pkg/driver/vz: Support ASIF as diffdisk

Depends on lima-vm/go-qcow2reader#61

How to setup ASIF as diffdisk:
1. Create an instance for test, then stop it.
```console
$ limactl start template:ubuntu --name=asif-test --tty=false --log-level=fatal; limactl stop asif-test --log-level=fatal
```
2. Convert `diffdisk` with ASIF image. (original will be renamed to `diffdisk.raw`)
```console
$ hack/convert-diffdisk-to-asif.sh asif-test
+ instance=asif-test
++ limactl list asif-test --format '{{.Dir}}'
+ instance_dir=/Users/norio/.lima/asif-test
++ head -c 4 /Users/norio/.lima/asif-test/diffdisk
+ head4bytes=
+ case "${head4bytes}" in
++ limactl list asif-test --format '{{.Status}}'
+ instance_state=Stopped
+ [[ Stopped == \S\t\o\p\p\e\d ]]
+ diskutil image create blank --fs none --format ASIF --size 100GiB /Users/norio/.lima/asif-test/diffdisk.asif

/Users/norio/.lima/asif-test/diffdisk.asif created
++ diskutil image attach -n /Users/norio/.lima/asif-test/diffdisk.asif
+ attached_device=/dev/disk5
+ dd if=/Users/norio/.lima/asif-test/diffdisk of=/dev/disk5 status=progress conv=sparse
  107152496640 bytes (107 GB, 100 GiB) transferred 115.003s, 932 MB/s
209715200+0 records in
209715200+0 records out
107374182400 bytes transferred in 115.228413 secs (931837727 bytes/sec)
+ hdiutil detach /dev/disk5
"disk5" ejected.
+ mv /Users/norio/.lima/asif-test/diffdisk /Users/norio/.lima/asif-test/diffdisk.raw
+ mv /Users/norio/.lima/asif-test/diffdisk.asif /Users/norio/.lima/asif-test/diffdisk
+ echo 'Converted diffdisk to ASIF format successfully'
Converted diffdisk to ASIF format successfully
```
3. Start the instance
```console
$ limactl start asif-test
```

Signed-off-by: Norio Nomura <norio.nomura@gmail.com>

Author: norio-nomura

go.mod

@@ -146,3 +146,5 @@ require (
 	sigs.k8s.io/randfill v1.0.0 // indirect
 	sigs.k8s.io/structured-merge-diff/v6 v6.3.0 // indirect
 )
+
+replace github.com/lima-vm/go-qcow2reader => github.com/norio-nomura/go-qcow2reader v0.6.1-0.20251110085027-73026bc16b7b

go.sum

@@ -162,8 +162,6 @@ github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/lima-vm/go-qcow2reader v0.6.0 h1:dNstUGQxEUPbmiiVnu/cek2x7scrHe2VJy5JseLLflo=
-github.com/lima-vm/go-qcow2reader v0.6.0/go.mod h1:ay45SlGOzU+2Vc21g5/lmQgPn7Hmf0JpPhm8cuOK1FI=
 github.com/lima-vm/sshocker v0.3.8 h1:nnIaqi1G1hvWihm++53YBXeI8/x7CQNzhEswPC0M2E0=
 github.com/lima-vm/sshocker v0.3.8/go.mod h1:sO9dTE0i+I0BHHVpyoKZWkPFtHtTkrqcfCkQguRMsx8=
 github.com/linuxkit/virtsock v0.0.0-20220523201153-1a23e78aa7a2 h1:DZMFueDbfz6PNc1GwDRA8+6lBx1TB9UnxDQliCqR73Y=
@@ -209,6 +207,8 @@ github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee h1:W5t00kpgFd
 github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
+github.com/norio-nomura/go-qcow2reader v0.6.1-0.20251110085027-73026bc16b7b h1:oP4ZY9Geumc+PmknrDpdXJc3V4XFVLHVuv3/sUhIlB4=
+github.com/norio-nomura/go-qcow2reader v0.6.1-0.20251110085027-73026bc16b7b/go.mod h1:ay45SlGOzU+2Vc21g5/lmQgPn7Hmf0JpPhm8cuOK1FI=
 github.com/nxadm/tail v1.4.11 h1:8feyoE3OzPrcshW5/MJ4sGESc5cqmGkGCWlco4l0bqY=
 github.com/nxadm/tail v1.4.11/go.mod h1:OTaG3NK980DZzxbRq6lEuzgU+mug70nY11sMd4JXXHc=
 github.com/onsi/ginkgo v1.16.5 h1:8xi0RTUf59SOSfEtZMvwTvXYMzG4gV23XVHOZiXNtnE=

hack/convert-diffdisk-to-asif.sh

@@ -0,0 +1,57 @@
+#!/bin/bash
+
+# SPDX-FileCopyrightText: Copyright The Lima Authors
+# SPDX-License-Identifier: Apache-2.0
+
+set -eux -o pipefail
+
+instance="${1:-asif-test}"
+
+# Get instance dir
+instance_dir=$(limactl list "${instance}" --format "{{.Dir}}") || {
+  echo "Failed to get instance dir for ${instance}"
+  exit 1
+}
+
+# Check diffdisk type
+head4bytes="$(head -c 4 "${instance_dir}/diffdisk")"
+case "${head4bytes}" in
+  shdw)
+    echo "diffdisk is already in ASIF format"
+    exit 1
+    ;;
+  QFI*)
+    echo "diffdisk is in QCOW2 format"
+    exit 1
+    ;;
+  *)
+    ;;
+esac
+
+# Check instance state
+instance_state="$(limactl list "${instance}" --format "{{.Status}}")" || {
+  echo "Failed to get instance state for ${instance}"
+  exit 1
+}
+[[ "${instance_state}" == "Stopped" ]] || {
+  echo "Instance ${instance} must be stopped"
+  exit 1
+}
+
+# Create ASIF image
+diskutil image create blank --fs none --format ASIF --size 100GiB "${instance_dir}/diffdisk.asif"
+
+# Attach ASIF image (`hdiutil attach` does not support attaching ASIF)
+attached_device=$(diskutil image attach -n "${instance_dir}/diffdisk.asif")
+
+# Write `diffdisk` content to attached device using `dd` with `conv=sparse` option (`diskutil` does not support sparse)
+dd if="${instance_dir}/diffdisk" of="${attached_device}" status=progress conv=sparse
+
+# Detach the device (`diskutil unmountDisk` does not detach the device)
+hdiutil detach "${attached_device}"
+
+# Replace `diffdisk` with `diffdisk.asif`
+mv "${instance_dir}/diffdisk" "${instance_dir}/diffdisk.raw"
+mv "${instance_dir}/diffdisk.asif" "${instance_dir}/diffdisk"
+
+echo "Converted diffdisk to ASIF format successfully"

pkg/driver/vz/vm_darwin.go

@@ -22,6 +22,7 @@ import (
 	"github.com/coreos/go-semver/semver"
 	"github.com/docker/go-units"
 	"github.com/lima-vm/go-qcow2reader"
+	"github.com/lima-vm/go-qcow2reader/image/asif"
 	"github.com/lima-vm/go-qcow2reader/image/raw"
 	"github.com/sirupsen/logrus"
 
@@ -451,7 +452,7 @@ func validateDiskFormat(diskPath string) error {
 	if err != nil {
 		return fmt.Errorf("failed to detect the format of %q: %w", diskPath, err)
 	}
-	if t := img.Type(); t != raw.Type {
+	if t := img.Type(); t != raw.Type && t != asif.Type {
 		return fmt.Errorf("expected the format of %q to be %q, got %q", diskPath, raw.Type, t)
 	}
 	// TODO: ensure that the disk is formatted with GPT or ISO9660