variable.c

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  VariableName                Name of the variable to be found
  VendorGuid                  Vendor GUID to be found.
  PtrTrack                    Variable Track Pointer structure that contains
                              Variable Information.
                              Contains the pointer of Variable header.
  Global                      VARIABLE_GLOBAL pointer

Returns:

  EFI STATUS

--*/
{
  VARIABLE_HEADER       *Variable[2];
  VARIABLE_STORE_HEADER *VariableStoreHeader[2];
  UINTN                 Index;
  VARIABLE_HEADER       *TempVariable;
  UINTN                 TempIndex;

  TempVariable = NULL;
  TempIndex    = (UINTN)-1;

  //
  // 0: Non-Volatile, 1: Volatile
  //
  VariableStoreHeader[0]  = (VARIABLE_STORE_HEADER *) ((UINTN) Global->NonVolatileVariableBase);
  VariableStoreHeader[1]  = (VARIABLE_STORE_HEADER *) ((UINTN) Global->VolatileVariableBase);

  //
  // Start Pointers for the variable.
  // Actual Data Pointer where data can be written.
  //
  Variable[0] = (VARIABLE_HEADER *) (VariableStoreHeader[0] + 1);
  Variable[1] = (VARIABLE_HEADER *) (VariableStoreHeader[1] + 1);

  if (VariableName[0] != 0 && VendorGuid == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  //
  // Find the variable by walk through non-volatile and volatile variable store
  //
  for (Index = 0; Index < 2; Index++) {
    PtrTrack->StartPtr  = (VARIABLE_HEADER *) (VariableStoreHeader[Index] + 1);
    PtrTrack->EndPtr    = GetEndPointer (VariableStoreHeader[Index]);

    while (IsValidVariableHeader (Variable[Index]) && (Variable[Index] <= GetEndPointer (VariableStoreHeader[Index]))) {
      if (Variable[Index]->State == VAR_ADDED) {
        if (!(EfiAtRuntime () && !(Variable[Index]->Attributes & EFI_VARIABLE_RUNTIME_ACCESS))) {
          if (VariableName[0] == 0) {
            PtrTrack->CurrPtr   = Variable[Index];
            PtrTrack->Volatile  = (BOOLEAN) Index;
            return EFI_SUCCESS;
          } else {
            if (EfiCompareGuid (VendorGuid, &Variable[Index]->VendorGuid)) {
              if (!EfiCompareMem (VariableName, GET_VARIABLE_NAME_PTR (Variable[Index]), ArrayLength (VariableName))) {
                PtrTrack->CurrPtr   = Variable[Index];
                PtrTrack->Volatile  = (BOOLEAN) Index;
                return EFI_SUCCESS;
              }
            }
          }
        }
      } else if (Variable[Index]->State == (VAR_ADDED & VAR_IN_DELETED_TRANSITION)) {
        //
        // VAR_IN_DELETED_TRANSITION should also be checked.
        //
        if (!(EfiAtRuntime () && !(Variable[Index]->Attributes & EFI_VARIABLE_RUNTIME_ACCESS))) {
          if (VariableName[0] == 0) {
            TempVariable = Variable[Index];
            TempIndex    = Index;
          } else {
            if (EfiCompareGuid (VendorGuid, &Variable[Index]->VendorGuid)) {
              if (!EfiCompareMem (VariableName, GET_VARIABLE_NAME_PTR (Variable[Index]), ArrayLength (VariableName))) {
                TempVariable = Variable[Index];
                TempIndex    = Index;
              }
            }
          }
        }
      }

      Variable[Index] = GetNextVariablePtr (Variable[Index]);
    }
    //
    // While (...)
    //
  }
  //
  // for (...)
  //
  
  //
  // if VAR_IN_DELETED_TRANSITION found, and VAR_ADDED not found,
  // we return it.
  //
  if (TempVariable != NULL) {
    PtrTrack->CurrPtr   = TempVariable;
    PtrTrack->Volatile  = (BOOLEAN) TempIndex;
    return EFI_SUCCESS;
  }
  
  PtrTrack->CurrPtr = NULL;
  return EFI_NOT_FOUND;
}

EFI_STATUS
EFIAPI
GetVariable (
  IN      CHAR16            *VariableName,
  IN      EFI_GUID          * VendorGuid,
  OUT     UINT32            *Attributes OPTIONAL,
  IN OUT  UINTN             *DataSize,
  OUT     VOID              *Data,
  IN      VARIABLE_GLOBAL   * Global,
  IN      UINT32            Instance
  )
/*++

Routine Description:

  This code finds variable in storage blocks (Volatile or Non-Volatile)

Arguments:

  VariableName                    Name of Variable to be found
  VendorGuid                      Variable vendor GUID
  Attributes OPTIONAL             Attribute value of the variable found
  DataSize                        Size of Data found. If size is less than the
                                  data, this value contains the required size.
  Data                            Data pointer
  Global                          Pointer to VARIABLE_GLOBAL structure
  Instance                        Instance of the Firmware Volume.

Returns:

  EFI STATUS

--*/
{
  VARIABLE_POINTER_TRACK  Variable;
  UINTN                   VarDataSize;
  EFI_STATUS              Status;

  if (VariableName == NULL || VendorGuid == NULL || DataSize == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  //
  // Find existing variable
  //
  Status = FindVariable (VariableName, VendorGuid, &Variable, Global);

  if (Variable.CurrPtr == NULL || EFI_ERROR (Status)) {
    return Status;
  }
  //
  // Get data size
  //
  VarDataSize = Variable.CurrPtr->DataSize;
  if (*DataSize >= VarDataSize) {
    if (Data == NULL) {
      return EFI_INVALID_PARAMETER;
    }

    EfiCopyMem (Data, GetVariableDataPtr (Variable.CurrPtr), VarDataSize);
    if (Attributes != NULL) {
      *Attributes = Variable.CurrPtr->Attributes;
    }

    *DataSize = VarDataSize;
    return EFI_SUCCESS;
  } else {
    *DataSize = VarDataSize;
    return EFI_BUFFER_TOO_SMALL;
  }
}

EFI_STATUS
EFIAPI
GetNextVariableName (
  IN OUT  UINTN             *VariableNameSize,
  IN OUT  CHAR16            *VariableName,
  IN OUT  EFI_GUID          *VendorGuid,
  IN      VARIABLE_GLOBAL   *Global,
  IN      UINT32            Instance
  )
/*++

Routine Description:

  This code Finds the Next available variable

Arguments:

  VariableNameSize            Size of the variable
  VariableName                Pointer to variable name
  VendorGuid                  Variable Vendor Guid
  Global                      VARIABLE_GLOBAL structure pointer.
  Instance                    FV instance

Returns:

  EFI STATUS

--*/
{
  VARIABLE_POINTER_TRACK  Variable;
  UINTN                   VarNameSize;
  EFI_STATUS              Status;

  if (VariableNameSize == NULL || VariableName == NULL || VendorGuid == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Status = FindVariable (VariableName, VendorGuid, &Variable, Global);

  if (Variable.CurrPtr == NULL || EFI_ERROR (Status)) {
    return Status;
  }

  if (VariableName[0] != 0) {
    //
    // If variable name is not NULL, get next variable
    //
    Variable.CurrPtr = GetNextVariablePtr (Variable.CurrPtr);
  }

  while (TRUE) {
    //
    // If both volatile and non-volatile variable store are parsed,
    // return not found
    //
    if (Variable.CurrPtr >= Variable.EndPtr || Variable.CurrPtr == NULL) {
      Variable.Volatile = (BOOLEAN) (Variable.Volatile ^ ((BOOLEAN) 0x1));
      if (Variable.Volatile) {
        Variable.StartPtr = (VARIABLE_HEADER *) ((UINTN) (Global->VolatileVariableBase + sizeof (VARIABLE_STORE_HEADER)));
        Variable.EndPtr = (VARIABLE_HEADER *) GetEndPointer ((VARIABLE_STORE_HEADER *) ((UINTN) Global->VolatileVariableBase));
      } else {
        return EFI_NOT_FOUND;
      }

      Variable.CurrPtr = Variable.StartPtr;
      if (!IsValidVariableHeader (Variable.CurrPtr)) {
        continue;
      }
    }
    //
    // Variable is found
    //
    if (IsValidVariableHeader (Variable.CurrPtr) && 
        ((Variable.CurrPtr->State == VAR_ADDED) ||
         (Variable.CurrPtr->State == (VAR_ADDED & VAR_IN_DELETED_TRANSITION)))) {
      if (!(EfiAtRuntime () && !(Variable.CurrPtr->Attributes & EFI_VARIABLE_RUNTIME_ACCESS))) {
        VarNameSize = Variable.CurrPtr->NameSize;
        if (VarNameSize <= *VariableNameSize) {
          EfiCopyMem (
            VariableName,
            GET_VARIABLE_NAME_PTR (Variable.CurrPtr),
            VarNameSize
            );
          EfiCopyMem (
            VendorGuid,
            &Variable.CurrPtr->VendorGuid,
            sizeof (EFI_GUID)
            );
          Status = EFI_SUCCESS;
        } else {
          Status = EFI_BUFFER_TOO_SMALL;
        }

        *VariableNameSize = VarNameSize;
        return Status;
      }
    }

    Variable.CurrPtr = GetNextVariablePtr (Variable.CurrPtr);
  }

  return EFI_NOT_FOUND;
}

EFI_STATUS
EFIAPI
SetVariable (
  IN CHAR16                  *VariableName,
  IN EFI_GUID                *VendorGuid,
  IN UINT32                  Attributes,
  IN UINTN                   DataSize,
  IN VOID                    *Data,
  IN VARIABLE_GLOBAL         *Global,
  IN UINTN                   *VolatileOffset,
  IN UINTN                   *NonVolatileOffset,
  IN UINT32                  Instance
  )
/*++

Routine Description:

  This code sets variable in storage blocks (Volatile or Non-Volatile)

Arguments:

  VariableName                    Name of Variable to be found
  VendorGuid                      Variable vendor GUID
  Attributes                      Attribute value of the variable found
  DataSize                        Size of Data found. If size is less than the
                                  data, this value contains the required size.
  Data                            Data pointer
  Global                          Pointer to VARIABLE_GLOBAL structure
  VolatileOffset                  The offset of last volatile variable
  NonVolatileOffset               The offset of last non-volatile variable
  Instance                        Instance of the Firmware Volume.

Returns:

  EFI STATUS
  EFI_INVALID_PARAMETER           - Invalid parameter
  EFI_SUCCESS                     - Set successfully
  EFI_OUT_OF_RESOURCES            - Resource not enough to set variable
  EFI_NOT_FOUND                   - Not found

--*/
{
  VARIABLE_POINTER_TRACK  Variable;
  EFI_STATUS              Status;
  VARIABLE_HEADER         *NextVariable;
  UINTN                   VarNameSize;
  UINTN                   VarNameOffset;
  UINTN                   VarDataOffset;
  UINTN                   VarSize;
  UINT8                   State;
  BOOLEAN                 Reclaimed;
  
  Reclaimed = FALSE;

  if (VariableName == NULL || VariableName[0] == 0 || VendorGuid == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Status = FindVariable (VariableName, VendorGuid, &Variable, Global);

  if (Status == EFI_INVALID_PARAMETER) {
    return Status;
  }
  //
  //  The size of the VariableName, including the Unicode Null in bytes plus
  //  the DataSize is limited to maximum size of MAX_VARIABLE_SIZE (1024) bytes.
  //
  else if ((DataSize > MAX_VARIABLE_SIZE) ||
           (sizeof (VARIABLE_HEADER) + ArrayLength (VariableName) + DataSize > MAX_VARIABLE_SIZE)) {
    return EFI_INVALID_PARAMETER;
  }
  //
  //  Make sure if runtime bit is set, boot service bit is set also
  //
  else if ((Attributes & (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)) == EFI_VARIABLE_RUNTIME_ACCESS
          ) {
    return EFI_INVALID_PARAMETER;
  }
  //
  // Runtime but Attribute is not Runtime
  //
  else if (EfiAtRuntime () && Attributes && !(Attributes & EFI_VARIABLE_RUNTIME_ACCESS)) {
    return EFI_INVALID_PARAMETER;
  }
  //
  // Cannot set volatile variable in Runtime
  //
  else if (EfiAtRuntime () && Attributes && !(Attributes & EFI_VARIABLE_NON_VOLATILE)) {
    return EFI_INVALID_PARAMETER;
  }
  //
  // Setting a data variable with no access, or zero DataSize attributes
  // specified causes it to be deleted.
  //
  else if (DataSize == 0 || Attributes == 0) {
    if (!EFI_ERROR (Status)) {
      State = Variable.CurrPtr->State;
      State &= VAR_DELETED;

      Status = UpdateVariableStore (
                Global,
                Variable.Volatile,
                FALSE,
                Instance,
                (UINTN) &Variable.CurrPtr->State,
                sizeof (UINT8),
                &State
                );
      if (EFI_ERROR (Status)) {
        return Status;
      }

      return EFI_SUCCESS;
    }

    return EFI_NOT_FOUND;
  } else {
    if (!EFI_ERROR (Status)) {
      //
      // If the variable is marked valid and the same data has been passed in
      // then return to the caller immediately.
      //
      if (Variable.CurrPtr->DataSize == DataSize &&
          !EfiCompareMem (Data, GetVariableDataPtr (Variable.CurrPtr), DataSize)
            ) {
        return EFI_SUCCESS;
      } else if ((Variable.CurrPtr->State == VAR_ADDED) ||
                 (Variable.CurrPtr->State == (VAR_ADDED & VAR_IN_DELETED_TRANSITION))) {
        //
        // Mark the old variable as in delete transition
        //
        State = Variable.CurrPtr->State;
        State &= VAR_IN_DELETED_TRANSITION;

        Status = UpdateVariableStore (
                  Global,
                  Variable.Volatile,
                  FALSE,
                  Instance,
                  (UINTN) &Variable.CurrPtr->State,
                  sizeof (UINT8),
                  &State
                  );
        if (EFI_ERROR (Status)) {
          return Status;
        }
      }
    }
    //
    // Create a new variable and copy the data.
    //
    // Tricky part: Use scratch data area at the end of volatile variable store
    // as a temporary storage.
    //
    NextVariable = GetEndPointer ((VARIABLE_STORE_HEADER *) ((UINTN) Global->VolatileVariableBase));

    EfiSetMem (NextVariable, SCRATCH_SIZE, 0xff);

    NextVariable->StartId     = VARIABLE_DATA;
    NextVariable->Attributes  = Attributes;
    //
    // NextVariable->State = VAR_ADDED;
    //
    NextVariable->Reserved  = 0;
    VarNameOffset           = sizeof (VARIABLE_HEADER);
    VarNameSize             = ArrayLength (VariableName);
    EfiCopyMem (
      (UINT8 *) ((UINTN) NextVariable + VarNameOffset),
      VariableName,
      VarNameSize
      );
    VarDataOffset = VarNameOffset + VarNameSize + GET_PAD_SIZE (VarNameSize);
    EfiCopyMem (
      (UINT8 *) ((UINTN) NextVariable + VarDataOffset),
      Data,
      DataSize
      );
    EfiCopyMem (&NextVariable->VendorGuid, VendorGuid, sizeof (EFI_GUID));
    //
    // There will be pad bytes after Data, the NextVariable->NameSize and
    // NextVariable->DataSize should not include pad size so that variable
    // service can get actual size in GetVariable
    //
    NextVariable->NameSize  = (UINT32)VarNameSize;
    NextVariable->DataSize  = (UINT32)DataSize;

    //
    // The actual size of the variable that stores in storage should
    // include pad size.
    //
    VarSize = VarDataOffset + DataSize + GET_PAD_SIZE (DataSize);
    if (Attributes & EFI_VARIABLE_NON_VOLATILE) {
      if ((UINT32) (VarSize +*NonVolatileOffset) >
            ((VARIABLE_STORE_HEADER *) ((UINTN) (Global->NonVolatileVariableBase)))->Size
            ) {
        if (EfiAtRuntime ()) {
          return EFI_OUT_OF_RESOURCES;
        }
        //
        // Perform garbage collection & reclaim operation
        //
        Status = Reclaim (Global->NonVolatileVariableBase, NonVolatileOffset, FALSE, Variable.CurrPtr);
        if (EFI_ERROR (Status)) {
          return Status;
        }
        //
        // If still no enough space, return out of resources
        //
        if ((UINT32) (VarSize +*NonVolatileOffset) >
              ((VARIABLE_STORE_HEADER *) ((UINTN) (Global->NonVolatileVariableBase)))->Size
              ) {
          return EFI_OUT_OF_RESOURCES;
        }
        
        Reclaimed = TRUE;
      }
      //
      // Three steps
      // 1. Write variable header
      // 2. Write variable data
      // 3. Set variable state to valid
      //
      //
      // Step 1:
      //
      Status = UpdateVariableStore (
                Global,
                FALSE,
                TRUE,
                Instance,
                *NonVolatileOffset,
                sizeof (VARIABLE_HEADER),
                (UINT8 *) NextVariable