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01f75b3927
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>
54 lines
1.8 KiB
C
54 lines
1.8 KiB
C
/** @file
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Metadata Handler Library.
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Copyright (c) 2025, Arm Limited. All rights reserved.
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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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#include <Library/MetadataObjLib.h>
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/** Query the MetadataObjLib for metadata matching the input (Type/Token).
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If the metadata exists, return it.
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Otherwise:
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- Generate a new metadata object
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- Add it to the MetadataObjLib
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- return it
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@param[in] Root Root of the Metadata information.
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@param[in] Type METADATA_TYPE of the entry to generate.
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@param[in] Token Token uniquely identifying an entry among other
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objects with the input METADATA_TYPE.
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@param[in] Context Optional context to use during the Metadata generation.
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@param[in, out] Metadata On input, can contain METADATA_TYPE-specific information.
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On output and if success, contains the generated
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Metadata object.
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@param[in] MetadataSize Size of the input Metadata.
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@retval EFI_SUCCESS Success.
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@retval EFI_INVALID_PARAMETER A parameter is invalid.
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**/
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EFI_STATUS
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EFIAPI
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MetadataHandlerGenerate (
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IN METADATA_ROOT_HANDLE Root,
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IN METADATA_TYPE Type,
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IN CM_OBJECT_TOKEN Token,
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IN VOID *Context,
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IN OUT VOID *Metadata,
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IN UINT32 MetadataSize
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);
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/** Validate the Metadata.
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@param[in] Root Root of the Metadata information.
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@retval EFI_SUCCESS Success.
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@retval EFI_INVALID_PARAMETER A parameter is invalid.
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**/
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EFI_STATUS
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EFIAPI
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MetadataHandlerValidate (
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IN METADATA_ROOT_HANDLE Root
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);
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