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comparison: security/sandbox/chromium/base/file_util_win.cc

security/sandbox/chromium/base/file_util_win.cc

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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/file_util.h"
6
7 #include <windows.h>
8 #include <psapi.h>
9 #include <shellapi.h>
10 #include <shlobj.h>
11 #include <time.h>
12
13 #include <algorithm>
14 #include <limits>
15 #include <string>
16
17 #include "base/files/file_path.h"
18 #include "base/logging.h"
19 #include "base/metrics/histogram.h"
20 #include "base/process/process_handle.h"
21 #include "base/rand_util.h"
22 #include "base/strings/string_number_conversions.h"
23 #include "base/strings/string_util.h"
24 #include "base/strings/utf_string_conversions.h"
25 #include "base/threading/thread_restrictions.h"
26 #include "base/time/time.h"
27 #include "base/win/scoped_handle.h"
28 #include "base/win/windows_version.h"
29
30 namespace base {
31
32 namespace {
33
34 const DWORD kFileShareAll =
35 FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
36
37 bool ShellCopy(const FilePath& from_path,
38 const FilePath& to_path,
39 bool recursive) {
40 // WinXP SHFileOperation doesn't like trailing separators.
41 FilePath stripped_from = from_path.StripTrailingSeparators();
42 FilePath stripped_to = to_path.StripTrailingSeparators();
43
44 ThreadRestrictions::AssertIOAllowed();
45
46 // NOTE: I suspect we could support longer paths, but that would involve
47 // analyzing all our usage of files.
48 if (stripped_from.value().length() >= MAX_PATH ||
49 stripped_to.value().length() >= MAX_PATH) {
50 return false;
51 }
52
53 // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
54 // so we have to use wcscpy because wcscpy_s writes non-NULLs
55 // into the rest of the buffer.
56 wchar_t double_terminated_path_from[MAX_PATH + 1] = {0};
57 wchar_t double_terminated_path_to[MAX_PATH + 1] = {0};
58 #pragma warning(suppress:4996) // don't complain about wcscpy deprecation
59 wcscpy(double_terminated_path_from, stripped_from.value().c_str());
60 #pragma warning(suppress:4996) // don't complain about wcscpy deprecation
61 wcscpy(double_terminated_path_to, stripped_to.value().c_str());
62
63 SHFILEOPSTRUCT file_operation = {0};
64 file_operation.wFunc = FO_COPY;
65 file_operation.pFrom = double_terminated_path_from;
66 file_operation.pTo = double_terminated_path_to;
67 file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION |
68 FOF_NOCONFIRMMKDIR;
69 if (!recursive)
70 file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
71
72 return (SHFileOperation(&file_operation) == 0);
73 }
74
75 } // namespace
76
77 FilePath MakeAbsoluteFilePath(const FilePath& input) {
78 ThreadRestrictions::AssertIOAllowed();
79 wchar_t file_path[MAX_PATH];
80 if (!_wfullpath(file_path, input.value().c_str(), MAX_PATH))
81 return FilePath();
82 return FilePath(file_path);
83 }
84
85 bool DeleteFile(const FilePath& path, bool recursive) {
86 ThreadRestrictions::AssertIOAllowed();
87
88 if (path.value().length() >= MAX_PATH)
89 return false;
90
91 if (!recursive) {
92 // If not recursing, then first check to see if |path| is a directory.
93 // If it is, then remove it with RemoveDirectory.
94 PlatformFileInfo file_info;
95 if (file_util::GetFileInfo(path, &file_info) && file_info.is_directory)
96 return RemoveDirectory(path.value().c_str()) != 0;
97
98 // Otherwise, it's a file, wildcard or non-existant. Try DeleteFile first
99 // because it should be faster. If DeleteFile fails, then we fall through
100 // to SHFileOperation, which will do the right thing.
101 if (::DeleteFile(path.value().c_str()) != 0)
102 return true;
103 }
104
105 // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
106 // so we have to use wcscpy because wcscpy_s writes non-NULLs
107 // into the rest of the buffer.
108 wchar_t double_terminated_path[MAX_PATH + 1] = {0};
109 #pragma warning(suppress:4996) // don't complain about wcscpy deprecation
110 if (g_bug108724_debug)
111 LOG(WARNING) << "copying ";
112 wcscpy(double_terminated_path, path.value().c_str());
113
114 SHFILEOPSTRUCT file_operation = {0};
115 file_operation.wFunc = FO_DELETE;
116 file_operation.pFrom = double_terminated_path;
117 file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION;
118 if (!recursive)
119 file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
120 if (g_bug108724_debug)
121 LOG(WARNING) << "Performing shell operation";
122 int err = SHFileOperation(&file_operation);
123 if (g_bug108724_debug)
124 LOG(WARNING) << "Done: " << err;
125
126 // Since we're passing flags to the operation telling it to be silent,
127 // it's possible for the operation to be aborted/cancelled without err
128 // being set (although MSDN doesn't give any scenarios for how this can
129 // happen). See MSDN for SHFileOperation and SHFILEOPTSTRUCT.
130 if (file_operation.fAnyOperationsAborted)
131 return false;
132
133 // Some versions of Windows return ERROR_FILE_NOT_FOUND (0x2) when deleting
134 // an empty directory and some return 0x402 when they should be returning
135 // ERROR_FILE_NOT_FOUND. MSDN says Vista and up won't return 0x402.
136 return (err == 0 || err == ERROR_FILE_NOT_FOUND || err == 0x402);
137 }
138
139 bool DeleteFileAfterReboot(const FilePath& path) {
140 ThreadRestrictions::AssertIOAllowed();
141
142 if (path.value().length() >= MAX_PATH)
143 return false;
144
145 return MoveFileEx(path.value().c_str(), NULL,
146 MOVEFILE_DELAY_UNTIL_REBOOT |
147 MOVEFILE_REPLACE_EXISTING) != FALSE;
148 }
149
150 bool ReplaceFile(const FilePath& from_path,
151 const FilePath& to_path,
152 PlatformFileError* error) {
153 ThreadRestrictions::AssertIOAllowed();
154 // Try a simple move first. It will only succeed when |to_path| doesn't
155 // already exist.
156 if (::MoveFile(from_path.value().c_str(), to_path.value().c_str()))
157 return true;
158 // Try the full-blown replace if the move fails, as ReplaceFile will only
159 // succeed when |to_path| does exist. When writing to a network share, we may
160 // not be able to change the ACLs. Ignore ACL errors then
161 // (REPLACEFILE_IGNORE_MERGE_ERRORS).
162 if (::ReplaceFile(to_path.value().c_str(), from_path.value().c_str(), NULL,
163 REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL)) {
164 return true;
165 }
166 if (error)
167 *error = LastErrorToPlatformFileError(GetLastError());
168 return false;
169 }
170
171 bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
172 bool recursive) {
173 ThreadRestrictions::AssertIOAllowed();
174
175 if (recursive)
176 return ShellCopy(from_path, to_path, true);
177
178 // The following code assumes that from path is a directory.
179 DCHECK(DirectoryExists(from_path));
180
181 // Instead of creating a new directory, we copy the old one to include the
182 // security information of the folder as part of the copy.
183 if (!PathExists(to_path)) {
184 // Except that Vista fails to do that, and instead do a recursive copy if
185 // the target directory doesn't exist.
186 if (base::win::GetVersion() >= base::win::VERSION_VISTA)
187 file_util::CreateDirectory(to_path);
188 else
189 ShellCopy(from_path, to_path, false);
190 }
191
192 FilePath directory = from_path.Append(L"*.*");
193 return ShellCopy(directory, to_path, false);
194 }
195
196 bool PathExists(const FilePath& path) {
197 ThreadRestrictions::AssertIOAllowed();
198 return (GetFileAttributes(path.value().c_str()) != INVALID_FILE_ATTRIBUTES);
199 }
200
201 bool PathIsWritable(const FilePath& path) {
202 ThreadRestrictions::AssertIOAllowed();
203 HANDLE dir =
204 CreateFile(path.value().c_str(), FILE_ADD_FILE, kFileShareAll,
205 NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
206
207 if (dir == INVALID_HANDLE_VALUE)
208 return false;
209
210 CloseHandle(dir);
211 return true;
212 }
213
214 bool DirectoryExists(const FilePath& path) {
215 ThreadRestrictions::AssertIOAllowed();
216 DWORD fileattr = GetFileAttributes(path.value().c_str());
217 if (fileattr != INVALID_FILE_ATTRIBUTES)
218 return (fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0;
219 return false;
220 }
221
222 } // namespace base
223
224 // -----------------------------------------------------------------------------
225
226 namespace file_util {
227
228 using base::DirectoryExists;
229 using base::FilePath;
230 using base::kFileShareAll;
231
232 bool GetTempDir(FilePath* path) {
233 base::ThreadRestrictions::AssertIOAllowed();
234
235 wchar_t temp_path[MAX_PATH + 1];
236 DWORD path_len = ::GetTempPath(MAX_PATH, temp_path);
237 if (path_len >= MAX_PATH || path_len <= 0)
238 return false;
239 // TODO(evanm): the old behavior of this function was to always strip the
240 // trailing slash. We duplicate this here, but it shouldn't be necessary
241 // when everyone is using the appropriate FilePath APIs.
242 *path = FilePath(temp_path).StripTrailingSeparators();
243 return true;
244 }
245
246 bool GetShmemTempDir(FilePath* path, bool executable) {
247 return GetTempDir(path);
248 }
249
250 bool CreateTemporaryFile(FilePath* path) {
251 base::ThreadRestrictions::AssertIOAllowed();
252
253 FilePath temp_file;
254
255 if (!GetTempDir(path))
256 return false;
257
258 if (CreateTemporaryFileInDir(*path, &temp_file)) {
259 *path = temp_file;
260 return true;
261 }
262
263 return false;
264 }
265
266 FILE* CreateAndOpenTemporaryShmemFile(FilePath* path, bool executable) {
267 base::ThreadRestrictions::AssertIOAllowed();
268 return CreateAndOpenTemporaryFile(path);
269 }
270
271 // On POSIX we have semantics to create and open a temporary file
272 // atomically.
273 // TODO(jrg): is there equivalent call to use on Windows instead of
274 // going 2-step?
275 FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path) {
276 base::ThreadRestrictions::AssertIOAllowed();
277 if (!CreateTemporaryFileInDir(dir, path)) {
278 return NULL;
279 }
280 // Open file in binary mode, to avoid problems with fwrite. On Windows
281 // it replaces \n's with \r\n's, which may surprise you.
282 // Reference: http://msdn.microsoft.com/en-us/library/h9t88zwz(VS.71).aspx
283 return OpenFile(*path, "wb+");
284 }
285
286 bool CreateTemporaryFileInDir(const FilePath& dir,
287 FilePath* temp_file) {
288 base::ThreadRestrictions::AssertIOAllowed();
289
290 wchar_t temp_name[MAX_PATH + 1];
291
292 if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
293 DPLOG(WARNING) << "Failed to get temporary file name in " << dir.value();
294 return false;
295 }
296
297 wchar_t long_temp_name[MAX_PATH + 1];
298 DWORD long_name_len = GetLongPathName(temp_name, long_temp_name, MAX_PATH);
299 if (long_name_len > MAX_PATH || long_name_len == 0) {
300 // GetLongPathName() failed, but we still have a temporary file.
301 *temp_file = FilePath(temp_name);
302 return true;
303 }
304
305 FilePath::StringType long_temp_name_str;
306 long_temp_name_str.assign(long_temp_name, long_name_len);
307 *temp_file = FilePath(long_temp_name_str);
308 return true;
309 }
310
311 bool CreateTemporaryDirInDir(const FilePath& base_dir,
312 const FilePath::StringType& prefix,
313 FilePath* new_dir) {
314 base::ThreadRestrictions::AssertIOAllowed();
315
316 FilePath path_to_create;
317
318 for (int count = 0; count < 50; ++count) {
319 // Try create a new temporary directory with random generated name. If
320 // the one exists, keep trying another path name until we reach some limit.
321 string16 new_dir_name;
322 new_dir_name.assign(prefix);
323 new_dir_name.append(base::IntToString16(::base::GetCurrentProcId()));
324 new_dir_name.push_back('_');
325 new_dir_name.append(base::IntToString16(base::RandInt(0, kint16max)));
326
327 path_to_create = base_dir.Append(new_dir_name);
328 if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {
329 *new_dir = path_to_create;
330 return true;
331 }
332 }
333
334 return false;
335 }
336
337 bool CreateNewTempDirectory(const FilePath::StringType& prefix,
338 FilePath* new_temp_path) {
339 base::ThreadRestrictions::AssertIOAllowed();
340
341 FilePath system_temp_dir;
342 if (!GetTempDir(&system_temp_dir))
343 return false;
344
345 return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
346 }
347
348 bool CreateDirectoryAndGetError(const FilePath& full_path,
349 base::PlatformFileError* error) {
350 base::ThreadRestrictions::AssertIOAllowed();
351
352 // If the path exists, we've succeeded if it's a directory, failed otherwise.
353 const wchar_t* full_path_str = full_path.value().c_str();
354 DWORD fileattr = ::GetFileAttributes(full_path_str);
355 if (fileattr != INVALID_FILE_ATTRIBUTES) {
356 if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
357 DVLOG(1) << "CreateDirectory(" << full_path_str << "), "
358 << "directory already exists.";
359 return true;
360 }
361 DLOG(WARNING) << "CreateDirectory(" << full_path_str << "), "
362 << "conflicts with existing file.";
363 if (error) {
364 *error = base::PLATFORM_FILE_ERROR_NOT_A_DIRECTORY;
365 }
366 return false;
367 }
368
369 // Invariant: Path does not exist as file or directory.
370
371 // Attempt to create the parent recursively. This will immediately return
372 // true if it already exists, otherwise will create all required parent
373 // directories starting with the highest-level missing parent.
374 FilePath parent_path(full_path.DirName());
375 if (parent_path.value() == full_path.value()) {
376 if (error) {
377 *error = base::PLATFORM_FILE_ERROR_NOT_FOUND;
378 }
379 return false;
380 }
381 if (!CreateDirectoryAndGetError(parent_path, error)) {
382 DLOG(WARNING) << "Failed to create one of the parent directories.";
383 if (error) {
384 DCHECK(*error != base::PLATFORM_FILE_OK);
385 }
386 return false;
387 }
388
389 if (!::CreateDirectory(full_path_str, NULL)) {
390 DWORD error_code = ::GetLastError();
391 if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
392 // This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
393 // were racing with someone creating the same directory, or a file
394 // with the same path. If DirectoryExists() returns true, we lost the
395 // race to create the same directory.
396 return true;
397 } else {
398 if (error)
399 *error = base::LastErrorToPlatformFileError(error_code);
400 DLOG(WARNING) << "Failed to create directory " << full_path_str
401 << ", last error is " << error_code << ".";
402 return false;
403 }
404 } else {
405 return true;
406 }
407 }
408
409 // TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
410 // them if we do decide to.
411 bool IsLink(const FilePath& file_path) {
412 return false;
413 }
414
415 bool GetFileInfo(const FilePath& file_path, base::PlatformFileInfo* results) {
416 base::ThreadRestrictions::AssertIOAllowed();
417
418 WIN32_FILE_ATTRIBUTE_DATA attr;
419 if (!GetFileAttributesEx(file_path.value().c_str(),
420 GetFileExInfoStandard, &attr)) {
421 return false;
422 }
423
424 ULARGE_INTEGER size;
425 size.HighPart = attr.nFileSizeHigh;
426 size.LowPart = attr.nFileSizeLow;
427 results->size = size.QuadPart;
428
429 results->is_directory =
430 (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
431 results->last_modified = base::Time::FromFileTime(attr.ftLastWriteTime);
432 results->last_accessed = base::Time::FromFileTime(attr.ftLastAccessTime);
433 results->creation_time = base::Time::FromFileTime(attr.ftCreationTime);
434
435 return true;
436 }
437
438 FILE* OpenFile(const FilePath& filename, const char* mode) {
439 base::ThreadRestrictions::AssertIOAllowed();
440 std::wstring w_mode = ASCIIToWide(std::string(mode));
441 return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
442 }
443
444 FILE* OpenFile(const std::string& filename, const char* mode) {
445 base::ThreadRestrictions::AssertIOAllowed();
446 return _fsopen(filename.c_str(), mode, _SH_DENYNO);
447 }
448
449 int ReadFile(const FilePath& filename, char* data, int size) {
450 base::ThreadRestrictions::AssertIOAllowed();
451 base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
452 GENERIC_READ,
453 FILE_SHARE_READ | FILE_SHARE_WRITE,
454 NULL,
455 OPEN_EXISTING,
456 FILE_FLAG_SEQUENTIAL_SCAN,
457 NULL));
458 if (!file)
459 return -1;
460
461 DWORD read;
462 if (::ReadFile(file, data, size, &read, NULL) &&
463 static_cast<int>(read) == size)
464 return read;
465 return -1;
466 }
467
468 int WriteFile(const FilePath& filename, const char* data, int size) {
469 base::ThreadRestrictions::AssertIOAllowed();
470 base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
471 GENERIC_WRITE,
472 0,
473 NULL,
474 CREATE_ALWAYS,
475 0,
476 NULL));
477 if (!file) {
478 DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
479 << filename.value();
480 return -1;
481 }
482
483 DWORD written;
484 BOOL result = ::WriteFile(file, data, size, &written, NULL);
485 if (result && static_cast<int>(written) == size)
486 return written;
487
488 if (!result) {
489 // WriteFile failed.
490 DLOG_GETLASTERROR(WARNING) << "writing file " << filename.value()
491 << " failed";
492 } else {
493 // Didn't write all the bytes.
494 DLOG(WARNING) << "wrote" << written << " bytes to "
495 << filename.value() << " expected " << size;
496 }
497 return -1;
498 }
499
500 int AppendToFile(const FilePath& filename, const char* data, int size) {
501 base::ThreadRestrictions::AssertIOAllowed();
502 base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
503 FILE_APPEND_DATA,
504 0,
505 NULL,
506 OPEN_EXISTING,
507 0,
508 NULL));
509 if (!file) {
510 DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
511 << filename.value();
512 return -1;
513 }
514
515 DWORD written;
516 BOOL result = ::WriteFile(file, data, size, &written, NULL);
517 if (result && static_cast<int>(written) == size)
518 return written;
519
520 if (!result) {
521 // WriteFile failed.
522 DLOG_GETLASTERROR(WARNING) << "writing file " << filename.value()
523 << " failed";
524 } else {
525 // Didn't write all the bytes.
526 DLOG(WARNING) << "wrote" << written << " bytes to "
527 << filename.value() << " expected " << size;
528 }
529 return -1;
530 }
531
532 // Gets the current working directory for the process.
533 bool GetCurrentDirectory(FilePath* dir) {
534 base::ThreadRestrictions::AssertIOAllowed();
535
536 wchar_t system_buffer[MAX_PATH];
537 system_buffer[0] = 0;
538 DWORD len = ::GetCurrentDirectory(MAX_PATH, system_buffer);
539 if (len == 0 || len > MAX_PATH)
540 return false;
541 // TODO(evanm): the old behavior of this function was to always strip the
542 // trailing slash. We duplicate this here, but it shouldn't be necessary
543 // when everyone is using the appropriate FilePath APIs.
544 std::wstring dir_str(system_buffer);
545 *dir = FilePath(dir_str).StripTrailingSeparators();
546 return true;
547 }
548
549 // Sets the current working directory for the process.
550 bool SetCurrentDirectory(const FilePath& directory) {
551 base::ThreadRestrictions::AssertIOAllowed();
552 BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
553 return ret != 0;
554 }
555
556 bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
557 base::ThreadRestrictions::AssertIOAllowed();
558 FilePath mapped_file;
559 if (!NormalizeToNativeFilePath(path, &mapped_file))
560 return false;
561 // NormalizeToNativeFilePath() will return a path that starts with
562 // "\Device\Harddisk...". Helper DevicePathToDriveLetterPath()
563 // will find a drive letter which maps to the path's device, so
564 // that we return a path starting with a drive letter.
565 return DevicePathToDriveLetterPath(mapped_file, real_path);
566 }
567
568 bool DevicePathToDriveLetterPath(const FilePath& nt_device_path,
569 FilePath* out_drive_letter_path) {
570 base::ThreadRestrictions::AssertIOAllowed();
571
572 // Get the mapping of drive letters to device paths.
573 const int kDriveMappingSize = 1024;
574 wchar_t drive_mapping[kDriveMappingSize] = {'\0'};
575 if (!::GetLogicalDriveStrings(kDriveMappingSize - 1, drive_mapping)) {
576 DLOG(ERROR) << "Failed to get drive mapping.";
577 return false;
578 }
579
580 // The drive mapping is a sequence of null terminated strings.
581 // The last string is empty.
582 wchar_t* drive_map_ptr = drive_mapping;
583 wchar_t device_path_as_string[MAX_PATH];
584 wchar_t drive[] = L" :";
585
586 // For each string in the drive mapping, get the junction that links
587 // to it. If that junction is a prefix of |device_path|, then we
588 // know that |drive| is the real path prefix.
589 while (*drive_map_ptr) {
590 drive[0] = drive_map_ptr[0]; // Copy the drive letter.
591
592 if (QueryDosDevice(drive, device_path_as_string, MAX_PATH)) {
593 FilePath device_path(device_path_as_string);
594 if (device_path == nt_device_path ||
595 device_path.IsParent(nt_device_path)) {
596 *out_drive_letter_path = FilePath(drive +
597 nt_device_path.value().substr(wcslen(device_path_as_string)));
598 return true;
599 }
600 }
601 // Move to the next drive letter string, which starts one
602 // increment after the '\0' that terminates the current string.
603 while (*drive_map_ptr++);
604 }
605
606 // No drive matched. The path does not start with a device junction
607 // that is mounted as a drive letter. This means there is no drive
608 // letter path to the volume that holds |device_path|, so fail.
609 return false;
610 }
611
612 bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path) {
613 base::ThreadRestrictions::AssertIOAllowed();
614 // In Vista, GetFinalPathNameByHandle() would give us the real path
615 // from a file handle. If we ever deprecate XP, consider changing the
616 // code below to a call to GetFinalPathNameByHandle(). The method this
617 // function uses is explained in the following msdn article:
618 // http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
619 base::win::ScopedHandle file_handle(
620 ::CreateFile(path.value().c_str(),
621 GENERIC_READ,
622 kFileShareAll,
623 NULL,
624 OPEN_EXISTING,
625 FILE_ATTRIBUTE_NORMAL,
626 NULL));
627 if (!file_handle)
628 return false;
629
630 // Create a file mapping object. Can't easily use MemoryMappedFile, because
631 // we only map the first byte, and need direct access to the handle. You can
632 // not map an empty file, this call fails in that case.
633 base::win::ScopedHandle file_map_handle(
634 ::CreateFileMapping(file_handle.Get(),
635 NULL,
636 PAGE_READONLY,
637 0,
638 1, // Just one byte. No need to look at the data.
639 NULL));
640 if (!file_map_handle)
641 return false;
642
643 // Use a view of the file to get the path to the file.
644 void* file_view = MapViewOfFile(file_map_handle.Get(),
645 FILE_MAP_READ, 0, 0, 1);
646 if (!file_view)
647 return false;
648
649 // The expansion of |path| into a full path may make it longer.
650 // GetMappedFileName() will fail if the result is longer than MAX_PATH.
651 // Pad a bit to be safe. If kMaxPathLength is ever changed to be less
652 // than MAX_PATH, it would be nessisary to test that GetMappedFileName()
653 // not return kMaxPathLength. This would mean that only part of the
654 // path fit in |mapped_file_path|.
655 const int kMaxPathLength = MAX_PATH + 10;
656 wchar_t mapped_file_path[kMaxPathLength];
657 bool success = false;
658 HANDLE cp = GetCurrentProcess();
659 if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
660 *nt_path = FilePath(mapped_file_path);
661 success = true;
662 }
663 ::UnmapViewOfFile(file_view);
664 return success;
665 }
666
667 int GetMaximumPathComponentLength(const FilePath& path) {
668 base::ThreadRestrictions::AssertIOAllowed();
669
670 wchar_t volume_path[MAX_PATH];
671 if (!GetVolumePathNameW(path.NormalizePathSeparators().value().c_str(),
672 volume_path,
673 arraysize(volume_path))) {
674 return -1;
675 }
676
677 DWORD max_length = 0;
678 if (!GetVolumeInformationW(volume_path, NULL, 0, NULL, &max_length, NULL,
679 NULL, 0)) {
680 return -1;
681 }
682
683 // Length of |path| with path separator appended.
684 size_t prefix = path.StripTrailingSeparators().value().size() + 1;
685 // The whole path string must be shorter than MAX_PATH. That is, it must be
686 // prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
687 int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
688 return std::min(whole_path_limit, static_cast<int>(max_length));
689 }
690
691 } // namespace file_util
692
693 namespace base {
694 namespace internal {
695
696 bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
697 ThreadRestrictions::AssertIOAllowed();
698
699 // NOTE: I suspect we could support longer paths, but that would involve
700 // analyzing all our usage of files.
701 if (from_path.value().length() >= MAX_PATH ||
702 to_path.value().length() >= MAX_PATH) {
703 return false;
704 }
705 if (MoveFileEx(from_path.value().c_str(), to_path.value().c_str(),
706 MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING) != 0)
707 return true;
708
709 // Keep the last error value from MoveFileEx around in case the below
710 // fails.
711 bool ret = false;
712 DWORD last_error = ::GetLastError();
713
714 if (DirectoryExists(from_path)) {
715 // MoveFileEx fails if moving directory across volumes. We will simulate
716 // the move by using Copy and Delete. Ideally we could check whether
717 // from_path and to_path are indeed in different volumes.
718 ret = internal::CopyAndDeleteDirectory(from_path, to_path);
719 }
720
721 if (!ret) {
722 // Leave a clue about what went wrong so that it can be (at least) picked
723 // up by a PLOG entry.
724 ::SetLastError(last_error);
725 }
726
727 return ret;
728 }
729
730 bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
731 ThreadRestrictions::AssertIOAllowed();
732
733 // NOTE: I suspect we could support longer paths, but that would involve
734 // analyzing all our usage of files.
735 if (from_path.value().length() >= MAX_PATH ||
736 to_path.value().length() >= MAX_PATH) {
737 return false;
738 }
739 return (::CopyFile(from_path.value().c_str(), to_path.value().c_str(),
740 false) != 0);
741 }
742
743 bool CopyAndDeleteDirectory(const FilePath& from_path,
744 const FilePath& to_path) {
745 ThreadRestrictions::AssertIOAllowed();
746 if (CopyDirectory(from_path, to_path, true)) {
747 if (DeleteFile(from_path, true))
748 return true;
749
750 // Like Move, this function is not transactional, so we just
751 // leave the copied bits behind if deleting from_path fails.
752 // If to_path exists previously then we have already overwritten
753 // it by now, we don't get better off by deleting the new bits.
754 }
755 return false;
756 }
757
758 } // namespace internal
759 } // namespace base

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