read/elf: Make it easier to parse ELF notes from /sys/kernel/notes

[mstange]

Here's some code which reads the kernel's ELF build ID by parsing /sys/kernel/notes: https://github.com/mstange/samply/blob/1d71084e3054a9d2b6bd9a399cfcd659f937f613/samply/src/linux_shared/kernel_symbols.rs#L34-L38

I had to copy the NoteIterator code into this file because IIRC there was no public API to construct it.

Edit: fixed link

[philipc]

I assume you meant to link to https://github.com/mstange/samply/blob/1d71084e3054a9d2b6bd9a399cfcd659f937f613/samply/src/linux_shared/kernel_symbols.rs.

Is adding a public API to construct it enough to close this issue?

[mstange]

Hah, yes, you found the right link. Yes, adding a public API for NoteIterator would be enough to close this issue.

And maybe a doc comment which says whether to pass 4 or 8 to the align argument when using it with /sys/kernel/notes - I didn't actually check how that works.