audk/IntelFrameworkModulePkg/Universal/BdsDxe/BootMaint/BmLib.c

/** @file
  Utility routines used by boot maintenance modules.

Copyright (c) 2004 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "BootMaint.h"

/**

  Function opens and returns a file handle to the root directory of a volume.

  @param DeviceHandle    A handle for a device

  @return A valid file handle or NULL is returned

**/
EFI_FILE_HANDLE
EfiLibOpenRoot (
  IN EFI_HANDLE                   DeviceHandle
  )
{
  EFI_STATUS                      Status;
  EFI_SIMPLE_FILE_SYSTEM_PROTOCOL *Volume;
  EFI_FILE_HANDLE                 File;

  File = NULL;

  //
  // File the file system interface to the device
  //
  Status = gBS->HandleProtocol (
                  DeviceHandle,
                  &gEfiSimpleFileSystemProtocolGuid,
                  (VOID *) &Volume
                  );

  //
  // Open the root directory of the volume
  //
  if (!EFI_ERROR (Status)) {
    Status = Volume->OpenVolume (
                      Volume,
                      &File
                      );
  }
  //
  // Done
  //
  return EFI_ERROR (Status) ? NULL : File;
}

/**

  Helper function called as part of the code needed
  to allocate the proper sized buffer for various
  EFI interfaces.


  @param Status          Current status
  @param Buffer          Current allocated buffer, or NULL
  @param BufferSize      Current buffer size needed

  @retval  TRUE  if the buffer was reallocated and the caller
                 should try the API again.
  @retval  FALSE The caller should not call this function again.

**/
BOOLEAN
EfiGrowBuffer (
  IN OUT EFI_STATUS   *Status,
  IN OUT VOID         **Buffer,
  IN UINTN            BufferSize
  )
{
  BOOLEAN TryAgain;

  //
  // If this is an initial request, buffer will be null with a new buffer size
  //
  if ((*Buffer == NULL) && (BufferSize != 0)) {
    *Status = EFI_BUFFER_TOO_SMALL;
  }
  //
  // If the status code is "buffer too small", resize the buffer
  //
  TryAgain = FALSE;
  if (*Status == EFI_BUFFER_TOO_SMALL) {

    if (*Buffer != NULL) {
      FreePool (*Buffer);
    }

    *Buffer = AllocateZeroPool (BufferSize);

    if (*Buffer != NULL) {
      TryAgain = TRUE;
    } else {
      *Status = EFI_OUT_OF_RESOURCES;
    }
  }
  //
  // If there's an error, free the buffer
  //
  if (!TryAgain && EFI_ERROR (*Status) && (*Buffer != NULL)) {
    FreePool (*Buffer);
    *Buffer = NULL;
  }

  return TryAgain;
}

/**
  Function returns the value of the specified variable.


  @param Name            A Null-terminated Unicode string that is
                         the name of the vendor's variable.
  @param VendorGuid      A unique identifier for the vendor.

  @return               The payload of the variable.
  @retval NULL          If the variable can't be read.

**/
VOID *
EfiLibGetVariable (
  IN CHAR16               *Name,
  IN EFI_GUID             *VendorGuid
  )
{
  UINTN VarSize;

  return BdsLibGetVariableAndSize (Name, VendorGuid, &VarSize);
}

/**
  Function deletes the variable specified by VarName and VarGuid.

  @param VarName           A Null-terminated Unicode string that is
                           the name of the vendor's variable.

  @param VarGuid           A unique identifier for the vendor.

  @retval  EFI_SUCCESS           The variable was found and removed
  @retval  EFI_UNSUPPORTED       The variable store was inaccessible
  @retval  EFI_OUT_OF_RESOURCES  The temporary buffer was not available
  @retval  EFI_NOT_FOUND         The variable was not found

**/
EFI_STATUS
EfiLibDeleteVariable (
  IN CHAR16   *VarName,
  IN EFI_GUID *VarGuid
  )
{
  VOID        *VarBuf;
  EFI_STATUS  Status;

  VarBuf  = EfiLibGetVariable (VarName, VarGuid);
  Status  = EFI_NOT_FOUND;

  if (VarBuf != NULL) {
    //
    // Delete variable from Storage
    //
    Status = gRT->SetVariable (
                    VarName,
                    VarGuid,
                    EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
                    0,
                    NULL
                    );
    //
    // Deleting variable with current variable implementation shouldn't fail.
    //
    ASSERT_EFI_ERROR (Status);
    FreePool (VarBuf);
  }

  return Status;
}

/**

  Function gets the file system information from an open file descriptor,
  and stores it in a buffer allocated from pool.


  @param FHand           The file handle.

  @return                A pointer to a buffer with file information.
  @retval                NULL is returned if failed to get Vaolume Label Info.

**/
EFI_FILE_SYSTEM_VOLUME_LABEL *
EfiLibFileSystemVolumeLabelInfo (
  IN EFI_FILE_HANDLE      FHand
  )
{
  EFI_STATUS                        Status;
  EFI_FILE_SYSTEM_VOLUME_LABEL      *Buffer;
  UINTN                             BufferSize;
  //
  // Initialize for GrowBuffer loop
  //
  Buffer      = NULL;
  BufferSize  = SIZE_OF_EFI_FILE_SYSTEM_VOLUME_LABEL + 200;

  //
  // Call the real function
  //
  while (EfiGrowBuffer (&Status, (VOID **) &Buffer, BufferSize)) {
    Status = FHand->GetInfo (
                      FHand,
                      &gEfiFileSystemVolumeLabelInfoIdGuid,
                      &BufferSize,
                      Buffer
                      );
  }

  return Buffer;
}

/**
  Duplicate a string.

  @param Src             The source.

  @return A new string which is duplicated copy of the source.
  @retval NULL If there is not enough memory.

**/
CHAR16 *
EfiStrDuplicate (
  IN CHAR16   *Src
  )
{
  CHAR16  *Dest;
  UINTN   Size;

  Size  = StrSize (Src);
  Dest  = AllocateZeroPool (Size);
  ASSERT (Dest != NULL);
  if (Dest != NULL) {
    CopyMem (Dest, Src, Size);
  }

  return Dest;
}

/**

  Function gets the file information from an open file descriptor, and stores it
  in a buffer allocated from pool.

  @param FHand           File Handle.

  @return                A pointer to a buffer with file information or NULL is returned

**/
EFI_FILE_INFO *
EfiLibFileInfo (
  IN EFI_FILE_HANDLE      FHand
  )
{
  EFI_STATUS    Status;
  EFI_FILE_INFO *Buffer;
  UINTN         BufferSize;

  //
  // Initialize for GrowBuffer loop
  //
  Buffer      = NULL;
  BufferSize  = SIZE_OF_EFI_FILE_INFO + 200;

  //
  // Call the real function
  //
  while (EfiGrowBuffer (&Status, (VOID **) &Buffer, BufferSize)) {
    Status = FHand->GetInfo (
                      FHand,
                      &gEfiFileInfoGuid,
                      &BufferSize,
                      Buffer
                      );
  }

  return Buffer;
}

/**
  Function is used to determine the number of device path instances
  that exist in a device path.


  @param DevicePath      A pointer to a device path data structure.

  @return This function counts and returns the number of device path instances
          in DevicePath.

**/
UINTN
EfiDevicePathInstanceCount (
  IN EFI_DEVICE_PATH_PROTOCOL      *DevicePath
  )
{
  UINTN Count;
  UINTN Size;

  Count = 0;
  while (GetNextDevicePathInstance (&DevicePath, &Size) != NULL) {
    Count += 1;
  }

  return Count;
}


/**
  Get a string from the Data Hub record based on
  a device path.

  @param DevPath         The device Path.

  @return A string located from the Data Hub records based on
          the device path.
  @retval NULL  If failed to get the String from Data Hub.

**/
UINT16 *
EfiLibStrFromDatahub (
  IN EFI_DEVICE_PATH_PROTOCOL                 *DevPath
  )
{
  return NULL;
}

/**

  Find the first instance of this Protocol
  in the system and return it's interface.


  @param ProtocolGuid    Provides the protocol to search for
  @param Interface       On return, a pointer to the first interface
                         that matches ProtocolGuid

  @retval  EFI_SUCCESS      A protocol instance matching ProtocolGuid was found
  @retval  EFI_NOT_FOUND    No protocol instances were found that match ProtocolGuid

**/
EFI_STATUS
EfiLibLocateProtocol (
  IN  EFI_GUID    *ProtocolGuid,
  OUT VOID        **Interface
  )
{
  EFI_STATUS  Status;

  Status = gBS->LocateProtocol (
                  ProtocolGuid,
                  NULL,
                  (VOID **) Interface
                  );
  return Status;
}