Method compareExternals

src/function_context.py:219–241

Compare the (matched) external function calls of both contexts and returns the matching score. Args: src_ctx (ComparableContext): context representing the source function bin_ctx (ComparableContext): context representing the binary function Return value

(src_ctx, bin_ctx)

    @staticmethod
    def compareExternals(src_ctx, bin_ctx):
        """Compare the (matched) external function calls of both contexts and returns the matching score.

        Args:
            src_ctx (ComparableContext): context representing the source function
            bin_ctx (ComparableContext): context representing the binary function

        Return value
            floating point score for the external calls comparison
        """
        # penalty for number of missing external calls
        score = -1 * abs(len(src_ctx.externals) - len(bin_ctx.externals)) * EXTERNAL_COUNT_SCORE
        for external in [x for x in src_ctx.externals if x.matched()]:
            # check for a hit
            if external.match in bin_ctx.externals:
                if external.name in libc.libc_function_names:
                    score += LIBC_COMP_FUNC_MATCH_SCORE if external.name in libc.libc_comp_function_names else LIBC_FUNC_MATCH_SCORE
                else:
                    score += EXT_FUNC_MATCH_SCORE
        # give a boost for a perfect match
        if len(src_ctx.externals) > 0 and len(src_ctx.externals) == len(bin_ctx.externals):
            score += ARTIFACT_MATCH_SCORE
        return score

# Technically, BinaryCodeContext is mapped (has an index), and Island don't have an index.
# However this is much easier to implement instead of having a diamond shaped inheritance...