syscalls: Add support for musl libc.

This commit allows using Guix on a foreign distro which uses musl libc,
for example, Alpine Linux. Usage of musl libc is detected via a new
musl-libc? variable using the Guile %host-type.

Using the new musl-libc? variable, we can now implement musl-specific
quirks. The two compatibility problems I encountered in this regard are
that musl dose not export a readdir64 and statfs64 symbol. On musl,
these two functions are implemented as CPP macros that expand to
readdir/statfs. To workaround that, a case-distinction was added.

The existing linux? variable has been modified to return true if the
%host-system contains "linux-" in order to ensure it is true for both
linux-gnu as well as linux-musl host systems.

The patch has been tested on Alpine Linux and is already used for the
downstream Guix package shipped in Alpine Linux's package repository.

* guix/build/syscalls.scm (musl-libc?): New variable.
(linux?): Truth value on any linux system.
(statfs, readdir-procedure): Support musl libc.

Signed-off-by: Sören Tempel <soeren@soeren-tempel.net>
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Change-Id: Icc4101a062381240f977f4550344bde696513c52

0 files changed, 0 insertions, 0 deletions