update_bootcfg(8): various improvements

- inherit a predefined set of system environment variables
  (the current set of inherited variables is: ahci; acpi; no_apic);
- auto-adjust the default menu option when lines are auto-removed;
- add variable substitution support for /etc/boot.cfg.local;
- make default menu options in boot.cfg.local relative to itself,
  allowing one to set the default to a menu option from this file.

commands/update_bootcfg/update_bootcfg.sh

@@ -6,26 +6,85 @@ DEFAULTCFG=/etc/boot.cfg.default
 LOCALCFG=/etc/boot.cfg.local
 TMP=/boot.cfg.temp
 DIRSBASE=/boot/minix
+INHERIT="ahci acpi no_apic"
 
-filter_missing_entries()
+filter_entries()
 {
+	# This routine performs three tasks:
+	# - substitute variables in the configuration lines;
+	# - remove multiboot entries that refer to nonexistent kernels;
+	# - adjust the default option for line removal and different files.
+	# The last part is handled by the awk part of the routine.
+
 	while read line
 	do
-		if ! echo "$line" | grep -s -q 'multiboot'
+		# Substitute variables like $rootdevname and $args
+		line=$(eval echo \"$line\")
+
+		if ! echo "$line" | grep -sq '^menu=.*multiboot'
 		then
 			echo "$line"
 			continue
 		fi
 
-		# Check if kernel presents
+		# Check if the referenced kernel is present
 		kernel=`echo "$line" | sed -n 's/.*multiboot[[:space:]]*\(\/[^[:space:]]*\).*/\1/p'`
 		if [ ! -r "$kernel" ]
 		then
 			echo "Warning: config contains entry for \"$kernel\" which is missing! Entry skipped." 1>&2
+			echo "menu=SKIP"
 		else
 			echo "$line"
 		fi
-	done
+	done | awk '
+		BEGIN {
+			count=1
+			base=0
+			default=0
+		}
+		/^menu=SKIP$/ {
+			# A menu entry discarded by the kernel check above
+			skip[count++]=1
+			next
+		}
+		/^menu=/ {
+			# A valid menu entry
+			skip[count++]=0
+			print
+			next
+		}
+		/^BASE=/ {
+			# The menu count base as passed in by count_entries()
+			sub(/^.*=/,"",$1)
+			base=$1+0
+			next
+		}
+		/^default=/ {
+			# The default option
+			# Correct for the menu count base and store for later
+			sub(/^.*=/,"",$1)
+			default=$1+base
+			next
+		}
+		{
+			# Any other line
+			print
+		}
+		END {
+			# If a default was given, correct for removed lines
+			# (do not bother to warn if the default itself is gone)
+			if (default) {
+				for (i = default; i > 0; i--)
+					if (skip[i]) default--;
+				print "default=" default
+			}
+		}
+	'
+}
+
+count_entries()
+{
+	echo -n "BASE="; grep -cs '^menu=' "$1"
 }
 
 if [ ! -b "$ROOT" ]
@@ -36,14 +95,22 @@ fi
 
 rootdevname=`echo $ROOT | sed 's/\/dev\///'`
 
+# Construct a list of inherited arguments for boot options to use. Note that
+# rootdevname must not be passed on this way, as it is changed during setup.
+args=""
+for k in $INHERIT; do
+	if sysenv | grep -sq "^$k="; then
+		kv=$(sysenv | grep "^$k=")
+		args="$args $kv"
+	fi
+done
+
 if [ -r $DEFAULTCFG ]
 then
-	default_cfg=`cat $DEFAULTCFG`
+	filter_entries < $DEFAULTCFG >> $TMP
-	# Substitute variables like $rootdevname
-	echo "$default_cfg" | while read line; do eval echo \"$line\" | filter_missing_entries >> $TMP; done
 fi
 
-if [ -e /boot/minix_latest -a -d /boot/minix_latest -o -h /boot/minix_latest ]
+if [ -d /boot/minix_latest -o -h /boot/minix_latest ]
 then
 	latest=`basename \`stat -f "%Y" /boot/minix_latest\``
 fi
@@ -53,11 +120,19 @@ do
 	build_name="`basename $i`"
 	if [ "$build_name" != "$latest" ]
 	then
-		echo "menu=Start MINIX 3 ($build_name):load_mods $DIRSBASE/$i/mod*;multiboot $DIRSBASE/$i/kernel rootdevname=$rootdevname" >> /$TMP
+		echo "menu=Start MINIX 3 ($build_name):load_mods $DIRSBASE/$i/mod*;multiboot $DIRSBASE/$i/kernel rootdevname=$rootdevname $args" >> $TMP
 	fi
 done
 
-[ -r $LOCALCFG ] && cat $LOCALCFG | filter_missing_entries >> $TMP
+if [ -r $LOCALCFG ]
+then
+	# If the local config supplies a "default" option, we assume that this
+	# refers to one of the options in the local config itself. Therefore,
+	# we increase this default by the number of options already present in
+	# the output so far. To this end, count_entries() inserts a special
+	# token that is recognized and filtered out by filter_entries().
+	(count_entries $TMP; cat $LOCALCFG) | filter_entries >> $TMP
+fi
 
 mv $TMP /boot.cfg
 

etc/boot.cfg.default

@@ -1,8 +1,8 @@
 clear=1
 timeout=5
 default=2
-menu=Start MINIX 3:load_mods /boot/minix_default/mod*;multiboot /boot/minix_default/kernel rootdevname=$rootdevname
+menu=Start MINIX 3:load_mods /boot/minix_default/mod*;multiboot /boot/minix_default/kernel rootdevname=$rootdevname $args
-menu=Start latest MINIX 3:load_mods /boot/minix_latest/mod*;multiboot /boot/minix_latest/kernel rootdevname=$rootdevname
+menu=Start latest MINIX 3:load_mods /boot/minix_latest/mod*;multiboot /boot/minix_latest/kernel rootdevname=$rootdevname $args
-menu=Start latest MINIX 3 in single user mode:load_mods /boot/minix_latest/mod*;multiboot /boot/minix_latest/kernel rootdevname=$rootdevname bootopts=-s
+menu=Start latest MINIX 3 in single user mode:load_mods /boot/minix_latest/mod*;multiboot /boot/minix_latest/kernel rootdevname=$rootdevname bootopts=-s $args
 menu=Edit menu option:edit
 menu=Drop to boot prompt:prompt