MdeModulePkg/Core/Dxe/FwVol/Ffs.c

   1 /** @file
   2   FFS file access utilities.
   3
   4 Copyright (c) 2006 - 2008, Intel Corporation. <BR>
   5 All rights reserved. This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15
  16 #include <DxeMain.h>
  17
  18
  19 /**
  20   Get the FFS file state by checking the highest bit set in the header's state field.
  21
  22   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  23   @param  FfsHeader      Points to the FFS file header
  24
  25   @return FFS File state
  26
  27 **/
  28 EFI_FFS_FILE_STATE
  29 GetFileState (
  30   IN UINT8                ErasePolarity,
  31   IN EFI_FFS_FILE_HEADER  *FfsHeader
  32   )
  33 {
  34   EFI_FFS_FILE_STATE      FileState;
  35   UINT8                   HighestBit;
  36
  37   FileState = FfsHeader->State;
  38
  39   if (ErasePolarity != 0) {
  40     FileState = (EFI_FFS_FILE_STATE)~FileState;
  41   }
  42
  43   HighestBit = 0x80;
  44   while (HighestBit != 0 && ((HighestBit & FileState) == 0)) {
  45     HighestBit >>= 1;
  46   }
  47
  48   return (EFI_FFS_FILE_STATE) HighestBit;
  49 }
  50
  51
  52
  53 /**
  54   Check if a block of buffer is erased.
  55
  56   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  57   @param  InBuffer       The buffer to be checked
  58   @param  BufferSize     Size of the buffer in bytes
  59
  60   @retval TRUE           The block of buffer is erased
  61   @retval FALSE          The block of buffer is not erased
  62
  63 **/
  64 BOOLEAN
  65 IsBufferErased (
  66   IN UINT8    ErasePolarity,
  67   IN VOID     *InBuffer,
  68   IN UINTN    BufferSize
  69   )
  70 {
  71   UINTN   Count;
  72   UINT8   EraseByte;
  73   UINT8   *Buffer;
  74
  75   if(ErasePolarity == 1) {
  76     EraseByte = 0xFF;
  77   } else {
  78     EraseByte = 0;
  79   }
  80
  81   Buffer = InBuffer;
  82   for (Count = 0; Count < BufferSize; Count++) {
  83     if (Buffer[Count] != EraseByte) {
  84       return FALSE;
  85     }
  86   }
  87
  88   return TRUE;
  89 }
  90
  91
  92
  93 /**
  94   Verify checksum of the firmware volume header.
  95
  96   @param  FvHeader       Points to the firmware volume header to be checked
  97
  98   @retval TRUE           Checksum verification passed
  99   @retval FALSE          Checksum verification failed
 100
 101 **/
 102 BOOLEAN
 103 VerifyFvHeaderChecksum (
 104   IN EFI_FIRMWARE_VOLUME_HEADER *FvHeader
 105   )
 106 {
 107   UINT32  Index;
 108   UINT32  HeaderLength;
 109   UINT16  Checksum;
 110   UINT16  *Ptr;
 111
 112   HeaderLength = FvHeader->HeaderLength;
 113   Ptr = (UINT16 *)FvHeader;
 114   Checksum = 0;
 115
 116   for (Index = 0; Index < HeaderLength / sizeof (UINT16); Index++) {
 117     Checksum = (UINT16)(Checksum + Ptr[Index]);
 118   }
 119
 120   if (Checksum == 0) {
 121     return TRUE;
 122   } else {
 123     return FALSE;
 124   }
 125 }
 126
 127
 128 /**
 129   Verify checksum of the FFS file header.
 130
 131   @param  FfsHeader      Points to the FFS file header to be checked
 132
 133   @retval TRUE           Checksum verification passed
 134   @retval FALSE          Checksum verification failed
 135
 136 **/
 137 BOOLEAN
 138 VerifyHeaderChecksum (
 139   IN EFI_FFS_FILE_HEADER  *FfsHeader
 140   )
 141 {
 142   UINT32            Index;
 143   UINT8             *Ptr;
 144   UINT8             HeaderChecksum;
 145
 146   Ptr = (UINT8 *)FfsHeader;
 147   HeaderChecksum = 0;
 148   for (Index = 0; Index < sizeof(EFI_FFS_FILE_HEADER); Index++) {
 149     HeaderChecksum = (UINT8)(HeaderChecksum + Ptr[Index]);
 150   }
 151
 152   HeaderChecksum = (UINT8) (HeaderChecksum - FfsHeader->State - FfsHeader->IntegrityCheck.Checksum.File);
 153
 154   if (HeaderChecksum == 0) {
 155     return TRUE;
 156   } else {
 157     return FALSE;
 158   }
 159 }
 160
 161
 162
 163 /**
 164   Check if it's a valid FFS file header.
 165
 166   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 167   @param  FfsHeader      Points to the FFS file header to be checked
 168   @param  FileState      FFS file state to be returned
 169
 170   @retval TRUE           Valid FFS file header
 171   @retval FALSE          Invalid FFS file header
 172
 173 **/
 174 BOOLEAN
 175 IsValidFfsHeader (
 176   IN UINT8                ErasePolarity,
 177   IN EFI_FFS_FILE_HEADER  *FfsHeader,
 178   OUT EFI_FFS_FILE_STATE  *FileState
 179   )
 180 {
 181   *FileState = GetFileState (ErasePolarity, FfsHeader);
 182
 183   switch (*FileState) {
 184   case EFI_FILE_HEADER_VALID:
 185   case EFI_FILE_DATA_VALID:
 186   case EFI_FILE_MARKED_FOR_UPDATE:
 187   case EFI_FILE_DELETED:
 188     //
 189     // Here we need to verify header checksum
 190     //
 191     return VerifyHeaderChecksum (FfsHeader);
 192
 193   case EFI_FILE_HEADER_CONSTRUCTION:
 194   case EFI_FILE_HEADER_INVALID:
 195   default:
 196     return FALSE;
 197   }
 198 }
 199
 200
 201 /**
 202   Check if it's a valid FFS file.
 203   Here we are sure that it has a valid FFS file header since we must call IsValidFfsHeader() first.
 204
 205   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 206   @param  FfsHeader      Points to the FFS file to be checked
 207
 208   @retval TRUE           Valid FFS file
 209   @retval FALSE          Invalid FFS file
 210
 211 **/
 212 BOOLEAN
 213 IsValidFfsFile (
 214   IN UINT8                ErasePolarity,
 215   IN EFI_FFS_FILE_HEADER  *FfsHeader
 216   )
 217 {
 218   EFI_FFS_FILE_STATE  FileState;
 219
 220   FileState = GetFileState (ErasePolarity, FfsHeader);
 221   switch (FileState) {
 222
 223   case EFI_FILE_DELETED:
 224   case EFI_FILE_DATA_VALID:
 225   case EFI_FILE_MARKED_FOR_UPDATE:
 226     //
 227     // Some other vliadation like file content checksum might be done here.
 228     // For performance issue, Tiano only do FileState check.
 229     //
 230     return TRUE;
 231
 232   default:
 233     return FALSE;
 234   }
 235 }
 236
 237