base/files/file_win.cc

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/files/file.h"

#include <windows.h>

#include <io.h>
#include <stdint.h>

#include <tuple>

#include "base/check.h"
#include "base/check_op.h"
#include "base/files/file_util.h"
#include "base/immediate_crash.h"
#include "base/metrics/histogram_functions.h"
#include "base/notreached.h"
#include "base/strings/string_util.h"
#include "base/threading/scoped_blocking_call.h"

namespace base {

// Make sure our Whence mappings match the system headers.
static_assert(File::FROM_BEGIN == FILE_BEGIN &&
                  File::FROM_CURRENT == FILE_CURRENT &&
                  File::FROM_END == FILE_END,
              "whence mapping must match the system headers");

bool File::IsValid() const {
  return file_.is_valid();
}

PlatformFile File::GetPlatformFile() const {
  return file_.get();
}

PlatformFile File::TakePlatformFile() {
  return file_.release();
}

void File::Close() {
  if (!file_.is_valid())
    return;

  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  SCOPED_FILE_TRACE("Close");
  file_.Close();
}

int64_t File::Seek(Whence whence, int64_t offset) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());

  SCOPED_FILE_TRACE_WITH_SIZE("Seek", offset);

  LARGE_INTEGER distance, res;
  distance.QuadPart = offset;
  DWORD move_method = static_cast<DWORD>(whence);
  if (!SetFilePointerEx(file_.get(), distance, &res, move_method))
    return -1;
  return res.QuadPart;
}

int File::Read(int64_t offset, char* data, int size) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());
  DCHECK(!async_);
  if (size < 0 || offset < 0)
    return -1;

  SCOPED_FILE_TRACE_WITH_SIZE("Read", size);

  ULARGE_INTEGER offset_li;
  offset_li.QuadPart = static_cast<uint64_t>(offset);

  OVERLAPPED overlapped = {};
  overlapped.Offset = offset_li.LowPart;
  overlapped.OffsetHigh = offset_li.HighPart;

  DWORD bytes_read;
  if (::ReadFile(file_.get(), data, static_cast<DWORD>(size), &bytes_read,
                 &overlapped)) {
    // TODO(crbug.com/40227936): Change to return some type with a uint64_t size
    // and eliminate this cast.
    return checked_cast<int>(bytes_read);
  }
  if (ERROR_HANDLE_EOF == GetLastError())
    return 0;

  return -1;
}

int File::ReadAtCurrentPos(char* data, int size) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());
  DCHECK(!async_);
  if (size < 0)
    return -1;

  SCOPED_FILE_TRACE_WITH_SIZE("ReadAtCurrentPos", size);

  DWORD bytes_read;
  if (::ReadFile(file_.get(), data, static_cast<DWORD>(size), &bytes_read,
                 NULL)) {
    // TODO(crbug.com/40227936): Change to return some type with a uint64_t size
    // and eliminate this cast.
    return checked_cast<int>(bytes_read);
  }
  if (ERROR_HANDLE_EOF == GetLastError())
    return 0;

  return -1;
}

int File::ReadNoBestEffort(int64_t offset, char* data, int size) {
  // TODO(dbeam): trace this separately?
  // SAFETY: required from caller, enforced by UNSAFE_BUFFER_USAGE in header.
  return UNSAFE_BUFFERS(Read(offset, data, size));
}

int File::ReadAtCurrentPosNoBestEffort(char* data, int size) {
  // TODO(dbeam): trace this separately?
  // SAFETY: required from caller, enforced by UNSAFE_BUFFER_USAGE in header.
  return UNSAFE_BUFFERS(ReadAtCurrentPos(data, size));
}

int File::Write(int64_t offset, const char* data, int size) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());
  DCHECK(!async_);
  if (size < 0 || offset < 0)
    return -1;

  SCOPED_FILE_TRACE_WITH_SIZE("Write", size);

  ULARGE_INTEGER offset_li;
  offset_li.QuadPart = static_cast<uint64_t>(offset);

  OVERLAPPED overlapped = {};
  overlapped.Offset = offset_li.LowPart;
  overlapped.OffsetHigh = offset_li.HighPart;

  DWORD bytes_written;
  if (::WriteFile(file_.get(), data, static_cast<DWORD>(size), &bytes_written,
                  &overlapped))
    return static_cast<int>(bytes_written);

  return -1;
}

int File::WriteAtCurrentPos(const char* data, int size) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());
  DCHECK(!async_);
  if (size < 0)
    return -1;

  SCOPED_FILE_TRACE_WITH_SIZE("WriteAtCurrentPos", size);

  DWORD bytes_written;
  if (::WriteFile(file_.get(), data, static_cast<DWORD>(size), &bytes_written,
                  NULL))
    return static_cast<int>(bytes_written);

  return -1;
}

int File::WriteAtCurrentPosNoBestEffort(const char* data, int size) {
  // SAFETY: required from caller, enforced by UNSAFE_BUFFER_USAGE in header.
  return UNSAFE_BUFFERS(WriteAtCurrentPos(data, size));
}

int64_t File::GetLength() const {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());

  SCOPED_FILE_TRACE("GetLength");

  LARGE_INTEGER size;
  if (!::GetFileSizeEx(file_.get(), &size))
    return -1;

  return static_cast<int64_t>(size.QuadPart);
}

bool File::SetLength(int64_t length) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());

  SCOPED_FILE_TRACE_WITH_SIZE("SetLength", length);

  // Get the current file pointer.
  LARGE_INTEGER file_pointer;
  LARGE_INTEGER zero;
  zero.QuadPart = 0;
  if (!::SetFilePointerEx(file_.get(), zero, &file_pointer, FILE_CURRENT))
    return false;

  LARGE_INTEGER length_li;
  length_li.QuadPart = length;
  // If length > file size, SetFilePointerEx() should extend the file
  // with zeroes on all Windows standard file systems (NTFS, FATxx).
  if (!::SetFilePointerEx(file_.get(), length_li, NULL, FILE_BEGIN))
    return false;

  // Set the new file length and move the file pointer to its old position.
  // This is consistent with ftruncate()'s behavior, even when the file
  // pointer points to a location beyond the end of the file.
  // TODO(rvargas): Emulating ftruncate details seem suspicious and it is not
  // promised by the interface (nor was promised by PlatformFile). See if this
  // implementation detail can be removed.
  return ((::SetEndOfFile(file_.get()) != FALSE) &&
          (::SetFilePointerEx(file_.get(), file_pointer, NULL, FILE_BEGIN) !=
           FALSE));
}

bool File::SetTimes(Time last_access_time, Time last_modified_time) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());

  SCOPED_FILE_TRACE("SetTimes");

  FILETIME last_access_filetime = last_access_time.ToFileTime();
  FILETIME last_modified_filetime = last_modified_time.ToFileTime();
  return (::SetFileTime(file_.get(), NULL, &last_access_filetime,
                        &last_modified_filetime) != FALSE);
}

bool File::GetInfo(Info* info) const {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());

  SCOPED_FILE_TRACE("GetInfo");

  BY_HANDLE_FILE_INFORMATION file_info;
  if (!GetFileInformationByHandle(file_.get(), &file_info))
    return false;

  ULARGE_INTEGER size;
  size.HighPart = file_info.nFileSizeHigh;
  size.LowPart = file_info.nFileSizeLow;
  // TODO(crbug.com/40227936): Change Info::size to uint64_t and eliminate this
  // cast.
  info->size = checked_cast<int64_t>(size.QuadPart);
  info->is_directory =
      (file_info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
  info->is_symbolic_link = false;  // Windows doesn't have symbolic links.
  info->last_modified = Time::FromFileTime(file_info.ftLastWriteTime);
  info->last_accessed = Time::FromFileTime(file_info.ftLastAccessTime);
  info->creation_time = Time::FromFileTime(file_info.ftCreationTime);
  return true;
}

namespace {

DWORD LockFileFlagsForMode(File::LockMode mode) {
  DWORD flags = LOCKFILE_FAIL_IMMEDIATELY;
  switch (mode) {
    case File::LockMode::kShared:
      return flags;
    case File::LockMode::kExclusive:
      return flags | LOCKFILE_EXCLUSIVE_LOCK;
  }
  NOTREACHED();
}

}  // namespace

File::Error File::Lock(File::LockMode mode) {
  DCHECK(IsValid());

  SCOPED_FILE_TRACE("Lock");

  OVERLAPPED overlapped = {};
  BOOL result =
      LockFileEx(file_.get(), LockFileFlagsForMode(mode), /*dwReserved=*/0,
                 /*nNumberOfBytesToLockLow=*/MAXDWORD,
                 /*nNumberOfBytesToLockHigh=*/MAXDWORD, &overlapped);
  if (!result)
    return GetLastFileError();
  return FILE_OK;
}

File::Error File::Unlock() {
  DCHECK(IsValid());

  SCOPED_FILE_TRACE("Unlock");

  OVERLAPPED overlapped = {};
  BOOL result =
      UnlockFileEx(file_.get(), /*dwReserved=*/0,
                   /*nNumberOfBytesToLockLow=*/MAXDWORD,
                   /*nNumberOfBytesToLockHigh=*/MAXDWORD, &overlapped);
  if (!result)
    return GetLastFileError();
  return FILE_OK;
}

File File::Duplicate() const {
  if (!IsValid())
    return File();

  SCOPED_FILE_TRACE("Duplicate");

  HANDLE other_handle = nullptr;

  if (!::DuplicateHandle(GetCurrentProcess(),  // hSourceProcessHandle
                         GetPlatformFile(),
                         GetCurrentProcess(),  // hTargetProcessHandle
                         &other_handle,
                         0,  // dwDesiredAccess ignored due to SAME_ACCESS
                         FALSE,  // !bInheritHandle
                         DUPLICATE_SAME_ACCESS)) {
    return File(GetLastFileError());
  }

  return File(ScopedPlatformFile(other_handle), async());
}

bool File::DeleteOnClose(bool delete_on_close) {
  FILE_DISPOSITION_INFO disposition = {delete_on_close};
  return ::SetFileInformationByHandle(GetPlatformFile(), FileDispositionInfo,
                                      &disposition, sizeof(disposition)) != 0;
}

// Static.
File::Error File::OSErrorToFileError(DWORD last_error) {
  switch (last_error) {
    case ERROR_SHARING_VIOLATION:
    case ERROR_UNABLE_TO_REMOVE_REPLACED:  // ReplaceFile failure cases.
    case ERROR_UNABLE_TO_MOVE_REPLACEMENT:
    case ERROR_UNABLE_TO_MOVE_REPLACEMENT_2:
      return FILE_ERROR_IN_USE;
    case ERROR_ALREADY_EXISTS:
    case ERROR_FILE_EXISTS:
      return FILE_ERROR_EXISTS;
    case ERROR_FILE_NOT_FOUND:
    case ERROR_PATH_NOT_FOUND:
      return FILE_ERROR_NOT_FOUND;
    case ERROR_ACCESS_DENIED:
    case ERROR_LOCK_VIOLATION:
      return FILE_ERROR_ACCESS_DENIED;
    case ERROR_TOO_MANY_OPEN_FILES:
      return FILE_ERROR_TOO_MANY_OPENED;
    case ERROR_OUTOFMEMORY:
    case ERROR_NOT_ENOUGH_MEMORY:
      return FILE_ERROR_NO_MEMORY;
    case ERROR_HANDLE_DISK_FULL:
    case ERROR_DISK_FULL:
    case ERROR_DISK_RESOURCES_EXHAUSTED:
      return FILE_ERROR_NO_SPACE;
    case ERROR_USER_MAPPED_FILE:
      return FILE_ERROR_INVALID_OPERATION;
    case ERROR_NOT_READY:         // The device is not ready.
    case ERROR_SECTOR_NOT_FOUND:  // The drive cannot find the sector requested.
    case ERROR_GEN_FAILURE:       // A device ... is not functioning.
    case ERROR_DEV_NOT_EXIST:  // Net resource or device is no longer available.
    case ERROR_IO_DEVICE:
    case ERROR_DISK_OPERATION_FAILED:
    case ERROR_FILE_CORRUPT:  // File or directory is corrupted and unreadable.
    case ERROR_DISK_CORRUPT:  // The disk structure is corrupted and unreadable.
      return FILE_ERROR_IO;
    default:
      // This function should only be called for errors.
      DCHECK_NE(static_cast<DWORD>(ERROR_SUCCESS), last_error);
      return FILE_ERROR_FAILED;
  }
}

void File::DoInitialize(const FilePath& path, uint32_t flags) {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(!IsValid());

  DWORD disposition = 0;

  if (flags & FLAG_OPEN)
    disposition = OPEN_EXISTING;

  if (flags & FLAG_CREATE) {
    DCHECK(!disposition);
    disposition = CREATE_NEW;
  }

  if (flags & FLAG_OPEN_ALWAYS) {
    DCHECK(!disposition);
    disposition = OPEN_ALWAYS;
  }

  if (flags & FLAG_CREATE_ALWAYS) {
    DCHECK(!disposition);
    DCHECK(flags & FLAG_WRITE);
    disposition = CREATE_ALWAYS;
  }

  if (flags & FLAG_OPEN_TRUNCATED) {
    DCHECK(!disposition);
    DCHECK(flags & FLAG_WRITE);
    disposition = TRUNCATE_EXISTING;
  }

  CHECK(disposition);

  DWORD access = 0;
  if (flags & FLAG_WRITE)
    access = GENERIC_WRITE;
  if (flags & FLAG_APPEND) {
    DCHECK(!access);
    access = FILE_APPEND_DATA;
  }
  if (flags & FLAG_READ)
    access |= GENERIC_READ;
  if (flags & FLAG_WRITE_ATTRIBUTES)
    access |= FILE_WRITE_ATTRIBUTES;
  if (flags & FLAG_WIN_EXECUTE) {
    // Specifying both FLAG_WIN_EXECUTE and FLAG_WIN_NO_EXECUTE would
    // constitute a security risk, so deny the access here.
    CHECK_EQ(flags & FLAG_WIN_NO_EXECUTE, 0U);
    access |= GENERIC_EXECUTE;
  }
  if (flags & FLAG_CAN_DELETE_ON_CLOSE)
    access |= DELETE;

  DWORD sharing = (flags & FLAG_WIN_EXCLUSIVE_READ) ? 0 : FILE_SHARE_READ;
  if (!(flags & FLAG_WIN_EXCLUSIVE_WRITE))
    sharing |= FILE_SHARE_WRITE;
  if (flags & FLAG_WIN_SHARE_DELETE)
    sharing |= FILE_SHARE_DELETE;

  DWORD create_flags = 0;
  if (flags & FLAG_ASYNC)
    create_flags |= FILE_FLAG_OVERLAPPED;
  if (flags & FLAG_WIN_TEMPORARY)
    create_flags |= FILE_ATTRIBUTE_TEMPORARY;
  if (flags & FLAG_WIN_HIDDEN)
    create_flags |= FILE_ATTRIBUTE_HIDDEN;
  if (flags & FLAG_DELETE_ON_CLOSE)
    create_flags |= FILE_FLAG_DELETE_ON_CLOSE;
  if (flags & FLAG_WIN_BACKUP_SEMANTICS)
    create_flags |= FILE_FLAG_BACKUP_SEMANTICS;
  if (flags & FLAG_WIN_SEQUENTIAL_SCAN)
    create_flags |= FILE_FLAG_SEQUENTIAL_SCAN;

  file_.Set(CreateFile(path.value().c_str(), access, sharing, NULL, disposition,
                       create_flags, NULL));

  if (file_.is_valid()) {
    error_details_ = FILE_OK;
    async_ = ((flags & FLAG_ASYNC) == FLAG_ASYNC);

    if (flags & (FLAG_OPEN_ALWAYS))
      created_ = (ERROR_ALREADY_EXISTS != GetLastError());
    else if (flags & (FLAG_CREATE_ALWAYS | FLAG_CREATE))
      created_ = true;
    if (flags & FLAG_WIN_NO_EXECUTE) {
      // These two DCHECKs make sure that no callers are trying to remove
      // execute permission from a file that might need to be mapped executable
      // later. If they hit in code then the file should not have
      // FLAG_WIN_NO_EXECUTE flag, but this will mean that the file cannot be
      // passed to renderers.
      DCHECK(!base::FilePath::CompareEqualIgnoreCase(FILE_PATH_LITERAL(".exe"),
                                                     path.Extension()));
      DCHECK(!base::FilePath::CompareEqualIgnoreCase(FILE_PATH_LITERAL(".dll"),
                                                     path.Extension()));

      // It is possible that the ACE could not be added if the file was created
      // in a path for which the caller does not have WRITE_DAC access. In this
      // case, ignore the error since if this is occurring then it's likely the
      // file cannot be opened for write and more serious I/O failures are
      // occurring or about to occur.
      std::ignore = PreventExecuteMapping(path);
    }
  } else {
    error_details_ = GetLastFileError();
  }
}

bool File::Flush() {
  ScopedBlockingCall scoped_blocking_call(FROM_HERE, BlockingType::MAY_BLOCK);
  DCHECK(IsValid());
  SCOPED_FILE_TRACE("Flush");

  // On Windows 8 and above, FlushFileBuffers is guaranteed to flush the storage
  // device's internal buffers (if they exist) before returning.
  // https://blogs.msdn.microsoft.com/oldnewthing/20170510-00/?p=95505
  return ::FlushFileBuffers(file_.get()) != FALSE;
}

void File::SetPlatformFile(PlatformFile file) {
  file_.Set(file);
}

// static
File::Error File::GetLastFileError() {
  return File::OSErrorToFileError(GetLastError());
}

}  // namespace base