Imagine: We have been given the source code of several software programs, some open source, others proprietary. What's the best strategy to analyze the source code in each case?
For example: We know that open source software is usually more reliable than commercial software. So I'm wondering if it's a good idea to, instead of inspecting the open source code line by line, download the original code from the web, and compare it with the code that's been given to us. If there's no difference, we conclude that the source code is probably safe and we can skip manual code inspection.
Is this practice acceptable? Are there other strategies that can speed up source code analysis?