diff -r 000000000000 -r 6474c204b198 security/sandbox/chromium/base/file_util_win.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/security/sandbox/chromium/base/file_util_win.cc	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,759 @@
+// 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_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;
+
+bool ShellCopy(const FilePath& from_path,
+               const FilePath& to_path,
+               bool recursive) {
+  // WinXP SHFileOperation doesn't like trailing separators.
+  FilePath stripped_from = from_path.StripTrailingSeparators();
+  FilePath stripped_to = to_path.StripTrailingSeparators();
+
+  ThreadRestrictions::AssertIOAllowed();
+
+  // NOTE: I suspect we could support longer paths, but that would involve
+  // analyzing all our usage of files.
+  if (stripped_from.value().length() >= MAX_PATH ||
+      stripped_to.value().length() >= MAX_PATH) {
+    return false;
+  }
+
+  // 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_from[MAX_PATH + 1] = {0};
+  wchar_t double_terminated_path_to[MAX_PATH + 1] = {0};
+#pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
+  wcscpy(double_terminated_path_from, stripped_from.value().c_str());
+#pragma warning(suppress:4996)  // don't complain about wcscpy deprecation
+  wcscpy(double_terminated_path_to, stripped_to.value().c_str());
+
+  SHFILEOPSTRUCT file_operation = {0};
+  file_operation.wFunc = FO_COPY;
+  file_operation.pFrom = double_terminated_path_from;
+  file_operation.pTo = double_terminated_path_to;
+  file_operation.fFlags = FOF_NOERRORUI | FOF_SILENT | FOF_NOCONFIRMATION |
+                          FOF_NOCONFIRMMKDIR;
+  if (!recursive)
+    file_operation.fFlags |= FOF_NORECURSION | FOF_FILESONLY;
+
+  return (SHFileOperation(&file_operation) == 0);
+}
+
+}  // 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.
+    PlatformFileInfo file_info;
+    if (file_util::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
+  if (g_bug108724_debug)
+    LOG(WARNING) << "copying ";
+  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;
+  if (g_bug108724_debug)
+    LOG(WARNING) << "Performing shell operation";
+  int err = SHFileOperation(&file_operation);
+  if (g_bug108724_debug)
+    LOG(WARNING) << "Done: " << err;
+
+  // 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,
+                 PlatformFileError* 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 = LastErrorToPlatformFileError(GetLastError());
+  return false;
+}
+
+bool CopyDirectory(const FilePath& from_path, const FilePath& to_path,
+                   bool recursive) {
+  ThreadRestrictions::AssertIOAllowed();
+
+  if (recursive)
+    return ShellCopy(from_path, to_path, true);
+
+  // The following code assumes that from path is a directory.
+  DCHECK(DirectoryExists(from_path));
+
+  // Instead of creating a new directory, we copy the old one to include the
+  // security information of the folder as part of the copy.
+  if (!PathExists(to_path)) {
+    // Except that Vista fails to do that, and instead do a recursive copy if
+    // the target directory doesn't exist.
+    if (base::win::GetVersion() >= base::win::VERSION_VISTA)
+      file_util::CreateDirectory(to_path);
+    else
+      ShellCopy(from_path, to_path, false);
+  }
+
+  FilePath directory = from_path.Append(L"*.*");
+  return ShellCopy(directory, to_path, false);
+}
+
+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;
+}
+
+}  // namespace base
+
+// -----------------------------------------------------------------------------
+
+namespace file_util {
+
+using base::DirectoryExists;
+using base::FilePath;
+using base::kFileShareAll;
+
+bool GetTempDir(FilePath* path) {
+  base::ThreadRestrictions::AssertIOAllowed();
+
+  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;
+}
+
+bool GetShmemTempDir(FilePath* path, bool executable) {
+  return GetTempDir(path);
+}
+
+bool CreateTemporaryFile(FilePath* path) {
+  base::ThreadRestrictions::AssertIOAllowed();
+
+  FilePath temp_file;
+
+  if (!GetTempDir(path))
+    return false;
+
+  if (CreateTemporaryFileInDir(*path, &temp_file)) {
+    *path = temp_file;
+    return true;
+  }
+
+  return false;
+}
+
+FILE* CreateAndOpenTemporaryShmemFile(FilePath* path, bool executable) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  return CreateAndOpenTemporaryFile(path);
+}
+
+// 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) {
+  base::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) {
+  base::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 " << 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) {
+  base::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(base::IntToString16(::base::GetCurrentProcId()));
+    new_dir_name.push_back('_');
+    new_dir_name.append(base::IntToString16(base::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) {
+  base::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,
+                                base::PlatformFileError* error) {
+  base::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 = base::PLATFORM_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 = base::PLATFORM_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 != base::PLATFORM_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 = base::LastErrorToPlatformFileError(error_code);
+      DLOG(WARNING) << "Failed to create directory " << full_path_str
+                    << ", last error is " << error_code << ".";
+      return false;
+    }
+  } else {
+    return true;
+  }
+}
+
+// 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, base::PlatformFileInfo* results) {
+  base::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 = base::Time::FromFileTime(attr.ftLastWriteTime);
+  results->last_accessed = base::Time::FromFileTime(attr.ftLastAccessTime);
+  results->creation_time = base::Time::FromFileTime(attr.ftCreationTime);
+
+  return true;
+}
+
+FILE* OpenFile(const FilePath& filename, const char* mode) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  std::wstring w_mode = ASCIIToWide(std::string(mode));
+  return _wfsopen(filename.value().c_str(), w_mode.c_str(), _SH_DENYNO);
+}
+
+FILE* OpenFile(const std::string& filename, const char* mode) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  return _fsopen(filename.c_str(), mode, _SH_DENYNO);
+}
+
+int ReadFile(const FilePath& filename, char* data, int size) {
+  base::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) {
+  base::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 "
+                               << 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 " << filename.value()
+                               << " failed";
+  } else {
+    // Didn't write all the bytes.
+    DLOG(WARNING) << "wrote" << written << " bytes to "
+                  << filename.value() << " expected " << size;
+  }
+  return -1;
+}
+
+int AppendToFile(const FilePath& filename, const char* data, int size) {
+  base::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 "
+                               << 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 " << filename.value()
+                               << " failed";
+  } else {
+    // Didn't write all the bytes.
+    DLOG(WARNING) << "wrote" << written << " bytes to "
+                  << filename.value() << " expected " << size;
+  }
+  return -1;
+}
+
+// Gets the current working directory for the process.
+bool GetCurrentDirectory(FilePath* dir) {
+  base::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) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  BOOL ret = ::SetCurrentDirectory(directory.value().c_str());
+  return ret != 0;
+}
+
+bool NormalizeFilePath(const FilePath& path, FilePath* real_path) {
+  base::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) {
+  base::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) {
+  base::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;
+}
+
+int GetMaximumPathComponentLength(const FilePath& path) {
+  base::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 file_util
+
+namespace base {
+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;
+  }
+  return (::CopyFile(from_path.value().c_str(), to_path.value().c_str(),
+                     false) != 0);
+}
+
+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