What

LibGSystem is a GIO-based library, targeted primarily for use by operating system components.

It is on track to being deprecated; some of its components have moved into GLib (the cleanup macros and subprocess). Other Linux-specific parts will move into a to-be-created git submodule (likely "libgsystem2").

Old Description

It has a few goals:

Provide macros for the GCC attribute(cleanup) that work with GLib data types. Using these can dramatically simplify local memory management inside functions.
Prototype and test APIs that will eventually be in GLib. Currently these include "GSSubprocess" for launching child processes, and some GFile helpers.
Provide Linux-specific APIs in a nicer GLib fashion, such as O_NOATIME.

Requirements

gio-unix-2.0 (libgsystem will not build on Windows)
GCC or CLang (the known compilers implementing attribute(cleanup)); compilers which are known to currently NOT implement this are MSVC and Sun Studio.

How

Libgsystem used to be a git submodule. If you are still using it this way, you can follow the submodule branch. To use it that way, see Projects/LibGSystem/SubmoduleInstructions.

Example users

OSTree

attribute(cleanup) macros

These macros allow automatically performing an unref/free on GLib data types when a variable goes out of scope. They're based on the GCC attribute(cleanup). See GCC manual, this post to gtk-devel-list, networkmanager-devel discussion.

Example:

static void
print_yes_if_file_exists (GFile *path)
{
  gs_unref_object GFileInfo *fileinfo = NULL;

  fileinfo = g_file_query_info (path, "standard::*", 0, NULL, NULL);
  if (!fileinfo)
    return; /* fileinfo is automatically unreffed here */
  g_print ("yes\n");
  /* fileinfo is automatically unreffed here */
}

GLib utility API

libgsystem includes at present high level file helpers, subprocess launching, and more.

Linux-specific APIs

While GLib transparently takes advantage of Linux features in may cases, not all APIs are wrapped nicely. An example API that libgsystem provides is reading a file with O_NOATIME.