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c9f80c49b1
Follow the new spec for ELF notes as detailed in https://systemd.io/ELF_PACKAGE_METADATA/. We can copy mostly verbatim the macros from systemd codebase. Example output: $ meson setup --native-file build-dev.ini -Dxz=disabled -Ddlopen=zlib build ... dlopen : zlib features : +ZSTD -XZ +ZLIB +OPENSSL $ dlopen-notes.py build/libkmod.so.2 # build/libkmod.so.2 [ { "feature": "xz", "description": "Support for uncompressing xz-compressed modules", "priority": "recommended", "soname": [ "liblzma.so.5" ] } ] Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com> Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com> Link: https://github.com/kmod-project/kmod/pull/262
54 lines
2.9 KiB
C
54 lines
2.9 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include "macro.h"
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/*
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* Originally from systemd codebase.
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*
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* Reference: https://systemd.io/ELF_PACKAGE_METADATA/
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*/
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// clang-format off
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#define ELF_NOTE_DLOPEN_VENDOR "FDO"
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#define ELF_NOTE_DLOPEN_TYPE UINT32_C(0x407c0c0a)
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#define ELF_NOTE_DLOPEN_PRIORITY_REQUIRED "required"
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#define ELF_NOTE_DLOPEN_PRIORITY_RECOMMENDED "recommended"
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#define ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED "suggested"
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/* Add an ".note.dlopen" ELF note to our binary that declares our weak dlopen() dependency. This
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* information can be read from an ELF file via "readelf -p .note.dlopen" or an equivalent command. */
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#define _ELF_NOTE_DLOPEN(json, variable_name) \
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__attribute__((used, section(".note.dlopen"))) _Alignas(sizeof(uint32_t)) static const struct { \
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struct { \
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uint32_t n_namesz, n_descsz, n_type; \
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} nhdr; \
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char name[sizeof(ELF_NOTE_DLOPEN_VENDOR)]; \
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_Alignas(sizeof(uint32_t)) char dlopen_json[sizeof(json)]; \
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} variable_name = { \
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.nhdr = { \
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.n_namesz = sizeof(ELF_NOTE_DLOPEN_VENDOR), \
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.n_descsz = sizeof(json), \
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.n_type = ELF_NOTE_DLOPEN_TYPE, \
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}, \
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.name = ELF_NOTE_DLOPEN_VENDOR, \
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.dlopen_json = json, \
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}
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#define _SONAME_ARRAY1(a) "[\""a"\"]"
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#define _SONAME_ARRAY2(a, b) "[\""a"\",\""b"\"]"
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#define _SONAME_ARRAY3(a, b, c) "[\""a"\",\""b"\",\""c"\"]"
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#define _SONAME_ARRAY4(a, b, c, d) "[\""a"\",\""b"\",\""c"\"",\""d"\"]"
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#define _SONAME_ARRAY5(a, b, c, d, e) "[\""a"\",\""b"\",\""c"\"",\""d"\",\""e"\"]"
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#define _SONAME_ARRAY_GET(_1,_2,_3,_4,_5,NAME,...) NAME
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#define _SONAME_ARRAY(...) _SONAME_ARRAY_GET(__VA_ARGS__, _SONAME_ARRAY5, _SONAME_ARRAY4, _SONAME_ARRAY3, _SONAME_ARRAY2, _SONAME_ARRAY1)(__VA_ARGS__)
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/* The 'priority' must be one of 'required', 'recommended' or 'suggested' as per specification, use the
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* macro defined above to specify it.
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* Multiple sonames can be passed and they will be automatically constructed into a json array (but note that
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* due to preprocessor language limitations if more than the limit defined above is used, a new
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* _SONAME_ARRAY<X+1> will need to be added). */
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#define ELF_NOTE_DLOPEN(feature, description, priority, ...) \
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_ELF_NOTE_DLOPEN("[{\"feature\":\"" feature "\",\"description\":\"" description "\",\"priority\":\"" priority "\",\"soname\":" _SONAME_ARRAY(__VA_ARGS__) "}]", UNIQ_T(s, UNIQ))
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