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9326c0eb0a
Replace traditional `#ifndef`/`#define`/`#endif` include guards with
`#pragma` once.
`#pragma once` is a widely supported preprocessor directive that
prevents header files from being included multiple times. It is
supported by all toolchains used to build edk2: GCC, Clang/LLVM, and
MSVC.
Compared to macro-based include guards, `#pragma once`:
- Eliminates the risk of macro name collisions or copy/paste errors
where two headers inadvertently use the same guard macro.
- Eliminate inconsistency in the way include guard macros are named
(e.g., some files use `__FILE_H__`, others use `FILE_H_`, etc.).
- Reduces boilerplate (three lines replaced by one).
- Avoids polluting the macro namespace with guard symbols.
- Can improve build times as the preprocessor can skip re-opening the
file entirely, rather than re-reading it to find the matching
`#endif` ("multiple-include optimization").
- Note that some compilers may already optimize traditional include
guards, by recognzining the idiomatic pattern.
This change is made acknowledging that overall portability of the
code will technically be reduced, as `#pragma once` is not part of the
C/C++ standards.
However, this is considered acceptable given:
1. edk2 already defines a subset of supported compilers in
BaseTools/Conf/tools_def.template, all of which have supported
`#pragma once` for over two decades.
2. There have been concerns raised to the project about inconsistent
include guard naming and potential macro collisions.
Approximate compiler support dates:
- MSVC: Supported since Visual C++ 4.2 (1996)
- GCC: Supported since 3.4 (2004)
(http://gnu.ist.utl.pt/software/gcc/gcc-3.4/changes.html)
- Clang (LLVM based): Since initial release in 2007
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
32 lines
1 KiB
C
32 lines
1 KiB
C
/** @file
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Provides a secure platform-specific method to detect physically present user.
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Copyright (c) 2011 - 2018, 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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#pragma once
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/**
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This function provides a platform-specific method to detect whether the platform
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is operating by a physically present user.
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Programmatic changing of platform security policy (such as disable Secure Boot,
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or switch between Standard/Custom Secure Boot mode) MUST NOT be possible during
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Boot Services or after exiting EFI Boot Services. Only a physically present user
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is allowed to perform these operations.
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NOTE THAT: This function cannot depend on any EFI Variable Service since they are
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not available when this function is called in AuthenticateVariable driver.
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@retval TRUE The platform is operated by a physically present user.
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@retval FALSE The platform is NOT operated by a physically present user.
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**/
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BOOLEAN
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EFIAPI
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UserPhysicalPresent (
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VOID
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);
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