xpcom/io/FileUtilsWin.h
author Steve Fink <sfink@mozilla.com>
Fri, 25 Mar 2016 11:41:54 -0700
changeset 299732 5762a8fba027bb667a621deb50540ddd5a884193
parent 216601 1e4f975958f2ee83619a287e512f4e7f2abf1038
child 395523 f6ef04a022f3c5aa861e438298302a989308369e
permissions -rw-r--r--
Bug 1259850 - Various refactorings, r=terrence MozReview-Commit-ID: GYrqbzK3U8W

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_FileUtilsWin_h
#define mozilla_FileUtilsWin_h

#include <windows.h>

#include "mozilla/Scoped.h"
#include "nsStringGlue.h"

namespace mozilla {

inline bool
EnsureLongPath(nsAString& aDosPath)
{
  uint32_t aDosPathOriginalLen = aDosPath.Length();
  auto inputPath = PromiseFlatString(aDosPath);
  // Try to get the long path, or else get the required length of the long path
  DWORD longPathLen = GetLongPathNameW(inputPath.get(),
                                       reinterpret_cast<wchar_t*>(aDosPath.BeginWriting()),
                                       aDosPathOriginalLen);
  if (longPathLen == 0) {
    return false;
  }
  aDosPath.SetLength(longPathLen);
  if (longPathLen <= aDosPathOriginalLen) {
    // Our string happened to be long enough for the first call to succeed.
    return true;
  }
  // Now we have a large enough buffer, get the actual string
  longPathLen = GetLongPathNameW(inputPath.get(),
                                 reinterpret_cast<wchar_t*>(aDosPath.BeginWriting()), aDosPath.Length());
  if (longPathLen == 0) {
    return false;
  }
  // This success check should always be less-than because longPathLen excludes
  // the null terminator on success, but includes it in the first call that
  // returned the required size.
  if (longPathLen < aDosPath.Length()) {
    aDosPath.SetLength(longPathLen);
    return true;
  }
  // We shouldn't reach this, but if we do then it's a failure!
  return false;
}

inline bool
NtPathToDosPath(const nsAString& aNtPath, nsAString& aDosPath)
{
  aDosPath.Truncate();
  if (aNtPath.IsEmpty()) {
    return true;
  }
  NS_NAMED_LITERAL_STRING(symLinkPrefix, "\\??\\");
  uint32_t ntPathLen = aNtPath.Length();
  uint32_t symLinkPrefixLen = symLinkPrefix.Length();
  if (ntPathLen >= 6 && aNtPath.CharAt(5) == L':' &&
      ntPathLen >= symLinkPrefixLen &&
      Substring(aNtPath, 0, symLinkPrefixLen).Equals(symLinkPrefix)) {
    // Symbolic link for DOS device. Just strip off the prefix.
    aDosPath = aNtPath;
    aDosPath.Cut(0, 4);
    return true;
  }
  nsAutoString logicalDrives;
  DWORD len = 0;
  while (true) {
    len = GetLogicalDriveStringsW(
      len, reinterpret_cast<wchar_t*>(logicalDrives.BeginWriting()));
    if (!len) {
      return false;
    } else if (len > logicalDrives.Length()) {
      logicalDrives.SetLength(len);
    } else {
      break;
    }
  }
  const char16_t* cur = logicalDrives.BeginReading();
  const char16_t* end = logicalDrives.EndReading();
  nsString targetPath;
  targetPath.SetLength(MAX_PATH);
  wchar_t driveTemplate[] = L" :";
  do {
    // Unfortunately QueryDosDevice doesn't support the idiom for querying the
    // output buffer size, so it may require retries.
    driveTemplate[0] = *cur;
    DWORD targetPathLen = 0;
    SetLastError(ERROR_SUCCESS);
    while (true) {
      targetPathLen = QueryDosDeviceW(driveTemplate,
                                      reinterpret_cast<wchar_t*>(targetPath.BeginWriting()),
                                      targetPath.Length());
      if (targetPathLen || GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
        break;
      }
      targetPath.SetLength(targetPath.Length() * 2);
    }
    if (targetPathLen) {
      // Need to use wcslen here because targetPath contains embedded NULL chars
      size_t firstTargetPathLen = wcslen(targetPath.get());
      const char16_t* pathComponent = aNtPath.BeginReading() +
                                      firstTargetPathLen;
      bool found = _wcsnicmp(char16ptr_t(aNtPath.BeginReading()), targetPath.get(),
                             firstTargetPathLen) == 0 &&
                   *pathComponent == L'\\';
      if (found) {
        aDosPath = driveTemplate;
        aDosPath += pathComponent;
        return EnsureLongPath(aDosPath);
      }
    }
    // Advance to the next NUL character in logicalDrives
    while (*cur++);
  } while (cur != end);
  // Try to handle UNC paths. NB: This must happen after we've checked drive
  // mappings in case a UNC path is mapped to a drive!
  NS_NAMED_LITERAL_STRING(uncPrefix, "\\\\");
  NS_NAMED_LITERAL_STRING(deviceMupPrefix, "\\Device\\Mup\\");
  if (StringBeginsWith(aNtPath, deviceMupPrefix)) {
    aDosPath = uncPrefix;
    aDosPath += Substring(aNtPath, deviceMupPrefix.Length());
    return true;
  }
  NS_NAMED_LITERAL_STRING(deviceLanmanRedirectorPrefix,
                          "\\Device\\LanmanRedirector\\");
  if (StringBeginsWith(aNtPath, deviceLanmanRedirectorPrefix)) {
    aDosPath = uncPrefix;
    aDosPath += Substring(aNtPath, deviceLanmanRedirectorPrefix.Length());
    return true;
  }
  return false;
}

bool
HandleToFilename(HANDLE aHandle, const LARGE_INTEGER& aOffset,
                 nsAString& aFilename);

} // namespace mozilla

#endif // mozilla_FileUtilsWin_h