* configure.ac: Check for xattr availability
* src/Makefile.am: Add xattr.c
* src/ftp.c: Include xattr.h.
(getftp): Set attributes if enabled.
* src/http.c: Include xattr.h.
(gethttp): Add parameter 'original_url',
set attributes if enabled.
(http_loop): Add 'original_url' to call of gethttp().
* src/init.c: Add new option --xattr.
* src/main.c: Add new option --xattr, add description to help text.
* src/options.h: Add new config member 'enable_xattr'.
* src/xatrr.c: New file.
* src/xattr.h: New file.
These attributes provide a lightweight method of later determining
where a file was downloaded from.
This patch changes:
* autoconf detects whether extended attributes are available and
enables the code if they are.
* The new flags --xattr and --no-xattr control whether xattr is enabled.
* The new command "xattr = (on|off)" can be used in ~/.wgetrc or /etc/wgetrc
* The original and redirected URLs are recorded as shown below.
* This works for both single fetches and recursive mode.
The attributes that are set are:
user.xdg.origin.url: The URL that the content was fetched from.
user.xdg.referrer.url: The URL that was originally requested.
Here is an example, where http://archive.org redirects to https://archive.org:
$ wget --xattr http://archive.org
...
$ getfattr -d index.html
user.xdg.origin.url="https://archive.org/"
user.xdg.referrer.url="http://archive.org/"
These attributes were chosen based on those stored by Google Chrome
https://bugs.chromium.org/p/chromium/issues/detail?id=45903
and curl https://github.com/curl/curl/blob/master/src/tool_xattr.c
