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>
Mark EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS as deprecated.
1. Make SetVariable/QueryVariableInfo return EFI_UNSUPPORTED with this
attribute
2. No change to GetVariable/GetNextVariableName
Also update several function descriptors accordingly
Cc: Long Qin <qin.long@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chao Zhang <chao.b.zhang@intel.com>
Reviewed-by: Long Qin <qin.long@intel.com>
What to do:
1. Add AuthVariableLib LibraryClass definitions.
2. Implement a NULL AuthVariableLib library instance.
3. Add VARIABLE_ENTRY_PROPERTY definition to VarCheck.h.
4. Add VARIABLE_ENTRY_CONSISTENCY and variable attribute
combinations definitions to VariableFormat.h.
Why to do:
1. Share code.
1.1. Separate auth variable service from Auth Variable driver in
SecurityPkg to AuthVariableLib. Then the AuthVariableLib could benefit
and be used by different implementation of Auth Variable drivers.
1.2 The VARIABLE_ENTRY_PROPERTY definition to VarCheck.h,
VARIABLE_ENTRY_CONSISTENCY and variable attribute
combinations definitions to VariableFormat.h will be shared
by merged Variable driver and AuthVariableLib.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17757 6f19259b-4bc3-4df7-8a09-765794883524
Michael Kubackiandmergify[bot]
Michael D Kinney
Zhang, Chao B
Star Zengandjljusten
