base/file_util_win.cc

   1 // Copyright (c) 2011 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 <propvarutil.h>
   9 #include <psapi.h>
  10 #include <shellapi.h>
  11 #include <shlobj.h>
  12 #include <time.h>
  13
  14 #include <limits>
  15 #include <string>
  16
  17 #include "base/file_path.h"
  18 #include "base/logging.h"
  19 #include "base/metrics/histogram.h"
  20 #include "base/win/pe_image.h"
  21 #include "base/win/scoped_handle.h"
  22 #include "base/string_number_conversions.h"
  23 #include "base/string_util.h"
  24 #include "base/threading/thread_restrictions.h"
  25 #include "base/time.h"
  26 #include "base/utf_string_conversions.h"
  27 #include "base/win/scoped_comptr.h"
  28 #include "base/win/win_util.h"
  29 #include "base/win/windows_version.h"
  30
  31 namespace file_util {
  32
  33 namespace {
  34
  35 const DWORD kFileShareAll =
  36     FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
  37
  38 // Helper for NormalizeFilePath(), defined below.
  39 bool DevicePathToDriveLetterPath(const FilePath& device_path,
  40                                  FilePath* drive_letter_path) {
  41   base::ThreadRestrictions::AssertIOAllowed();
  42
  43   // Get the mapping of drive letters to device paths.
  44   const int kDriveMappingSize = 1024;
  45   wchar_t drive_mapping[kDriveMappingSize] = {'\0'};
  46   if (!::GetLogicalDriveStrings(kDriveMappingSize - 1, drive_mapping)) {
  47     LOG(ERROR) << "Failed to get drive mapping.";
  48     return false;
  49   }
  50
  51   // The drive mapping is a sequence of null terminated strings.
  52   // The last string is empty.
  53   wchar_t* drive_map_ptr = drive_mapping;
  54   wchar_t device_name[MAX_PATH];
  55   wchar_t drive[] = L" :";
  56
  57   // For each string in the drive mapping, get the junction that links
  58   // to it.  If that junction is a prefix of |device_path|, then we
  59   // know that |drive| is the real path prefix.
  60   while (*drive_map_ptr) {
  61     drive[0] = drive_map_ptr[0];  // Copy the drive letter.
  62
  63     if (QueryDosDevice(drive, device_name, MAX_PATH) &&
  64         StartsWith(device_path.value(), device_name, true)) {
  65       *drive_letter_path = FilePath(drive +
  66           device_path.value().substr(wcslen(device_name)));
  67       return true;
  68     }
  69     // Move to the next drive letter string, which starts one
  70     // increment after the '\0' that terminates the current string.
  71     while (*drive_map_ptr++);
  72   }
  73
  74   // No drive matched.  The path does not start with a device junction
  75   // that is mounted as a drive letter.  This means there is no drive
  76   // letter path to the volume that holds |device_path|, so fail.
  77   return false;
  78 }
  79
  80 }  // namespace
  81
  82 bool AbsolutePath(FilePath* path) {
  83   base::ThreadRestrictions::AssertIOAllowed();
  84   wchar_t file_path_buf[MAX_PATH];
  85   if (!_wfullpath(file_path_buf, path->value().c_str(), MAX_PATH))
  86     return false;
  87   *path = FilePath(file_path_buf);
  88   return true;
  89 }
  90
  91 int CountFilesCreatedAfter(const FilePath& path,
  92                            const base::Time& comparison_time) {
  93   base::ThreadRestrictions::AssertIOAllowed();
  94
  95   int file_count = 0;
  96   FILETIME comparison_filetime(comparison_time.ToFileTime());
  97
  98   WIN32_FIND_DATA find_file_data;
  99   // All files in given dir
 100   std::wstring filename_spec = path.Append(L"*").value();
 101   HANDLE find_handle = FindFirstFile(filename_spec.c_str(), &find_file_data);
 102   if (find_handle != INVALID_HANDLE_VALUE) {
 103     do {
 104       // Don't count current or parent directories.
 105       if ((wcscmp(find_file_data.cFileName, L"..") == 0) ||
 106           (wcscmp(find_file_data.cFileName, L".") == 0))
 107         continue;
 108
 109       long result = CompareFileTime(&find_file_data.ftCreationTime,  // NOLINT
 110                                     &comparison_filetime);
 111       // File was created after or on comparison time
 112       if ((result == 1) || (result == 0))
 113         ++file_count;
 114     } while (FindNextFile(find_handle,  &find_file_data));
 115     FindClose(find_handle);
 116   }
 117
 118   return file_count;
 119 }
 120
 121 bool Delete(const FilePath& path, bool recursive) {
 122   base::ThreadRestrictions::AssertIOAllowed();
 123
 124   if (path.value().length() >= MAX_PATH)
 125     return false;
 126
 127   if (!recursive) {
 128     // If not recursing, then first check to see if |path| is a directory.
 129     // If it is, then remove it with RemoveDirectory.
 130     base::PlatformFileInfo file_info;
 131     if (GetFileInfo(path, &file_info) && file_info.is_directory)
 132       return RemoveDirectory(path.value().c_str()) != 0;
 133
 134     // Otherwise, it's a file, wildcard or non-existant. Try DeleteFile first
 135     // because it should be faster. If DeleteFile fails, then we fall through
 136     // to SHFileOperation, which will do the right thing.
 137     if (DeleteFile(path.value().c_str()) != 0)
 138       return true;
 139   }
 140
 141   // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
 142   // so we have to use wcscpy because wcscpy_s writes non-NULLs
 143   // into the rest of the buffer.
 144   wchar_t double_terminated_path[MAX_PATH + 1] = {0};
 145 #pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
 146   wcscpy(double_terminated_path, path.value().c_str());
 147
 148   SHFILEOPSTRUCT file_operation = {0};
 149   file_operation.wFunc = FO_DELETE;
 150   file_operation.pFrom = double_terminated_path;
 151   file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION;
 152   if (!recursive)
 153     file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
 154   int err = SHFileOperation(&file_operation);
 155
 156   // Since we're passing flags to the operation telling it to be silent,
 157   // it's possible for the operation to be aborted/cancelled without err
 158   // being set (although MSDN doesn't give any scenarios for how this can
 159   // happen).  See MSDN for SHFileOperation and SHFILEOPTSTRUCT.
 160   if (file_operation.fAnyOperationsAborted)
 161     return false;
 162
 163   // Some versions of Windows return ERROR_FILE_NOT_FOUND (0x2) when deleting
 164   // an empty directory and some return 0x402 when they should be returning
 165   // ERROR_FILE_NOT_FOUND. MSDN says Vista and up won't return 0x402.
 166   return (err == 0 || err == ERROR_FILE_NOT_FOUND || err == 0x402);
 167 }
 168
 169 bool DeleteAfterReboot(const FilePath& path) {
 170   base::ThreadRestrictions::AssertIOAllowed();
 171
 172   if (path.value().length() >= MAX_PATH)
 173     return false;
 174
 175   return MoveFileEx(path.value().c_str(), NULL,
 176                     MOVEFILE_DELAY_UNTIL_REBOOT |
 177                         MOVEFILE_REPLACE_EXISTING) != FALSE;
 178 }
 179
 180 bool Move(const FilePath& from_path, const FilePath& to_path) {
 181   base::ThreadRestrictions::AssertIOAllowed();
 182
 183   // NOTE: I suspect we could support longer paths, but that would involve
 184   // analyzing all our usage of files.
 185   if (from_path.value().length() >= MAX_PATH ||
 186       to_path.value().length() >= MAX_PATH) {
 187     return false;
 188   }
 189   if (MoveFileEx(from_path.value().c_str(), to_path.value().c_str(),
 190                  MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING) != 0)
 191     return true;
 192
 193   // Keep the last error value from MoveFileEx around in case the below
 194   // fails.
 195   bool ret = false;
 196   DWORD last_error = ::GetLastError();
 197
 198   if (DirectoryExists(from_path)) {
 199     // MoveFileEx fails if moving directory across volumes. We will simulate
 200     // the move by using Copy and Delete. Ideally we could check whether
 201     // from_path and to_path are indeed in different volumes.
 202     ret = CopyAndDeleteDirectory(from_path, to_path);
 203   }
 204
 205   if (!ret) {
 206     // Leave a clue about what went wrong so that it can be (at least) picked
 207     // up by a PLOG entry.
 208     ::SetLastError(last_error);
 209   }
 210
 211   return ret;
 212 }
 213
 214 bool ReplaceFile(const FilePath& from_path, const FilePath& to_path) {
 215   base::ThreadRestrictions::AssertIOAllowed();
 216
 217   // Make sure that the target file exists.
 218   HANDLE target_file = ::CreateFile(
 219       to_path.value().c_str(),
 220       0,
 221       FILE_SHARE_READ | FILE_SHARE_WRITE,
 222       NULL,
 223       CREATE_NEW,
 224       FILE_ATTRIBUTE_NORMAL,
 225       NULL);
 226   if (target_file != INVALID_HANDLE_VALUE)
 227     ::CloseHandle(target_file);
 228   // When writing to a network share, we may not be able to change the ACLs.
 229   // Ignore ACL errors then (REPLACEFILE_IGNORE_MERGE_ERRORS).
 230   return ::ReplaceFile(to_path.value().c_str(),
 231       from_path.value().c_str(), NULL,
 232       REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL) ? true : false;
 233 }
 234
 235 bool CopyFile(const FilePath& from_path, const FilePath& to_path) {
 236   base::ThreadRestrictions::AssertIOAllowed();
 237
 238   // NOTE: I suspect we could support longer paths, but that would involve
 239   // analyzing all our usage of files.
 240   if (from_path.value().length() >= MAX_PATH ||
 241       to_path.value().length() >= MAX_PATH) {
 242     return false;
 243   }
 244   return (::CopyFile(from_path.value().c_str(), to_path.value().c_str(),
 245                      false) != 0);
 246 }
 247
 248 bool ShellCopy(const FilePath& from_path, const FilePath& to_path,
 249                bool recursive) {
 250   base::ThreadRestrictions::AssertIOAllowed();
 251
 252   // NOTE: I suspect we could support longer paths, but that would involve
 253   // analyzing all our usage of files.
 254   if (from_path.value().length() >= MAX_PATH ||
 255       to_path.value().length() >= MAX_PATH) {
 256     return false;
 257   }
 258
 259   // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
 260   // so we have to use wcscpy because wcscpy_s writes non-NULLs
 261   // into the rest of the buffer.
 262   wchar_t double_terminated_path_from[MAX_PATH + 1] = {0};
 263   wchar_t double_terminated_path_to[MAX_PATH + 1] = {0};
 264 #pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
 265   wcscpy(double_terminated_path_from, from_path.value().c_str());
 266 #pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
 267   wcscpy(double_terminated_path_to, to_path.value().c_str());
 268
 269   SHFILEOPSTRUCT file_operation = {0};
 270   file_operation.wFunc = FO_COPY;
 271   file_operation.pFrom = double_terminated_path_from;
 272   file_operation.pTo = double_terminated_path_to;
 273   file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION |
 274                           FOF_NOCONFIRMMKDIR;
 275   if (!recursive)
 276     file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
 277
 278   return (SHFileOperation(&file_operation) == 0);
 279 }
 280
 281 bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
 282                    bool recursive) {
 283   base::ThreadRestrictions::AssertIOAllowed();
 284
 285   if (recursive)
 286     return ShellCopy(from_path, to_path, true);
 287
 288   // The following code assumes that from path is a directory.
 289   DCHECK(DirectoryExists(from_path));
 290
 291   // Instead of creating a new directory, we copy the old one to include the
 292   // security information of the folder as part of the copy.
 293   if (!PathExists(to_path)) {
 294     // Except that Vista fails to do that, and instead do a recursive copy if
 295     // the target directory doesn't exist.
 296     if (base::win::GetVersion() >= base::win::VERSION_VISTA)
 297       CreateDirectory(to_path);
 298     else
 299       ShellCopy(from_path, to_path, false);
 300   }
 301
 302   FilePath directory = from_path.Append(L"*.*");
 303   return ShellCopy(directory, to_path, false);
 304 }
 305
 306 bool CopyAndDeleteDirectory(const FilePath& from_path,
 307                             const FilePath& to_path) {
 308   base::ThreadRestrictions::AssertIOAllowed();
 309   if (CopyDirectory(from_path, to_path, true)) {
 310     if (Delete(from_path, true)) {
 311       return true;
 312     }
 313     // Like Move, this function is not transactional, so we just
 314     // leave the copied bits behind if deleting from_path fails.
 315     // If to_path exists previously then we have already overwritten
 316     // it by now, we don't get better off by deleting the new bits.
 317   }
 318   return false;
 319 }
 320
 321
 322 bool PathExists(const FilePath& path) {
 323   base::ThreadRestrictions::AssertIOAllowed();
 324   return (GetFileAttributes(path.value().c_str()) != INVALID_FILE_ATTRIBUTES);
 325 }
 326
 327 bool PathIsWritable(const FilePath& path) {
 328   base::ThreadRestrictions::AssertIOAllowed();
 329   HANDLE dir =
 330       CreateFile(path.value().c_str(), FILE_ADD_FILE, kFileShareAll,
 331                  NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
 332
 333   if (dir == INVALID_HANDLE_VALUE)
 334     return false;
 335
 336   CloseHandle(dir);
 337   return true;
 338 }
 339
 340 bool DirectoryExists(const FilePath& path) {
 341   base::ThreadRestrictions::AssertIOAllowed();
 342   DWORD fileattr = GetFileAttributes(path.value().c_str());
 343   if (fileattr != INVALID_FILE_ATTRIBUTES)
 344     return (fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0;
 345   return false;
 346 }
 347
 348 bool GetFileCreationLocalTimeFromHandle(HANDLE file_handle,
 349                                         LPSYSTEMTIME creation_time) {
 350   base::ThreadRestrictions::AssertIOAllowed();
 351   if (!file_handle)
 352     return false;
 353
 354   FILETIME utc_filetime;
 355   if (!GetFileTime(file_handle, &utc_filetime, NULL, NULL))
 356     return false;
 357
 358   FILETIME local_filetime;
 359   if (!FileTimeToLocalFileTime(&utc_filetime, &local_filetime))
 360     return false;
 361
 362   return !!FileTimeToSystemTime(&local_filetime, creation_time);
 363 }
 364
 365 bool GetFileCreationLocalTime(const std::wstring& filename,
 366                               LPSYSTEMTIME creation_time) {
 367   base::ThreadRestrictions::AssertIOAllowed();
 368   base::win::ScopedHandle file_handle(
 369       CreateFile(filename.c_str(), GENERIC_READ, kFileShareAll, NULL,
 370                  OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL));
 371   return GetFileCreationLocalTimeFromHandle(file_handle.Get(), creation_time);
 372 }
 373
 374 bool ResolveShortcut(FilePath* path) {
 375   base::ThreadRestrictions::AssertIOAllowed();
 376
 377   HRESULT result;
 378   base::win::ScopedComPtr<IShellLink> i_shell_link;
 379   bool is_resolved = false;
 380
 381   // Get pointer to the IShellLink interface
 382   result = i_shell_link.CreateInstance(CLSID_ShellLink, NULL,
 383                                        CLSCTX_INPROC_SERVER);
 384   if (SUCCEEDED(result)) {
 385     base::win::ScopedComPtr<IPersistFile> persist;
 386     // Query IShellLink for the IPersistFile interface
 387     result = persist.QueryFrom(i_shell_link);
 388     if (SUCCEEDED(result)) {
 389       WCHAR temp_path[MAX_PATH];
 390       // Load the shell link
 391       result = persist->Load(path->value().c_str(), STGM_READ);
 392       if (SUCCEEDED(result)) {
 393         // Try to find the target of a shortcut
 394         result = i_shell_link->Resolve(0, SLR_NO_UI);
 395         if (SUCCEEDED(result)) {
 396           result = i_shell_link->GetPath(temp_path, MAX_PATH,
 397                                   NULL, SLGP_UNCPRIORITY);
 398           *path = FilePath(temp_path);
 399           is_resolved = true;
 400         }
 401       }
 402     }
 403   }
 404
 405   return is_resolved;
 406 }
 407
 408 bool CreateShortcutLink(const wchar_t *source, const wchar_t *destination,
 409                         const wchar_t *working_dir, const wchar_t *arguments,
 410                         const wchar_t *description, const wchar_t *icon,
 411                         int icon_index, const wchar_t* app_id) {
 412   base::ThreadRestrictions::AssertIOAllowed();
 413
 414   // Length of arguments and description must be less than MAX_PATH.
 415   DCHECK(lstrlen(arguments) < MAX_PATH);
 416   DCHECK(lstrlen(description) < MAX_PATH);
 417
 418   base::win::ScopedComPtr<IShellLink> i_shell_link;
 419   base::win::ScopedComPtr<IPersistFile> i_persist_file;
 420
 421   // Get pointer to the IShellLink interface
 422   HRESULT result = i_shell_link.CreateInstance(CLSID_ShellLink, NULL,
 423                                                CLSCTX_INPROC_SERVER);
 424   if (FAILED(result))
 425     return false;
 426
 427   // Query IShellLink for the IPersistFile interface
 428   result = i_persist_file.QueryFrom(i_shell_link);
 429   if (FAILED(result))
 430     return false;
 431
 432   if (FAILED(i_shell_link->SetPath(source)))
 433     return false;
 434
 435   if (working_dir && FAILED(i_shell_link->SetWorkingDirectory(working_dir)))
 436     return false;
 437
 438   if (arguments && FAILED(i_shell_link->SetArguments(arguments)))
 439     return false;
 440
 441   if (description && FAILED(i_shell_link->SetDescription(description)))
 442     return false;
 443
 444   if (icon && FAILED(i_shell_link->SetIconLocation(icon, icon_index)))
 445     return false;
 446
 447   if (app_id && (base::win::GetVersion() >= base::win::VERSION_WIN7)) {
 448     base::win::ScopedComPtr<IPropertyStore> property_store;
 449     if (FAILED(property_store.QueryFrom(i_shell_link)))
 450       return false;
 451
 452     if (!base::win::SetAppIdForPropertyStore(property_store, app_id))
 453       return false;
 454   }
 455
 456   result = i_persist_file->Save(destination, TRUE);
 457   return SUCCEEDED(result);
 458 }
 459
 460 bool UpdateShortcutLink(const wchar_t *source, const wchar_t *destination,
 461                         const wchar_t *working_dir, const wchar_t *arguments,
 462                         const wchar_t *description, const wchar_t *icon,
 463                         int icon_index, const wchar_t* app_id) {
 464   base::ThreadRestrictions::AssertIOAllowed();
 465
 466   // Length of arguments and description must be less than MAX_PATH.
 467   DCHECK(lstrlen(arguments) < MAX_PATH);
 468   DCHECK(lstrlen(description) < MAX_PATH);
 469
 470   // Get pointer to the IPersistFile interface and load existing link
 471   base::win::ScopedComPtr<IShellLink> i_shell_link;
 472   if (FAILED(i_shell_link.CreateInstance(CLSID_ShellLink, NULL,
 473                                          CLSCTX_INPROC_SERVER)))
 474     return false;
 475
 476   base::win::ScopedComPtr<IPersistFile> i_persist_file;
 477   if (FAILED(i_persist_file.QueryFrom(i_shell_link)))
 478     return false;
 479
 480   if (FAILED(i_persist_file->Load(destination, STGM_READWRITE)))
 481     return false;
 482
 483   if (source && FAILED(i_shell_link->SetPath(source)))
 484     return false;
 485
 486   if (working_dir && FAILED(i_shell_link->SetWorkingDirectory(working_dir)))
 487     return false;
 488
 489   if (arguments && FAILED(i_shell_link->SetArguments(arguments)))
 490     return false;
 491
 492   if (description && FAILED(i_shell_link->SetDescription(description)))
 493     return false;
 494
 495   if (icon && FAILED(i_shell_link->SetIconLocation(icon, icon_index)))
 496     return false;
 497
 498   if (app_id && base::win::GetVersion() >= base::win::VERSION_WIN7) {
 499     base::win::ScopedComPtr<IPropertyStore> property_store;
 500     if (FAILED(property_store.QueryFrom(i_shell_link)))
 501       return false;
 502
 503     if (!base::win::SetAppIdForPropertyStore(property_store, app_id))
 504       return false;
 505   }
 506
 507   HRESULT result = i_persist_file->Save(destination, TRUE);
 508
 509   i_persist_file.Release();
 510   i_shell_link.Release();
 511
 512   // If we successfully updated the icon, notify the shell that we have done so.
 513   if (SUCCEEDED(result)) {
 514     SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST | SHCNF_FLUSHNOWAIT,
 515                    NULL, NULL);
 516   }
 517
 518   return SUCCEEDED(result);
 519 }
 520
 521 bool TaskbarPinShortcutLink(const wchar_t* shortcut) {
 522   base::ThreadRestrictions::AssertIOAllowed();
 523
 524   // "Pin to taskbar" is only supported after Win7.
 525   if (base::win::GetVersion() < base::win::VERSION_WIN7)
 526     return false;
 527
 528   int result = reinterpret_cast<int>(ShellExecute(NULL, L"taskbarpin", shortcut,
 529       NULL, NULL, 0));
 530   return result > 32;
 531 }
 532
 533 bool TaskbarUnpinShortcutLink(const wchar_t* shortcut) {
 534   base::ThreadRestrictions::AssertIOAllowed();
 535
 536   // "Unpin from taskbar" is only supported after Win7.
 537   if (base::win::GetVersion() < base::win::VERSION_WIN7)
 538     return false;
 539
 540   int result = reinterpret_cast<int>(ShellExecute(NULL, L"taskbarunpin",
 541       shortcut, NULL, NULL, 0));
 542   return result > 32;
 543 }
 544
 545 bool GetTempDir(FilePath* path) {
 546   base::ThreadRestrictions::AssertIOAllowed();
 547
 548   wchar_t temp_path[MAX_PATH + 1];
 549   DWORD path_len = ::GetTempPath(MAX_PATH, temp_path);
 550   if (path_len >= MAX_PATH || path_len <= 0)
 551     return false;
 552   // TODO(evanm): the old behavior of this function was to always strip the
 553   // trailing slash.  We duplicate this here, but it shouldn't be necessary
 554   // when everyone is using the appropriate FilePath APIs.
 555   *path = FilePath(temp_path).StripTrailingSeparators();
 556   return true;
 557 }
 558
 559 bool GetShmemTempDir(FilePath* path) {
 560   return GetTempDir(path);
 561 }
 562
 563 bool CreateTemporaryFile(FilePath* path) {
 564   base::ThreadRestrictions::AssertIOAllowed();
 565
 566   FilePath temp_file;
 567
 568   if (!GetTempDir(path))
 569     return false;
 570
 571   if (CreateTemporaryFileInDir(*path, &temp_file)) {
 572     *path = temp_file;
 573     return true;
 574   }
 575
 576   return false;
 577 }
 578
 579 FILE* CreateAndOpenTemporaryShmemFile(FilePath* path) {
 580   base::ThreadRestrictions::AssertIOAllowed();
 581   return CreateAndOpenTemporaryFile(path);
 582 }
 583
 584 // On POSIX we have semantics to create and open a temporary file
 585 // atomically.
 586 // TODO(jrg): is there equivalent call to use on Windows instead of
 587 // going 2-step?
 588 FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path) {
 589   base::ThreadRestrictions::AssertIOAllowed();
 590   if (!CreateTemporaryFileInDir(dir, path)) {
 591     return NULL;
 592   }
 593   // Open file in binary mode, to avoid problems with fwrite. On Windows
 594   // it replaces \n's with \r\n's, which may surprise you.
 595   // Reference: http://msdn.microsoft.com/en-us/library/h9t88zwz(VS.71).aspx
 596   return OpenFile(*path, "wb+");
 597 }
 598
 599 bool CreateTemporaryFileInDir(const FilePath& dir,
 600                               FilePath* temp_file) {
 601   base::ThreadRestrictions::AssertIOAllowed();
 602
 603   wchar_t temp_name[MAX_PATH + 1];
 604
 605   if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
 606     PLOG(WARNING) << "Failed to get temporary file name in " << dir.value();
 607     return false;
 608   }
 609
 610   DWORD path_len = GetLongPathName(temp_name, temp_name, MAX_PATH);
 611   if (path_len > MAX_PATH + 1 || path_len == 0) {
 612     PLOG(WARNING) << "Failed to get long path name for " << temp_name;
 613     return false;
 614   }
 615
 616   std::wstring temp_file_str;
 617   temp_file_str.assign(temp_name, path_len);
 618   *temp_file = FilePath(temp_file_str);
 619   return true;
 620 }
 621
 622 bool CreateTemporaryDirInDir(const FilePath& base_dir,
 623                              const FilePath::StringType& prefix,
 624                              FilePath* new_dir) {
 625   base::ThreadRestrictions::AssertIOAllowed();
 626
 627   FilePath path_to_create;
 628   srand(static_cast<uint32>(time(NULL)));
 629
 630   for (int count = 0; count < 50; ++count) {
 631     // Try create a new temporary directory with random generated name. If
 632     // the one exists, keep trying another path name until we reach some limit.
 633     string16 new_dir_name;
 634     new_dir_name.assign(prefix);
 635     new_dir_name.append(base::IntToString16(rand() % kint16max));
 636
 637     path_to_create = base_dir.Append(new_dir_name);
 638     if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {
 639       *new_dir = path_to_create;
 640       return true;
 641     }
 642   }
 643
 644   return false;
 645 }
 646
 647 bool CreateNewTempDirectory(const FilePath::StringType& prefix,
 648                             FilePath* new_temp_path) {
 649   base::ThreadRestrictions::AssertIOAllowed();
 650
 651   FilePath system_temp_dir;
 652   if (!GetTempDir(&system_temp_dir))
 653     return false;
 654
 655   return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
 656 }
 657
 658 bool CreateDirectory(const FilePath& full_path) {
 659   base::ThreadRestrictions::AssertIOAllowed();
 660
 661   // If the path exists, we've succeeded if it's a directory, failed otherwise.
 662   const wchar_t* full_path_str = full_path.value().c_str();
 663   DWORD fileattr = ::GetFileAttributes(full_path_str);
 664   if (fileattr != INVALID_FILE_ATTRIBUTES) {
 665     if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
 666       DVLOG(1) << "CreateDirectory(" << full_path_str << "), "
 667                << "directory already exists.";
 668       return true;
 669     }
 670     LOG(WARNING) << "CreateDirectory(" << full_path_str << "), "
 671                  << "conflicts with existing file.";
 672     return false;
 673   }
 674
 675   // Invariant:  Path does not exist as file or directory.
 676
 677   // Attempt to create the parent recursively.  This will immediately return
 678   // true if it already exists, otherwise will create all required parent
 679   // directories starting with the highest-level missing parent.
 680   FilePath parent_path(full_path.DirName());
 681   if (parent_path.value() == full_path.value()) {
 682     return false;
 683   }
 684   if (!CreateDirectory(parent_path)) {
 685     DLOG(WARNING) << "Failed to create one of the parent directories.";
 686     return false;
 687   }
 688
 689   if (!::CreateDirectory(full_path_str, NULL)) {
 690     DWORD error_code = ::GetLastError();
 691     if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
 692       // This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
 693       // were racing with someone creating the same directory, or a file
 694       // with the same path.  If DirectoryExists() returns true, we lost the
 695       // race to create the same directory.
 696       return true;
 697     } else {
 698       LOG(WARNING) << "Failed to create directory " << full_path_str
 699                    << ", last error is " << error_code << ".";
 700       return false;
 701     }
 702   } else {
 703     return true;
 704   }
 705 }
 706
 707 // TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
 708 // them if we do decide to.
 709 bool IsLink(const FilePath& file_path) {
 710   return false;
 711 }
 712
 713 bool GetFileInfo(const FilePath& file_path, base::PlatformFileInfo* results) {
 714   base::ThreadRestrictions::AssertIOAllowed();
 715
 716   WIN32_FILE_ATTRIBUTE_DATA attr;
 717   if (!GetFileAttributesEx(file_path.value().c_str(),
 718                            GetFileExInfoStandard, &attr)) {
 719     return false;
 720   }
 721
 722   ULARGE_INTEGER size;
 723   size.HighPart = attr.nFileSizeHigh;
 724   size.LowPart = attr.nFileSizeLow;
 725   results->size = size.QuadPart;
 726
 727   results->is_directory =
 728       (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
 729   results->last_modified = base::Time::FromFileTime(attr.ftLastWriteTime);
 730   results->last_accessed = base::Time::FromFileTime(attr.ftLastAccessTime);
 731   results->creation_time = base::Time::FromFileTime(attr.ftCreationTime);
 732
 733   return true;
 734 }
 735
 736 FILE* OpenFile(const FilePath& filename, const char* mode) {
 737   base::ThreadRestrictions::AssertIOAllowed();
 738   std::wstring w_mode = ASCIIToWide(std::string(mode));
 739   return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
 740 }
 741
 742 FILE* OpenFile(const std::string& filename, const char* mode) {
 743   base::ThreadRestrictions::AssertIOAllowed();
 744   return _fsopen(filename.c_str(), mode, _SH_DENYNO);
 745 }
 746
 747 int ReadFile(const FilePath& filename, char* data, int size) {
 748   base::ThreadRestrictions::AssertIOAllowed();
 749   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 750                                           GENERIC_READ,
 751                                           FILE_SHARE_READ | FILE_SHARE_WRITE,
 752                                           NULL,
 753                                           OPEN_EXISTING,
 754                                           FILE_FLAG_SEQUENTIAL_SCAN,
 755                                           NULL));
 756   if (!file)
 757     return -1;
 758
 759   DWORD read;
 760   if (::ReadFile(file, data, size, &read, NULL) &&
 761       static_cast<int>(read) == size)
 762     return read;
 763   return -1;
 764 }
 765
 766 int WriteFile(const FilePath& filename, const char* data, int size) {
 767   base::ThreadRestrictions::AssertIOAllowed();
 768   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 769                                           GENERIC_WRITE,
 770                                           0,
 771                                           NULL,
 772                                           CREATE_ALWAYS,
 773                                           0,
 774                                           NULL));
 775   if (!file) {
 776     LOG(WARNING) << "CreateFile failed for path " << filename.value()
 777                  << " error code=" << GetLastError();
 778     return -1;
 779   }
 780
 781   DWORD written;
 782   BOOL result = ::WriteFile(file, data, size, &written, NULL);
 783   if (result && static_cast<int>(written) == size)
 784     return written;
 785
 786   if (!result) {
 787     // WriteFile failed.
 788     LOG(WARNING) << "writing file " << filename.value()
 789                  << " failed, error code=" << GetLastError();
 790   } else {
 791     // Didn't write all the bytes.
 792     LOG(WARNING) << "wrote" << written << " bytes to " <<
 793         filename.value() << " expected " << size;
 794   }
 795   return -1;
 796 }
 797
 798 bool RenameFileAndResetSecurityDescriptor(const FilePath& source_file_path,
 799                                           const FilePath& target_file_path) {
 800   base::ThreadRestrictions::AssertIOAllowed();
 801
 802   // The parameters to SHFileOperation must be terminated with 2 NULL chars.
 803   std::wstring source = source_file_path.value();
 804   std::wstring target = target_file_path.value();
 805
 806   source.append(1, L'\0');
 807   target.append(1, L'\0');
 808
 809   SHFILEOPSTRUCT move_info = {0};
 810   move_info.wFunc = FO_MOVE;
 811   move_info.pFrom = source.c_str();
 812   move_info.pTo = target.c_str();
 813   move_info.fFlags = FOF_SILENT | FOF_NOCONFIRMATION | FOF_NOERRORUI |
 814                      FOF_NOCONFIRMMKDIR | FOF_NOCOPYSECURITYATTRIBS;
 815
 816   if (0 != SHFileOperation(&move_info))
 817     return false;
 818
 819   return true;
 820 }
 821
 822 // Gets the current working directory for the process.
 823 bool GetCurrentDirectory(FilePath* dir) {
 824   base::ThreadRestrictions::AssertIOAllowed();
 825
 826   wchar_t system_buffer[MAX_PATH];
 827   system_buffer[0] = 0;
 828   DWORD len = ::GetCurrentDirectory(MAX_PATH, system_buffer);
 829   if (len == 0 || len > MAX_PATH)
 830     return false;
 831   // TODO(evanm): the old behavior of this function was to always strip the
 832   // trailing slash.  We duplicate this here, but it shouldn't be necessary
 833   // when everyone is using the appropriate FilePath APIs.
 834   std::wstring dir_str(system_buffer);
 835   *dir = FilePath(dir_str).StripTrailingSeparators();
 836   return true;
 837 }
 838
 839 // Sets the current working directory for the process.
 840 bool SetCurrentDirectory(const FilePath& directory) {
 841   base::ThreadRestrictions::AssertIOAllowed();
 842   BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
 843   return ret != 0;
 844 }
 845
 846 ///////////////////////////////////////////////
 847 // FileEnumerator
 848
 849 FileEnumerator::FileEnumerator(const FilePath& root_path,
 850                                bool recursive,
 851                                FileEnumerator::FILE_TYPE file_type)
 852     : recursive_(recursive),
 853       file_type_(file_type),
 854       has_find_data_(false),
 855       find_handle_(INVALID_HANDLE_VALUE) {
 856   // INCLUDE_DOT_DOT must not be specified if recursive.
 857   DCHECK(!(recursive && (INCLUDE_DOT_DOT & file_type_)));
 858   pending_paths_.push(root_path);
 859 }
 860
 861 FileEnumerator::FileEnumerator(const FilePath& root_path,
 862                                bool recursive,
 863                                FileEnumerator::FILE_TYPE file_type,
 864                                const FilePath::StringType& pattern)
 865     : recursive_(recursive),
 866       file_type_(file_type),
 867       has_find_data_(false),
 868       pattern_(pattern),
 869       find_handle_(INVALID_HANDLE_VALUE) {
 870   // INCLUDE_DOT_DOT must not be specified if recursive.
 871   DCHECK(!(recursive && (INCLUDE_DOT_DOT & file_type_)));
 872   pending_paths_.push(root_path);
 873 }
 874
 875 FileEnumerator::~FileEnumerator() {
 876   if (find_handle_ != INVALID_HANDLE_VALUE)
 877     FindClose(find_handle_);
 878 }
 879
 880 void FileEnumerator::GetFindInfo(FindInfo* info) {
 881   DCHECK(info);
 882
 883   if (!has_find_data_)
 884     return;
 885
 886   memcpy(info, &find_data_, sizeof(*info));
 887 }
 888
 889 bool FileEnumerator::IsDirectory(const FindInfo& info) {
 890   return (info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
 891 }
 892
 893 // static
 894 FilePath FileEnumerator::GetFilename(const FindInfo& find_info) {
 895   return FilePath(find_info.cFileName);
 896 }
 897
 898 // static
 899 int64 FileEnumerator::GetFilesize(const FindInfo& find_info) {
 900   ULARGE_INTEGER size;
 901   size.HighPart = find_info.nFileSizeHigh;
 902   size.LowPart = find_info.nFileSizeLow;
 903   DCHECK_LE(size.QuadPart, std::numeric_limits<int64>::max());
 904   return static_cast<int64>(size.QuadPart);
 905 }
 906
 907 // static
 908 base::Time FileEnumerator::GetLastModifiedTime(const FindInfo& find_info) {
 909   return base::Time::FromFileTime(find_info.ftLastWriteTime);
 910 }
 911
 912 FilePath FileEnumerator::Next() {
 913   base::ThreadRestrictions::AssertIOAllowed();
 914
 915   while (has_find_data_ || !pending_paths_.empty()) {
 916     if (!has_find_data_) {
 917       // The last find FindFirstFile operation is done, prepare a new one.
 918       root_path_ = pending_paths_.top();
 919       pending_paths_.pop();
 920
 921       // Start a new find operation.
 922       FilePath src = root_path_;
 923
 924       if (pattern_.empty())
 925         src = src.Append(L"*");  // No pattern = match everything.
 926       else
 927         src = src.Append(pattern_);
 928
 929       find_handle_ = FindFirstFile(src.value().c_str(), &find_data_);
 930       has_find_data_ = true;
 931     } else {
 932       // Search for the next file/directory.
 933       if (!FindNextFile(find_handle_, &find_data_)) {
 934         FindClose(find_handle_);
 935         find_handle_ = INVALID_HANDLE_VALUE;
 936       }
 937     }
 938
 939     if (INVALID_HANDLE_VALUE == find_handle_) {
 940       has_find_data_ = false;
 941
 942       // This is reached when we have finished a directory and are advancing to
 943       // the next one in the queue. We applied the pattern (if any) to the files
 944       // in the root search directory, but for those directories which were
 945       // matched, we want to enumerate all files inside them. This will happen
 946       // when the handle is empty.
 947       pattern_ = FilePath::StringType();
 948
 949       continue;
 950     }
 951
 952     FilePath cur_file(find_data_.cFileName);
 953     if (ShouldSkip(cur_file))
 954       continue;
 955
 956     // Construct the absolute filename.
 957     cur_file = root_path_.Append(find_data_.cFileName);
 958
 959     if (find_data_.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
 960       if (recursive_) {
 961         // If |cur_file| is a directory, and we are doing recursive searching,
 962         // add it to pending_paths_ so we scan it after we finish scanning this
 963         // directory.
 964         pending_paths_.push(cur_file);
 965       }
 966       if (file_type_ & FileEnumerator::DIRECTORIES)
 967         return cur_file;
 968     } else if (file_type_ & FileEnumerator::FILES) {
 969       return cur_file;
 970     }
 971   }
 972
 973   return FilePath();
 974 }
 975
 976 ///////////////////////////////////////////////
 977 // MemoryMappedFile
 978
 979 MemoryMappedFile::MemoryMappedFile()
 980     : file_(INVALID_HANDLE_VALUE),
 981       file_mapping_(INVALID_HANDLE_VALUE),
 982       data_(NULL),
 983       length_(INVALID_FILE_SIZE) {
 984 }
 985
 986 bool MemoryMappedFile::InitializeAsImageSection(const FilePath& file_name) {
 987   if (IsValid())
 988     return false;
 989   file_ = base::CreatePlatformFile(
 990       file_name, base::PLATFORM_FILE_OPEN | base::PLATFORM_FILE_READ,
 991       NULL, NULL);
 992
 993   if (file_ == base::kInvalidPlatformFileValue) {
 994     LOG(ERROR) << "Couldn't open " << file_name.value();
 995     return false;
 996   }
 997
 998   if (!MapFileToMemoryInternalEx(SEC_IMAGE)) {
 999     CloseHandles();
1000     return false;
1001   }
1002
1003   return true;
1004 }
1005
1006 bool MemoryMappedFile::MapFileToMemoryInternal() {
1007   return MapFileToMemoryInternalEx(0);
1008 }
1009
1010 bool MemoryMappedFile::MapFileToMemoryInternalEx(int flags) {
1011   base::ThreadRestrictions::AssertIOAllowed();
1012
1013   if (file_ == INVALID_HANDLE_VALUE)
1014     return false;
1015
1016   length_ = ::GetFileSize(file_, NULL);
1017   if (length_ == INVALID_FILE_SIZE)
1018     return false;
1019
1020   file_mapping_ = ::CreateFileMapping(file_, NULL, PAGE_READONLY | flags,
1021                                       0, 0, NULL);
1022   if (!file_mapping_) {
1023     // According to msdn, system error codes are only reserved up to 15999.
1024     // http://msdn.microsoft.com/en-us/library/ms681381(v=VS.85).aspx.
1025     UMA_HISTOGRAM_ENUMERATION("MemoryMappedFile.CreateFileMapping",
1026                               logging::GetLastSystemErrorCode(), 16000);
1027     return false;
1028   }
1029
1030   data_ = static_cast<uint8*>(
1031       ::MapViewOfFile(file_mapping_, FILE_MAP_READ, 0, 0, 0));
1032   if (!data_) {
1033     UMA_HISTOGRAM_ENUMERATION("MemoryMappedFile.MapViewOfFile",
1034                               logging::GetLastSystemErrorCode(), 16000);
1035   }
1036   return data_ != NULL;
1037 }
1038
1039 void MemoryMappedFile::CloseHandles() {
1040   if (data_)
1041     ::UnmapViewOfFile(data_);
1042   if (file_mapping_ != INVALID_HANDLE_VALUE)
1043     ::CloseHandle(file_mapping_);
1044   if (file_ != INVALID_HANDLE_VALUE)
1045     ::CloseHandle(file_);
1046
1047   data_ = NULL;
1048   file_mapping_ = file_ = INVALID_HANDLE_VALUE;
1049   length_ = INVALID_FILE_SIZE;
1050 }
1051
1052 bool HasFileBeenModifiedSince(const FileEnumerator::FindInfo& find_info,
1053                               const base::Time& cutoff_time) {
1054   base::ThreadRestrictions::AssertIOAllowed();
1055   long result = CompareFileTime(&find_info.ftLastWriteTime,  // NOLINT
1056                                 &cutoff_time.ToFileTime());
1057   return result == 1 || result == 0;
1058 }
1059
1060 bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
1061   base::ThreadRestrictions::AssertIOAllowed();
1062   FilePath mapped_file;
1063   if (!NormalizeToNativeFilePath(path, &mapped_file))
1064     return false;
1065   // NormalizeToNativeFilePath() will return a path that starts with
1066   // "\Device\Harddisk...".  Helper DevicePathToDriveLetterPath()
1067   // will find a drive letter which maps to the path's device, so
1068   // that we return a path starting with a drive letter.
1069   return DevicePathToDriveLetterPath(mapped_file, real_path);
1070 }
1071
1072 bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path) {
1073   base::ThreadRestrictions::AssertIOAllowed();
1074   // In Vista, GetFinalPathNameByHandle() would give us the real path
1075   // from a file handle.  If we ever deprecate XP, consider changing the
1076   // code below to a call to GetFinalPathNameByHandle().  The method this
1077   // function uses is explained in the following msdn article:
1078   // http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
1079   base::win::ScopedHandle file_handle(
1080       ::CreateFile(path.value().c_str(),
1081                    GENERIC_READ,
1082                    kFileShareAll,
1083                    NULL,
1084                    OPEN_EXISTING,
1085                    FILE_ATTRIBUTE_NORMAL,
1086                    NULL));
1087   if (!file_handle)
1088     return false;
1089
1090   // Create a file mapping object.  Can't easily use MemoryMappedFile, because
1091   // we only map the first byte, and need direct access to the handle. You can
1092   // not map an empty file, this call fails in that case.
1093   base::win::ScopedHandle file_map_handle(
1094       ::CreateFileMapping(file_handle.Get(),
1095                           NULL,
1096                           PAGE_READONLY,
1097                           0,
1098                           1,  // Just one byte.  No need to look at the data.
1099                           NULL));
1100   if (!file_map_handle)
1101     return false;
1102
1103   // Use a view of the file to get the path to the file.
1104   void* file_view = MapViewOfFile(file_map_handle.Get(),
1105                                   FILE_MAP_READ, 0, 0, 1);
1106   if (!file_view)
1107     return false;
1108
1109   // The expansion of |path| into a full path may make it longer.
1110   // GetMappedFileName() will fail if the result is longer than MAX_PATH.
1111   // Pad a bit to be safe.  If kMaxPathLength is ever changed to be less
1112   // than MAX_PATH, it would be nessisary to test that GetMappedFileName()
1113   // not return kMaxPathLength.  This would mean that only part of the
1114   // path fit in |mapped_file_path|.
1115   const int kMaxPathLength = MAX_PATH + 10;
1116   wchar_t mapped_file_path[kMaxPathLength];
1117   bool success = false;
1118   HANDLE cp = GetCurrentProcess();
1119   if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
1120     *nt_path = FilePath(mapped_file_path);
1121     success = true;
1122   }
1123   ::UnmapViewOfFile(file_view);
1124   return success;
1125 }
1126
1127 bool PreReadImage(const wchar_t* file_path, size_t size_to_read,
1128                   size_t step_size) {
1129   base::ThreadRestrictions::AssertIOAllowed();
1130   if (base::win::GetVersion() > base::win::VERSION_XP) {
1131     // Vista+ branch. On these OSes, the forced reads through the DLL actually
1132     // slows warm starts. The solution is to sequentially read file contents
1133     // with an optional cap on total amount to read.
1134     base::win::ScopedHandle file(
1135         CreateFile(file_path,
1136                    GENERIC_READ,
1137                    FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
1138                    NULL,
1139                    OPEN_EXISTING,
1140                    FILE_FLAG_SEQUENTIAL_SCAN,
1141                    NULL));
1142
1143     if (!file.IsValid())
1144       return false;
1145
1146     // Default to 1MB sequential reads.
1147     const DWORD actual_step_size = std::max(static_cast<DWORD>(step_size),
1148                                             static_cast<DWORD>(1024*1024));
1149     LPVOID buffer = ::VirtualAlloc(NULL,
1150                                    actual_step_size,
1151                                    MEM_COMMIT,
1152                                    PAGE_READWRITE);
1153
1154     if (buffer == NULL)
1155       return false;
1156
1157     DWORD len;
1158     size_t total_read = 0;
1159     while (::ReadFile(file, buffer, actual_step_size, &len, NULL) &&
1160            len > 0 &&
1161            (size_to_read ? total_read < size_to_read : true)) {
1162       total_read += static_cast<size_t>(len);
1163     }
1164     ::VirtualFree(buffer, 0, MEM_RELEASE);
1165   } else {
1166     // WinXP branch. Here, reading the DLL from disk doesn't do
1167     // what we want so instead we pull the pages into memory by loading
1168     // the DLL and touching pages at a stride.
1169     HMODULE dll_module = ::LoadLibraryExW(
1170         file_path,
1171         NULL,
1172         LOAD_WITH_ALTERED_SEARCH_PATH | DONT_RESOLVE_DLL_REFERENCES);
1173
1174     if (!dll_module)
1175       return false;
1176
1177     base::win::PEImage pe_image(dll_module);
1178     PIMAGE_NT_HEADERS nt_headers = pe_image.GetNTHeaders();
1179     size_t actual_size_to_read = size_to_read ? size_to_read :
1180                                  nt_headers->OptionalHeader.SizeOfImage;
1181     volatile uint8* touch = reinterpret_cast<uint8*>(dll_module);
1182     size_t offset = 0;
1183     while (offset < actual_size_to_read) {
1184       uint8 unused = *(touch + offset);
1185       offset += step_size;
1186     }
1187     FreeLibrary(dll_module);
1188   }
1189
1190   return true;
1191 }
1192
1193 }  // namespace file_util