(j3.2006) Public Comment J32006

[Michael Ingrassia]

                                                            08-220
To: J3
From: Michael Ingrassia
Subject: Public Comment J32006
Date: 2008 July 08
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Commenter's Subject was "Restore the restrictions on internal procedures"

The Fortran 2008 draft allows internal procedures to be
pointer targets and dummy arguments.  The only practical
implementation of the functionality as specified in the
current draft requires the use of self-modifying code.
Self-modifying code has long been established to be a
security problem.  Some secure operating systems, such as
SELinux and Trusted Debian, can be built in ways that do
not allow self-modifying code.  Recent versions of Mac OS
require users to mark executables that allow self-modifying
code.

The functionality could be provided in ways that do not
require self-modifying code.  Traditionally, pointers to
internal procedures have been implemented as two parts:
the address of the entry point of the internal procedure
and the context in which the procedure is to be executed.
In modern languages, such pointers are called "closures."
Adding a way to declare closures would permit the
functionality of pointers to internal procedures without
putting security at risk.

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