base/file_util

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This source file includes following definitions.
MakeAbsoluteFilePath
DeleteFile
DeleteFileAfterReboot
ReplaceFile
CopyDirectory
PathExists
PathIsWritable
DirectoryExists
GetTempDir
GetHomeDir
CreateTemporaryFile
CreateAndOpenTemporaryFileInDir
CreateTemporaryFileInDir
CreateTemporaryDirInDir
CreateNewTempDirectory
CreateDirectoryAndGetError
NormalizeFilePath
DevicePathToDriveLetterPath
NormalizeToNativeFilePath
IsLink
GetFileInfo
OpenFile
ReadFile
WriteFile
AppendToFile
GetCurrentDirectory
SetCurrentDirectory
GetMaximumPathComponentLength
MoveUnsafe
CopyFileUnsafe
CopyAndDeleteDirectory
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/file_util.h"

#include <windows.h>
#include <psapi.h>
#include <shellapi.h>
#include <shlobj.h>
#include <time.h>

#include <algorithm>
#include <limits>
#include <string>

#include "base/files/file_enumerator.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/metrics/histogram.h"
#include "base/process/process_handle.h"
#include "base/rand_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/thread_restrictions.h"
#include "base/time/time.h"
#include "base/win/scoped_handle.h"
#include "base/win/windows_version.h"

namespace base {

namespace {

const DWORD kFileShareAll =
    FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;

}  // namespace

FilePath MakeAbsoluteFilePath(const FilePath& input) {
  ThreadRestrictions::AssertIOAllowed();
  wchar_t file_path[MAX_PATH];
  if (!_wfullpath(file_path, input.value().c_str(), MAX_PATH))
    return FilePath();
  return FilePath(file_path);
}

bool DeleteFile(const FilePath& path, bool recursive) {
  ThreadRestrictions::AssertIOAllowed();

  if (path.value().length() >= MAX_PATH)
    return false;

  if (!recursive) {
    // If not recursing, then first check to see if |path| is a directory.
    // If it is, then remove it with RemoveDirectory.
    File::Info file_info;
    if (GetFileInfo(path, &file_info) && file_info.is_directory)
      return RemoveDirectory(path.value().c_str()) != 0;

    // Otherwise, it's a file, wildcard or non-existant. Try DeleteFile first
    // because it should be faster. If DeleteFile fails, then we fall through
    // to SHFileOperation, which will do the right thing.
    if (::DeleteFile(path.value().c_str()) != 0)
      return true;
  }

  // SHFILEOPSTRUCT wants the path to be terminated with two NULLs,
  // so we have to use wcscpy because wcscpy_s writes non-NULLs
  // into the rest of the buffer.
  wchar_t double_terminated_path[MAX_PATH + 1] = {0};
#pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
  wcscpy(double_terminated_path, path.value().c_str());

  SHFILEOPSTRUCT file_operation = {0};
  file_operation.wFunc = FO_DELETE;
  file_operation.pFrom = double_terminated_path;
  file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION;
  if (!recursive)
    file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
  int err = SHFileOperation(&file_operation);

  // Since we're passing flags to the operation telling it to be silent,
  // it's possible for the operation to be aborted/cancelled without err
  // being set (although MSDN doesn't give any scenarios for how this can
  // happen).  See MSDN for SHFileOperation and SHFILEOPTSTRUCT.
  if (file_operation.fAnyOperationsAborted)
    return false;

  // Some versions of Windows return ERROR_FILE_NOT_FOUND (0x2) when deleting
  // an empty directory and some return 0x402 when they should be returning
  // ERROR_FILE_NOT_FOUND. MSDN says Vista and up won't return 0x402.
  return (err == 0 || err == ERROR_FILE_NOT_FOUND || err == 0x402);
}

bool DeleteFileAfterReboot(const FilePath& path) {
  ThreadRestrictions::AssertIOAllowed();

  if (path.value().length() >= MAX_PATH)
    return false;

  return MoveFileEx(path.value().c_str(), NULL,
                    MOVEFILE_DELAY_UNTIL_REBOOT |
                        MOVEFILE_REPLACE_EXISTING) != FALSE;
}

bool ReplaceFile(const FilePath& from_path,
                 const FilePath& to_path,
                 File::Error* error) {
  ThreadRestrictions::AssertIOAllowed();
  // Try a simple move first.  It will only succeed when |to_path| doesn't
  // already exist.
  if (::MoveFile(from_path.value().c_str(), to_path.value().c_str()))
    return true;
  // Try the full-blown replace if the move fails, as ReplaceFile will only
  // succeed when |to_path| does exist. When writing to a network share, we may
  // not be able to change the ACLs. Ignore ACL errors then
  // (REPLACEFILE_IGNORE_MERGE_ERRORS).
  if (::ReplaceFile(to_path.value().c_str(), from_path.value().c_str(), NULL,
                    REPLACEFILE_IGNORE_MERGE_ERRORS, NULL, NULL)) {
    return true;
  }
  if (error)
    *error = File::OSErrorToFileError(GetLastError());
  return false;
}

bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
                   bool recursive) {
  // NOTE(maruel): Previous version of this function used to call
  // SHFileOperation().  This used to copy the file attributes and extended
  // attributes, OLE structured storage, NTFS file system alternate data
  // streams, SECURITY_DESCRIPTOR. In practice, this is not what we want, we
  // want the containing directory to propagate its SECURITY_DESCRIPTOR.
  ThreadRestrictions::AssertIOAllowed();

  // NOTE: I suspect we could support longer paths, but that would involve
  // analyzing all our usage of files.
  if (from_path.value().length() >= MAX_PATH ||
      to_path.value().length() >= MAX_PATH) {
    return false;
  }

  // This function does not properly handle destinations within the source.
  FilePath real_to_path = to_path;
  if (PathExists(real_to_path)) {
    real_to_path = MakeAbsoluteFilePath(real_to_path);
    if (real_to_path.empty())
      return false;
  } else {
    real_to_path = MakeAbsoluteFilePath(real_to_path.DirName());
    if (real_to_path.empty())
      return false;
  }
  FilePath real_from_path = MakeAbsoluteFilePath(from_path);
  if (real_from_path.empty())
    return false;
  if (real_to_path.value().size() >= real_from_path.value().size() &&
      real_to_path.value().compare(0, real_from_path.value().size(),
                                   real_from_path.value()) == 0) {
    return false;
  }

  int traverse_type = FileEnumerator::FILES;
  if (recursive)
    traverse_type |= FileEnumerator::DIRECTORIES;
  FileEnumerator traversal(from_path, recursive, traverse_type);

  if (!PathExists(from_path)) {
    DLOG(ERROR) << "CopyDirectory() couldn't stat source directory: "
                << from_path.value().c_str();
    return false;
  }
  // TODO(maruel): This is not necessary anymore.
  DCHECK(recursive || DirectoryExists(from_path));

  FilePath current = from_path;
  bool from_is_dir = DirectoryExists(from_path);
  bool success = true;
  FilePath from_path_base = from_path;
  if (recursive && DirectoryExists(to_path)) {
    // If the destination already exists and is a directory, then the
    // top level of source needs to be copied.
    from_path_base = from_path.DirName();
  }

  while (success && !current.empty()) {
    // current is the source path, including from_path, so append
    // the suffix after from_path to to_path to create the target_path.
    FilePath target_path(to_path);
    if (from_path_base != current) {
      if (!from_path_base.AppendRelativePath(current, &target_path)) {
        success = false;
        break;
      }
    }

    if (from_is_dir) {
      if (!DirectoryExists(target_path) &&
          !::CreateDirectory(target_path.value().c_str(), NULL)) {
        DLOG(ERROR) << "CopyDirectory() couldn't create directory: "
                    << target_path.value().c_str();
        success = false;
      }
    } else if (!internal::CopyFileUnsafe(current, target_path)) {
      DLOG(ERROR) << "CopyDirectory() couldn't create file: "
                  << target_path.value().c_str();
      success = false;
    }

    current = traversal.Next();
    if (!current.empty())
      from_is_dir = traversal.GetInfo().IsDirectory();
  }

  return success;
}

bool PathExists(const FilePath& path) {
  ThreadRestrictions::AssertIOAllowed();
  return (GetFileAttributes(path.value().c_str()) != INVALID_FILE_ATTRIBUTES);
}

bool PathIsWritable(const FilePath& path) {
  ThreadRestrictions::AssertIOAllowed();
  HANDLE dir =
      CreateFile(path.value().c_str(), FILE_ADD_FILE, kFileShareAll,
                 NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);

  if (dir == INVALID_HANDLE_VALUE)
    return false;

  CloseHandle(dir);
  return true;
}

bool DirectoryExists(const FilePath& path) {
  ThreadRestrictions::AssertIOAllowed();
  DWORD fileattr = GetFileAttributes(path.value().c_str());
  if (fileattr != INVALID_FILE_ATTRIBUTES)
    return (fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0;
  return false;
}

bool GetTempDir(FilePath* path) {
  wchar_t temp_path[MAX_PATH + 1];
  DWORD path_len = ::GetTempPath(MAX_PATH, temp_path);
  if (path_len >= MAX_PATH || path_len <= 0)
    return false;
  // TODO(evanm): the old behavior of this function was to always strip the
  // trailing slash.  We duplicate this here, but it shouldn't be necessary
  // when everyone is using the appropriate FilePath APIs.
  *path = FilePath(temp_path).StripTrailingSeparators();
  return true;
}

FilePath GetHomeDir() {
  char16 result[MAX_PATH];
  if (SUCCEEDED(SHGetFolderPath(NULL, CSIDL_PROFILE, NULL, SHGFP_TYPE_CURRENT,
                                result)) &&
      result[0]) {
    return FilePath(result);
  }

  // Fall back to the temporary directory on failure.
  FilePath temp;
  if (GetTempDir(&temp))
    return temp;

  // Last resort.
  return FilePath(L"C:\\");
}

bool CreateTemporaryFile(FilePath* path) {
  ThreadRestrictions::AssertIOAllowed();

  FilePath temp_file;

  if (!GetTempDir(path))
    return false;

  if (CreateTemporaryFileInDir(*path, &temp_file)) {
    *path = temp_file;
    return true;
  }

  return false;
}

// On POSIX we have semantics to create and open a temporary file
// atomically.
// TODO(jrg): is there equivalent call to use on Windows instead of
// going 2-step?
FILE* CreateAndOpenTemporaryFileInDir(const FilePath& dir, FilePath* path) {
  ThreadRestrictions::AssertIOAllowed();
  if (!CreateTemporaryFileInDir(dir, path)) {
    return NULL;
  }
  // Open file in binary mode, to avoid problems with fwrite. On Windows
  // it replaces \n's with \r\n's, which may surprise you.
  // Reference: http://msdn.microsoft.com/en-us/library/h9t88zwz(VS.71).aspx
  return OpenFile(*path, "wb+");
}

bool CreateTemporaryFileInDir(const FilePath& dir, FilePath* temp_file) {
  ThreadRestrictions::AssertIOAllowed();

  wchar_t temp_name[MAX_PATH + 1];

  if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
    DPLOG(WARNING) << "Failed to get temporary file name in "
                   << UTF16ToUTF8(dir.value());
    return false;
  }

  wchar_t long_temp_name[MAX_PATH + 1];
  DWORD long_name_len = GetLongPathName(temp_name, long_temp_name, MAX_PATH);
  if (long_name_len > MAX_PATH || long_name_len == 0) {
    // GetLongPathName() failed, but we still have a temporary file.
    *temp_file = FilePath(temp_name);
    return true;
  }

  FilePath::StringType long_temp_name_str;
  long_temp_name_str.assign(long_temp_name, long_name_len);
  *temp_file = FilePath(long_temp_name_str);
  return true;
}

bool CreateTemporaryDirInDir(const FilePath& base_dir,
                             const FilePath::StringType& prefix,
                             FilePath* new_dir) {
  ThreadRestrictions::AssertIOAllowed();

  FilePath path_to_create;

  for (int count = 0; count < 50; ++count) {
    // Try create a new temporary directory with random generated name. If
    // the one exists, keep trying another path name until we reach some limit.
    string16 new_dir_name;
    new_dir_name.assign(prefix);
    new_dir_name.append(IntToString16(GetCurrentProcId()));
    new_dir_name.push_back('_');
    new_dir_name.append(IntToString16(RandInt(0, kint16max)));

    path_to_create = base_dir.Append(new_dir_name);
    if (::CreateDirectory(path_to_create.value().c_str(), NULL)) {
      *new_dir = path_to_create;
      return true;
    }
  }

  return false;
}

bool CreateNewTempDirectory(const FilePath::StringType& prefix,
                            FilePath* new_temp_path) {
  ThreadRestrictions::AssertIOAllowed();

  FilePath system_temp_dir;
  if (!GetTempDir(&system_temp_dir))
    return false;

  return CreateTemporaryDirInDir(system_temp_dir, prefix, new_temp_path);
}

bool CreateDirectoryAndGetError(const FilePath& full_path,
                                File::Error* error) {
  ThreadRestrictions::AssertIOAllowed();

  // If the path exists, we've succeeded if it's a directory, failed otherwise.
  const wchar_t* full_path_str = full_path.value().c_str();
  DWORD fileattr = ::GetFileAttributes(full_path_str);
  if (fileattr != INVALID_FILE_ATTRIBUTES) {
    if ((fileattr & FILE_ATTRIBUTE_DIRECTORY) != 0) {
      DVLOG(1) << "CreateDirectory(" << full_path_str << "), "
               << "directory already exists.";
      return true;
    }
    DLOG(WARNING) << "CreateDirectory(" << full_path_str << "), "
                  << "conflicts with existing file.";
    if (error) {
      *error = File::FILE_ERROR_NOT_A_DIRECTORY;
    }
    return false;
  }

  // Invariant:  Path does not exist as file or directory.

  // Attempt to create the parent recursively.  This will immediately return
  // true if it already exists, otherwise will create all required parent
  // directories starting with the highest-level missing parent.
  FilePath parent_path(full_path.DirName());
  if (parent_path.value() == full_path.value()) {
    if (error) {
      *error = File::FILE_ERROR_NOT_FOUND;
    }
    return false;
  }
  if (!CreateDirectoryAndGetError(parent_path, error)) {
    DLOG(WARNING) << "Failed to create one of the parent directories.";
    if (error) {
      DCHECK(*error != File::FILE_OK);
    }
    return false;
  }

  if (!::CreateDirectory(full_path_str, NULL)) {
    DWORD error_code = ::GetLastError();
    if (error_code == ERROR_ALREADY_EXISTS && DirectoryExists(full_path)) {
      // This error code ERROR_ALREADY_EXISTS doesn't indicate whether we
      // were racing with someone creating the same directory, or a file
      // with the same path.  If DirectoryExists() returns true, we lost the
      // race to create the same directory.
      return true;
    } else {
      if (error)
        *error = File::OSErrorToFileError(error_code);
      DLOG(WARNING) << "Failed to create directory " << full_path_str
                    << ", last error is " << error_code << ".";
      return false;
    }
  } else {
    return true;
  }
}

bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
  ThreadRestrictions::AssertIOAllowed();
  FilePath mapped_file;
  if (!NormalizeToNativeFilePath(path, &mapped_file))
    return false;
  // NormalizeToNativeFilePath() will return a path that starts with
  // "\Device\Harddisk...".  Helper DevicePathToDriveLetterPath()
  // will find a drive letter which maps to the path's device, so
  // that we return a path starting with a drive letter.
  return DevicePathToDriveLetterPath(mapped_file, real_path);
}

bool DevicePathToDriveLetterPath(const FilePath& nt_device_path,
                                 FilePath* out_drive_letter_path) {
  ThreadRestrictions::AssertIOAllowed();

  // Get the mapping of drive letters to device paths.
  const int kDriveMappingSize = 1024;
  wchar_t drive_mapping[kDriveMappingSize] = {'\0'};
  if (!::GetLogicalDriveStrings(kDriveMappingSize - 1, drive_mapping)) {
    DLOG(ERROR) << "Failed to get drive mapping.";
    return false;
  }

  // The drive mapping is a sequence of null terminated strings.
  // The last string is empty.
  wchar_t* drive_map_ptr = drive_mapping;
  wchar_t device_path_as_string[MAX_PATH];
  wchar_t drive[] = L" :";

  // For each string in the drive mapping, get the junction that links
  // to it.  If that junction is a prefix of |device_path|, then we
  // know that |drive| is the real path prefix.
  while (*drive_map_ptr) {
    drive[0] = drive_map_ptr[0];  // Copy the drive letter.

    if (QueryDosDevice(drive, device_path_as_string, MAX_PATH)) {
      FilePath device_path(device_path_as_string);
      if (device_path == nt_device_path ||
          device_path.IsParent(nt_device_path)) {
        *out_drive_letter_path = FilePath(drive +
            nt_device_path.value().substr(wcslen(device_path_as_string)));
        return true;
      }
    }
    // Move to the next drive letter string, which starts one
    // increment after the '\0' that terminates the current string.
    while (*drive_map_ptr++);
  }

  // No drive matched.  The path does not start with a device junction
  // that is mounted as a drive letter.  This means there is no drive
  // letter path to the volume that holds |device_path|, so fail.
  return false;
}

bool NormalizeToNativeFilePath(const FilePath& path, FilePath* nt_path) {
  ThreadRestrictions::AssertIOAllowed();
  // In Vista, GetFinalPathNameByHandle() would give us the real path
  // from a file handle.  If we ever deprecate XP, consider changing the
  // code below to a call to GetFinalPathNameByHandle().  The method this
  // function uses is explained in the following msdn article:
  // http://msdn.microsoft.com/en-us/library/aa366789(VS.85).aspx
  base::win::ScopedHandle file_handle(
      ::CreateFile(path.value().c_str(),
                   GENERIC_READ,
                   kFileShareAll,
                   NULL,
                   OPEN_EXISTING,
                   FILE_ATTRIBUTE_NORMAL,
                   NULL));
  if (!file_handle)
    return false;

  // Create a file mapping object.  Can't easily use MemoryMappedFile, because
  // we only map the first byte, and need direct access to the handle. You can
  // not map an empty file, this call fails in that case.
  base::win::ScopedHandle file_map_handle(
      ::CreateFileMapping(file_handle.Get(),
                          NULL,
                          PAGE_READONLY,
                          0,
                          1,  // Just one byte.  No need to look at the data.
                          NULL));
  if (!file_map_handle)
    return false;

  // Use a view of the file to get the path to the file.
  void* file_view = MapViewOfFile(file_map_handle.Get(),
                                  FILE_MAP_READ, 0, 0, 1);
  if (!file_view)
    return false;

  // The expansion of |path| into a full path may make it longer.
  // GetMappedFileName() will fail if the result is longer than MAX_PATH.
  // Pad a bit to be safe.  If kMaxPathLength is ever changed to be less
  // than MAX_PATH, it would be nessisary to test that GetMappedFileName()
  // not return kMaxPathLength.  This would mean that only part of the
  // path fit in |mapped_file_path|.
  const int kMaxPathLength = MAX_PATH + 10;
  wchar_t mapped_file_path[kMaxPathLength];
  bool success = false;
  HANDLE cp = GetCurrentProcess();
  if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
    *nt_path = FilePath(mapped_file_path);
    success = true;
  }
  ::UnmapViewOfFile(file_view);
  return success;
}

// TODO(rkc): Work out if we want to handle NTFS junctions here or not, handle
// them if we do decide to.
bool IsLink(const FilePath& file_path) {
  return false;
}

bool GetFileInfo(const FilePath& file_path, File::Info* results) {
  ThreadRestrictions::AssertIOAllowed();

  WIN32_FILE_ATTRIBUTE_DATA attr;
  if (!GetFileAttributesEx(file_path.value().c_str(),
                           GetFileExInfoStandard, &attr)) {
    return false;
  }

  ULARGE_INTEGER size;
  size.HighPart = attr.nFileSizeHigh;
  size.LowPart = attr.nFileSizeLow;
  results->size = size.QuadPart;

  results->is_directory =
      (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
  results->last_modified = Time::FromFileTime(attr.ftLastWriteTime);
  results->last_accessed = Time::FromFileTime(attr.ftLastAccessTime);
  results->creation_time = Time::FromFileTime(attr.ftCreationTime);

  return true;
}

FILE* OpenFile(const FilePath& filename, const char* mode) {
  ThreadRestrictions::AssertIOAllowed();
  std::wstring w_mode = ASCIIToWide(std::string(mode));
  return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
}

int ReadFile(const FilePath& filename, char* data, int size) {
  ThreadRestrictions::AssertIOAllowed();
  base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
                                          GENERIC_READ,
                                          FILE_SHARE_READ | FILE_SHARE_WRITE,
                                          NULL,
                                          OPEN_EXISTING,
                                          FILE_FLAG_SEQUENTIAL_SCAN,
                                          NULL));
  if (!file)
    return -1;

  DWORD read;
  if (::ReadFile(file, data, size, &read, NULL) &&
      static_cast<int>(read) == size)
    return read;
  return -1;
}

int WriteFile(const FilePath& filename, const char* data, int size) {
  ThreadRestrictions::AssertIOAllowed();
  base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
                                          GENERIC_WRITE,
                                          0,
                                          NULL,
                                          CREATE_ALWAYS,
                                          0,
                                          NULL));
  if (!file) {
    DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
                               << UTF16ToUTF8(filename.value());
    return -1;
  }

  DWORD written;
  BOOL result = ::WriteFile(file, data, size, &written, NULL);
  if (result && static_cast<int>(written) == size)
    return written;

  if (!result) {
    // WriteFile failed.
    DLOG_GETLASTERROR(WARNING) << "writing file "
                               << UTF16ToUTF8(filename.value()) << " failed";
  } else {
    // Didn't write all the bytes.
    DLOG(WARNING) << "wrote" << written << " bytes to "
                  << UTF16ToUTF8(filename.value()) << " expected " << size;
  }
  return -1;
}

int AppendToFile(const FilePath& filename, const char* data, int size) {
  ThreadRestrictions::AssertIOAllowed();
  base::win::ScopedHandle file(CreateFile(filename.value().c_str(),
                                          FILE_APPEND_DATA,
                                          0,
                                          NULL,
                                          OPEN_EXISTING,
                                          0,
                                          NULL));
  if (!file) {
    DLOG_GETLASTERROR(WARNING) << "CreateFile failed for path "
                               << UTF16ToUTF8(filename.value());
    return -1;
  }

  DWORD written;
  BOOL result = ::WriteFile(file, data, size, &written, NULL);
  if (result && static_cast<int>(written) == size)
    return written;

  if (!result) {
    // WriteFile failed.
    DLOG_GETLASTERROR(WARNING) << "writing file "
                               << UTF16ToUTF8(filename.value())
                               << " failed";
  } else {
    // Didn't write all the bytes.
    DLOG(WARNING) << "wrote" << written << " bytes to "
                  << UTF16ToUTF8(filename.value()) << " expected " << size;
  }
  return -1;
}

// Gets the current working directory for the process.
bool GetCurrentDirectory(FilePath* dir) {
  ThreadRestrictions::AssertIOAllowed();

  wchar_t system_buffer[MAX_PATH];
  system_buffer[0] = 0;
  DWORD len = ::GetCurrentDirectory(MAX_PATH, system_buffer);
  if (len == 0 || len > MAX_PATH)
    return false;
  // TODO(evanm): the old behavior of this function was to always strip the
  // trailing slash.  We duplicate this here, but it shouldn't be necessary
  // when everyone is using the appropriate FilePath APIs.
  std::wstring dir_str(system_buffer);
  *dir = FilePath(dir_str).StripTrailingSeparators();
  return true;
}

// Sets the current working directory for the process.
bool SetCurrentDirectory(const FilePath& directory) {
  ThreadRestrictions::AssertIOAllowed();
  BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
  return ret != 0;
}

int GetMaximumPathComponentLength(const FilePath& path) {
  ThreadRestrictions::AssertIOAllowed();

  wchar_t volume_path[MAX_PATH];
  if (!GetVolumePathNameW(path.NormalizePathSeparators().value().c_str(),
                          volume_path,
                          arraysize(volume_path))) {
    return -1;
  }

  DWORD max_length = 0;
  if (!GetVolumeInformationW(volume_path, NULL, 0, NULL, &max_length, NULL,
                             NULL, 0)) {
    return -1;
  }

  // Length of |path| with path separator appended.
  size_t prefix = path.StripTrailingSeparators().value().size() + 1;
  // The whole path string must be shorter than MAX_PATH. That is, it must be
  // prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
  int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
  return std::min(whole_path_limit, static_cast<int>(max_length));
}

// -----------------------------------------------------------------------------

namespace internal {

bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
  ThreadRestrictions::AssertIOAllowed();

  // NOTE: I suspect we could support longer paths, but that would involve
  // analyzing all our usage of files.
  if (from_path.value().length() >= MAX_PATH ||
      to_path.value().length() >= MAX_PATH) {
    return false;
  }
  if (MoveFileEx(from_path.value().c_str(), to_path.value().c_str(),
                 MOVEFILE_COPY_ALLOWED | MOVEFILE_REPLACE_EXISTING) != 0)
    return true;

  // Keep the last error value from MoveFileEx around in case the below
  // fails.
  bool ret = false;
  DWORD last_error = ::GetLastError();

  if (DirectoryExists(from_path)) {
    // MoveFileEx fails if moving directory across volumes. We will simulate
    // the move by using Copy and Delete. Ideally we could check whether
    // from_path and to_path are indeed in different volumes.
    ret = internal::CopyAndDeleteDirectory(from_path, to_path);
  }

  if (!ret) {
    // Leave a clue about what went wrong so that it can be (at least) picked
    // up by a PLOG entry.
    ::SetLastError(last_error);
  }

  return ret;
}

bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
  ThreadRestrictions::AssertIOAllowed();

  // NOTE: I suspect we could support longer paths, but that would involve
  // analyzing all our usage of files.
  if (from_path.value().length() >= MAX_PATH ||
      to_path.value().length() >= MAX_PATH) {
    return false;
  }

  // Unlike the posix implementation that copies the file manually and discards
  // the ACL bits, CopyFile() copies the complete SECURITY_DESCRIPTOR and access
  // bits, which is usually not what we want. We can't do much about the
  // SECURITY_DESCRIPTOR but at least remove the read only bit.
  const wchar_t* dest = to_path.value().c_str();
  if (!::CopyFile(from_path.value().c_str(), dest, false)) {
    // Copy failed.
    return false;
  }
  DWORD attrs = GetFileAttributes(dest);
  if (attrs == INVALID_FILE_ATTRIBUTES) {
    return false;
  }
  if (attrs & FILE_ATTRIBUTE_READONLY) {
    SetFileAttributes(dest, attrs & ~FILE_ATTRIBUTE_READONLY);
  }
  return true;
}

bool CopyAndDeleteDirectory(const FilePath& from_path,
                            const FilePath& to_path) {
  ThreadRestrictions::AssertIOAllowed();
  if (CopyDirectory(from_path, to_path, true)) {
    if (DeleteFile(from_path, true))
      return true;

    // Like Move, this function is not transactional, so we just
    // leave the copied bits behind if deleting from_path fails.
    // If to_path exists previously then we have already overwritten
    // it by now, we don't get better off by deleting the new bits.
  }
  return false;
}

}  // namespace internal
}  // namespace base
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root/base/file_util_win.cc

DEFINITIONS
