readelf: add support for ELF package metadata note
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Authored by emaste on Nov 12 2024, 2:45 PM.

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rG74051cfb3d18: readelf: Add support for ELF package metadata note
rGc18512056301: readelf: Add support for ELF package metadata note

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emaste requested review of this revision.Nov 12 2024, 2:45 PM

emaste created this revision.

fuz added a subscriber: fuz.Nov 12 2024, 2:56 PM

fuz added inline comments.

contrib/elftoolchain/readelf/readelf.c
3838	Can we get a symbolic constant for this type?
3841–3842	Cast to avoid sign-extension, clearer code. Is the charset of these ASCII? Or is it UTF-8?

The general idea seems fine.

Selfishly, it's convenient to see someone else driving a need for JSON handling in ELF files since we're going to want something like that for CHERI compartmentalization. CC @jhb

contrib/elftoolchain/readelf/readelf.c
3841–3842	From the systemd.io link "The format is a single JSON object, encoded as a zero-terminated UTF-8 string". We should probably act accordingly.

emaste added a parent revision: D57525: elf_common: Add FDO package metadata note type.Jun 10 2026, 1:22 PM

emaste added inline comments.Jun 10 2026, 3:14 PM

contrib/elftoolchain/readelf/readelf.c
3838	D57525
3841–3842	Yes, although it seems we need some generalized safe UTF-8 printing function. GNU readelf just passes it to printf %s.

fuz added inline comments.Jun 10 2026, 4:37 PM

contrib/elftoolchain/readelf/readelf.c
3841–3842	Scratch that, my code is still wrong. `buf` is a `const char *`, so `buf[i]` can be negative. The `isprint` call should be `isprint((unsigned char)buf[i])`. For more comprehensive support, we could call `iconv` to transcode the buffer contents into the current locale.