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 FilePath GetHomeDir() {
 258   char16 result[MAX_PATH];
 259   if (SUCCEEDED(SHGetFolderPath(NULL, CSIDL_PROFILE, NULL, SHGFP_TYPE_CURRENT,
 260                                 result)) &&
 261       result[0]) {
 262     return FilePath(result);
 263   }
 264
 265   // Fall back to the temporary directory on failure.
 266   FilePath temp;
 267   if (GetTempDir(&temp))
 268     return temp;
 269
 270   // Last resort.
 271   return FilePath(L"C:\\");
 272 }
 273
 274 bool CreateTemporaryFile(FilePath* path) {
 275   ThreadRestrictions::AssertIOAllowed();
 276
 277   FilePath temp_file;
 278
 279   if (!GetTempDir(path))
 280     return false;
 281
 282   if (CreateTemporaryFileInDir(*path, &temp_file)) {
 283     *path = temp_file;
 284     return true;
 285   }
 286
 287   return false;
 288 }
 289
 290 // On POSIX we have semantics to create and open a temporary file
 291 // atomically.
 292 // TODO(jrg): is there equivalent call to use on Windows instead of
 293 // going 2-step?
 294 FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path) {
 295   ThreadRestrictions::AssertIOAllowed();
 296   if (!CreateTemporaryFileInDir(dir, path)) {
 297     return NULL;
 298   }
 299   // Open file in binary mode, to avoid problems with fwrite. On Windows
 300   // it replaces \n's with \r\n's, which may surprise you.
 301   // Reference: http://msdn.microsoft.com/en-us/library/h9t88zwz(VS.71).aspx
 302   return OpenFile(*path, "wb+");
 303 }
 304
 305 bool CreateTemporaryFileInDir(const FilePath& dir, FilePath* temp_file) {
 306   ThreadRestrictions::AssertIOAllowed();
 307
 308   wchar_t temp_name[MAX_PATH + 1];
 309
 310   if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
 311     DPLOG(WARNING) << "Failed to get temporary file name in "
 312                    << UTF16ToUTF8(dir.value());
 313     return false;
 314   }
 315
 316   wchar_t long_temp_name[MAX_PATH + 1];
 317   DWORD long_name_len = GetLongPathName(temp_name, long_temp_name, MAX_PATH);
 318   if (long_name_len > MAX_PATH || long_name_len == 0) {
 319     // GetLongPathName() failed, but we still have a temporary file.
 320     *temp_file = FilePath(temp_name);
 321     return true;
 322   }
 323
 324   FilePath::StringType long_temp_name_str;
 325   long_temp_name_str.assign(long_temp_name, long_name_len);
 326   *temp_file = FilePath(long_temp_name_str);
 327   return true;
 328 }
 329
 330 bool CreateTemporaryDirInDir(const FilePath& base_dir,
 331                              const FilePath::StringType& prefix,
 332                              FilePath* new_dir) {
 333   ThreadRestrictions::AssertIOAllowed();
 334
 335   FilePath path_to_create;
 336
 337   for (int count = 0; count < 50; ++count) {
 338     // Try create a new temporary directory with random generated name. If
 339     // the one exists, keep trying another path name until we reach some limit.
 340     string16 new_dir_name;
 341     new_dir_name.assign(prefix);
 342     new_dir_name.append(IntToString16(GetCurrentProcId()));
 343     new_dir_name.push_back('_');
 344     new_dir_name.append(IntToString16(RandInt(0, kint16max)));
 345
 346     path_to_create = base_dir.Append(new_dir_name);
 347     if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {
 348       *new_dir = path_to_create;
 349       return true;
 350     }
 351   }
 352
 353   return false;
 354 }
 355
 356 bool CreateNewTempDirectory(const FilePath::StringType& prefix,
 357                             FilePath* new_temp_path) {
 358   ThreadRestrictions::AssertIOAllowed();
 359
 360   FilePath system_temp_dir;
 361   if (!GetTempDir(&system_temp_dir))
 362     return false;
 363
 364   return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
 365 }
 366
 367 bool CreateDirectoryAndGetError(const FilePath& full_path,
 368                                 File::Error* error) {
 369   ThreadRestrictions::AssertIOAllowed();
 370
 371   // If the path exists, we've succeeded if it's a directory, failed otherwise.
 372   const wchar_t* full_path_str = full_path.value().c_str();
 373   DWORD fileattr = ::GetFileAttributes(full_path_str);
 374   if (fileattr != INVALID_FILE_ATTRIBUTES) {
 375     if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
 376       DVLOG(1) << "CreateDirectory(" << full_path_str << "), "
 377                << "directory already exists.";
 378       return true;
 379     }
 380     DLOG(WARNING) << "CreateDirectory(" << full_path_str << "), "
 381                   << "conflicts with existing file.";
 382     if (error) {
 383       *error = File::FILE_ERROR_NOT_A_DIRECTORY;
 384     }
 385     return false;
 386   }
 387
 388   // Invariant:  Path does not exist as file or directory.
 389
 390   // Attempt to create the parent recursively.  This will immediately return
 391   // true if it already exists, otherwise will create all required parent
 392   // directories starting with the highest-level missing parent.
 393   FilePath parent_path(full_path.DirName());
 394   if (parent_path.value() == full_path.value()) {
 395     if (error) {
 396       *error = File::FILE_ERROR_NOT_FOUND;
 397     }
 398     return false;
 399   }
 400   if (!CreateDirectoryAndGetError(parent_path, error)) {
 401     DLOG(WARNING) << "Failed to create one of the parent directories.";
 402     if (error) {
 403       DCHECK(*error != File::FILE_OK);
 404     }
 405     return false;
 406   }
 407
 408   if (!::CreateDirectory(full_path_str, NULL)) {
 409     DWORD error_code = ::GetLastError();
 410     if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
 411       // This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
 412       // were racing with someone creating the same directory, or a file
 413       // with the same path.  If DirectoryExists() returns true, we lost the
 414       // race to create the same directory.
 415       return true;
 416     } else {
 417       if (error)
 418         *error = File::OSErrorToFileError(error_code);
 419       DLOG(WARNING) << "Failed to create directory " << full_path_str
 420                     << ", last error is " << error_code << ".";
 421       return false;
 422     }
 423   } else {
 424     return true;
 425   }
 426 }
 427
 428 bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
 429   ThreadRestrictions::AssertIOAllowed();
 430   FilePath mapped_file;
 431   if (!NormalizeToNativeFilePath(path, &mapped_file))
 432     return false;
 433   // NormalizeToNativeFilePath() will return a path that starts with
 434   // "\Device\Harddisk...".  Helper DevicePathToDriveLetterPath()
 435   // will find a drive letter which maps to the path's device, so
 436   // that we return a path starting with a drive letter.
 437   return DevicePathToDriveLetterPath(mapped_file, real_path);
 438 }
 439
 440 bool DevicePathToDriveLetterPath(const FilePath& nt_device_path,
 441                                  FilePath* out_drive_letter_path) {
 442   ThreadRestrictions::AssertIOAllowed();
 443
 444   // Get the mapping of drive letters to device paths.
 445   const int kDriveMappingSize = 1024;
 446   wchar_t drive_mapping[kDriveMappingSize] = {'\0'};
 447   if (!::GetLogicalDriveStrings(kDriveMappingSize - 1, drive_mapping)) {
 448     DLOG(ERROR) << "Failed to get drive mapping.";
 449     return false;
 450   }
 451
 452   // The drive mapping is a sequence of null terminated strings.
 453   // The last string is empty.
 454   wchar_t* drive_map_ptr = drive_mapping;
 455   wchar_t device_path_as_string[MAX_PATH];
 456   wchar_t drive[] = L" :";
 457
 458   // For each string in the drive mapping, get the junction that links
 459   // to it.  If that junction is a prefix of |device_path|, then we
 460   // know that |drive| is the real path prefix.
 461   while (*drive_map_ptr) {
 462     drive[0] = drive_map_ptr[0];  // Copy the drive letter.
 463
 464     if (QueryDosDevice(drive, device_path_as_string, MAX_PATH)) {
 465       FilePath device_path(device_path_as_string);
 466       if (device_path == nt_device_path ||
 467           device_path.IsParent(nt_device_path)) {
 468         *out_drive_letter_path = FilePath(drive +
 469             nt_device_path.value().substr(wcslen(device_path_as_string)));
 470         return true;
 471       }
 472     }
 473     // Move to the next drive letter string, which starts one
 474     // increment after the '\0' that terminates the current string.
 475     while (*drive_map_ptr++);
 476   }
 477
 478   // No drive matched.  The path does not start with a device junction
 479   // that is mounted as a drive letter.  This means there is no drive
 480   // letter path to the volume that holds |device_path|, so fail.
 481   return false;
 482 }
 483
 484 bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path) {
 485   ThreadRestrictions::AssertIOAllowed();
 486   // In Vista, GetFinalPathNameByHandle() would give us the real path
 487   // from a file handle.  If we ever deprecate XP, consider changing the
 488   // code below to a call to GetFinalPathNameByHandle().  The method this
 489   // function uses is explained in the following msdn article:
 490   // http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
 491   base::win::ScopedHandle file_handle(
 492       ::CreateFile(path.value().c_str(),
 493                    GENERIC_READ,
 494                    kFileShareAll,
 495                    NULL,
 496                    OPEN_EXISTING,
 497                    FILE_ATTRIBUTE_NORMAL,
 498                    NULL));
 499   if (!file_handle)
 500     return false;
 501
 502   // Create a file mapping object.  Can't easily use MemoryMappedFile, because
 503   // we only map the first byte, and need direct access to the handle. You can
 504   // not map an empty file, this call fails in that case.
 505   base::win::ScopedHandle file_map_handle(
 506       ::CreateFileMapping(file_handle.Get(),
 507                           NULL,
 508                           PAGE_READONLY,
 509                           0,
 510                           1,  // Just one byte.  No need to look at the data.
 511                           NULL));
 512   if (!file_map_handle)
 513     return false;
 514
 515   // Use a view of the file to get the path to the file.
 516   void* file_view = MapViewOfFile(file_map_handle.Get(),
 517                                   FILE_MAP_READ, 0, 0, 1);
 518   if (!file_view)
 519     return false;
 520
 521   // The expansion of |path| into a full path may make it longer.
 522   // GetMappedFileName() will fail if the result is longer than MAX_PATH.
 523   // Pad a bit to be safe.  If kMaxPathLength is ever changed to be less
 524   // than MAX_PATH, it would be nessisary to test that GetMappedFileName()
 525   // not return kMaxPathLength.  This would mean that only part of the
 526   // path fit in |mapped_file_path|.
 527   const int kMaxPathLength = MAX_PATH + 10;
 528   wchar_t mapped_file_path[kMaxPathLength];
 529   bool success = false;
 530   HANDLE cp = GetCurrentProcess();
 531   if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
 532     *nt_path = FilePath(mapped_file_path);
 533     success = true;
 534   }
 535   ::UnmapViewOfFile(file_view);
 536   return success;
 537 }
 538
 539 // TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
 540 // them if we do decide to.
 541 bool IsLink(const FilePath& file_path) {
 542   return false;
 543 }
 544
 545 bool GetFileInfo(const FilePath& file_path, File::Info* results) {
 546   ThreadRestrictions::AssertIOAllowed();
 547
 548   WIN32_FILE_ATTRIBUTE_DATA attr;
 549   if (!GetFileAttributesEx(file_path.value().c_str(),
 550                            GetFileExInfoStandard, &attr)) {
 551     return false;
 552   }
 553
 554   ULARGE_INTEGER size;
 555   size.HighPart = attr.nFileSizeHigh;
 556   size.LowPart = attr.nFileSizeLow;
 557   results->size = size.QuadPart;
 558
 559   results->is_directory =
 560       (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
 561   results->last_modified = Time::FromFileTime(attr.ftLastWriteTime);
 562   results->last_accessed = Time::FromFileTime(attr.ftLastAccessTime);
 563   results->creation_time = Time::FromFileTime(attr.ftCreationTime);
 564
 565   return true;
 566 }
 567
 568 FILE* OpenFile(const FilePath& filename, const char* mode) {
 569   ThreadRestrictions::AssertIOAllowed();
 570   std::wstring w_mode = ASCIIToWide(std::string(mode));
 571   return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
 572 }
 573
 574 int ReadFile(const FilePath& filename, char* data, int size) {
 575   ThreadRestrictions::AssertIOAllowed();
 576   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 577                                           GENERIC_READ,
 578                                           FILE_SHARE_READ | FILE_SHARE_WRITE,
 579                                           NULL,
 580                                           OPEN_EXISTING,
 581                                           FILE_FLAG_SEQUENTIAL_SCAN,
 582                                           NULL));
 583   if (!file)
 584     return -1;
 585
 586   DWORD read;
 587   if (::ReadFile(file, data, size, &read, NULL) &&
 588       static_cast<int>(read) == size)
 589     return read;
 590   return -1;
 591 }
 592
 593 int WriteFile(const FilePath& filename, const char* data, int size) {
 594   ThreadRestrictions::AssertIOAllowed();
 595   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 596                                           GENERIC_WRITE,
 597                                           0,
 598                                           NULL,
 599                                           CREATE_ALWAYS,
 600                                           0,
 601                                           NULL));
 602   if (!file) {
 603     DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
 604                                << UTF16ToUTF8(filename.value());
 605     return -1;
 606   }
 607
 608   DWORD written;
 609   BOOL result = ::WriteFile(file, data, size, &written, NULL);
 610   if (result && static_cast<int>(written) == size)
 611     return written;
 612
 613   if (!result) {
 614     // WriteFile failed.
 615     DLOG_GETLASTERROR(WARNING) << "writing file "
 616                                << UTF16ToUTF8(filename.value()) << " failed";
 617   } else {
 618     // Didn't write all the bytes.
 619     DLOG(WARNING) << "wrote" << written << " bytes to "
 620                   << UTF16ToUTF8(filename.value()) << " expected " << size;
 621   }
 622   return -1;
 623 }
 624
 625 int AppendToFile(const FilePath& filename, const char* data, int size) {
 626   ThreadRestrictions::AssertIOAllowed();
 627   base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
 628                                           FILE_APPEND_DATA,
 629                                           0,
 630                                           NULL,
 631                                           OPEN_EXISTING,
 632                                           0,
 633                                           NULL));
 634   if (!file) {
 635     DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
 636                                << UTF16ToUTF8(filename.value());
 637     return -1;
 638   }
 639
 640   DWORD written;
 641   BOOL result = ::WriteFile(file, data, size, &written, NULL);
 642   if (result && static_cast<int>(written) == size)
 643     return written;
 644
 645   if (!result) {
 646     // WriteFile failed.
 647     DLOG_GETLASTERROR(WARNING) << "writing file "
 648                                << UTF16ToUTF8(filename.value())
 649                                << " failed";
 650   } else {
 651     // Didn't write all the bytes.
 652     DLOG(WARNING) << "wrote" << written << " bytes to "
 653                   << UTF16ToUTF8(filename.value()) << " expected " << size;
 654   }
 655   return -1;
 656 }
 657
 658 // Gets the current working directory for the process.
 659 bool GetCurrentDirectory(FilePath* dir) {
 660   ThreadRestrictions::AssertIOAllowed();
 661
 662   wchar_t system_buffer[MAX_PATH];
 663   system_buffer[0] = 0;
 664   DWORD len = ::GetCurrentDirectory(MAX_PATH, system_buffer);
 665   if (len == 0 || len > MAX_PATH)
 666     return false;
 667   // TODO(evanm): the old behavior of this function was to always strip the
 668   // trailing slash.  We duplicate this here, but it shouldn't be necessary
 669   // when everyone is using the appropriate FilePath APIs.
 670   std::wstring dir_str(system_buffer);
 671   *dir = FilePath(dir_str).StripTrailingSeparators();
 672   return true;
 673 }
 674
 675 // Sets the current working directory for the process.
 676 bool SetCurrentDirectory(const FilePath& directory) {
 677   ThreadRestrictions::AssertIOAllowed();
 678   BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
 679   return ret != 0;
 680 }
 681
 682 int GetMaximumPathComponentLength(const FilePath& path) {
 683   ThreadRestrictions::AssertIOAllowed();
 684
 685   wchar_t volume_path[MAX_PATH];
 686   if (!GetVolumePathNameW(path.NormalizePathSeparators().value().c_str(),
 687                           volume_path,
 688                           arraysize(volume_path))) {
 689     return -1;
 690   }
 691
 692   DWORD max_length = 0;
 693   if (!GetVolumeInformationW(volume_path, NULL, 0, NULL, &max_length, NULL,
 694                              NULL, 0)) {
 695     return -1;
 696   }
 697
 698   // Length of |path| with path separator appended.
 699   size_t prefix = path.StripTrailingSeparators().value().size() + 1;
 700   // The whole path string must be shorter than MAX_PATH. That is, it must be
 701   // prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
 702   int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
 703   return std::min(whole_path_limit, static_cast<int>(max_length));
 704 }
 705
 706 // -----------------------------------------------------------------------------
 707
 708 namespace internal {
 709
 710 bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
 711   ThreadRestrictions::AssertIOAllowed();
 712
 713   // NOTE: I suspect we could support longer paths, but that would involve
 714   // analyzing all our usage of files.
 715   if (from_path.value().length() >= MAX_PATH ||
 716       to_path.value().length() >= MAX_PATH) {
 717     return false;
 718   }
 719   if (MoveFileEx(from_path.value().c_str(), to_path.value().c_str(),
 720                  MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING) != 0)
 721     return true;
 722
 723   // Keep the last error value from MoveFileEx around in case the below
 724   // fails.
 725   bool ret = false;
 726   DWORD last_error = ::GetLastError();
 727
 728   if (DirectoryExists(from_path)) {
 729     // MoveFileEx fails if moving directory across volumes. We will simulate
 730     // the move by using Copy and Delete. Ideally we could check whether
 731     // from_path and to_path are indeed in different volumes.
 732     ret = internal::CopyAndDeleteDirectory(from_path, to_path);
 733   }
 734
 735   if (!ret) {
 736     // Leave a clue about what went wrong so that it can be (at least) picked
 737     // up by a PLOG entry.
 738     ::SetLastError(last_error);
 739   }
 740
 741   return ret;
 742 }
 743
 744 bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
 745   ThreadRestrictions::AssertIOAllowed();
 746
 747   // NOTE: I suspect we could support longer paths, but that would involve
 748   // analyzing all our usage of files.
 749   if (from_path.value().length() >= MAX_PATH ||
 750       to_path.value().length() >= MAX_PATH) {
 751     return false;
 752   }
 753
 754   // Unlike the posix implementation that copies the file manually and discards
 755   // the ACL bits, CopyFile() copies the complete SECURITY_DESCRIPTOR and access
 756   // bits, which is usually not what we want. We can't do much about the
 757   // SECURITY_DESCRIPTOR but at least remove the read only bit.
 758   const wchar_t* dest = to_path.value().c_str();
 759   if (!::CopyFile(from_path.value().c_str(), dest, false)) {
 760     // Copy failed.
 761     return false;
 762   }
 763   DWORD attrs = GetFileAttributes(dest);
 764   if (attrs == INVALID_FILE_ATTRIBUTES) {
 765     return false;
 766   }
 767   if (attrs & FILE_ATTRIBUTE_READONLY) {
 768     SetFileAttributes(dest, attrs & ~FILE_ATTRIBUTE_READONLY);
 769   }
 770   return true;
 771 }
 772
 773 bool CopyAndDeleteDirectory(const FilePath& from_path,
 774                             const FilePath& to_path) {
 775   ThreadRestrictions::AssertIOAllowed();
 776   if (CopyDirectory(from_path, to_path, true)) {
 777     if (DeleteFile(from_path, true))
 778       return true;
 779
 780     // Like Move, this function is not transactional, so we just
 781     // leave the copied bits behind if deleting from_path fails.
 782     // If to_path exists previously then we have already overwritten
 783     // it by now, we don't get better off by deleting the new bits.
 784   }
 785   return false;
 786 }
 787
 788 }  // namespace internal
 789 }  // namespace base