swupd-image.bbclass: remove assumption about OS version numbering

It is not guaranteed that OS versions always increment in steps of 10
and that deltas are desired for "current version - 10, -20, etc.". For
example, previous versions might be 10, 20, and the current one 21
because it is a minor update. In such a case no delta packs would be
generated because OS versions 11 and 1 do not exist.

Ostro OS outside of the CI derives the OS version from datetime, which
leads to high version numbers like 33014500. Counting down from that
in steps of ten in shell under pseudo was surprisingly slow and
unusable, running for minutes without even getting close to completion
when it does not hit existing version numbers.

So now the simplified approach is to generate delta packs for exactly
the last SWUPD_N_DELTAPACK older versions, regardless what their
numbering is.

If a more sophisticated approach is needed, it can still be added
later on, for example as part of YOCTO #9321.

Signed-off-by: Patrick Ohly <[email protected]>

meta-swupd/classes/swupd-image.bbclass

@@ -56,10 +56,6 @@ SWUPD_GENERATE ??= "1"
 SWUPD_DELTAPACKS ??= "1"
 # Create delta packs for N versions back — default 2
 SWUPD_N_DELTAPACK ??= "2"
-# Amount the OS_VERSION should be increased by for each release, used by the
-# delta pack looping to generate delta packs going back up toSWUPD_N_DELTAPACK
-# releases
-SWUPD_VERSION_STEP ??= "10"
 
 # This version number *must* map to VERSION_ID in /etc/os-release and *must* be
 # a non-negative integer that fits in an int.
@@ -503,25 +499,15 @@ END
 
     # Generate delta-packs going back SWUPD_N_DELTAPACK versions
     if [ ${SWUPD_DELTAPACKS} -eq 1 -a ${SWUPD_N_DELTAPACK} -gt 0 -a $PREVREL -gt 0 ]; then
-        bbdebug 1 "Generating delta pack with previous release $PREVREL"
         bundles="os-core ${SWUPD_BUNDLES}"
         for bndl in $bundles; do
             bndlcnt=0
-            prevver=$PREVREL
-            while [ $bndlcnt -lt ${SWUPD_N_DELTAPACK} -a $prevver -gt 0 ]; do
-                if [ -e ${DEPLOY_DIR_SWUPD}/image/$prevver/$bndl ]; then
-                    bbdebug 2 "Generating delta pack from $prevver to ${OS_VERSION} for $bndl"
-                    ${STAGING_BINDIR_NATIVE}/swupd_make_pack -S ${DEPLOY_DIR_SWUPD} $prevver ${OS_VERSION} $bndl
-                    bndlcnt=`expr $bndlcnt + 1`
-                fi
-                # Both let and expr return 1 if the expression evaluates to 0,
-                # bitbake catches the non-zero exit code from a shell command
-                # end exits with an error - special case to work around this.
-                if [ $prevver -eq ${SWUPD_VERSION_STEP} ]; then
-                    prevver=0
-                else
-                    prevver=`expr $prevver - ${SWUPD_VERSION_STEP}`
-                fi
+            # Build list of previous versions and pick the last n ones to build
+            # deltas against. Ignore the latest one, which is the one we build
+            # right now.
+            ls -d -1 ${DEPLOY_DIR_SWUPD}/image/*/$bndl | sed -e 's;${DEPLOY_DIR_SWUPD}/image/\([^/]*\)/.*;\1;' | grep -e '^[0-9]*$' | sort -n | head -n -1 | tail -n ${SWUPD_N_DELTAPACK} | while read prevver; do
+                bbdebug 2 "Generating delta pack from $prevver to ${OS_VERSION} for $bndl"
+                ${STAGING_BINDIR_NATIVE}/swupd_make_pack -S ${DEPLOY_DIR_SWUPD} $prevver ${OS_VERSION} $bndl
             done
         done
     fi