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 #include "FwVolDriver.h"
  18
  19
  20 /**
  21   Get the FFS file state by checking the highest bit set in the header's state field.
  22
  23   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  24   @param  FfsHeader      Points to the FFS file header
  25
  26   @return FFS File state
  27
  28 **/
  29 EFI_FFS_FILE_STATE
  30 GetFileState (
  31   IN UINT8                ErasePolarity,
  32   IN EFI_FFS_FILE_HEADER  *FfsHeader
  33   )
  34 {
  35   EFI_FFS_FILE_STATE      FileState;
  36   UINT8                   HighestBit;
  37
  38   FileState = FfsHeader->State;
  39
  40   if (ErasePolarity != 0) {
  41     FileState = (EFI_FFS_FILE_STATE)~FileState;
  42   }
  43
  44   HighestBit = 0x80;
  45   while (HighestBit != 0 && ((HighestBit & FileState) == 0)) {
  46     HighestBit >>= 1;
  47   }
  48
  49   return (EFI_FFS_FILE_STATE) HighestBit;
  50 }
  51
  52
  53
  54 /**
  55   Check if a block of buffer is erased.
  56
  57   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  58   @param  InBuffer       The buffer to be checked
  59   @param  BufferSize     Size of the buffer in bytes
  60
  61   @retval TRUE           The block of buffer is erased
  62   @retval FALSE          The block of buffer is not erased
  63
  64 **/
  65 BOOLEAN
  66 IsBufferErased (
  67   IN UINT8    ErasePolarity,
  68   IN VOID     *InBuffer,
  69   IN UINTN    BufferSize
  70   )
  71 {
  72   UINTN   Count;
  73   UINT8   EraseByte;
  74   UINT8   *Buffer;
  75
  76   if(ErasePolarity == 1) {
  77     EraseByte = 0xFF;
  78   } else {
  79     EraseByte = 0;
  80   }
  81
  82   Buffer = InBuffer;
  83   for (Count = 0; Count < BufferSize; Count++) {
  84     if (Buffer[Count] != EraseByte) {
  85       return FALSE;
  86     }
  87   }
  88
  89   return TRUE;
  90 }
  91
  92
  93
  94 /**
  95   Verify checksum of the firmware volume header.
  96
  97   @param  FvHeader       Points to the firmware volume header to be checked
  98
  99   @retval TRUE           Checksum verification passed
 100   @retval FALSE          Checksum verification failed
 101
 102 **/
 103 BOOLEAN
 104 VerifyFvHeaderChecksum (
 105   IN EFI_FIRMWARE_VOLUME_HEADER *FvHeader
 106   )
 107 {
 108   UINT32  Index;
 109   UINT32  HeaderLength;
 110   UINT16  Checksum;
 111   UINT16  *Ptr;
 112
 113   HeaderLength = FvHeader->HeaderLength;
 114   Ptr = (UINT16 *)FvHeader;
 115   Checksum = 0;
 116
 117   for (Index = 0; Index < HeaderLength / sizeof (UINT16); Index++) {
 118     Checksum = (UINT16)(Checksum + Ptr[Index]);
 119   }
 120
 121   if (Checksum == 0) {
 122     return TRUE;
 123   } else {
 124     return FALSE;
 125   }
 126 }
 127
 128
 129 /**
 130   Verify checksum of the FFS file header.
 131
 132   @param  FfsHeader      Points to the FFS file header to be checked
 133
 134   @retval TRUE           Checksum verification passed
 135   @retval FALSE          Checksum verification failed
 136
 137 **/
 138 BOOLEAN
 139 VerifyHeaderChecksum (
 140   IN EFI_FFS_FILE_HEADER  *FfsHeader
 141   )
 142 {
 143   UINT32            Index;
 144   UINT8             *Ptr;
 145   UINT8             HeaderChecksum;
 146
 147   Ptr = (UINT8 *)FfsHeader;
 148   HeaderChecksum = 0;
 149   for (Index = 0; Index < sizeof(EFI_FFS_FILE_HEADER); Index++) {
 150     HeaderChecksum = (UINT8)(HeaderChecksum + Ptr[Index]);
 151   }
 152
 153   HeaderChecksum = (UINT8) (HeaderChecksum - FfsHeader->State - FfsHeader->IntegrityCheck.Checksum.File);
 154
 155   if (HeaderChecksum == 0) {
 156     return TRUE;
 157   } else {
 158     return FALSE;
 159   }
 160 }
 161
 162
 163
 164 /**
 165   Check if it's a valid FFS file header.
 166
 167   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 168   @param  FfsHeader      Points to the FFS file header to be checked
 169   @param  FileState      FFS file state to be returned
 170
 171   @retval TRUE           Valid FFS file header
 172   @retval FALSE          Invalid FFS file header
 173
 174 **/
 175 BOOLEAN
 176 IsValidFfsHeader (
 177   IN UINT8                ErasePolarity,
 178   IN EFI_FFS_FILE_HEADER  *FfsHeader,
 179   OUT EFI_FFS_FILE_STATE  *FileState
 180   )
 181 {
 182   *FileState = GetFileState (ErasePolarity, FfsHeader);
 183
 184   switch (*FileState) {
 185   case EFI_FILE_HEADER_VALID:
 186   case EFI_FILE_DATA_VALID:
 187   case EFI_FILE_MARKED_FOR_UPDATE:
 188   case EFI_FILE_DELETED:
 189     //
 190     // Here we need to verify header checksum
 191     //
 192     return VerifyHeaderChecksum (FfsHeader);
 193
 194   case EFI_FILE_HEADER_CONSTRUCTION:
 195   case EFI_FILE_HEADER_INVALID:
 196   default:
 197     return FALSE;
 198   }
 199 }
 200
 201
 202 /**
 203   Check if it's a valid FFS file.
 204   Here we are sure that it has a valid FFS file header since we must call IsValidFfsHeader() first.
 205
 206   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 207   @param  FfsHeader      Points to the FFS file to be checked
 208
 209   @retval TRUE           Valid FFS file
 210   @retval FALSE          Invalid FFS file
 211
 212 **/
 213 BOOLEAN
 214 IsValidFfsFile (
 215   IN UINT8                ErasePolarity,
 216   IN EFI_FFS_FILE_HEADER  *FfsHeader
 217   )
 218 {
 219   EFI_FFS_FILE_STATE  FileState;
 220
 221   FileState = GetFileState (ErasePolarity, FfsHeader);
 222   switch (FileState) {
 223
 224   case EFI_FILE_DELETED:
 225   case EFI_FILE_DATA_VALID:
 226   case EFI_FILE_MARKED_FOR_UPDATE:
 227     //
 228     // Some other vliadation like file content checksum might be done here.
 229     // For performance issue, Tiano only do FileState check.
 230     //
 231     return TRUE;
 232
 233   default:
 234     return FALSE;
 235   }
 236 }
 237
 238