[libc] implement pathconf/fpathconf

[SchrodingerZhu]

Now that #86169 added linux_statfs and linux_fstatvs. We can be use them to implement pathconf and fpathconf.

See also:

• https://android.googlesource.com/platform/bionic/+/refs/heads/main/libc/bionic/pathconf.cpp
• https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/
• https://linux.die.net/man/3/pathconf

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

Now that #86169 added `linux_statfs` and `linux_fstatvs`. We can be use them to implement `pathconf` and `fpathconf`.

See also:
https://android.googlesource.com/platform/bionic/+/refs/heads/main/libc/bionic/pathconf.cpp

[SchrodingerZhu]

@robincaloudis want to take a look?

[llvmbot]

@llvm/issue-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

Now that #86169 added `linux_statfs` and `linux_fstatvs`. We can be use them to implement `pathconf` and `fpathconf`.

See also:
https://android.googlesource.com/platform/bionic/+/refs/heads/main/libc/bionic/pathconf.cpp

[changkhothuychung]

If this is available I would like to take this issue.

[robincaloudis]

@changkhothuychung, sure, go ahead. @SchrodingerZhu, I would overtake in case no patch is provided. The necessary steps seem to be clear. However, as I am on vacation for a few days, it is going to take me until mid/end of next week. In case that's too late for you, you or someone else is more than welcome to overtake.

[Unique-Usman]

@changkhothuychung I noticed you are working on an issue different from this, are you still working on it, if not I will like to work on it.

[SchrodingerZhu]

I will assign @changkhothuychung first since they signed up earlier for this. Feel free to update me if there is anything changed.

[changkhothuychung]

@SchrodingerZhu Thanks for assigning this to me. I have a question, since you mentioned the link of the implementation from android, am I allowed to reference it to implement in libc?

[nickdesaulniers]

It's ok to look at bionic sources. I'll encourage you not to copy+paste it.