Auto-detect the Windows 11 installation ISO

Instead of a hard-coded file name, find the ISO in install-iso/ by
matching *Win*11*x64*.iso (case-insensitive), picking the highest
version-sorted name when several match. The QCOW2 path is derived from
the detected ISO name, falling back to an existing *Win*11*x64*.qcow2
in base-qcow2/ when the ISO is absent.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ks2ixr4KHXBtLuCet7Ch5Z

README.md

@@ -22,7 +22,10 @@ Download or check selected targets:
 ```
 
 The Windows installation ISO is not downloaded because Microsoft's temporary
-download URLs expire. Supply it manually at the path reported by
+download URLs expire. Place it manually in `install-iso/`; the script finds it
+automatically by matching `Win`, `11`, `x64` and `.iso` in that order
+(`*Win*11*x64*.iso`, case-insensitive). If several files match, the highest
+version-sorted name is used. Check which file was picked with
 `./download-images.sh --print-path windows11 --iso`.
 
 ## Query image paths
@@ -39,7 +42,10 @@ The path interface prints one absolute path without downloading anything:
 ```
 
 The Windows target prints the QCOW2 path by default. Add `--iso` to print its
-manually supplied installation ISO path.
+manually supplied installation ISO path. The QCOW2 is named after the detected
+ISO (for example `Win11_25H2_English_x64_v2.iso` →
+`base-qcow2/Win11_25H2_English_x64_v2.qcow2`); if no ISO is present, an
+existing `*Win*11*x64*.qcow2` in `base-qcow2/` is used instead.
 
 Download URLs can be overridden with `DEBIAN_IMAGE_URL`, `ALMA_IMAGE_URL`,
 `FEDORA_IMAGE_URL`, and `VIRTIO_WIN_ISO_URL`. The Fedora checksum can be

download-images.sh

@@ -42,8 +42,42 @@ else
 fi
 
 virtio_image="${tools_iso_dir}/virtio-win.iso"
-windows_qcow2_image="${base_qcow2_dir}/Win11_25H2_English_x64_v2.qcow2"
-windows_iso_image="${install_iso_dir}/Win11_25H2_English_x64_v2.iso"
+
+# Find a Windows 11 x64 file in a directory by matching "Win", "11", "x64" and
+# the extension in that order (case-insensitive). When several match, the
+# highest version-sorted name wins.
+find_windows_image() {
+  local dir="$1"
+  local extension="$2"
+  local match
+
+  match="$(
+    shopt -s nullglob nocaseglob
+    files=("${dir}"/*Win*11*x64*."${extension}")
+    ((${#files[@]} == 0)) || printf '%s\n' "${files[@]}" | sort -V | tail -n 1
+  )"
+  [[ -n "$match" ]] && printf '%s\n' "$match"
+}
+
+windows_iso_path() {
+  if ! find_windows_image "$install_iso_dir" iso; then
+    printf 'Error: no Windows 11 x64 ISO (*Win*11*x64*.iso) found in %s\n' "$install_iso_dir" >&2
+    return 1
+  fi
+}
+
+# The QCOW2 is named after the installation ISO. If the ISO has been removed,
+# fall back to an existing matching QCOW2.
+windows_qcow2_path() {
+  local iso
+  if iso="$(find_windows_image "$install_iso_dir" iso)"; then
+    iso="$(basename -- "$iso")"
+    printf '%s/%s.qcow2\n' "$base_qcow2_dir" "${iso%.*}"
+  elif ! find_windows_image "$base_qcow2_dir" qcow2; then
+    printf 'Error: no Windows 11 x64 ISO (*Win*11*x64*.iso) found in %s\n' "$install_iso_dir" >&2
+    return 1
+  fi
+}
 
 debian_url="${DEBIAN_IMAGE_URL:-$debian_url_default}"
 alma_url="${ALMA_IMAGE_URL:-$alma_url_default}"
@@ -67,6 +101,8 @@ is auto-detected from the host; override it with VM_IMAGE_ARCH.
 then downloads them again from the beginning.
 --print-path prints only the absolute image path without downloading it.
 For windows11 it prints the QCOW2 path by default; add --iso for the ISO path.
+The Windows ISO is found automatically in install-iso/ by matching
+*Win*11*x64*.iso; the QCOW2 path is named after that ISO.
 EOF
 }
 
@@ -81,9 +117,9 @@ print_image_path() {
     virtio-win) printf '%s\n' "$virtio_image" ;;
     windows11)
       if [[ "$media" == iso ]]; then
-        printf '%s\n' "$windows_iso_image"
+        windows_iso_path
       else
-        printf '%s\n' "$windows_qcow2_image"
+        windows_qcow2_path
       fi
       ;;
     *)