I am the upstream gtkdoc developer and maintainer and work on https://bugzilla.gnome.org/show_bug.cgi?id=742404 that will be part of the next gtk-doc release. With some luck I noticed that Ubuntu applies gzip compression to some of gtkdoc's data files.
Please don't do this. While I can probably use popen for this case, I cannot handle this for all possible cases (e.g. some distro using bzip2 instead). These files are only installed on developer machines and I don't think the space saving are worth it. I'd believe most developers rather get better performance.
ll /usr/share/gtk-doc/html/*/*.devhelp2.gz | sort
-rw-r--r-- 1 root root 29061 Sep 25 2014 /usr/share/gtk-doc/html/glib/glib.devhelp2,gz
-rw-r--r-- 1 root root 10128 Sep 25 2014 /usr/share/gtk-doc/html/gobject/gobject.devhelp2.gz
-rw-r--r-- 1 root root 10502 Mar 18 2014 /usr/share/gtk-doc/html/pango/pango.devhelp2.gz
-rw-r--r-- 1 root root 10694 Jan 15 14:44 /usr/share/gtk-doc/html/gdk3/gdk3.devhelp2.gz
-rw-r--r-- 1 root root 32728 Sep 25 2014 /usr/share/gtk-doc/html/gio/gio.devhelp2.gz
-rw-r--r-- 1 root root 3318 Feb 13 2014 /usr/share/gtk-doc/html/libgnomecanvas/libgnomecanvas.devhelp2.gz
-rw-r--r-- 1 root root 3763 Mar 4 23:43 /usr/share/gtk-doc/html/polkit-1/polkit-1.devhelp2.gz
-rw-r--r-- 1 root root 6057 Jan 23 2014 /usr/share/gtk-doc/html/gsf/gsf.devhelp2.gz
-rw-r--r-- 1 root root 77077 Jan 15 14:44 /usr/share/gtk-doc/html/gtk3/gtk3.devhelp2.gz
-rw-r--r-- 1 root root 80638 Feb 4 2014 /usr/share/gtk-doc/html/telepathy-glib/telepathy-glib.devhelp2.gz
-rw-r--r-- 1 root root 8261 Jan 30 01:52 /usr/share/gtk-doc/html/webkitgtk-3.0/webkitgtk.devhelp2.gz
For previous discussion on the same issue regarding index.sgml files: https:/