Document and enforce the new spaces-only indentation policy.

* cfg.mk (disable_temporarily): Remove sc_TAB_in_indentation,
to enable the "make syntax-check" that enforces this.
* .x-sc_TAB_in_indentation: New file.  Exceptions.
* HACKING: Document the policy, with tips on how to conform.

1 files changed, 23 insertions, 0 deletions

diff --git a/HACKING b/HACKING
index c6a30227..815ee16e 100644
--- a/HACKING
+++ b/HACKING
@@ -24,6 +24,29 @@ Please make sure that the code compiles without warnings.
 
 Please test any changes.
 
+Code indentation
+----------------------------------------------------------------------
+Our C source code generally adheres to some basic code-formatting
+conventions.  The existing code base is not totally consistent on this
+front, but we do prefer that contributed code be formatted similarly.
+In short, use spaces-not-TABs for indentation, use 2 spaces for each
+indentation level, and other than that, follow the K&R style.
+
+If you use Emacs, add the following to one of one of your start-up files
+(e.g., ~/.emacs), to help ensure that you get indentation right:
+
+  ;;; When editing C sources in libguestfs, use this style.
+  (defun libguestfs-c-mode ()
+    "C mode with adjusted defaults for use with libguestfs."
+    (interactive)
+    (c-set-style "K&R")
+    (setq indent-tabs-mode nil) ; indent using spaces, not TABs
+    (setq c-indent-level 2)
+    (setq c-basic-offset 2))
+  (add-hook 'c-mode-hook
+	    '(lambda () (if (string-match "/libguestfs" (buffer-file-name))
+			    (libguestfs-c-mode))))
+
 Directories
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