Revamp efi_well_known_* variable handling

[nvinson]

The current implementation attempts to use the linker to create aliases for efi_well_known_guids and efi_well_known_names. It also tries to use the linker to generate the variables efi_well_known_guids_end and efi_well_known_names_end.

When building with clang, the generated linker result results in a broken libefivar.so that causes programs to segfault when linked against it. This change does away with linker script hacker and instead introduces pointers to store the locations of efi_well_known_guids_end and efi_well_known_names_end.

Additionally, efi_well_known_guids and efi_well_known_names are now created as pointers that point to the beginning of their respective arrays.

Signed-off-by: Nicholas Vinson nvinson234@gmail.com
Fixes: #234

[tedbrandston]

For what it's worth: I ran into an issue trying to switch from 37 -> 38 where the latter would cause my application to fail with error while loading shared libraries: libefivar.so.1: ELF load command address/offset not page-aligned. This patch does appear to fix my issue, though I don't think I'm exercising the functionality this touches.

Happy to provide any additional info I can.

[ghost]

Thanks a lot for your work on this @nvinson! i was having a similar problem while trying to build static efivar libraries, by compiling from your branch i managed to get rid of those errors

[nvinson]

@vathpela @frozencemetery Could this PR be merged please? It's been in review for almost 3 months with no negative reviews.

[juliakreger]

So I was chatting with @jayofdoom and he raised this patch up to my attention in passing, and I took a look. Looks okay to me, but I'll caveat that statement on my C days being far off in the past. :)

[WavyEbuilder]

Nice work @nvinson! RedHat, you should merge this.

[heitbaum]

• I can confirm Building efibootmgr 17 and 18 with efivar 38 is failing efibootmgr#164 is fixed with this patch.