Array length inference for C library bindings

Abstract

Simultaneous use of multiple programming languages (polyglot programming) assists in creating efficient, coherent, modern programs in the face of legacy code. However, manually creating bindings to low-level languages like C is tedious and error-prone. We offer relief in the formof an automated suite of analyses, designed to enhance the quality of automatically produced bindings. These analyses recover high-level array length information that is missing from C's type system. We emit annotations in the style of GObject-Introspection, which produces bindings from annotations on function signatures. We annotate each array argument as terminated by a special sentinel value, fixed-length, or of length determined by another argument. These properties help produce more idiomatic, efficient bindings. We correctly annotate at least 70% of all arrays with these length types, and our results are comparable to those produced by human annotators, but take far less time to produce.