#+title: POSIX SYSCALLS

* POSIX_SYSCALLS contrib

Created to respond to <https://mailman.common-lisp.net/pipermail/armedbear-devel/2023-April/004308.html>.

This ABCL contrib provides and demonstrates the scaffolding for
extending the implementation by use of direct syscalls via the foreign
function interface (FFI) afforded by the JNA library.

On loading this system, new implementations of the EXT:GETENV and
UIOP/OS:GETENV functions are provided which use FFI to directly call
the setenv() and getenv() library functions.  The setenv()
functionality is provided by DEFSETF expander.

** Usage

*** Initialization 
#+begin_src lisp
  (require :abcl-contrib)
  (asdf:load-system :posix-syscalls)
#+end_src

*** Example

#+begin_src 
CL-USER> (uiop/os:getenv "PATH")
"/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin"
CL-USER> (setf (uiop/os:getenv "PATH") "/usr/sbin")
"/usr/sbin"
CL-USER> (uiop/os:getenv "PATH")
"/usr/sbin"
CL-USER> 
#+end_src

** Notes

CFFI isn't used to minimize dependencies.

Posix syscalls is perhaps a terrible name.

This isn't expected work on Windows (untested).


* Colophon  
  #+begin_example
    Mark <evenson@not.org>
    Created: 24-MAY-2023
    Revised: <2023-05-25 Thu 08:38>
  #+end_example