[libc] implement realpath

[michaelrj-google]

Described in POSIX: https://pubs.opengroup.org/onlinepubs/9799919799/functions/realpath.html#

The realpath function resolves a path so that it doesn't have any /./ or /../ in it. It may also allocate a string of none is provided, similar to strdup.

Here's a checklist for what you'll need to do for this:

• Add the implementation of realpath in /src/stdlib
• Add tests for realpath in /test/src/stdlib
• Add realpath to entrypoints.txt for at least x86_64 and whatever you're building on
• Add realpath to include/stdlib.yaml

(Reserved for specific assignee)

[llvmbot]

@llvm/issue-subscribers-libc

Author: Michael Jones (michaelrj-google)

Described in POSIX: https://pubs.opengroup.org/onlinepubs/9799919799/functions/realpath.html#

The realpath function resolves a path so that it doesn't have any /./ or /../ in it. It may also allocate a string of none is provided, similar to strdup.

Here's a checklist for what you'll need to do for this:

• Add the implementation of realpath in /src/stdlib
• Add tests for realpath in /test/src/stdlib
• Add realpath to entrypoints.txt for at least x86_64 and whatever you're building on
• Add realpath to include/stdlib.yaml

(Reserved for specific assignee)

[jtstogel]

I'd like to implement this!

[hulxv]

@jtstogel are you still working on this? I want to take it if you are busy

[michaelrj-google]

@hulxv This issue is intended as a first issue for jstogel to get him up to speed on the team. I've found another function that's available to implement instead if you're interested: mbrtoc32, which should be very similar in implementation to the current mbrtowc since the current conversion code assumes wchar is char32. If you are interested I'm happy to file an issue and assign it to you.

[hulxv]

@michaelrj-google ok great i will take it! Assign me please when open it

[michaelrj-google]

Created #156556 and assigned to @hulxv