MdePkg/Include/Ppi/ReadOnlyVariable2.h

   1 /** @file
   2   This file declares Read-only Variable Service2 PPI.
   3   This ppi permits read-only access to the UEFI variable store during the PEI phase.
   4
   5 Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
   6 SPDX-License-Identifier: BSD-2-Clause-Patent
   7
   8   @par Revision Reference:
   9   This PPI is introduced in PI Version 1.0.
  10
  11 **/
  12
  13 #ifndef __PEI_READ_ONLY_VARIABLE2_PPI_H__
  14 #define __PEI_READ_ONLY_VARIABLE2_PPI_H__
  15
  16 #define EFI_PEI_READ_ONLY_VARIABLE2_PPI_GUID \
  17   { 0x2ab86ef5, 0xecb5, 0x4134, { 0xb5, 0x56, 0x38, 0x54, 0xca, 0x1f, 0xe1, 0xb4 } }
  18
  19
  20 typedef struct _EFI_PEI_READ_ONLY_VARIABLE2_PPI  EFI_PEI_READ_ONLY_VARIABLE2_PPI;
  21
  22 /**
  23   This service retrieves a variable's value using its name and GUID.
  24
  25   Read the specified variable from the UEFI variable store. If the Data
  26   buffer is too small to hold the contents of the variable,
  27   the error EFI_BUFFER_TOO_SMALL is returned and DataSize is set to the
  28   required buffer size to obtain the data.
  29
  30   @param  This                  A pointer to this instance of the EFI_PEI_READ_ONLY_VARIABLE2_PPI.
  31   @param  VariableName          A pointer to a null-terminated string that is the variable's name.
  32   @param  VariableGuid          A pointer to an EFI_GUID that is the variable's GUID. The combination of
  33                                 VariableGuid and VariableName must be unique.
  34   @param  Attributes            If non-NULL, on return, points to the variable's attributes.
  35   @param  DataSize              On entry, points to the size in bytes of the Data buffer.
  36                                 On return, points to the size of the data returned in Data.
  37   @param  Data                  Points to the buffer which will hold the returned variable value.
  38                                 May be NULL with a zero DataSize in order to determine the size of the buffer needed.
  39
  40   @retval EFI_SUCCESS           The variable was read successfully.
  41   @retval EFI_NOT_FOUND         The variable was not found.
  42   @retval EFI_BUFFER_TOO_SMALL  The DataSize is too small for the resulting data.
  43                                 DataSize is updated with the size required for
  44                                 the specified variable.
  45   @retval EFI_INVALID_PARAMETER VariableName, VariableGuid, DataSize or Data is NULL.
  46   @retval EFI_DEVICE_ERROR      The variable could not be retrieved because of a device error.
  47
  48 **/
  49 typedef
  50 EFI_STATUS
  51 (EFIAPI *EFI_PEI_GET_VARIABLE2)(
  52   IN CONST  EFI_PEI_READ_ONLY_VARIABLE2_PPI *This,
  53   IN CONST  CHAR16                          *VariableName,
  54   IN CONST  EFI_GUID                        *VariableGuid,
  55   OUT       UINT32                          *Attributes,
  56   IN OUT    UINTN                           *DataSize,
  57   OUT       VOID                            *Data OPTIONAL
  58   );
  59
  60
  61 /**
  62   Return the next variable name and GUID.
  63
  64   This function is called multiple times to retrieve the VariableName
  65   and VariableGuid of all variables currently available in the system.
  66   On each call, the previous results are passed into the interface,
  67   and, on return, the interface returns the data for the next
  68   interface. When the entire variable list has been returned,
  69   EFI_NOT_FOUND is returned.
  70
  71   @param  This              A pointer to this instance of the EFI_PEI_READ_ONLY_VARIABLE2_PPI.
  72
  73   @param  VariableNameSize  On entry, points to the size of the buffer pointed to by VariableName.
  74                             On return, the size of the variable name buffer.
  75   @param  VariableName      On entry, a pointer to a null-terminated string that is the variable's name.
  76                             On return, points to the next variable's null-terminated name string.
  77
  78   @param  VariableGuid      On entry, a pointer to an EFI_GUID that is the variable's GUID.
  79                             On return, a pointer to the next variable's GUID.
  80
  81   @retval EFI_SUCCESS           The variable was read successfully.
  82   @retval EFI_NOT_FOUND         The variable could not be found.
  83   @retval EFI_BUFFER_TOO_SMALL  The VariableNameSize is too small for the resulting
  84                                 data. VariableNameSize is updated with the size
  85                                 required for the specified variable.
  86   @retval EFI_INVALID_PARAMETER VariableName, VariableGuid or
  87                                 VariableNameSize is NULL.
  88   @retval EFI_DEVICE_ERROR      The variable could not be retrieved because of a device error.
  89
  90 **/
  91 typedef
  92 EFI_STATUS
  93 (EFIAPI *EFI_PEI_GET_NEXT_VARIABLE_NAME2)(
  94   IN CONST  EFI_PEI_READ_ONLY_VARIABLE2_PPI *This,
  95   IN OUT    UINTN                           *VariableNameSize,
  96   IN OUT    CHAR16                          *VariableName,
  97   IN OUT    EFI_GUID                        *VariableGuid
  98   );
  99
 100 ///
 101 /// This PPI provides a lightweight, read-only variant of the full EFI
 102 /// variable services.
 103 ///
 104 struct _EFI_PEI_READ_ONLY_VARIABLE2_PPI {
 105   EFI_PEI_GET_VARIABLE2           GetVariable;
 106   EFI_PEI_GET_NEXT_VARIABLE_NAME2 NextVariableName;
 107 };
 108
 109 extern EFI_GUID gEfiPeiReadOnlyVariable2PpiGuid;
 110
 111 #endif