Linux Part II

in

Tags

If you are using etags, stop doing that. The best tag system is gnu global, it is simply amazing. If you are on a debian machine, I recommend getting gnu global from sourc hand. The reason is that the version of gnu global on apt-get is incredibly outdated. Once you have it installed, go to the root of your linux, or any C project, directory and type gtags. This will create all the infrastructure that we will soon be using in emacs. Note that the gtags file for Linux takes a few moments and clocks in at about 100mb, this is Linux source code after all…

Emacs Side

Now that we have gtags up and running, we can now focus on the emacs portion of things. Here’s my hook for C-mode in emacs:

(add-hook 'c-mode-hook '(lambda ()
                          (setq-local show-trailing-whitespace t)
                          (semantic-mode)
                          (auto-complete-mode -1)
                          (company-mode)
                          (global-set-key (kbd "C-c C-f") 'helm-command-prefix)
                          (global-unset-key (kbd "C-x c"))
                          (define-key helm-gtags-mode-map (kbd "M-s") 'helm-gtags-select)
                          (setq helm-quick-update                     t ; do not display invisible candidates
                                helm-split-window-in-side-p           t ; open helm buffer inside current window, not occupy whole other window
                                helm-buffers-fuzzy-matching           t ; fuzzy matching buffer names when non--nil
                                helm-move-to-line-cycle-in-source     t ; move to end or beginning of source when reaching top or bottom of source.
                                helm-ff-search-library-in-sexp        t ; search for library in `require' and `declare-function' sexp.
                                helm-scroll-amount                    8 ; scroll 8 lines other window using M-<next>/M-<prior>
                                helm-ff-file-name-history-use-recentf t
                                helm-gtags-ignore-case t
                                helm-gtags-auto-update t
                                helm-gtags-use-input-at-cursor t
                                helm-gtags-pulse-at-cursor t
                                helm-gtags-prefix-key "\C-cg"
                                helm-gtags-suggested-key-mapping t)
                          (helm-gtags-mode)
                          (define-key helm-gtags-mode-map (kbd "M-.") 'helm-gtags-dwim)
                          (define-key helm-gtags-mode-map (kbd "M-,") 'helm-gtags-pop-stack)
                          ;;Too complex for me right now. 
                          ;;(helm-mode)
                          (define-key company-mode-map (kbd "M-h") 'company-c-headers)
                          (hs-minor-mode)
                          (define-key hs-minor-mode-map (kbd "C-c C-t") 'hs-toggle-hiding)
                          (define-key c-mode-map (kbd "C-c C-c") 'compile)
                          (semantic-mru-bookmark-mode)
                          (define-key semantic-mode-map (kbd "M-]") 'semantic-ia-fast-jump)
                          (define-key semantic-mode-map (kbd "M-[") 'semantic-ia-fast-jump-back)
                          (define-key c-mode-map (kbd "C-c C-i") 'default-c-includes)
                          (ggtags-mode)
                          (define-key ggtags-mode-map (kbd "M-.") nil)
                          (define-key ggtags-mode-map (kbd "M-<") nil)
                          (define-key ggtags-mode-map (kbd "M->") nil)
                          (define-key ggtags-mode-map (kbd "M-n") nil)
                          (define-key ggtags-mode-map (kbd "M-p") nil)
                          (define-key ggtags-mode-map (kbd "M-,") nil)
                          (define-key ggtags-mode-map (kbd "M-]") nil)
                          (define-key ggtags-mode-map (kbd "M--") 'ggtags-find-reference)
                          ;;Flycheck has issues with tramp, just FYI. 
                          ;;(flycheck-mode)
                          (linux-c-mode)))

That’s quite a bit, but I’ll explain all the relevant parts. I don’t really use helm, other than for the features of helm-gtags-dwin and helm-gtags-pop-stack simply because Helm is too big for my tastes and it goes against how most of emacs “does” things. Basically whenever I want to find where a struct, function, etc is defined, I can just hit M-. and gtags will take me there, if I want to come back to where I was before looking up the definition, then I hit M-,. The reader might notice that I define many of the keys from ggtags-mode-map to nil, this is because the keys conflicted with my desired key bindings and the only thing that I found of use from ggtags-mode was finding all the references made to a piece of code, this is via the ggtags-find-reference function. This is a feature that Semantic can supposedly do, but getting it to work right with the remote machine and the messed up header paths was just too much work, plus it had some issues about call-process. Ggtags-mode is able to do this incredibly well and fast. Finally there is the call to linux-c-mode, that is simply defined as:

(defun linux-c-mode ()
  "C mode with adjusted defaults for use with the linux kernel."
  (interactive)
  (setq c-set-style "linux")
  (setq c-brace-offset -8)
  (setq c-default-style "linux")
  (setq c-basic-offset 8)
  (setq tab-width 8))

Since our homework assignments had Linux’s checkpatch.pl script run against them, it made sense to just start out with Linux style C-coding enforced in emacs itself.

Wrapping up

That’s basically it. I skipped over a few things, but if you have questions, feel free to ask in the comments and I’ll try to answer them. For reference, my init.el is [[https://github.com/fxfactorial/emacsd/blob/m other goodies.