wstring(L"\\ShellEx\\PropertySheetHandlers\\") + name;
482 #endif
483 
484         write_reg_key(HKEY_CLASSES_ROOT, path, nullptr, clsidstring);
485     } catch (...) {
486         CoTaskMemFree(clsidstring);
487         throw;
488     }
489 }
490 
491 static void unreg_prop_sheet_handler(const wstring& filetype, const wstring& name) {
492 #ifndef __REACTOS__
493     reg_delete_tree(HKEY_CLASSES_ROOT, filetype + L"\\ShellEx\\PropertySheetHandlers\\"s + name);
494 #else
495     wstring path = filetype + wstring(L"\\ShellEx\\PropertySheetHandlers\\") + name;
496     reg_delete_tree(HKEY_CLASSES_ROOT, path);
497 #endif
498 }
499 
500 STDAPI DllRegisterServer(void) {
501     try {
502         register_clsid(CLSID_ShellBtrfsIconHandler, COM_DESCRIPTION_ICON_HANDLER);
503         register_clsid(CLSID_ShellBtrfsContextMenu, COM_DESCRIPTION_CONTEXT_MENU);
504         register_clsid(CLSID_ShellBtrfsPropSheet, COM_DESCRIPTION_PROP_SHEET);
505         register_clsid(CLSID_ShellBtrfsVolPropSheet, COM_DESCRIPTION_VOL_PROP_SHEET);
506 
507         reg_icon_overlay(CLSID_ShellBtrfsIconHandler, ICON_OVERLAY_NAME);
508 
509         reg_context_menu_handler(CLSID_ShellBtrfsContextMenu, L"Directory\\Background", ICON_OVERLAY_NAME);
510         reg_context_menu_handler(CLSID_ShellBtrfsContextMenu, L"Folder", ICON_OVERLAY_NAME);
511 
512         reg_prop_sheet_handler(CLSID_ShellBtrfsPropSheet, L"Folder", ICON_OVERLAY_NAME);
513         reg_prop_sheet_handler(CLSID_ShellBtrfsPropSheet, L"*", ICON_OVERLAY_NAME);
514         reg_prop_sheet_handler(CLSID_ShellBtrfsVolPropSheet, L"Drive", ICON_OVERLAY_NAME);
515     } catch (const exception& e) {
516         error_message(nullptr, e.what());
517         return E_FAIL;
518     }
519 
520     return S_OK;
521 }
522 
523 STDAPI DllUnregisterServer(void) {
524     try {
525         unreg_prop_sheet_handler(L"Folder", ICON_OVERLAY_NAME);
526         unreg_prop_sheet_handler(L"*", ICON_OVERLAY_NAME);
527         unreg_prop_sheet_handler(L"Drive", ICON_OVERLAY_NAME);
528         unreg_context_menu_handler(L"Folder", ICON_OVERLAY_NAME);
529         unreg_context_menu_handler(L"Directory\\Background", ICON_OVERLAY_NAME);
530         unreg_icon_overlay(ICON_OVERLAY_NAME);
531 
532         unregister_clsid(CLSID_ShellBtrfsVolPropSheet);
533         unregister_clsid(CLSID_ShellBtrfsPropSheet);
534         unregister_clsid(CLSID_ShellBtrfsContextMenu);
535         unregister_clsid(CLSID_ShellBtrfsIconHandler);
536     } catch (const exception& e) {
537         error_message(nullptr, e.what());
538         return E_FAIL;
539     }
540 
541     return S_OK;
542 }
543 
544 STDAPI DllInstall(BOOL bInstall, LPCWSTR pszCmdLine) {
545     if (bInstall)
546         return DllRegisterServer();
547     else
548         return DllUnregisterServer();
549 }
550 
551 extern "C" BOOL APIENTRY DllMain(HANDLE hModule, DWORD dwReason, void* lpReserved) {
552     if (dwReason == DLL_PROCESS_ATTACH)
553         module = (HMODULE)hModule;
554 
555     return true;
556 }
557 
558 static void create_subvol(const wstring& fn) {
559     size_t found = fn.rfind(L"\\");
560     wstring path, file;
561     win_handle h;
562     btrfs_create_subvol* bcs;
563     IO_STATUS_BLOCK iosb;
564 
565     if (found == wstring::npos) {
566         path = L"";
567         file = fn;
568     } else {
569         path = fn.substr(0, found);
570         file = fn.substr(found + 1);
571     }
572     path += L"\\";
573 
574     h = CreateFileW(path.c_str(), FILE_ADD_SUBDIRECTORY, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
575 
576     if (h == INVALID_HANDLE_VALUE)
577         return;
578 
579     size_t bcslen = offsetof(btrfs_create_subvol, name[0]) + (file.length() * sizeof(WCHAR));
580     bcs = (btrfs_create_subvol*)malloc(bcslen);
581 
582     bcs->readonly = false;
583     bcs->posix = false;
584     bcs->namelen = (uint16_t)(file.length() * sizeof(WCHAR));
585     memcpy(bcs->name, file.c_str(), bcs->namelen);
586 
587     NtFsControlFile(h, nullptr, nullptr, nullptr, &iosb, FSCTL_BTRFS_CREATE_SUBVOL, bcs, (ULONG)bcslen, nullptr, 0);
588 }
589 
590 extern "C" void CALLBACK CreateSubvolW(HWND hwnd, HINSTANCE hinst, LPWSTR lpszCmdLine, int nCmdShow) {
591     vector<wstring> args;
592 
593     command_line_to_args(lpszCmdLine, args);
594 
595     if (args.size() >= 1)
596         create_subvol(args[0]);
597 }
598 
599 static void create_snapshot2(const wstring& source, const wstring& fn) {
600     size_t found = fn.rfind(L"\\");
601     wstring path, file;
602     win_handle h, src;
603     btrfs_create_snapshot* bcs;
604     IO_STATUS_BLOCK iosb;
605 
606     if (found == wstring::npos) {
607         path = L"";
608         file = fn;
609     } else {
610         path = fn.substr(0, found);
611         file = fn.substr(found + 1);
612     }
613     path += L"\\";
614 
615     src = CreateFileW(source.c_str(), FILE_TRAVERSE, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
616     if (src == INVALID_HANDLE_VALUE)
617         return;
618 
619     h = CreateFileW(path.c_str(), FILE_ADD_SUBDIRECTORY, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
620 
621     if (h == INVALID_HANDLE_VALUE)
622         return;
623 
624     size_t bcslen = offsetof(btrfs_create_snapshot, name[0]) + (file.length() * sizeof(WCHAR));
625     bcs = (btrfs_create_snapshot*)malloc(bcslen);
626 
627     bcs->readonly = false;
628     bcs->posix = false;
629     bcs->namelen = (uint16_t)(file.length() * sizeof(WCHAR));
630     memcpy(bcs->name, file.c_str(), bcs->namelen);
631     bcs->subvol = src;
632 
633     NtFsControlFile(h, nullptr, nullptr, nullptr, &iosb, FSCTL_BTRFS_CREATE_SNAPSHOT, bcs, (ULONG)bcslen, nullptr, 0);
634 }
635 
636 extern "C" void CALLBACK CreateSnapshotW(HWND hwnd, HINSTANCE hinst, LPWSTR lpszCmdLine, int nCmdShow) {
637     vector<wstring> args;
638 
639     command_line_to_args(lpszCmdLine, args);
640 
641     if (args.size() >= 2)
642         create_snapshot2(args[0], args[1]);
643 }
644 
645 void command_line_to_args(LPWSTR cmdline, vector<wstring>& args) {
646     LPWSTR* l;
647     int num_args;
648 
649     args.clear();
650 
651     l = CommandLineToArgvW(cmdline, &num_args);
652 
653     if (!l)
654         return;
655 
656     try {
657         args.reserve(num_args);
658 
659         for (unsigned int i = 0; i < (unsigned int)num_args; i++) {
660             args.push_back(l[i]);
661         }
662     } catch (...) {
663         LocalFree(l);
664         throw;
665     }
666 
667     LocalFree(l);
668 }
669 
670 static string utf16_to_utf8(const wstring_view& utf16) {
671     string utf8;
672     char* buf;
673 
674     if (utf16.empty())
675         return "";
676 
677     auto utf8len = WideCharToMultiByte(CP_UTF8, 0, utf16.data(), static_cast<int>(utf16.length()), nullptr, 0, nullptr, nullptr);
678 
679     if (utf8len == 0)
680         throw last_error(GetLastError());
681 
682     buf = (char*)malloc(utf8len + sizeof(char));
683 
684     if (!buf)
685         throw string_error(IDS_OUT_OF_MEMORY);
686 
687     if (WideCharToMultiByte(CP_UTF8, 0, utf16.data(), static_cast<int>(utf16.length()), buf, utf8len, nullptr, nullptr) == 0) {
688         auto le = GetLastError();
689         free(buf);
690         throw last_error(le);
691     }
692 
693     buf[utf8len] = 0;
694 
695     utf8 = buf;
696 
697     free(buf);
698 
699     return utf8;
700 }
701 
702 #ifdef _MSC_VER
703 #pragma warning(push)
704 #pragma warning(disable: 4996)
705 #endif
706 
707 string_error::string_error(int resno, ...) {
708     wstring fmt, s;
709     int len;
710     va_list args;
711 
712     if (!load_string(module, resno, fmt))
713         throw runtime_error("LoadString failed."); // FIXME
714 
715     va_start(args, resno);
716     len = _vsnwprintf(nullptr, 0, fmt.c_str(), args);
717 
718     if (len == 0)
719         s = L"";
720     else {
721         s.resize(len);
722         _vsnwprintf((wchar_t*)s.c_str(), len, fmt.c_str(), args);
723     }
724 
725     va_end(args);
726 
727     msg = utf16_to_utf8(s);
728 }
729 
730 #ifdef _MSC_VER
731 #pragma warning(pop)
732 #endif
733 
734 wstring utf8_to_utf16(const string_view& utf8) {
735     wstring ret;
736     WCHAR* buf;
737 
738     if (utf8.empty())
739         return L"";
740 
741     auto utf16len = MultiByteToWideChar(CP_UTF8, 0, utf8.data(), (int)utf8.length(), nullptr, 0);
742 
743     if (utf16len == 0)
744         throw last_error(GetLastError());
745 
746     buf = (WCHAR*)malloc((utf16len + 1) * sizeof(WCHAR));
747 
748     if (!buf)
749         throw string_error(IDS_OUT_OF_MEMORY);
750 
751     if (MultiByteToWideChar(CP_UTF8, 0, utf8.data(), (int)utf8.length(), buf, utf16len) == 0) {
752         auto le = GetLastError();
753         free(buf);
754         throw last_error(le);
755     }
756 
757     buf[utf16len] = 0;
758 
759     ret = buf;
760 
761     free(buf);
762 
763     return ret;
764 }
765 
766 last_error::last_error(DWORD errnum) {
767     WCHAR* buf;
768 
769     if (FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
770         errnum, 0, (WCHAR*)&buf, 0, nullptr) == 0)
771         throw runtime_error("FormatMessage failed");
772 
773     try {
774         msg = utf16_to_utf8(buf);
775     } catch (...) {
776         LocalFree(buf);
777         throw;
778     }
779 
780     LocalFree(buf);
781 }
782 
783 void error_message(HWND hwnd, const char* msg) {
784     wstring title;
785 
786     load_string(module, IDS_ERROR, title);
787 
788     auto wmsg = utf8_to_utf16(msg);
789 
790     MessageBoxW(hwnd, wmsg.c_str(), title.c_str(), MB_ICONERROR);
791 }
792 
793 ntstatus_error::ntstatus_error(NTSTATUS Status) : Status(Status) {
794     _RtlNtStatusToDosError RtlNtStatusToDosError;
795     HMODULE ntdll = LoadLibraryW(L"ntdll.dll");
796     WCHAR* buf;
797 
798     if (!ntdll)
799         throw runtime_error("Error loading ntdll.dll.");
800 
801     try {
802         RtlNtStatusToDosError = (_RtlNtStatusToDosError)GetProcAddress(ntdll, "RtlNtStatusToDosError");
803 
804         if (!RtlNtStatusToDosError)
805             throw runtime_error("Error loading RtlNtStatusToDosError in ntdll.dll.");
806 
807         if (FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
808             RtlNtStatusToDosError(Status), 0, (WCHAR*)&buf, 0, nullptr) == 0)
809             throw runtime_error("FormatMessage failed");
810 
811         try {
812             msg = utf16_to_utf8(buf);
813         } catch (...) {
814             LocalFree(buf);
815             throw;
816         }
817 
818         LocalFree(buf);
819     } catch (...) {
820         FreeLibrary(ntdll);
821         throw;
822     }
823 
824     FreeLibrary(ntdll);
825 }
826