[libvirt] [PATCH 2/3] wireshark: Try a bunch of possible prefixes

[Andrea Bolognani]

If we can't obtain Wireshark's plugindir variable from
pkg-config, we fall back to building it ourselves starting
from $libdir.

The problem with that is that we have zero insights on what
$libdir actually looks like, so we can't simply strip $prefix
and call it a day. On the other hand, we have to do *something*
or $ws_plugindir will be unusable.

Our solution is to try the four most likely prefixes, and use
the first one that matches. It's not perfect, but should be
able to cope with all but the weirdest setups.

Worst case scenario, the user can pass --with-ws-plugindir to
configure and explicitly provide a suitable installation path.
---
 m4/virt-wireshark.m4 | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/m4/virt-wireshark.m4 b/m4/virt-wireshark.m4
index 556272a..75786de 100644
--- a/m4/virt-wireshark.m4
+++ b/m4/virt-wireshark.m4
@@ -35,11 +35,20 @@ AC_DEFUN([LIBVIRT_CHECK_WIRESHARK],[
         dnl On some systems the plugindir variable may not be stored within pkg config.
         dnl Fall back to older style of constructing the plugin dir path.
         ws_plugindir="$libdir/wireshark/plugins/$ws_modversion"
-        ws_prefix="$prefix"
+        dnl We have no idea what the contents of $libdir look like, so we'll
+        dnl have to play a bit of a guessing game: let's try stripping off
+        dnl a bunch of likels prefixed and pick the first one that matches.
+        dnl Even if none does, we'll still have one last shot later
+        for try in "$prefix" "$exec_prefix" '${prefix}' '${exec_prefix}'; do
+          if test "x${ws_plugindir#$try}" != "x$ws_plugindir"; then
+            ws_prefix="$try"
+            break
+          fi
+        done
       fi
       if test "x$ws_prefix" = "x" ; then
-        dnl If the wireshark prefix cannot be retrieved from pkg-config,
-        dnl /usr is our best bet
+        dnl If the wireshark prefix cannot be retrieved from pkg-config
+        dnl or otherwise guessed, /usr is our best bet
         ws_prefix="/usr"
       fi
       dnl Replace the wireshark prefix with our own.
-- 
2.7.4