A method for Fortran programs reverse engineering using algebraic specifications

When maintenance is neglected within program development, it is usually done in an empirical way and this leads to program deterioration. To cover up this problem in the legacy systems framework, a broader approach can be followed which first involves reverse engineering. Reverse engineering generates abstract descriptions of a program from its source. These descriptions are used to generate the improved program source (inconsistencies removal, optimization of the source code, updating the documentation), and to assist maintenance tasks. We present here a reverse engineering method which systematically leads to structural and functional descriptions of a Fortran program using algebraic specifications. We emphasize the problems arisen by the Fortran programming language and by some kind of computing styles (few possibilities for type construction, bad use of global variables, errors within the source code, etc). It is important to notice that this process also leads to the detection of code defaults : it is thus possible to remove them before the code generation following the reverse engineering.