Verification of correctness properties of programs that read input files

Abstract

This thesis presents new techniques for verifying correctness properties of programs that process input files. These techniques apply to programs written in standard programming languages such as C and focus on relationships that must hold between program execution points, the current location of file position indicator of the open input file, and the contents of the input file. The thesis presents a specification language that developers can use to express these relationships and insert them into the program as assertions involving the file position indicator and file contents at different program points. It also presents a program verification system that verifies, for all possible input files and all possible input file contents, that the assertions hold in all program executions. The soundness of the verification system has been proved, based on the formal definition of the syntax and semantics of the specification language. The system synthesized verification conditions from the specifications for a PNG image viewer and a JPEG image converter, and successfully verified all of them.