Merge branch main into debian

1 files changed, 108 insertions, 22 deletions

diff --git a/debvm-run b/debvm-run
index edb01ad..d6a5422 100755
--- a/debvm-run
+++ b/debvm-run
@@ -2,46 +2,132 @@
 # Copyright 2022 Helmut Grohne <helmut@subdivi.de>
 # SPDX-License-Identifier: MIT
 
+: <<'POD2MAN'
+=head1 NAME
+
+debvm-run - Run a VM image created by debvm-create
+
+=head1 SYNOPSIS
+
+B<debvm-run> [B<-g>] [B<-i> I<image>] [B<-s> I<sshport>] [B<--> I<qemu options>]
+
+=head1 DESCRIPTION
+
+B<debvm-run> is essentially a thin wrapper around B<qemu> for running a virtual machine image created by B<debvm-create> or something compatible.
+The virtual machine image is expected to be a raw ext4 image with file system label B<debvm>.
+The architecture of the machine is detected from the contained B</bin/true>.
+It must contain a symbolic link pointing to a kernel image at B</vmlinuz> or B</vmlinux> depending on the architecture and a symbolic link pointing to an initrd image at B</initrd.img>.
+Both are extracted and passed to B<qemu>.
+A net interface configured for user mode is added automatically.
+
+=head1 OPTIONS
+
+=over 8
+
+=item B<-g>, B<--graphical>
+
+By default, the option B<-nographic> is passed to B<qemu> and one interacts with the serial console of the machine.
+This configuration is skipped in the presence of this option.
+
+=item B<-i> I<image>, B<--image>=I<image>
+
+This option specifies the location of the virtual machine image file.
+By default B<rootfs.ext4> in the working directory is used.
+
+=item B<-s> I<sshport>, B<--sshport>=I<sshport>
+
+If given, B<qemu> is configured to pass connections to I<127.0.0.1:sshport> to port 22 of the virtual machine.
+
+=item B<--> I<qemu options>
+
+All options beyond a double dash are passed to B<qemu>.
+This can be used to configure additional hardware components.
+One possible use of this method is passing B<-snapshot> to avoid modifying the virtual machine image.
+
+=back
+
+=head1 LIMITATIONS
+
+Due to the way kernel and bootloader are being extracted before running B<qemu>, one cannot upgrade a kernel and then just reboot.
+Attempting to do so, will still use the old kernel.
+Instead, B<qemu> must be terminated and B<debvm-run> should be launched again to pick up the new kernel.
+In order to avoid accidental reboots, one may pass B<-no-reboot> to B<qemu>.
+
+=head1 SEE ALSO
+
+    debvm-create(1) qemu(1)
+
+=cut
+POD2MAN
+
 set -u
 
-IMAGE=rootfs.ext2
+IMAGE=rootfs.ext4
 SSHPORT=
 GRAPHICAL=
 
+nth_arg() {
+	shift "$1"
+	printf "%s" "$1"
+}
+
 die() {
 	echo "$*" 1>&2
 	exit 1
 }
-
 usage() {
 	die "usage: $0 [-g] [-i image] [-s sshport] [-- qemu options]"
 }
+usage_error() {
+	echo "error: $*" 1>&2
+	usage
+}
 
-while test "$#" -gt 0; do
-	case "$1" in
-		-g)
-			GRAPHICAL=1
-			shift
-		;;
-		-i)
-			test "$#" -eq 1 && usage
-			IMAGE=$2
-			shift 2
+opt_graphical() {
+	GRAPHICAL=1
+}
+opt_image() {
+	IMAGE=$1
+}
+opt_sshport() {
+	SSHPORT=$1
+}
+
+while getopts :gi:s:-: OPTCHAR; do
+	case "$OPTCHAR" in
+		g)	opt_graphical		;;
+		i)	opt_image "$OPTARG"	;;
+		s)	opt_sshport "$OPTARG"	;;
+		-)
+			case "$OPTARG" in
+				help)
+					usage
+				;;
+				graphical|image|sshport)
+					test "$OPTIND" -gt "$#" && usage_error "missing argument for --$OPTARG"
+					"opt_$OPTARG" "$(nth_arg "$OPTIND" "$@")"
+					OPTIND=$((OPTIND+1))
+				;;
+				image=*|sshport=*)
+					"opt_${OPTARG%%=*}" "${OPTARG#*=}"
+				;;
+				*)
+					usage_error "unrecognized option --$OPTARG"
+				;;
+			esac
 		;;
-		-s)
-			test "$#" -eq 1 && usage
-			SSHPORT=$2
-			shift 2
+		:)
+			usage_error "missing argument for -$OPTARG"
 		;;
-		--)
-			shift
-			break
+		'?')
+			usage_erro "unrecognized option -$OPTARG"
 		;;
 		*)
-			usage
+			die "internal error while parsing command options, please report a bug"
 		;;
 	esac
 done
+shift "$((OPTIND - 1))"
 
 test -f "$IMAGE" || die "image '$IMAGE' not found"
 test -s "$IMAGE" || die "image '$IMAGE' is empty"
@@ -140,9 +226,9 @@ else
 		;;
 	esac
 fi
-if test "$MAX_SMP" -gt 1; then
+if test -z "$MAX_SMP" || test "$MAX_SMP" -gt 1; then
 	NPROC=$(nproc)
-	test "$NPROC" -gt "$MAX_SMP" && NPROC=$MAX_SMP
+	test -n "$MAX_SMP" && test "$NPROC" -gt "$MAX_SMP" && NPROC=$MAX_SMP
 	set -- -smp "$NPROC" "$@"
 fi