Ffs.c

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#include "DxeMain.h"
#include "FwVolDriver.h"
 
EFI_FFS_FILE_STATE
GetFileState (
  IN UINT8                ErasePolarity,
  IN EFI_FFS_FILE_HEADER  *FfsHeader
  )
{
  EFI_FFS_FILE_STATE  FileState;
  UINT8               HighestBit;
 
  FileState = FfsHeader->State;
 
  if (ErasePolarity != 0) {
    FileState = (EFI_FFS_FILE_STATE) ~FileState;
  }
 
  HighestBit = 0x80;
  while (HighestBit != 0 && ((HighestBit & FileState) == 0)) {
    HighestBit >>= 1;
  }
 
  return (EFI_FFS_FILE_STATE)HighestBit;
}
 
BOOLEAN
IsBufferErased (
  IN UINT8  ErasePolarity,
  IN VOID   *InBuffer,
  IN UINTN  BufferSize
  )
{
  UINTN  Count;
  UINT8  EraseByte;
  UINT8  *Buffer;
 
  if (ErasePolarity == 1) {
    EraseByte = 0xFF;
  } else {
    EraseByte = 0;
  }
 
  Buffer = InBuffer;
  for (Count = 0; Count < BufferSize; Count++) {
    if (Buffer[Count] != EraseByte) {
      return FALSE;
    }
  }
 
  return TRUE;
}
 
BOOLEAN
VerifyFvHeaderChecksum (
  IN EFI_FIRMWARE_VOLUME_HEADER  *FvHeader
  )
{
  UINT16  Checksum;
 
  Checksum = CalculateSum16 ((UINT16 *)FvHeader, FvHeader->HeaderLength);
 
  if (Checksum == 0) {
    return TRUE;
  } else {
    return FALSE;
  }
}
 
BOOLEAN
VerifyHeaderChecksum (
  IN EFI_FFS_FILE_HEADER  *FfsHeader
  )
{
  UINT8  HeaderChecksum;
 
  if (IS_FFS_FILE2 (FfsHeader)) {
    HeaderChecksum = CalculateSum8 ((UINT8 *)FfsHeader, sizeof (EFI_FFS_FILE_HEADER2));
  } else {
    HeaderChecksum = CalculateSum8 ((UINT8 *)FfsHeader, sizeof (EFI_FFS_FILE_HEADER));
  }
 
  HeaderChecksum = (UINT8)(HeaderChecksum - FfsHeader->State - FfsHeader->IntegrityCheck.Checksum.File);
 
  if (HeaderChecksum == 0) {
    return TRUE;
  } else {
    return FALSE;
  }
}
 
BOOLEAN
IsValidFfsHeader (
  IN UINT8                ErasePolarity,
  IN EFI_FFS_FILE_HEADER  *FfsHeader,
  OUT EFI_FFS_FILE_STATE  *FileState
  )
{
  *FileState = GetFileState (ErasePolarity, FfsHeader);
 
  switch (*FileState) {
    case EFI_FILE_HEADER_VALID:
    case EFI_FILE_DATA_VALID:
    case EFI_FILE_MARKED_FOR_UPDATE:
    case EFI_FILE_DELETED:
      //
      // Here we need to verify header checksum
      //
      return VerifyHeaderChecksum (FfsHeader);
 
    case EFI_FILE_HEADER_CONSTRUCTION:
    case EFI_FILE_HEADER_INVALID:
    default:
      return FALSE;
  }
}
 
BOOLEAN
IsValidFfsFile (
  IN UINT8                ErasePolarity,
  IN EFI_FFS_FILE_HEADER  *FfsHeader
  )
{
  EFI_FFS_FILE_STATE  FileState;
  UINT8               DataCheckSum;
 
  FileState = GetFileState (ErasePolarity, FfsHeader);
  switch (FileState) {
    case EFI_FILE_DELETED:
    case EFI_FILE_DATA_VALID:
    case EFI_FILE_MARKED_FOR_UPDATE:
      DataCheckSum = FFS_FIXED_CHECKSUM;
      if ((FfsHeader->Attributes & FFS_ATTRIB_CHECKSUM) == FFS_ATTRIB_CHECKSUM) {
        if (IS_FFS_FILE2 (FfsHeader)) {
          DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *)FfsHeader + sizeof (EFI_FFS_FILE_HEADER2), FFS_FILE2_SIZE (FfsHeader) - sizeof (EFI_FFS_FILE_HEADER2));
        } else {
          DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *)FfsHeader + sizeof (EFI_FFS_FILE_HEADER), FFS_FILE_SIZE (FfsHeader) - sizeof (EFI_FFS_FILE_HEADER));
        }
      }
 
      if (FfsHeader->IntegrityCheck.Checksum.File == DataCheckSum) {
        return TRUE;
      }
 
    default:
      return FALSE;
  }
}