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