readelf: Handle note types from different operating systems

[emaste]

Summary

Previously elftoolchain readelf(1) only displayed correct names for Linux note types.
Upstream elftoolchain ticket #473 https://sourceforge.net/p/elftoolchain/tickets/473/

[rpaulo]

This looks odd. Why are we relying on magic numbers instead of constants/enums like before?

[emaste]

In D1428#3, @rpaulo wrote:

This looks odd. Why are we relying on magic numbers instead of constants/enums like before?

Some of the constants in the previous version are Linux-specific, and don't exist in our ELF headers.

We could make up our own constants (e.g. NT_LINUX_AUXV) but it doesn't seem like that would provide much value. The same constant name may have different values on different OSes.

[rpaulo]

In D1428#5, @emaste wrote:

In D1428#3, @rpaulo wrote:

This looks odd. Why are we relying on magic numbers instead of constants/enums like before?

Some of the constants in the previous version are Linux-specific, and don't exist in our ELF headers.

We could make up our own constants (e.g. NT_LINUX_AUXV) but it doesn't seem like that would provide much value. The same constant name may have different values on different OSes.

The Linux note types are Linux specific. Are you saying that FreeBSD reuses them ?

[emaste]

In D1428#6, @rpaulo wrote:

The Linux note types are Linux specific. Are you saying that FreeBSD reuses them ?

Not quite, just that the note types are vendor-specific and in a namespace specific to the note name (vendor). NT_PRSTATUS, NT_FPREGSET, and NT_FPREGSET happen to have the same value on Linux and FreeBSD. We don't currently have definitions in our ELF headers for Linux-specific note types like NT_LWPSTATUS, and I'd find it somewhat odd to add them without somehow putting them in a namespace in the header.

[emaste]

Closed by commit rS276705 (authored by @emaste).