Isn't that kinda to be expected if you want to provide dynamic loading functionality (dlopen)?
Is the windows situation really all that different/better (with GetProcAddress in kernel32.dll)?
Is the windows situation really all that different/better (with GetProcAddress in kernel32.dll)?
On Windows, things are less modular, so it's less of an issue. That said, there's also weird shenanigans when it comes to the CRT (which can be statically linked) vs ntdll (which provides the actual linker implementation), that can make certain niche features of the linker misbehave (delay loading in particular is weird).
You could make the argument that the glibc developers should split ld.so into its own subprojects. What for? That would just bring the extra responsibility of making sure that variations in glibc version work with variations in ld.so version for whatever reason.
What would happen in practice is that they would keep their version numbers in lock step, and systems integrators would use the same version. While the upstream glibc has to go through a dance of pretending that someone cares about their independence.
it seems nixos could set up a wrapper that invokes the right ld.so based on the executable. though at this point they could probably edit the ELF binaries and patch the fixed path to ld.so when nix is installing the program.
yeah, it seems strange that this needs kernel support. but more eBFP extension points are usually welcome, so sure, why not?
That's exactly what they're doing right now - though instead of being "when installing the program", it's "when compiling the program". The problem with hardcoding the path is that it pins the "nix store" (where nix installs all of its programs) to a hardcoded location. If you want to move it, you have to rebuild all your packages - which is suboptimal.
In theory, nix could have a system in place to just patch all binaries when moving the nix store, but that would be incompatible with content-addressed derivation and otherwise break some other nice properties of the nix store.
extern int errno;
You could have a very slim libdlopen that is used by both loader and libc, but I don't really see how that's any improvement/much different.
So your C stdlib does not have dlopen() (in fact, it's not really part of C stdlib in POSIX anyway!) but you can link with standard OS-level ABI to OS-provided runtime services like "find a library and symbol from it" - AmigaOS did something similar.