This library provides a collection of (macro-based) functions for
performing safe integer operations across platform and architecture
with a straightforward API.

It supports two modes of use: header-only and linked dynamic library.
The linked, dynamic library supplies a format-string based interface
which is in pre-alpha.  The header-only mode supplies integer and sign
overflow and underflow pre-condition checks using checks derived from
the CERT secure coding guide.  The checks do not rely on twos complement
arithmetic and should not at any point perform an arithmetic operations
that may overflow.  It also performs basic type agreement checks to
ensure that the macros are being used (somewhat) correctly.

WWW: http://BSDforge.com/projects/devel/safe-iop/