[bug#72395] [PATCH] syscalls: Support musl libc in openpty and login-tty

[Sören Tempel]

Hi!

Z572 <zhengjunjie@iscas.ac.cn> wrote:
> In my understanding, when we can't find libutil, will try to find it in
> libc. Do you have any problems using it?

Yea, for example consider the invocation `guix import pypi cart`.
Without this patch, this emits the following error message for me
on Alpine Linux Edge (a musl-based Linux distribution):

        guix import: error: no source release for pypi package cart 1.2.2

        hint: Backtrace:
        In ice-9/boot-9.scm:
          1685:16 19 (raise-exception _ #:continuable? _)
        In guix/ui.scm:
           867:16 18 (_ _)
           340:43 17 (display-hint "This indicates that the\npackage is a…" . 
#)
        In ice-9/boot-9.scm:
          1747:15 16 (with-exception-handler #<procedure 7f8c8f9b2660 at ic…> 
…)
          3474:28 15 (_)
          3327:17 14 (resolve-interface (guix build syscalls) #:select _ # _ 
…)
        In ice-9/threads.scm:
            390:8 13 (_ _)
        In ice-9/boot-9.scm:
          3253:13 12 (_)
        In ice-9/threads.scm:
            390:8 11 (_ _)
        In ice-9/boot-9.scm:
          3544:20 10 (_)
           2836:4  9 (save-module-excursion #<procedure 7f8c8f9b2600 at 
ice-…>)
          3564:26  8 (_)
        In unknown file:
                   7 (primitive-load-path "guix/build/syscalls" #<procedure 
…>)
        In guix/build/syscalls.scm:
          2385:14  6 (_)
        In ice-9/boot-9.scm:
          1747:15  5 (with-exception-handler #<procedure 7f8c8fa3b270 at ic…> 
…)
        In guix/build/syscalls.scm:
           456:39  4 (_)
        In ice-9/boot-9.scm:
          1747:15  3 (with-exception-handler #<procedure 7f8c8fa3b240 at ic…> 
…)
        In unknown file:
                   2 (dynamic-link "libutil")
        In system/foreign-library.scm:
           190:25  1 (load-foreign-library _ #:extensions _ # _ #:search-path 
…)
        In unknown file:
                   0 (dlopen "libutil.so" 1)

        ERROR: In procedure dlopen:
        In procedure dlopen: file "libutil.so", message "libutil.so: cannot 
open shared object file: No such file or directory"

With this patch applied, I instead get:

        guix import: error: no source release for pypi package cart 1.2.2

        hint: This indicates that the package is available on PyPI, but only as 
a "wheel" containing
        binaries, not source.  To build it from source, refer to the upstream 
repository at
        `https://github.com/CybercentreCanada/cart'.

I assume the fallback code in syscall->procedure does not work correctly
then and the "correct fix" would be to fix this fallback code?

Greetings,
Sören