update-alternative.bbclass: add batch alternatives support

With new batch ability, we can use below simple 2 lines for multiple alternatives
updates:

ALTERNATIVE_LINKS = "${bindir}/cmd1 {sbindir}/cmd2 ..."
ALTERNATIVE_PRIORITY = "100"

Then for each command "/path/cmd" listed in ALTERNATIVE_LINKS, below is done
automatically:

    ${D}/path/cmd is renamed to ${D}/path/cmd.{PN}
    a new alternative named 'cmd' is created which:
        links /path/cmd to /path/cmd.{PN} with priority specified in ALTERNATIVE_PRIORITY

This way the recipe with multiple alternatives could be simplified a lot. There
are still some cases where above assumptions may break, but I expect more recipes
should benefit from this simple enhancement

Fix [BUGID #257]

Signed-off-by: Kevin Tian <kevin.tian@intel.com>

1 files changed, 81 insertions, 2 deletions

diff --git a/meta/classes/update-alternatives.bbclass b/meta/classes/update-alternatives.bbclass
index ddbf4c1947..fdb4214b65 100644
--- a/meta/classes/update-alternatives.bbclass
+++ b/meta/classes/update-alternatives.bbclass
@@ -1,3 +1,41 @@
+# This class is used to help the alternatives system which is useful when
+# multiple sources provide same command. You can use update-alternatives
+# command directly in your recipe, but in most cases this class simplifies
+# that job.
+#
+# There're two basic modes supported: 'single update' and 'batch update'
+#
+# 'single update' is used for a single alternative command, and you're
+# expected to provide at least below keywords:
+#
+#     ALTERNATIVE_NAME - the name that the alternative is registered
+#     ALTERNATIVE_PATH - the path of installed alternative
+#
+# ALTENATIVE_PRIORITY and ALTERNATIVE_LINK are optional which have defautls
+# in this class.
+#
+# 'batch update' is used if you have multiple alternatives to be updated.
+# Unlike 'single update', 'batch update' in most times only require two
+# parameter:
+#
+#     ALTERNATIVE_LINKS - a list of symbol links for which you'd like to
+#                         create alternatives, with space as delimiter, e.g:
+#
+#         ALTERNATIVE_LINKS = "${bindir}/cmd1 ${sbindir}/cmd2 ..."
+#
+#     ALTNERATIVE_PRIORITY - optional, applies to all
+#
+# To simplify the design, this class has the assumption that for a name
+# listed in ALTERNATIVE_LINKS, say /path/cmd:
+#
+#     the name of the alternative would be: cmd
+#     the path of installed alternative would be: /path/cmd.${PN}
+#     ${D}/path/cmd will be renamed to ${D}/path/cmd.{PN} automatically
+#     priority will be the same from ALTERNATIVE_PRIORITY
+#
+# If above assumption breaks your requirement, then you still need to use
+# your own update-alternatives command directly.
+
 # defaults
 ALTERNATIVE_PRIORITY = "10"
 ALTERNATIVE_LINK = "${bindir}/${ALTERNATIVE_NAME}"
@@ -10,7 +48,42 @@ update_alternatives_postrm() {
 update-alternatives --remove ${ALTERNATIVE_NAME} ${ALTERNATIVE_PATH}
 }
 
+# for batch alternatives, we use a simple approach to require only one parameter
+# with the rest info deduced implicitly
+update_alternatives_batch_postinst() {
+for link in ${ALTERNATIVE_LINKS}
+do
+	name=`basename ${link}`
+	path=${link}.${PN}
+	update-alternatives --install ${link} ${name} ${path} ${ALTERNATIVE_PRIORITY}
+done
+}
+
+update_alternatives_batch_postrm() {
+for link in ${ALTERNATIVE_LINKS}
+do
+	name=`basename ${link}`
+	path=${link}.${PN}
+	update-alternatives --remove ${name} $path
+done
+}
+
+update_alternatives_batch_doinstall() {
+if [ "${PN}" = "${BPN}" ] ; then
+	for link in ${ALTERNATIVE_LINKS}
+	do
+		mv ${D}${link} ${D}${link}.${PN}
+	done
+fi
+}
+
 def update_alternatives_after_parse(d):
+    if bb.data.getVar('ALTERNATIVE_LINKS', d) != None:
+        doinstall = bb.data.getVar('do_install', d, 1)
+        doinstall += bb.data.getVar('update_alternatives_batch_doinstall', d, 1)
+        bb.data.setVar('do_install', doinstall, d)
+        return
+
     if bb.data.getVar('ALTERNATIVE_NAME', d) == None:
         raise bb.build.FuncFailed, "%s inherits update-alternatives but doesn't set ALTERNATIVE_NAME" % bb.data.getVar('FILE', d)
     if bb.data.getVar('ALTERNATIVE_PATH', d) == None:
@@ -26,11 +99,17 @@ python populate_packages_prepend () {
 	postinst = bb.data.getVar('pkg_postinst_%s' % pkg, d, 1) or bb.data.getVar('pkg_postinst', d, 1)
 	if not postinst:
 		postinst = '#!/bin/sh\n'
-	postinst += bb.data.getVar('update_alternatives_postinst', d, 1)
+	if bb.data.getVar('ALTERNATIVE_LINKS', d) != None:
+		postinst += bb.data.getVar('update_alternatives_batch_postinst', d, 1)
+	else:
+		postinst += bb.data.getVar('update_alternatives_postinst', d, 1)
 	bb.data.setVar('pkg_postinst_%s' % pkg, postinst, d)
 	postrm = bb.data.getVar('pkg_postrm_%s' % pkg, d, 1) or bb.data.getVar('pkg_postrm', d, 1)
 	if not postrm:
 		postrm = '#!/bin/sh\n'
-	postrm += bb.data.getVar('update_alternatives_postrm', d, 1)
+	if bb.data.getVar('ALTERNATIVE_LINKS', d) != None:
+		postrm += bb.data.getVar('update_alternatives_batch_postrm', d, 1)
+	else:
+		postrm += bb.data.getVar('update_alternatives_postrm', d, 1)
 	bb.data.setVar('pkg_postrm_%s' % pkg, postrm, d)
 }