[PATCH v2 1/4] CODING-STYLE: add .editorconfig to clarify indentation uses spaces

[Edwin Török <edvin.torok@xxxxxxxxxx>]

Add an .editorconfig to make it easier to keep patches compatible with
Xen's coding style, and to reemphasize what Xen's coding style is.

I thought that Xen demands tabs rather than spaces (which is more
difficult with OCaml because indentation tools use spaces,
and the use of tabs requires changing editor settings),
however CODING-STYLE says it is spaces.

Document this explicitly by adding a .editorconfig file (see editorconfig.org),
which is an editor agnostic format for specifying basic style properties like
indentation, either with native support in editors or via plugins.

It is safer than modelines because it only supports controlling a
restricted set of editor properties and not arbitrary commands as Vim
modelines would have, and works with editors other than Vim too.
(Vim has a deny list for modeline sandboxing, which is error-prone
because every time a new command gets added it needs to be added to the
deny list, which has been the source of a few CVEs in the past
and I disable Vim modelines everywhere as a precaution).

This file is added as a convenience for those who might have an editor
that supports it, and its presence should have no impact on those that
do not (want to) use it.
It also won't cause re-indentation of existing files when edited, only
newly added lines would follow the convention.

No functional change.

Signed-off-by: Edwin Török <edvin.torok@xxxxxxxxxx>
---
 .editorconfig | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 .editorconfig

diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000000..cb2f27c581
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,20 @@
+# See ./CODING_STYLE
+root = true
+
+[*]
+end_of_line = lf
+indent_style = space
+charset = utf-8
+max_line_length = 79
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+# Makefiles must use tabs, otherwise they don't work
+[{Makefile,*.mk,Makefile.rules}]
+indent_style = tabs
+
+[*.{c,h}]
+indent_size = 4
+
+[*.{ml,mli}]
+indent_size = 2
-- 
2.34.1