Previously, the actual behavior of magic lookup and one described in its
commit description have not matched. Instead of being weak definitions
in a library that is always in the end of load order, the definitions
were normal ones and thus were able to override other weak definitions
in LibC. While this was consistent with how DynamicLoader resolves
ambiguity between normal and weak relocations, this is not the behavior
POSIX mandates -- we should always choose first available definition wrt
load order. To fix this problem, the patch makes sure we don't define
any of magic symbols in LibC.
In addition to this, it makes all provided magic symbols functions
(instead of objects), what renders MagicWeakSymbol class unnecessary.
This works by defining a set of weak symbols in dynamic linker whose
value would be provided by it. This has the same effect as preloading
library that magically knows right addresses of functions shared between
dynamic linker and LibC.
We were previously passing the same information by rewriting values
based on hardcoded library name, so the new approach seems a little
nicer to me.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
