-EFI_STATUS
-GetEnvironmentVariable (
- IN CONST CHAR16* VariableName,
- IN VOID* DefaultValue,
- IN OUT UINTN* Size,
- OUT VOID** Value
- )
-{
- EFI_STATUS Status;
- UINTN VariableSize;
-
- // Try to get the variable size.
- *Value = NULL;
- VariableSize = 0;
- Status = gRT->GetVariable ((CHAR16 *) VariableName, &gEfiGlobalVariableGuid, NULL, &VariableSize, *Value);
- if (Status == EFI_NOT_FOUND) {
- if ((DefaultValue != NULL) && (Size != NULL) && (*Size != 0)) {
- // If the environment variable does not exist yet then set it with the default value
- Status = gRT->SetVariable (
- (CHAR16*)VariableName,
- &gEfiGlobalVariableGuid,
- EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
- *Size,
- DefaultValue
- );
- *Value = DefaultValue;
- } else {
- return EFI_NOT_FOUND;
- }
- } else if (Status == EFI_BUFFER_TOO_SMALL) {
- // Get the environment variable value
- *Value = AllocatePool (VariableSize);
- if (*Value == NULL) {
- return EFI_OUT_OF_RESOURCES;
- }
-
- Status = gRT->GetVariable ((CHAR16 *)VariableName, &gEfiGlobalVariableGuid, NULL, &VariableSize, *Value);
- if (EFI_ERROR (Status)) {
- FreePool(*Value);
- return EFI_INVALID_PARAMETER;
- }
-
- if (Size) {
- *Size = VariableSize;
- }
- } else {
- *Value = DefaultValue;
- return Status;
- }
-
- return EFI_SUCCESS;
-}
-