doc_id: impl.secure
title: securing m4 runtime

This file is copyright (c) 2004,2005,2006,2011 by Panu Kalliokoski
and released under the w_link(../LICENSE, stx2any license).

Attempt to kill all possibly dangerous commands.  It would be nice to
"partially kill" `include' and `undivert', but that does not seem to be
possible.

Provide some sensible information on what went wrong.
{{{
define(`w_gag_cmd',
`undefine(`$1')'dnl
`define(`$1',
   `w_warning(`attempt to use "$1" in secure environment')`$1'($@)')')
}}}

These are the commands to kill.
{{{
w_gag_cmd(`builtin')
w_gag_cmd(`syscmd')
w_gag_cmd(`esyscmd')
}}}