update.sh: add checksum to update log for the update delta

The cksum utility is sued for the value.
It's not cryptographically secure, but this is just a simple update
check. The actual cryptographic verification is already done by
verifycerts(). Plus, cksum is POSIX amd universally available.

res/util/func-resdl.sh

@@ -34,17 +34,22 @@ updatedelta() {
     file="$entry";
     line="$(grep "FILE: $file[,;]" "$reldir/update-$newlog.log" | head -n1)";
     url="$(echo "$line" | grep -oE "URL: [^,;]*" | cut -d" " -f2)";
+    cksum="$(echo "$line" | grep -oE "CKSUM: [^,;]*" | cut -d" " -f2)";
     oldline="";
     for log in $oldlogs; do
       oldline="$(grep "FILE: $file[,;]" "$reldir/update-$log.log" | head -n1)";
       [ "$oldline" ] && break;
     done;
     oldurl="$(echo "$oldline" | grep -oE "URL: [^,;]*" | cut -d" " -f2)";
+    oldcksum="$(echo "$oldline" | grep -oE "CKSUM: [^,;]*" | cut -d" " -f2)";
     [ "$oldurl" ] || oldurl="None";
-    [ "$url" = "$oldurl" ] && continue;
+    [ "$oldcksum" ] || oldcksum="None";
+    [ "$url" = "$oldurl" ] && [ "$cksum" = "$oldcksum" ] && continue;
     echo " -- Updated file: $file";
     echo "   ++ Old URL: $oldurl";
     echo "   ++ New URL: $url";
+    echo "   ++ Old CKSUM: $oldcksum";
+    echo "   ++ New CKSUM: $cksum";
     echo "   ++ Old name: $(basename "$oldurl")";
     echo "   ++ New name: $(basename "$url")";
   done;

update.sh

@@ -39,7 +39,7 @@ echo "--       Minimal MicroG Update Script       --";
 echo "--      The Essentials Only MicroG Pack     --";
 
 # Bin check
-for bin in chmod cp curl find grep head jq mv rm sort tr unzip; do
+for bin in chmod cksum cp curl find grep head jq mv rm sort tr unzip; do
   command -v "$bin" >/dev/null || abort "No $bin found";
 done;
 
@@ -165,7 +165,8 @@ for object in $(echo "$stuff_download" | select_word 1); do
       objectfile="$tmpdir/$objectname";
       echo " ---- Downloading $objecturl";
       curl -L "$objecturl" -o "$objectfile" || { echo "ERROR: $object failed to download"; continue; }
-      echo "NAME: $objectname, FILE: $object, URL: $objecturl;" >> "$updatelog";
+      objectcksum="$(cksum "$objectfile" | select_word 1)";
+      echo "NAME: $objectname, FILE: $object, URL: $objecturl, CKSUM: $objectcksum;" >> "$updatelog";
     ;;
   esac;
   mkdir -p "$resdldir/$(dirname "$object")";