patch 9.0.1962: No support for writing extended attributesv9.0.1962

Problem:  No support for writing extended attributes
Solution: Add extended attribute support for linux

It's been a long standing issue, that if you write a file with extended
attributes and backupcopy is set to no, the file will loose the extended
attributes.

So this patch adds support for retrieving the extended attributes and
copying it to the new file. It currently only works on linux, mainly
because I don't know the different APIs for other systems (BSD, MacOSX and
Solaris).  On linux, this should be supported since Kernel 2.4 or
something, so this should be pretty safe to use now.

Enable the extended attribute support with normal builds.

I also added it explicitly to the :version output as well as make it
able to check using `:echo has("xattr")`, to have users easily check
that this is available.

In contrast to the similar support for SELINUX and SMACK support (which
also internally uses extended attributes), I have made this a FEAT_XATTR
define, instead of the similar HAVE_XATTR.

Add a test and change CI to include relevant packages so that CI can
test that extended attributes are correctly written.

closes: #306
closes: #13203

Signed-off-by: Christian Brabandt <cb@256bit.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8c2e5396b7..cd1615f9f4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -110,6 +110,8 @@ jobs:
               tcl-dev \
               cscope \
               libsodium-dev \
+              attr \
+              libattr1-dev
             )
           fi
           sudo apt-get update && sudo apt-get install -y "${PKGS[@]}"