base/file_util_win.cc

   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_enumerator.h"
  18 #include "base/files/file_path.h"
  19 #include "base/logging.h"
  20 #include "base/metrics/histogram.h"
  21 #include "base/process/process_handle.h"
  22 #include "base/rand_util.h"
  23 #include "base/strings/string_number_conversions.h"
  24 #include "base/strings/string_util.h"
  25 #include "base/strings/utf_string_conversions.h"
  26 #include "base/threading/thread_restrictions.h"
  27 #include "base/time/time.h"
  28 #include "base/win/scoped_handle.h"
  29 #include "base/win/windows_version.h"
  30
  31 namespace base {
  32
  33 namespace {
  34
  35 const DWORD kFileShareAll =
  36     FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
  37
  38 }  // namespace
  39
  40 FilePath MakeAbsoluteFilePath(const FilePath& input) {
  41   ThreadRestrictions::AssertIOAllowed();
  42   wchar_t file_path[MAX_PATH];
  43   if (!_wfullpath(file_path, input.value().c_str(), MAX_PATH))
  44     return FilePath();
  45   return FilePath(file_path);
  46 }
  47
  48 bool DeleteFile(const FilePath& path, bool recursive) {
  49   ThreadRestrictions::AssertIOAllowed();
  50
  51   if (path.value().length() >= MAX_PATH)
  52     return false;
  53
  54   if (!recursive) {
  55     // If not recursing, then first check to see if |path| is a directory.
  56     // If it is, then remove it with RemoveDirectory.
  57     File::Info file_info;
  58     if (GetFileInfo(path, &file_info) && file_info.is_directory)
  59       return RemoveDirectory(path.value().c_str()) != 0;
  60
  61     // Otherwise, it's a file, wildcard or non-existant. Try DeleteFile first
  62     // because it should be faster. If DeleteFile fails, then we fall through
  63     // to SHFileOperation, which will do the right thing.
  64     if (::DeleteFile(path.value().c_str()) != 0)
  65       return true;
  66   }
  67
  68   // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
  69   // so we have to use wcscpy because wcscpy_s writes non-NULLs
  70   // into the rest of the buffer.
  71   wchar_t double_terminated_path[MAX_PATH + 1] = {0};
  72 #pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
  73   wcscpy(double_terminated_path, path.value().c_str());
  74
  75   SHFILEOPSTRUCT file_operation = {0};
  76   file_operation.wFunc = FO_DELETE;
  77   file_operation.pFrom = double_terminated_path;
  78   file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION;
  79   if (!recursive)
  80     file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
  81   int err = SHFileOperation(&file_operation);
  82
  83   // Since we're passing flags to the operation telling it to be silent,
  84   // it's possible for the operation to be aborted/cancelled without err
  85   // being set (although MSDN doesn't give any scenarios for how this can
  86   // happen).  See MSDN for SHFileOperation and SHFILEOPTSTRUCT.
  87   if (file_operation.fAnyOperationsAborted)
  88     return false;
  89
  90   // Some versions of Windows return ERROR_FILE_NOT_FOUND (0x2) when deleting
  91   // an empty directory and some return 0x402 when they should be returning
  92   // ERROR_FILE_NOT_FOUND. MSDN says Vista and up won't return 0x402.
  93   return (err == 0 || err == ERROR_FILE_NOT_FOUND || err == 0x402);
  94 }
  95
  96 bool DeleteFileAfterReboot(const FilePath& path) {
  97   ThreadRestrictions::AssertIOAllowed();
  98
  99   if (path.value().length() >= MAX_PATH)
 100     return false;
 101
 102   return MoveFileEx(path.value().c_str(), NULL,
 103                     MOVEFILE_DELAY_UNTIL_REBOOT |
 104                         MOVEFILE_REPLACE_EXISTING) != FALSE;
 105 }
 106
 107 bool ReplaceFile(const FilePath& from_path,
 108                  const FilePath& to_path,
 109                  File::Error* error) {
 110   ThreadRestrictions::AssertIOAllowed();
 111   // Try a simple move first.  It will only succeed when |to_path| doesn't
 112   // already exist.
 113   if (::MoveFile(from_path.value().c_str(), to_path.value().c_str()))
 114     return true;
 115   // Try the full-blown replace if the move fails, as ReplaceFile will only
 116   // succeed when |to_path| does exist. When writing to a network share, we may
 117   // not be able to change the ACLs. Ignore ACL errors then
 118   // (REPLACEFILE_IGNORE_MERGE_ERRORS).
 119   if (::ReplaceFile(to_path.value().c_str(), from_path.value().c_str(), NULL,
 120                     REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL)) {
 121     return true;
 122   }
 123   if (error)
 124     *error = File::OSErrorToFileError(GetLastError());
 125   return false;
 126 }
 127
 128 bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
 129                    bool recursive) {
 130   // NOTE(maruel): Previous version of this function used to call
 131   // SHFileOperation().  This used to copy the file attributes and extended
 132   // attributes, OLE structured storage, NTFS file system alternate data
 133   // streams, SECURITY_DESCRIPTOR. In practice, this is not what we want, we
 134   // want the containing directory to propagate its SECURITY_DESCRIPTOR.
 135   ThreadRestrictions::AssertIOAllowed();
 136
 137   // NOTE: I suspect we could support longer paths, but that would involve
 138   // analyzing all our usage of files.
 139   if (from_path.value().length() >= MAX_PATH ||
 140       to_path.value().length() >= MAX_PATH) {
 141     return false;
 142   }
 143
 144   // This function does not properly handle destinations within the source.
 145   FilePath real_to_path = to_path;
 146   if (PathExists(real_to_path)) {
 147     real_to_path = MakeAbsoluteFilePath(real_to_path);
 148     if (real_to_path.empty())
 149       return false;
 150   } else {
 151     real_to_path = MakeAbsoluteFilePath(real_to_path.DirName());
 152     if (real_to_path.empty())
 153       return false;
 154   }
 155   FilePath real_from_path = MakeAbsoluteFilePath(from_path);
 156   if (real_from_path.empty())
 157     return false;
 158   if (real_to_path.value().size() >= real_from_path.value().size() &&
 159       real_to_path.value().compare(0, real_from_path.value().size(),
 160                                    real_from_path.value()) == 0) {
 161     return false;
 162   }
 163
 164   int traverse_type = FileEnumerator::FILES;
 165   if (recursive)
 166     traverse_type |= FileEnumerator::DIRECTORIES;
 167   FileEnumerator traversal(from_path, recursive, traverse_type);
 168
 169   if (!PathExists(from_path)) {
 170     DLOG(ERROR) << "CopyDirectory() couldn't stat source directory: "
 171                 << from_path.value().c_str();
 172     return false;
 173   }
 174   // TODO(maruel): This is not necessary anymore.
 175   DCHECK(recursive || DirectoryExists(from_path));
 176
 177   FilePath current = from_path;
 178   bool from_is_dir = DirectoryExists(from_path);
 179   bool success = true;
 180   FilePath from_path_base = from_path;
 181   if (recursive && DirectoryExists(to_path)) {
 182     // If the destination already exists and is a directory, then the
 183     // top level of source needs to be copied.
 184     from_path_base = from_path.DirName();
 185   }
 186
 187   while (success && !current.empty()) {
 188     // current is the source path, including from_path, so append
 189     // the suffix after from_path to to_path to create the target_path.
 190     FilePath target_path(to_path);
 191     if (from_path_base != current) {
 192       if (!from_path_base.AppendRelativePath(current, &target_path)) {
 193         success = false;
 194         break;
 195       }
 196     }
 197
 198     if (from_is_dir) {
 199       if (!DirectoryExists(target_path) &&
 200           !::CreateDirectory(target_path.value().c_str(), NULL)) {
 201         DLOG(ERROR) << "CopyDirectory() couldn't create directory: "
 202                     << target_path.value().c_str();
 203         success = false;
 204       }
 205     } else if (!internal::CopyFileUnsafe(current, target_path)) {
 206       DLOG(ERROR) << "CopyDirectory() couldn't create file: "
 207                   << target_path.value().c_str();
 208       success = false;
 209     }
 210
 211     current = traversal.Next();
 212     if (!current.empty())
 213       from_is_dir = traversal.GetInfo().IsDirectory();
 214   }
 215
 216   return success;
 217 }
 218
 219 bool PathExists(const FilePath& path) {
 220   ThreadRestrictions::AssertIOAllowed();
 221   return (GetFileAttributes(path.value().c_str()) != INVALID_FILE_ATTRIBUTES);
 222 }
 223
 224 bool PathIsWritable(const FilePath& path) {
 225   ThreadRestrictions::AssertIOAllowed();
 226   HANDLE dir =
 227       CreateFile(path.value().c_str(), FILE_ADD_FILE, kFileShareAll,
 228                  NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
 229
 230   if (dir == INVALID_HANDLE_VALUE)
 231     return false;
 232
 233   CloseHandle(dir);
 234   return true;
 235 }
 236
 237 bool DirectoryExists(const FilePath& path) {
 238   ThreadRestrictions::AssertIOAllowed();
 239   DWORD fileattr = GetFileAttributes(path.value().c_str());
 240   if (fileattr != INVALID_FILE_ATTRIBUTES)
 241     return (fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0;
 242   return false;
 243 }
 244
 245 bool GetTempDir(FilePath* path) {
 246   wchar_t temp_path[MAX_PATH + 1];
 247   DWORD path_len = ::GetTempPath(MAX_PATH, temp_path);
 248   if (path_len >= MAX_PATH || path_len <= 0)
 249     return false;
 250   // TODO(evanm): the old behavior of this function was to always strip the
 251   // trailing slash.  We duplicate this here, but it shouldn't be necessary
 252   // when everyone is using the appropriate FilePath APIs.
 253   *path = FilePath(temp_path).StripTrailingSeparators();
 254   return true;
 255 }
 256
 257 bool GetShmemTempDir(bool executable, FilePath* path) {
 258   return GetTempDir(path);
 259 }
 260
 261 bool CreateTemporaryFile(FilePath* path) {
 262   ThreadRestrictions::AssertIOAllowed();
 263
 264   FilePath temp_file;
 265
 266   if (!GetTempDir(path))
 267     return false;
 268
 269   if (CreateTemporaryFileInDir(*path, &temp_file)) {
 270     *path = temp_file;
 271     return true;
 272   }
 273
 274   return false;
 275 }
 276
 277 FILE* CreateAndOpenTemporaryShmemFile(FilePath* path, bool executable) {
 278   ThreadRestrictions::AssertIOAllowed();
 279   return CreateAndOpenTemporaryFile(path);
 280 }
 281
 282 // On POSIX we have semantics to create and open a temporary file
 283 // atomically.
 284 // TODO(jrg): is there equivalent call to use on Windows instead of
 285 // going 2-step?
 286 FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path) {
 287   ThreadRestrictions::AssertIOAllowed();
 288   if (!CreateTemporaryFileInDir(dir, path)) {
 289     return NULL;
 290   }
 291   // Open file in binary mode, to avoid problems with fwrite. On Windows
 292   // it replaces \n's with \r\n's, which may surprise you.
 293   // Reference: http://msdn.microsoft.com/en-us/library/h9t88zwz(VS.71).aspx
 294   return OpenFile(*path, "wb+");
 295 }
 296
 297 bool CreateTemporaryFileInDir(const FilePath& dir, FilePath* temp_file) {
 298   ThreadRestrictions::AssertIOAllowed();
 299
 300   wchar_t temp_name[MAX_PATH + 1];
 301
 302   if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
 303     DPLOG(WARNING) << "Failed to get temporary file name in "
 304                    << UTF16ToUTF8(dir.value());
 305     return false;
 306   }
 307
 308   wchar_t long_temp_name[MAX_PATH + 1];
 309   DWORD long_name_len = GetLongPathName(temp_name, long_temp_name, MAX_PATH);
 310   if (long_name_len > MAX_PATH || long_name_len == 0) {
 311     // GetLongPathName() failed, but we still have a temporary file.
 312     *temp_file = FilePath(temp_name);
 313     return true;
 314   }
 315
 316   FilePath::StringType long_temp_name_str;
 317   long_temp_name_str.assign(long_temp_name, long_name_len);
 318   *temp_file = FilePath(long_temp_name_str);
 319   return true;
 320 }
 321
 322 bool CreateTemporaryDirInDir(const FilePath& base_dir,
 323                              const FilePath::StringType& prefix,
 324                              FilePath* new_dir) {
 325   ThreadRestrictions::AssertIOAllowed();
 326
 327   FilePath path_to_create;
 328
 329   for (int count = 0; count < 50; ++count) {
 330     // Try create a new temporary directory with random generated name. If
 331     // the one exists, keep trying another path name until we reach some limit.
 332     string16 new_dir_name;
 333     new_dir_name.assign(prefix);
 334     new_dir_name.append(IntToString16(GetCurrentProcId()));
 335     new_dir_name.push_back('_');
 336     new_dir_name.append(IntToString16(RandInt(0, kint16max)));
 337
 338     path_to_create = base_dir.Append(new_dir_name);
 339     if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {
 340       *new_dir = path_to_create;
 341       return true;
 342     }
 343   }
 344
 345   return false;
 346 }
 347
 348 bool CreateNewTempDirectory(const FilePath::StringType& prefix,
 349                             FilePath* new_temp_path) {
 350   ThreadRestrictions::AssertIOAllowed();
 351
 352   FilePath system_temp_dir;
 353   if (!GetTempDir(&system_temp_dir))
 354     return false;
 355
 356   return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
 357 }
 358
 359 bool CreateDirectoryAndGetError(const FilePath& full_path,
 360                                 File::Error* error) {
 361   ThreadRestrictions::AssertIOAllowed();
 362
 363   // If the path exists, we've succeeded if it's a directory, failed otherwise.
 364   const wchar_t* full_path_str = full_path.value().c_str();
 365   DWORD fileattr = ::GetFileAttributes(full_path_str);
 366   if (fileattr != INVALID_FILE_ATTRIBUTES) {
 367     if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
 368       DVLOG(1) << "CreateDirectory(" << full_path_str << "), "
 369                << "directory already exists.";
 370       return true;
 371     }
 372     DLOG(WARNING) << "CreateDirectory(" << full_path_str << "), "
 373                   << "conflicts with existing file.";
 374     if (error) {
 375       *error = File::FILE_ERROR_NOT_A_DIRECTORY;
 376     }
 377     return false;
 378   }
 379
 380   // Invariant:  Path does not exist as file or directory.
 381
 382   // Attempt to create the parent recursively.  This will immediately return
 383   // true if it already exists, otherwise will create all required parent
 384   // directories starting with the highest-level missing parent.
 385   FilePath parent_path(full_path.DirName());
 386   if (parent_path.value() == full_path.value()) {
 387     if (error) {
 388       *error = File::FILE_ERROR_NOT_FOUND;
 389     }
 390     return false;
 391   }
 392   if (!CreateDirectoryAndGetError(parent_path, error)) {
 393     DLOG(WARNING) << "Failed to create one of the parent directories.";
 394     if (error) {
 395       DCHECK(*error != File::FILE_OK);
 396     }
 397     return false;
 398   }
 399
 400   if (!::CreateDirectory(full_path_str, NULL)) {
 401     DWORD error_code = ::GetLastError();
 402     if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
 403       // This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
 404       // were racing with someone creating the same directory, or a file
 405       // with the same path.  If DirectoryExists() returns true, we lost the
 406       // race to create the same directory.
 407       return true;
 408     } else {
 409       if (error)
 410         *error = File::OSErrorToFileError(error_code);
 411       DLOG(WARNING) << "Failed to create directory " << full_path_str
 412                     << ", last error is " << error_code << ".";
 413       return false;
 414     }
 415   } else {
 416     return true;
 417   }
 418 }
 419
 420 bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
 421   ThreadRestrictions::AssertIOAllowed();
 422   FilePath mapped_file;
 423   if (!NormalizeToNativeFilePath(path, &mapped_file))
 424     return false;
 425   // NormalizeToNativeFilePath() will return a path that starts with
 426   // "\Device\Harddisk...".  Helper DevicePathToDriveLetterPath()
 427   // will find a drive letter which maps to the path's device, so
 428   // that we return a path starting with a drive letter.
 429   return DevicePathToDriveLetterPath(mapped_file, real_path);
 430 }
 431
 432 bool DevicePathToDriveLetterPath(const FilePath& nt_device_path,
 433                                  FilePath* out_drive_letter_path) {
 434   ThreadRestrictions::AssertIOAllowed();
 435
 436   // Get the mapping of drive letters to device paths.
 437   const int kDriveMappingSize = 1024;
 438   wchar_t drive_mapping[kDriveMappingSize] = {'\0'};
 439   if (!::GetLogicalDriveStrings(kDriveMappingSize - 1, drive_mapping)) {
 440     DLOG(ERROR) << "Failed to get drive mapping.";
 441     return false;
 442   }
 443
 444   // The drive mapping is a sequence of null terminated strings.
 445   // The last string is empty.
 446   wchar_t* drive_map_ptr = drive_mapping;
 447   wchar_t device_path_as_string[MAX_PATH];
 448   wchar_t drive[] = L" :";
 449
 450   // For each string in the drive mapping, get the junction that links
 451   // to it.  If that junction is a prefix of |device_path|, then we
 452   // know that |drive| is the real path prefix.
 453   while (*drive_map_ptr) {
 454     drive[0] = drive_map_ptr[0];  // Copy the drive letter.
 455
 456     if (QueryDosDevice(drive, device_path_as_string, MAX_PATH)) {
 457       FilePath device_path(device_path_as_string);
 458       if (device_path == nt_device_path ||
 459           device_path.IsParent(nt_device_path)) {
 460         *out_drive_letter_path = FilePath(drive +
 461             nt_device_path.value().substr(wcslen(device_path_as_string)));
 462         return true;
 463       }
 464     }
 465     // Move to the next drive letter string, which starts one
 466     // increment after the '\0' that terminates the current string.
 467     while (*drive_map_ptr++);
 468   }
 469
 470   // No drive matched.  The path does not start with a device junction
 471   // that is mounted as a drive letter.  This means there is no drive
 472   // letter path to the volume that holds |device_path|, so fail.
 473   return false;
 474 }
 475
 476 bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path) {
 477   ThreadRestrictions::AssertIOAllowed();
 478   // In Vista, GetFinalPathNameByHandle() would give us the real path
 479   // from a file handle.  If we ever deprecate XP, consider changing the
 480   // code below to a call to GetFinalPathNameByHandle().  The method this
 481   // function uses is explained in the following msdn article:
 482   // http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
 483   base::win::ScopedHandle file_handle(
 484       ::CreateFile(path.value().c_str(),
 485                    GENERIC_READ,
 486                    kFileShareAll,
 487                    NULL,
 488                    OPEN_EXISTING,
 489                    FILE_ATTRIBUTE_NORMAL,
 490                    NULL));
 491   if (!file_handle)
 492     return false;
 493
 494   // Create a file mapping object.  Can't easily use MemoryMappedFile, because
 495   // we only map the first byte, and need direct access to the handle. You can
 496   // not map an empty file, this call fails in that case.
 497   base::win::ScopedHandle file_map_handle(
 498       ::CreateFileMapping(file_handle.Get(),
 499                           NULL,
 500                           PAGE_READONLY,
 501                           0,
 502                           1,  // Just one byte.  No need to look at the data.
 503                           NULL));
 504   if (!file_map_handle)
 505     return false;
 506
 507   // Use a view of the file to get the path to the file.
 508   void* file_view = MapViewOfFile(file_map_handle.Get(),
 509                                   FILE_MAP_READ, 0, 0, 1);
 510   if (!file_view)
 511     return false;
 512
 513   // The expansion of |path| into a full path may make it longer.
 514   // GetMappedFileName() will fail if the result is longer than MAX_PATH.
 515   // Pad a bit to be safe.  If kMaxPathLength is ever changed to be less
 516   // than MAX_PATH, it would be nessisary to test that GetMappedFileName()
 517   // not return kMaxPathLength.  This would mean that only part of the
 518   // path fit in |mapped_file_path|.
 519   const int kMaxPathLength = MAX_PATH + 10;
 520   wchar_t mapped_file_path[kMaxPathLength];
 521   bool success = false;
 522   HANDLE cp = GetCurrentProcess();
 523   if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
 524     *nt_path = FilePath(mapped_file_path);
 525     success = true;
 526   }
 527   ::UnmapViewOfFile(file_view);
 528   return success;
 529 }
 530
 531 // TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
 532 // them if we do decide to.
 533 bool IsLink(const FilePath& file_path) {
 534   return false;
 535 }
 536
 537 bool GetFileInfo(const FilePath& file_path, File::Info* results) {
 538   ThreadRestrictions::AssertIOAllowed();
 539
 540   WIN32_FILE_ATTRIBUTE_DATA attr;
 541   if (!GetFileAttributesEx(file_path.value().c_str(),
 542                            GetFileExInfoStandard, &attr)) {
 543     return false;
 544   }
 545
 546   ULARGE_INTEGER size;
 547   size.HighPart = attr.nFileSizeHigh;
 548   size.LowPart = attr.nFileSizeLow;
 549   results->size = size.QuadPart;
 550
 551   results->is_directory =
 552       (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
 553   results->last_modified = Time::FromFileTime(attr.ftLastWriteTime);
 554   results->last_accessed = Time::FromFileTime(attr.ftLastAccessTime);
 555   results->creation_time = Time::FromFileTime(attr.ftCreationTime);
 556
 557   return true;
 558 }
 559
 560 FILE* OpenFile(const FilePath& filename, const char* mode) {
 561   ThreadRestrictions::AssertIOAllowed();
 562   std::wstring w_mode = ASCIIToWide(std::string(mode));
 563   return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
 564 }
 565
 566 int ReadFile(const FilePath& filename, char* data, int size) {
 567   ThreadRestrictions::AssertIOAllowed();
 568   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 569                                           GENERIC_READ,
 570                                           FILE_SHARE_READ | FILE_SHARE_WRITE,
 571                                           NULL,
 572                                           OPEN_EXISTING,
 573                                           FILE_FLAG_SEQUENTIAL_SCAN,
 574                                           NULL));
 575   if (!file)
 576     return -1;
 577
 578   DWORD read;
 579   if (::ReadFile(file, data, size, &read, NULL) &&
 580       static_cast<int>(read) == size)
 581     return read;
 582   return -1;
 583 }
 584
 585 }  // namespace base
 586
 587 // -----------------------------------------------------------------------------
 588
 589 namespace file_util {
 590
 591 using base::DirectoryExists;
 592 using base::FilePath;
 593 using base::kFileShareAll;
 594
 595 FILE* OpenFile(const std::string& filename, const char* mode) {
 596   base::ThreadRestrictions::AssertIOAllowed();
 597   return _fsopen(filename.c_str(), mode, _SH_DENYNO);
 598 }
 599
 600 int WriteFile(const FilePath& filename, const char* data, int size) {
 601   base::ThreadRestrictions::AssertIOAllowed();
 602   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 603                                           GENERIC_WRITE,
 604                                           0,
 605                                           NULL,
 606                                           CREATE_ALWAYS,
 607                                           0,
 608                                           NULL));
 609   if (!file) {
 610     DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
 611                                << filename.value();
 612     return -1;
 613   }
 614
 615   DWORD written;
 616   BOOL result = ::WriteFile(file, data, size, &written, NULL);
 617   if (result && static_cast<int>(written) == size)
 618     return written;
 619
 620   if (!result) {
 621     // WriteFile failed.
 622     DLOG_GETLASTERROR(WARNING) << "writing file " << filename.value()
 623                                << " failed";
 624   } else {
 625     // Didn't write all the bytes.
 626     DLOG(WARNING) << "wrote" << written << " bytes to "
 627                   << filename.value() << " expected " << size;
 628   }
 629   return -1;
 630 }
 631
 632 int AppendToFile(const FilePath& filename, const char* data, int size) {
 633   base::ThreadRestrictions::AssertIOAllowed();
 634   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 635                                           FILE_APPEND_DATA,
 636                                           0,
 637                                           NULL,
 638                                           OPEN_EXISTING,
 639                                           0,
 640                                           NULL));
 641   if (!file) {
 642     DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
 643                                << filename.value();
 644     return -1;
 645   }
 646
 647   DWORD written;
 648   BOOL result = ::WriteFile(file, data, size, &written, NULL);
 649   if (result && static_cast<int>(written) == size)
 650     return written;
 651
 652   if (!result) {
 653     // WriteFile failed.
 654     DLOG_GETLASTERROR(WARNING) << "writing file " << filename.value()
 655                                << " failed";
 656   } else {
 657     // Didn't write all the bytes.
 658     DLOG(WARNING) << "wrote" << written << " bytes to "
 659                   << filename.value() << " expected " << size;
 660   }
 661   return -1;
 662 }
 663
 664 // Gets the current working directory for the process.
 665 bool GetCurrentDirectory(FilePath* dir) {
 666   base::ThreadRestrictions::AssertIOAllowed();
 667
 668   wchar_t system_buffer[MAX_PATH];
 669   system_buffer[0] = 0;
 670   DWORD len = ::GetCurrentDirectory(MAX_PATH, system_buffer);
 671   if (len == 0 || len > MAX_PATH)
 672     return false;
 673   // TODO(evanm): the old behavior of this function was to always strip the
 674   // trailing slash.  We duplicate this here, but it shouldn't be necessary
 675   // when everyone is using the appropriate FilePath APIs.
 676   std::wstring dir_str(system_buffer);
 677   *dir = FilePath(dir_str).StripTrailingSeparators();
 678   return true;
 679 }
 680
 681 // Sets the current working directory for the process.
 682 bool SetCurrentDirectory(const FilePath& directory) {
 683   base::ThreadRestrictions::AssertIOAllowed();
 684   BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
 685   return ret != 0;
 686 }
 687
 688 int GetMaximumPathComponentLength(const FilePath& path) {
 689   base::ThreadRestrictions::AssertIOAllowed();
 690
 691   wchar_t volume_path[MAX_PATH];
 692   if (!GetVolumePathNameW(path.NormalizePathSeparators().value().c_str(),
 693                           volume_path,
 694                           arraysize(volume_path))) {
 695     return -1;
 696   }
 697
 698   DWORD max_length = 0;
 699   if (!GetVolumeInformationW(volume_path, NULL, 0, NULL, &max_length, NULL,
 700                              NULL, 0)) {
 701     return -1;
 702   }
 703
 704   // Length of |path| with path separator appended.
 705   size_t prefix = path.StripTrailingSeparators().value().size() + 1;
 706   // The whole path string must be shorter than MAX_PATH. That is, it must be
 707   // prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
 708   int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
 709   return std::min(whole_path_limit, static_cast<int>(max_length));
 710 }
 711
 712 }  // namespace file_util
 713
 714 namespace base {
 715 namespace internal {
 716
 717 bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
 718   ThreadRestrictions::AssertIOAllowed();
 719
 720   // NOTE: I suspect we could support longer paths, but that would involve
 721   // analyzing all our usage of files.
 722   if (from_path.value().length() >= MAX_PATH ||
 723       to_path.value().length() >= MAX_PATH) {
 724     return false;
 725   }
 726   if (MoveFileEx(from_path.value().c_str(), to_path.value().c_str(),
 727                  MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING) != 0)
 728     return true;
 729
 730   // Keep the last error value from MoveFileEx around in case the below
 731   // fails.
 732   bool ret = false;
 733   DWORD last_error = ::GetLastError();
 734
 735   if (DirectoryExists(from_path)) {
 736     // MoveFileEx fails if moving directory across volumes. We will simulate
 737     // the move by using Copy and Delete. Ideally we could check whether
 738     // from_path and to_path are indeed in different volumes.
 739     ret = internal::CopyAndDeleteDirectory(from_path, to_path);
 740   }
 741
 742   if (!ret) {
 743     // Leave a clue about what went wrong so that it can be (at least) picked
 744     // up by a PLOG entry.
 745     ::SetLastError(last_error);
 746   }
 747
 748   return ret;
 749 }
 750
 751 bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
 752   ThreadRestrictions::AssertIOAllowed();
 753
 754   // NOTE: I suspect we could support longer paths, but that would involve
 755   // analyzing all our usage of files.
 756   if (from_path.value().length() >= MAX_PATH ||
 757       to_path.value().length() >= MAX_PATH) {
 758     return false;
 759   }
 760
 761   // Unlike the posix implementation that copies the file manually and discards
 762   // the ACL bits, CopyFile() copies the complete SECURITY_DESCRIPTOR and access
 763   // bits, which is usually not what we want. We can't do much about the
 764   // SECURITY_DESCRIPTOR but at least remove the read only bit.
 765   const wchar_t* dest = to_path.value().c_str();
 766   if (!::CopyFile(from_path.value().c_str(), dest, false)) {
 767     // Copy failed.
 768     return false;
 769   }
 770   DWORD attrs = GetFileAttributes(dest);
 771   if (attrs == INVALID_FILE_ATTRIBUTES) {
 772     return false;
 773   }
 774   if (attrs & FILE_ATTRIBUTE_READONLY) {
 775     SetFileAttributes(dest, attrs & ~FILE_ATTRIBUTE_READONLY);
 776   }
 777   return true;
 778 }
 779
 780 bool CopyAndDeleteDirectory(const FilePath& from_path,
 781                             const FilePath& to_path) {
 782   ThreadRestrictions::AssertIOAllowed();
 783   if (CopyDirectory(from_path, to_path, true)) {
 784     if (DeleteFile(from_path, true))
 785       return true;
 786
 787     // Like Move, this function is not transactional, so we just
 788     // leave the copied bits behind if deleting from_path fails.
 789     // If to_path exists previously then we have already overwritten
 790     // it by now, we don't get better off by deleting the new bits.
 791   }
 792   return false;
 793 }
 794
 795 }  // namespace internal
 796 }  // namespace base