OvmfPkg/Library/NvVarsFileLib/NvVarsFileLib.c

/** @file
  Save Non-Volatile Variables to a file system.

  Copyright (c) 2009, Intel Corporation. All rights reserved.<BR>
  SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "NvVarsFileLib.h"
#include <Library/DebugLib.h>
#include <Library/NvVarsFileLib.h>

EFI_HANDLE  mNvVarsFileLibFsHandle = NULL;

/**
  Attempts to connect the NvVarsFileLib to the specified file system.

  @param[in]  FsHandle - Handle for a gEfiSimpleFileSystemProtocolGuid instance

  @return     The EFI_STATUS while attempting to connect the NvVarsFileLib
              to the file system instance.
  @retval     EFI_SUCCESS - The given file system was connected successfully

**/
EFI_STATUS
EFIAPI
ConnectNvVarsToFileSystem (
  IN EFI_HANDLE  FsHandle
  )
{
  EFI_STATUS  Status;

  if (FeaturePcdGet (PcdSecureBootSupported) ||
      FeaturePcdGet (PcdBootRestrictToFirmware))
  {
    return EFI_UNSUPPORTED;
  }

  //
  // We might fail to load the variable, since the file system initially
  // will not have the NvVars file.
  //
  LoadNvVarsFromFs (FsHandle);

  //
  // We must be able to save the variables successfully to the file system
  // to have connected successfully.
  //
  Status = SaveNvVarsToFs (FsHandle);
  if (!EFI_ERROR (Status)) {
    mNvVarsFileLibFsHandle = FsHandle;
  }

  return Status;
}

/**
  Update non-volatile variables stored on the file system.

  @return     The EFI_STATUS while attempting to update the variable on
              the connected file system.
  @retval     EFI_SUCCESS - The non-volatile variables were saved to the disk
  @retval     EFI_NOT_STARTED - A file system has not been connected

**/
EFI_STATUS
EFIAPI
UpdateNvVarsOnFileSystem (
  )
{
  if (mNvVarsFileLibFsHandle == NULL) {
    //
    // A file system had not been connected to the library.
    //
    return EFI_NOT_STARTED;
  } else {
    return SaveNvVarsToFs (mNvVarsFileLibFsHandle);
  }
}