/** @file
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PEI Variable Read Lib
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This library provides phase agnostic access to the UEFI Variable Services.
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This is done by implementing a wrapper on top of the phase specific mechanism
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for reading from UEFI variables. For example, the PEI implementation of this
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library uses EFI_PEI_READ_ONLY_VARIABLE2_PPI. The DXE implementation accesses
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the UEFI Runtime Services Table, and the SMM implementation uses
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EFI_SMM_VARIABLE_PROTOCOL.
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Using this library allows code to be written in a generic manner that can be
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used in PEI, DXE, or SMM without modification.
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Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <PiPei.h>
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#include <Ppi/ReadOnlyVariable2.h>
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#include <Library/DebugLib.h>
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#include <Library/PeiServicesLib.h>
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/**
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Returns the value of a variable.
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@param[in] VariableName A Null-terminated string that is the name of the vendor's
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variable.
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@param[in] VendorGuid A unique identifier for the vendor.
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@param[out] Attributes If not NULL, a pointer to the memory location to return the
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attributes bitmask for the variable.
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@param[in, out] DataSize On input, the size in bytes of the return Data buffer.
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On output the size of data returned in Data.
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@param[out] Data The buffer to return the contents of the variable. May be NULL
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with a zero DataSize in order to determine the size buffer needed.
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@retval EFI_SUCCESS The function completed successfully.
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@retval EFI_NOT_FOUND The variable was not found.
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@retval EFI_BUFFER_TOO_SMALL The DataSize is too small for the result.
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@retval EFI_INVALID_PARAMETER VariableName is NULL.
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@retval EFI_INVALID_PARAMETER VendorGuid is NULL.
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@retval EFI_INVALID_PARAMETER DataSize is NULL.
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@retval EFI_INVALID_PARAMETER The DataSize is not too small and Data is NULL.
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@retval EFI_DEVICE_ERROR The variable could not be retrieved due to a hardware error.
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@retval EFI_SECURITY_VIOLATION The variable could not be retrieved due to an authentication failure.
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@retval EFI_UNSUPPORTED This function is not implemented by this instance of the LibraryClass
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**/
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EFI_STATUS
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EFIAPI
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VarLibGetVariable (
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IN CHAR16 *VariableName,
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IN EFI_GUID *VendorGuid,
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OUT UINT32 *Attributes, OPTIONAL
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IN OUT UINTN *DataSize,
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OUT VOID *Data OPTIONAL
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)
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{
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EFI_STATUS Status;
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EFI_PEI_READ_ONLY_VARIABLE2_PPI *VariablePpi;
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//
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// Locate the variable PPI.
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//
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Status = PeiServicesLocatePpi (
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&gEfiPeiReadOnlyVariable2PpiGuid,
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0,
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NULL,
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&VariablePpi
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);
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ASSERT_EFI_ERROR (Status);
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if (EFI_ERROR (Status)) {
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return Status;
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}
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if (VariablePpi != NULL) {
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Status = VariablePpi->GetVariable (
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VariablePpi,
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VariableName,
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VendorGuid,
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Attributes,
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DataSize,
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Data
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);
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} else {
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Status = EFI_UNSUPPORTED;
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}
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return Status;
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}
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/**
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Enumerates the current variable names.
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@param[in, out] VariableNameSize The size of the VariableName buffer. The size must be large
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enough to fit input string supplied in VariableName buffer.
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@param[in, out] VariableName On input, supplies the last VariableName that was returned
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by GetNextVariableName(). On output, returns the Nullterminated
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string of the current variable.
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@param[in, out] VendorGuid On input, supplies the last VendorGuid that was returned by
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GetNextVariableName(). On output, returns the
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VendorGuid of the current variable.
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@retval EFI_SUCCESS The function completed successfully.
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@retval EFI_NOT_FOUND The next variable was not found.
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@retval EFI_BUFFER_TOO_SMALL The VariableNameSize is too small for the result.
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VariableNameSize has been updated with the size needed to complete the request.
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@retval EFI_INVALID_PARAMETER VariableNameSize is NULL.
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@retval EFI_INVALID_PARAMETER VariableName is NULL.
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@retval EFI_INVALID_PARAMETER VendorGuid is NULL.
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@retval EFI_INVALID_PARAMETER The input values of VariableName and VendorGuid are not a name and
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GUID of an existing variable.
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@retval EFI_INVALID_PARAMETER Null-terminator is not found in the first VariableNameSize bytes of
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the input VariableName buffer.
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@retval EFI_DEVICE_ERROR The variable could not be retrieved due to a hardware error.
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@retval EFI_UNSUPPORTED This function is not implemented by this instance of the LibraryClass
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**/
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EFI_STATUS
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EFIAPI
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VarLibGetNextVariableName (
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IN OUT UINTN *VariableNameSize,
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IN OUT CHAR16 *VariableName,
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IN OUT EFI_GUID *VendorGuid
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)
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{
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EFI_STATUS Status;
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EFI_PEI_READ_ONLY_VARIABLE2_PPI *VariablePpi;
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//
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// Locate the variable PPI.
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//
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Status = PeiServicesLocatePpi (
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&gEfiPeiReadOnlyVariable2PpiGuid,
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0,
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NULL,
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&VariablePpi
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);
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ASSERT_EFI_ERROR (Status);
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if (EFI_ERROR (Status)) {
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return Status;
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}
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if (VariablePpi != NULL) {
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Status = VariablePpi->NextVariableName (
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VariablePpi,
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VariableNameSize,
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VariableName,
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VendorGuid
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);
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} else {
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Status = EFI_UNSUPPORTED;
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}
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return Status;
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}
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