externalize version extraction to download agent

Having the version readily available means that multiple functions in
the PKGBUILD can use it without extracting it again every time.

Unfortunately, makepkg escapes DLAGENTS in a way that makes adding a
complex one quite ugly: It splits arguments on free spaces, so all
spaces in the quote-enclosed argument to "bash -c" have to be escaped.
On top of that, there are many sed expressions and even sed expressions
in sed expressions containing escaped symbols which now have to be
escaped again or even three times.

1 files changed, 18 insertions, 4 deletions

diff --git a/PKGBUILD b/PKGBUILD
index ae3b9c1cf78f..d971ea2a62ba 100644
--- a/PKGBUILD
+++ b/PKGBUILD
@@ -9,14 +9,28 @@ arch=('any')
 url="http://opendesktop.org/content/show.php?content=170523"
 license=('GPL3')
 optdepends=("gtk-engine-murrine: for GTK2 themes")
-source=("version.html::$url"
+source=("version::version${url#http}"
         "http://gnome-look.org/CONTENT/content-files/${url##*=}-Dark-Aurora.tar.gz")
-sha256sums=('68991e89036a271fec7f8b6408416a6c2817f298ef326365117fe41b1b5222b5'
+sha256sums=('6f34484abaf76f7175264de32610a92447408d63c06a91dfb6e5744023e8d831'
             '506332ec0d86b90f0e41be79875fa7b40bb923caf01c1412cf02020a6d056f28')
 
+# The following is very convoluted script because of makepkg's DLAGENTS escaping logic.
+# An agent is added for the protocol "version". It is treated like http, which is done by processing
+# the input url %u with sed, replacing the protocol back to http. Everything downloaded is then not
+# immediatley saved to the output file name %o, but first piped through sed, which finds the
+# gnome-shell version string in the Dark Aurora page on GNOME-Look.org.
+# This makes a file containing the version readily available to both pkgver and package so that they
+# not both have to sed out the version from the webpage themselves.
+DLAGENTS=("version::/usr/bin/bash -c $(
+  printf '%s\n' "${DLAGENTS[@]}" | sed -n 's/http::\(.*\)/\1/p' \
+    | sed 's/-[^ ] %o //' | sed 's/ /\\ /g' | sed 's/%u/$(echo\\ %u\\ |\\ sed\\ "s\/^version\/http\/")/'
+)\ |\ sed\ -n\ 's/$(
+  ).*<h1.*>Dark\ Aurora<\\\\/h1>.*<span\ class=\"contentdata\">$(
+  )\\\\([^<]\\\\+\\\\)<\\\\/span>.*/\\\\1/p'\ >\ %o"
+"${DLAGENTS[@]}")
+
 pkgver() {
-  sed -n 's/.*<h1.*>Dark Aurora<\/h1>.*<span class="contentdata">\([^<]\+\)<\/span>.*/\1/p' \
-    version.html | tr '\n' '.'
+  tr '\n' '.' < version
   while read -rd $'\0'
   do
     if [[ "$REPLY" -gt "$max" ]]