xenserver: Only replace XenServer hosts scripts that we recognize.

Open vSwitch comes with slightly improved versions of upstream Citrix
XenSever host scripts.  Until now, the Open vSwitch RPMs have always
installed its own versions of the scripts over the Citrix versions.  This
commit changes behavior to replace the scripts only if we recognize the
exact versions being replaced.  This approach seems safer given that the
benefits of the OVS changes are minor and we don't want to break any
upstream changes inadvertently.

Signed-off-by: Ben Pfaff <blp@nicira.com>

diff --git a/xenserver/openvswitch-xen.spec b/xenserver/openvswitch-xen.spec
index 56db2e5..20f309b 100644 (file)
--- a/xenserver/openvswitch-xen.spec
+++ b/xenserver/openvswitch-xen.spec
@@ -1,6 +1,6 @@
 # Spec file for Open vSwitch.
 
-# Copyright (C) 2009, 2010, 2011 Nicira Networks, Inc.
+# Copyright (C) 2009, 2010, 2011, 2012 Nicira Networks, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # are permitted in any medium without royalty provided the copyright
@@ -129,6 +129,74 @@ install -d -m 755 $RPM_BUILD_ROOT/var/lib/openvswitch
 rm -rf $RPM_BUILD_ROOT
 
 %post
+# A list of Citrix XenServer scripts that we might need to replace
+# with our own versions.
+scripts="
+    /etc/xensource/scripts/vif
+    /opt/xensource/libexec/InterfaceReconfigure.py
+    /opt/xensource/libexec/InterfaceReconfigureBridge.py
+    /opt/xensource/libexec/InterfaceReconfigureVswitch.py
+    /opt/xensource/libexec/interface-reconfigure"
+
+# Calculate into $md5sums a comma-separated set of md5sums of the
+# Citrix XenServer scripts that we might need to replace.  We might be
+# upgrading an older version of the package that moved the files out
+# of the way, so we need to look for the files in those out-of-the-way
+# locations first.
+md5sums=
+for script in $scripts; do
+    b=$(basename "$script")
+    if test -e /usr/lib/openvswitch/xs-saved/"$b"; then
+        f=/usr/lib/openvswitch/xs-saved/"$b"
+    elif test -e /usr/lib/openvswitch/xs-original/"$b"; then
+        f=/usr/lib/openvswitch/xs-original/"$b"
+    elif test -e "$script" && test ! -h "$script"; then
+        f=$script
+    else
+        printf "\n$script: not found\n"
+        f=/dev/null
+    fi
+    md5sums="$md5sums,$(md5sum $f | awk '{print $1}')"
+done
+md5sums=${md5sums#,}
+
+# Now check the md5sums against the known sets of md5sums:
+#
+#   - If they are known to be a version of XenServer scripts that we should
+#     replace, we replace them (by putting $scripts into $replace_files).
+#
+#   - Otherwise, we guess that it's better not to replace them, because the
+#     improvements that our versions of the scripts provide are minimal, so
+#     it's better to avoid possibly breaking any changes made upstream by
+#     Citrix.
+case $md5sums in
+    cf09a68d9f8b434e79a4c83b01a3bb4b,395866df1b0b20c12c4dd2f7de0ecdb4,9d493545ae81463239d3162cbc798852,862d0939b441de9264a900628e950fe9,21f85db25599d7f026cd489385d58aa6)
+        keep_files=
+        replace_files=$scripts
+        printf "\nVerified host scripts from XenServer 6.0.0.\n"
+        ;;
+        
+    c5f48246577a17cf1b971fb5ce4e920b,2e2c912f86f9c536c89adc34ff3c2b2b,28d3ff72d72bdec4f37d70699f5edb76,67e1d0af16fc1ddf10009c5c063ad2ba,24bae6906d182ba47668174f8e480cc6)
+        keep_files=
+        replace_files=$scripts
+        printf "\nVerified host scripts from XenServer 5.6-FP1.\n"
+        ;;
+
+    *)
+        keep_files=$scripts
+        replace_files=
+        cat <<EOF
+
+The host scripts on this machine are not those of any supported
+version of XenServer.  On XenServer earlier than 5.6-FP1, your Open
+vSwitch installation will not work.  On XenServer 5.6-FP1 or later,
+Open vSwitch is not verified to work, which could lead to unexpected
+behavior.
+
+EOF
+        ;;
+esac
+
 if grep -F net.ipv4.conf.all.arp_filter /etc/sysctl.conf >/dev/null 2>&1; then :; else
     cat >>/etc/sysctl.conf <<EOF
 # This works around an issue in xhad, which binds to a particular
@@ -184,13 +252,7 @@ fi
 # Replace XenServer files by our versions.
 mkdir -p /usr/lib/openvswitch/xs-saved \
     || printf "Could not create script backup directory.\n"
-for f in \
-    /opt/xensource/libexec/interface-reconfigure \
-    /opt/xensource/libexec/InterfaceReconfigure.py \
-    /opt/xensource/libexec/InterfaceReconfigureBridge.py \
-    /opt/xensource/libexec/InterfaceReconfigureVswitch.py \
-    /etc/xensource/scripts/vif
-do
+for f in $replace_files; do
     s=$(basename "$f")
     t=$(readlink "$f")
     if [ -f "$f" ] && [ "$t" != "/usr/share/openvswitch/scripts/$s" ]; then
@@ -205,10 +267,7 @@ done
 # provided by OVS. Any time a replacement script is removed from OVS,
 # it should be added here to ensure correct reversion from old versions of
 # OVS that don't clean up dangling symlinks during the uninstall phase.
-for orig in \
-    /usr/sbin/brctl \
-    /usr/sbin/xen-bugtool
-do
+for orig in /usr/sbin/brctl /usr/sbin/xen-bugtool $keep_files; do
     saved=/usr/lib/openvswitch/xs-saved/$(basename "$orig")
     [ -e "$saved" ] && mv -f "$saved" "$orig"
 done