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>
Make use the newly introduced ShellPrintHiiDefaultEx() alias and
replace wherever it is possible:
- "ShellPrintHiiEx (-1, -1, NULL,"
with:
- "ShellPrintHiiDefaultEx ("
No functional change is introduced.
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Adds a new module (dynamic shell command) to ShellPkg that lists
variable policy information for all UEFI variables on the system.
Some other UEFI variable related functionality is also included to
give a greater sense of platform UEFI variable state. This command
is intended to help make variable policies more transparent and
easier to understand and configure on a platform.
Like all dynamic shell commands, a platform only needs to include
`VariablePolicyDynamicCommand.inf` in their flash image to have
the command registered in their UEFI shell.
Include the following lines in platform DSC (in DXE components section):
```
ShellPkg/DynamicCommand/VariablePolicyDynamicCommand/VariablePolicyDynamicCommand.inf {
<PcdsFixedAtBuild>
gEfiShellPkgTokenSpaceGuid.PcdShellLibAutoInitialize|FALSE
}
```
Include the following line in platform FDF:
```
INF ShellPkg/DynamicCommand/VariablePolicyDynamicCommand/VariablePolicyDynamicCommand.inf
```
A standalone UEFI application can also be built that uses the same
underlying functional code as the dynamic shell command.
The path to use in the DSC and FDF for the app:
```
ShellPkg/DynamicCommand/VariablePolicyDynamicCommand/VariablePolicyApp.inf
```
Cc: Zhichao Gao <zhichao.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
Message-Id: <20231030203112.736-3-mikuback@linux.microsoft.com>
