[Libguestfs] [PATCH FOR DISCUSSION ONLY 1/2] scripts: Add a script for formatting all C code in the project.

~~~ Not to be applied, for discussion only ~~~ I think we need some kind of "checkpatch" script to catch all the annoying, nitpicky code style issues that submitters trip up on. I looked at a few scripts that exist, primarily the ones from Linux and qemu (massive and complicated), and libvirt (small and sane). There are a couple of problems: (1) Linux/qemu-style checkpatch only verifies new code that is submitted, leaving the old code in its current, possibly inconsistent state. (2) The libvirt one only checks a whitelist of known issues (but actually, it's still quite a good script). I thought a different approach might be to run 'indent' across the whole code base. As long as we force the indent style settings, and get submitters and reviews to run the command, then it should ensure all our code, past and future, has a consistent style. GNU indent isn't very good for this, but clang-format is a lot more configurable. Therefore: the first commit adds a wrapper around clang-format which runs it with the correct settings, and also does a bit of post- processing. Note you need clang-format 3.8.0, currently available in Fedora 24+ The second patch shows the changes that would be made. It's not too bad, but there are some problems: (a) The way struct initializers are formatted is weird. I'm not even sure I understand what rules clang is following, since structs get all sorts of different styles with no rhyme or reason. (b) It splits up long string constants (although it doesn't resplit string constants which are already sufficiently split). (c) It gets horribly confused by our start_element()...end_element() XML macros. This doesn't solve the whole problem. We would still need further scripts to look for problems such as: (i) Error messages terminated/not terminated by full stop. (ii) Not calling reply_with_* functions on error paths. and so on. Rich.