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