Patch Control Mechanism for Large Scale Software

Applying patches to large scale software is often difficult because unofficial patches and user modifications conflict with any "official'' patches. Version control systems such as RCS[1], CVS[2], and configuration management[3,4,5] are useful solutions for this problem when the baseline of the software is fixed. However, an official patch that is developed externally changes the baseline and any local changes based on this become obsolete. Thus we must re-apply various unofficial patches and modifications, identify the causes of conflict, change or remove patches, and repeat the patch and unpatch operations. This paper presents a mechanism for (1) managing versions of a software package based on patches, (2) automating the application of unofficial patches and modifications by the user, and (3) rebuilding the package using file versions instead of timestamps. Using this mechanism, it becomes easy to apply patches and re-build software.