示例#1
0
文件: Test.c 项目: jief666/clover
EFI_STATUS
EFIAPI
GetVolumeHandleWithDir(CHAR16 *SearchDir, OUT EFI_HANDLE *Handle)
{
	EFI_STATUS		Status;
	UINTN			HandlesSize;
	UINTN			Idx;
	EFI_HANDLE		*Handles;
	EFI_SIMPLE_FILE_SYSTEM_PROTOCOL *FS = NULL;
	EFI_FILE_PROTOCOL				*FP = NULL;
	EFI_FILE_PROTOCOL				*FP2 = NULL;
	
	// get all handles with EFI_SIMPLE_FILE_SYSTEM_PROTOCOL
	Status = gBS->LocateHandleBuffer(ByProtocol, &gEfiSimpleFileSystemProtocolGuid, NULL, &HandlesSize, &Handles);
	if (EFI_ERROR(Status)) {
		Print(L"LocateHandleBuffer: %r\n", Status);
		return Status;
	}
	Print(L"LocateHandleBuffer: %r, got %d handles\n", Status, HandlesSize);
	
	// find handle that contains SearchDir 
	for (Idx = 0; Idx < HandlesSize; Idx++) {
		// get EFI_SIMPLE_FILE_SYSTEM_PROTOCOL first
		Print(L"Trying handle: %p\n", Handles[Idx]);
		Status = gBS->OpenProtocol(Handles[Idx], &gEfiSimpleFileSystemProtocolGuid, (void **)&FS, gImageHandle, NULL, EFI_OPEN_PROTOCOL_GET_PROTOCOL);
		if (EFI_ERROR(Status)) {
			Print(L"OpenProtocol(gEfiSimpleFileSystemProtocolGuid): %r\n", Status);
			continue;
		}
		// open volume
		Status = FS->OpenVolume(FS, &FP);
		if (EFI_ERROR(Status)) {
			Print(L"OpenVolume(): %r\n", Status);
			gBS->CloseProtocol(Handles[Idx], &gEfiSimpleFileSystemProtocolGuid, gImageHandle, NULL);
			continue;
		}
		// try to open injection dir
		Status = FP->Open(FP, &FP2, SearchDir, EFI_FILE_MODE_READ, 0);
		if (EFI_ERROR(Status)) {
			Print(L"Open(%s): %r\n", SearchDir, Status);
			FP->Close(FP);
			gBS->CloseProtocol(Handles[Idx], &gEfiSimpleFileSystemProtocolGuid, gImageHandle, NULL);
			continue;
		}
		// we have found it - close it and return handle
		FP2->Close(FP2);
		FP->Close(FP);
		*Handle = Handles[Idx];
		return EFI_SUCCESS;
	}
	// not found
	return EFI_NOT_FOUND;
}
示例#2
0
/**
  Set the size of a file.

  This is a helper function for SetFileInfo().

  @param[in]  Instance  A pointer to the description of the volume
                        the file belongs to.
  @param[in]  File      A pointer to the description of the file.
  @param[in]  NewSize   The requested new size for the file.

  @retval  EFI_SUCCESS           The size was set.
  @retval  EFI_OUT_OF_RESOURCES  An allocation needed to process the request failed.

**/
STATIC
EFI_STATUS
SetFileSize (
  IN BOOTMON_FS_INSTANCE  *Instance,
  IN BOOTMON_FS_FILE      *BootMonFsFile,
  IN UINTN                 NewSize
  )
{
  EFI_STATUS              Status;
  UINT32                  OldSize;
  LIST_ENTRY              *RegionToFlushLink;
  LIST_ENTRY              *NextRegionToFlushLink;
  BOOTMON_FS_FILE_REGION  *Region;
  EFI_FILE_PROTOCOL       *File;
  CHAR8                   *Buffer;
  UINTN                   BufferSize;
  UINT64                  StoredPosition;

  OldSize = BootMonFsFile->Info->FileSize;

  //
  // In case of file truncation, force the regions waiting for writing to
  // not overflow the new size of the file.
  //
  if (NewSize < OldSize) {
    for (RegionToFlushLink = GetFirstNode (&BootMonFsFile->RegionToFlushLink);
         !IsNull (&BootMonFsFile->RegionToFlushLink, RegionToFlushLink);
         )
    {
      NextRegionToFlushLink = GetNextNode (&BootMonFsFile->RegionToFlushLink, RegionToFlushLink);
      Region = (BOOTMON_FS_FILE_REGION*)RegionToFlushLink;
      if (Region->Offset > NewSize) {
        RemoveEntryList (RegionToFlushLink);
        FreePool (Region->Buffer);
        FreePool (Region);
      } else {
        Region->Size = MIN (Region->Size, NewSize - Region->Offset);
      }
      RegionToFlushLink = NextRegionToFlushLink;
    }

  } else if (NewSize > OldSize) {
    // Increasing a file's size is potentially complicated as it may require
    // moving the image description on media. The simplest way to do it is to
    // seek past the end of the file (which is valid in UEFI) and perform a
    // Write.
    File = &BootMonFsFile->File;

    // Save position
    Status = File->GetPosition (File, &StoredPosition);
    if (EFI_ERROR (Status)) {
      return Status;
    }
    // Set position at the end of the file
    Status = File->SetPosition (File, OldSize);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    BufferSize = NewSize - OldSize;
    Buffer = AllocateZeroPool (BufferSize);
    if (Buffer == NULL) {
      return EFI_OUT_OF_RESOURCES;
    }

    Status = File->Write (File, &BufferSize, Buffer);
    FreePool (Buffer);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    // Restore saved position
    Status = File->SetPosition (File, StoredPosition);
    if (EFI_ERROR (Status)) {
      return Status;
    }
  }

  BootMonFsFile->Info->FileSize = NewSize;

  return EFI_SUCCESS;
}
示例#3
0
文件: Ls.c 项目: shijunjing/edk2
/**
  print out the standard format output volume entry.

  @param[in] TheList           a list of files from the volume.
**/
EFI_STATUS
PrintSfoVolumeInfoTableEntry(
  IN CONST EFI_SHELL_FILE_INFO *TheList
  )
{
  EFI_STATUS            Status;
  EFI_SHELL_FILE_INFO   *Node;
  CHAR16                *DirectoryName;
  EFI_FILE_SYSTEM_INFO  *SysInfo;
  UINTN                 SysInfoSize;
  SHELL_FILE_HANDLE     ShellFileHandle;
  EFI_FILE_PROTOCOL     *EfiFpHandle;

  //
  // Get the first valid handle (directories)
  //
  for ( Node = (EFI_SHELL_FILE_INFO *)GetFirstNode(&TheList->Link)
      ; !IsNull(&TheList->Link, &Node->Link) && Node->Handle == NULL
      ; Node = (EFI_SHELL_FILE_INFO *)GetNextNode(&TheList->Link, &Node->Link)
     );

  if (Node->Handle == NULL) {
    DirectoryName = GetFullyQualifiedPath(((EFI_SHELL_FILE_INFO *)GetFirstNode(&TheList->Link))->FullName);

    //
    // We need to open something up to get system information
    //
    Status = gEfiShellProtocol->OpenFileByName(
      DirectoryName,
      &ShellFileHandle,
      EFI_FILE_MODE_READ
      );

    ASSERT_EFI_ERROR(Status);
    FreePool(DirectoryName);

    //
    // Get the Volume Info from ShellFileHandle
    //
    SysInfo     = NULL;
    SysInfoSize = 0;
    EfiFpHandle = ConvertShellHandleToEfiFileProtocol(ShellFileHandle);
    Status = EfiFpHandle->GetInfo(
      EfiFpHandle,
      &gEfiFileSystemInfoGuid,
      &SysInfoSize,
      SysInfo
      );

    if (Status == EFI_BUFFER_TOO_SMALL) {
      SysInfo = AllocateZeroPool(SysInfoSize);
      Status = EfiFpHandle->GetInfo(
        EfiFpHandle,
        &gEfiFileSystemInfoGuid,
        &SysInfoSize,
        SysInfo
        );
    }

    ASSERT_EFI_ERROR(Status);

    gEfiShellProtocol->CloseFile(ShellFileHandle);
  } else {
    //
    // Get the Volume Info from Node->Handle
    //
    SysInfo = NULL;
    SysInfoSize = 0;
    EfiFpHandle = ConvertShellHandleToEfiFileProtocol(Node->Handle);
    Status = EfiFpHandle->GetInfo(
      EfiFpHandle,
      &gEfiFileSystemInfoGuid,
      &SysInfoSize,
      SysInfo
      );

    if (Status == EFI_BUFFER_TOO_SMALL) {
      SysInfo = AllocateZeroPool(SysInfoSize);
      Status = EfiFpHandle->GetInfo(
        EfiFpHandle,
        &gEfiFileSystemInfoGuid,
        &SysInfoSize,
        SysInfo
        );
    }

    ASSERT_EFI_ERROR(Status);
  }

  ShellPrintHiiEx (
    -1,
    -1,
    NULL,
    STRING_TOKEN (STR_GEN_SFO_HEADER),
    gShellLevel2HiiHandle,
    L"ls"
    );
  //
  // print VolumeInfo table
  //
  ASSERT(SysInfo != NULL);
  ShellPrintHiiEx (
    0,
    gST->ConOut->Mode->CursorRow,
    NULL,
    STRING_TOKEN (STR_LS_SFO_VOLINFO),
    gShellLevel2HiiHandle,
    SysInfo->VolumeLabel,
    SysInfo->VolumeSize,
    SysInfo->ReadOnly?L"TRUE":L"FALSE",
    SysInfo->FreeSpace,
    SysInfo->BlockSize
    );

  SHELL_FREE_NON_NULL(SysInfo);

  return (Status);
}
示例#4
0
文件: Cp.c 项目: Cutty/edk2
/**
  Function to Copy one file to another location

  If the destination exists the user will be prompted and the result put into *resp

  @param[in] Source     pointer to source file name
  @param[in] Dest       pointer to destination file name
  @param[out] Resp      pointer to response from question.  Pass back on looped calling
  @param[in] SilentMode whether to run in quiet mode or not

  @retval SHELL_SUCCESS   The source file was copied to the destination
**/
SHELL_STATUS
EFIAPI
CopySingleFile(
  IN CONST CHAR16 *Source,
  IN CONST CHAR16 *Dest,
  OUT VOID        **Resp,
  IN BOOLEAN      SilentMode
  )
{
  VOID                  *Response;
  UINTN                 ReadSize;
  SHELL_FILE_HANDLE     SourceHandle;
  SHELL_FILE_HANDLE     DestHandle;
  EFI_STATUS            Status;
  VOID                  *Buffer;
  CHAR16                *TempName;
  UINTN                 Size;
  EFI_SHELL_FILE_INFO   *List;
  SHELL_STATUS          ShellStatus;
  UINT64                SourceFileSize;
  UINT64                DestFileSize;
  EFI_FILE_PROTOCOL     *DestVolumeFP;
  EFI_FILE_SYSTEM_INFO  *DestVolumeInfo;
  UINTN                 DestVolumeInfoSize;

  ASSERT(Resp != NULL);

  SourceHandle    = NULL;
  DestHandle      = NULL;
  Response        = *Resp;
  List            = NULL;
  DestVolumeInfo  = NULL;

  ReadSize = PcdGet16(PcdShellFileOperationSize);
  // Why bother copying a file to itself
  if (StrCmp(Source, Dest) == 0) {
    return (SHELL_SUCCESS);
  }

  //
  // Open destination file without create
  //
  Status = ShellOpenFileByName(Dest, &DestHandle, EFI_FILE_MODE_READ|EFI_FILE_MODE_WRITE, 0);

  //
  // close file
  //
  if (DestHandle != NULL) {
    ShellCloseFile(&DestHandle);
    DestHandle   = NULL;
  }

  //
  // if the destination file existed check response and possibly prompt user
  //
  if (!EFI_ERROR(Status)) {
    if (Response == NULL && !SilentMode) {
      Status = ShellPromptForResponseHii(ShellPromptResponseTypeYesNoAllCancel, STRING_TOKEN (STR_GEN_DEST_EXIST_OVR), gShellLevel2HiiHandle, &Response);
    }
    //
    // possibly return based on response
    //
    if (!SilentMode) {
      switch (*(SHELL_PROMPT_RESPONSE*)Response) {
        case ShellPromptResponseNo:
          //
          // return success here so we dont stop the process
          //
          return (SHELL_SUCCESS);
        case ShellPromptResponseCancel:
          *Resp = Response;
          //
          // indicate to stop everything
          //
          return (SHELL_ABORTED);
        case ShellPromptResponseAll:
          *Resp = Response;
        case ShellPromptResponseYes:
          break;
        default:
          return SHELL_ABORTED;
      }
    }
  }

  if (ShellIsDirectory(Source) == EFI_SUCCESS) {
    Status = ShellCreateDirectory(Dest, &DestHandle);
    if (EFI_ERROR(Status)) {
      return (SHELL_ACCESS_DENIED);
    }

    //
    // Now copy all the files under the directory...
    //
    TempName    = NULL;
    Size        = 0;
    StrnCatGrow(&TempName, &Size, Source, 0);
    StrnCatGrow(&TempName, &Size, L"\\*", 0);
    if (TempName != NULL) {
      ShellOpenFileMetaArg((CHAR16*)TempName, EFI_FILE_MODE_READ, &List);
      *TempName = CHAR_NULL;
      StrnCatGrow(&TempName, &Size, Dest, 0);
      StrnCatGrow(&TempName, &Size, L"\\", 0);
      ShellStatus = ValidateAndCopyFiles(List, TempName, SilentMode, TRUE, Resp);
      ShellCloseFileMetaArg(&List);
      SHELL_FREE_NON_NULL(TempName);
      Size = 0;
    }
  } else {
      //
      // open file with create enabled
      //
      Status = ShellOpenFileByName(Dest, &DestHandle, EFI_FILE_MODE_READ|EFI_FILE_MODE_WRITE|EFI_FILE_MODE_CREATE, 0);
      if (EFI_ERROR(Status)) {
        return (SHELL_ACCESS_DENIED);
      }

      //
      // open source file
      //
      Status = ShellOpenFileByName(Source, &SourceHandle, EFI_FILE_MODE_READ, 0);
      ASSERT_EFI_ERROR(Status);

      //
      //get file size of source file and freespace available on destination volume
      //
      ShellGetFileSize(SourceHandle, &SourceFileSize);
      ShellGetFileSize(DestHandle, &DestFileSize);

      //
      //if the destination file already exists then it will be replaced, meaning the sourcefile effectively needs less storage space
      //
      if(DestFileSize < SourceFileSize){
        SourceFileSize -= DestFileSize;
      } else {
        SourceFileSize = 0;
      }

      //
      //get the system volume info to check the free space
      //
      DestVolumeFP = ConvertShellHandleToEfiFileProtocol(DestHandle);
      DestVolumeInfo = NULL;
      DestVolumeInfoSize = 0;
      Status = DestVolumeFP->GetInfo(
        DestVolumeFP,
        &gEfiFileSystemInfoGuid,
        &DestVolumeInfoSize,
        DestVolumeInfo
        );

      if (Status == EFI_BUFFER_TOO_SMALL) {
        DestVolumeInfo = AllocateZeroPool(DestVolumeInfoSize);
        Status = DestVolumeFP->GetInfo(
          DestVolumeFP,
          &gEfiFileSystemInfoGuid,
          &DestVolumeInfoSize,
          DestVolumeInfo
          );
      }

      //
      //check if enough space available on destination drive to complete copy
      //
      if (DestVolumeInfo->FreeSpace < SourceFileSize) {
        //
        //not enough space on destination directory to copy file
        //
        SHELL_FREE_NON_NULL(DestVolumeInfo);
        ShellPrintHiiEx(-1, -1, NULL, STRING_TOKEN (STR_GEN_CPY_FAIL), gShellLevel2HiiHandle);
        return(SHELL_VOLUME_FULL);
      } else {
        //
        // copy data between files
        //
        Buffer = AllocateZeroPool(ReadSize);
        ASSERT(Buffer != NULL);
        while (ReadSize == PcdGet16(PcdShellFileOperationSize) && !EFI_ERROR(Status)) {
          Status = ShellReadFile(SourceHandle, &ReadSize, Buffer);
          Status = ShellWriteFile(DestHandle, &ReadSize, Buffer);
        }
      }
      SHELL_FREE_NON_NULL(DestVolumeInfo);
    }

  //
  // close files
  //
  if (DestHandle != NULL) {
    ShellCloseFile(&DestHandle);
    DestHandle   = NULL;
  }
  if (SourceHandle != NULL) {
    ShellCloseFile(&SourceHandle);
    SourceHandle = NULL;
  }

  //
  // return
  //
  return (SHELL_SUCCESS);
}
示例#5
0
EFI_STATUS
BdsFileSystemLoadImage (
    IN     EFI_DEVICE_PATH *DevicePath,
    IN     EFI_HANDLE Handle,
    IN     EFI_DEVICE_PATH *RemainingDevicePath,
    IN     EFI_ALLOCATE_TYPE     Type,
    IN OUT EFI_PHYSICAL_ADDRESS* Image,
    OUT    UINTN                 *ImageSize
)
{
    FILEPATH_DEVICE_PATH*             FilePathDevicePath;
    EFI_SIMPLE_FILE_SYSTEM_PROTOCOL     *FsProtocol;
    EFI_FILE_PROTOCOL                   *Fs;
    EFI_STATUS Status;
    EFI_FILE_INFO       *FileInfo;
    EFI_FILE_PROTOCOL   *File;
    UINTN               Size;

    ASSERT (IS_DEVICE_PATH_NODE(RemainingDevicePath,MEDIA_DEVICE_PATH,MEDIA_FILEPATH_DP));

    FilePathDevicePath = (FILEPATH_DEVICE_PATH*)RemainingDevicePath;

    Status = gBS->HandleProtocol(Handle,&gEfiSimpleFileSystemProtocolGuid, (VOID **)&FsProtocol);
    if (EFI_ERROR(Status)) {
        return Status;
    }

    // Try to Open the volume and get root directory
    Status = FsProtocol->OpenVolume (FsProtocol, &Fs);
    if (EFI_ERROR(Status)) {
        return Status;
    }

    File = NULL;
    Status = Fs->Open(Fs, &File, FilePathDevicePath->PathName, EFI_FILE_MODE_READ, 0);
    if (EFI_ERROR(Status)) {
        return Status;
    }

    Size = 0;
    File->GetInfo(File, &gEfiFileInfoGuid, &Size, NULL);
    FileInfo = AllocatePool (Size);
    Status = File->GetInfo(File, &gEfiFileInfoGuid, &Size, FileInfo);
    if (EFI_ERROR(Status)) {
        return Status;
    }

    // Get the file size
    Size = FileInfo->FileSize;
    if (ImageSize) {
        *ImageSize = Size;
    }
    FreePool(FileInfo);

    Status = gBS->AllocatePages (Type, EfiBootServicesCode, EFI_SIZE_TO_PAGES(Size), Image);
    // Try to allocate in any pages if failed to allocate memory at the defined location
    if ((Status == EFI_OUT_OF_RESOURCES) && (Type != AllocateAnyPages)) {
        Status = gBS->AllocatePages (AllocateAnyPages, EfiBootServicesCode, EFI_SIZE_TO_PAGES(Size), Image);
    }
    if (!EFI_ERROR(Status)) {
        Status = File->Read (File, &Size, (VOID*)(UINTN)(*Image));
    }

    return Status;
}
示例#6
0
EFI_STATUS LoadFile(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE* systab,
		CHAR16* filename, VOID** dataPtr, UINTN* size,
		EFI_DEVICE_PATH_PROTOCOL** dev_path)
{
	EFI_GUID LoadedImageProtocolGuid = EFI_LOADED_IMAGE_PROTOCOL_GUID;
	EFI_GUID FileInfoGuid = EFI_FILE_INFO_ID;
	EFI_GUID FileSystemGuid = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID;
	EFI_STATUS res;

	EFI_BOOT_SERVICES* BS = systab->BootServices;

	//get image info
	EFI_LOADED_IMAGE_PROTOCOL* img_proto;
	res = BS->HandleProtocol(ImageHandle, &LoadedImageProtocolGuid,
			(void**) &img_proto);

	if (res)
	{
		ErrorPrint(L"Failed to get image protocol. (Error %d)\r\n", res);
		return EFI_LOAD_ERROR ;
	}

	EFI_HANDLE img_device_handle = img_proto->DeviceHandle;

	//Get filesystem protocol from device
	EFI_SIMPLE_FILE_SYSTEM_PROTOCOL* fs_proto;
	res = BS->HandleProtocol(img_device_handle, &FileSystemGuid,
			(VOID**) &fs_proto);

	if (res)
	{
		ErrorPrint(L"Failed to get file system protocol. (Error %d)\r\n", res);
		return EFI_LOAD_ERROR ;
	}

	//open volume
	EFI_FILE_PROTOCOL* volume;
	res = fs_proto->OpenVolume(fs_proto, &volume);

	if (res)
	{
		ErrorPrint(L"Failed to open file volume. (Error %d)\r\n", res);
		return EFI_LOAD_ERROR ;
	}

	//open file
	EFI_FILE_PROTOCOL* file;
	res = volume->Open(volume, &file, filename, EFI_FILE_MODE_READ, 0);

	if (res)
	{
		//don't print error here
		//ErrorPrint(L"Failed to open file '%s'. (Error %d)\r\n", filename, res);
		return EFI_NOT_FOUND ;
	}

	//get file info, two try process
	EFI_FILE_INFO* file_info = NULL;
	UINTN file_info_size = 0;
	res = file->GetInfo(file, &FileInfoGuid, &file_info_size, NULL );

	if (res != EFI_BUFFER_TOO_SMALL )
	{
		ErrorPrint(L"Failed to stat file '%s'. (Error %d)\r\n", filename, res);
		return EFI_NOT_FOUND ;
	}

	res = BS->AllocatePool(EfiLoaderData, file_info_size, (void**) &file_info);

	if (res)
	{
		ErrorPrint(L"Failed to allocate file info memory. (Error %d)\r\n", res);
		return EFI_OUT_OF_RESOURCES ;
	}

	res = file->GetInfo(file, &FileInfoGuid, &file_info_size,
			(void*) file_info);

	if (res)
	{
		BS->FreePool(file_info);
		ErrorPrint(L"Failed to stat file '%s'. (Error %d)\r\n", filename, res);
		return EFI_NOT_FOUND ;
	}

	if (dev_path != NULL )
	{
		*dev_path = FileDevicePath(img_device_handle, filename);
	}

	UINT64 file_size = file_info->FileSize;

	BS->FreePool(file_info);
	file_info = NULL;

	void* data = NULL;
	res = BS->AllocatePool(EfiLoaderData, file_size, (void**) &data);

	if (res)
	{
		ErrorPrint(L"Failed to allocate file data memory. (Error %d)\r\n", res);
		return EFI_OUT_OF_RESOURCES ;
	}

	//read the file
	res = file->Read(file, &file_size, (void*) data);

	if (res)
	{
		BS->FreePool(data);
		ErrorPrint(L"Failed to read file '%s'. (Error %d)\r\n", filename, res);
		return EFI_NOT_FOUND ;
	}

	//close the file
	file->Close(file);
	volume->Close(volume);

	//set the pointer and data size
	*dataPtr = data;
	*size = file_size;

	//return success
	return EFI_SUCCESS;
}
示例#7
0
// Set the file's size (NB "size", not "physical size"). If the change amounts
// to an increase, simply do a write followed by a flush.
// (This is a helper function for SetFileInfo.)
STATIC
EFI_STATUS
SetFileSize (
  IN BOOTMON_FS_INSTANCE *Instance,
  IN BOOTMON_FS_FILE     *BootMonFsFile,
  IN UINTN                NewSize
  )
{
  UINT64             StoredPosition;
  EFI_STATUS         Status;
  EFI_FILE_PROTOCOL *File;
  CHAR8              Buffer;
  UINTN              BufferSize;
  UINT32             OldSize;

  OldSize = BootMonFsFile->HwDescription.Region[0].Size;

  if (OldSize == NewSize) {
    return EFI_SUCCESS;
  }

  Buffer = 0;
  BufferSize = sizeof (Buffer);

  File = &BootMonFsFile->File;

  if (!(BootMonFsFile->OpenMode & EFI_FILE_MODE_WRITE)) {
    return EFI_ACCESS_DENIED;
  }

  if (NewSize <= OldSize) {
    OldSize = NewSize;
  } else {
    // Increasing a file's size is potentially complicated as it may require
    // moving the image description on media. The simplest way to do it is to
    // seek past the end of the file (which is valid in UEFI) and perform a
    // Write.

    // Save position
    Status = File->GetPosition (File, &StoredPosition);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    Status = File->SetPosition (File, NewSize - 1);
    if (EFI_ERROR (Status)) {
      return Status;
    }
    Status = File->Write (File, &BufferSize, &Buffer);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    // Restore saved position
    Status = File->SetPosition (File, NewSize - 1);
    if (EFI_ERROR (Status)) {
      return Status;
    }

    Status = File->Flush (File);
    if (EFI_ERROR (Status)) {
      return Status;
    }
  }
  return EFI_SUCCESS;
}