fix(iso): validate memtest with xorriso fallback

iso/builder/build.sh

@@ -111,6 +111,45 @@ resolve_iso_version() {
     resolve_audit_version
 }
 
+iso_list_files() {
+    iso_path="$1"
+
+    if command -v bsdtar >/dev/null 2>&1; then
+        bsdtar -tf "$iso_path"
+        return $?
+    fi
+
+    if command -v xorriso >/dev/null 2>&1; then
+        xorriso -indev "$iso_path" -find / -type f -print 2>/dev/null | sed 's#^/##'
+        return $?
+    fi
+
+    return 127
+}
+
+iso_extract_file() {
+    iso_path="$1"
+    iso_member="$2"
+
+    if command -v bsdtar >/dev/null 2>&1; then
+        bsdtar -xOf "$iso_path" "$iso_member"
+        return $?
+    fi
+
+    if command -v xorriso >/dev/null 2>&1; then
+        xorriso -osirrox on -indev "$iso_path" -cat "/$iso_member" 2>/dev/null
+        return $?
+    fi
+
+    return 127
+}
+
+require_iso_reader() {
+    command -v bsdtar >/dev/null 2>&1 && return 0
+    command -v xorriso >/dev/null 2>&1 && return 0
+    memtest_fail "ISO reader is required for validation/debug (expected bsdtar or xorriso)" "${1:-}"
+}
+
 dump_memtest_debug() {
     phase="$1"
     lb_dir="${2:-}"
@@ -174,13 +213,13 @@ dump_memtest_debug() {
 
         if [ -n "$iso_path" ] && [ -f "$iso_path" ]; then
             echo "-- ISO memtest files --"
-            bsdtar -tf "$iso_path" | grep 'memtest' | sed 's/^/  /' || echo "  (no memtest files in ISO)"
+            iso_list_files "$iso_path" | grep 'memtest' | sed 's/^/  /' || echo "  (no memtest files in ISO)"
 
             echo "-- ISO GRUB memtest lines --"
-            bsdtar -xOf "$iso_path" boot/grub/grub.cfg 2>/dev/null | grep -n 'Memory Test\|memtest' || echo "  (no memtest lines in boot/grub/grub.cfg)"
+            iso_extract_file "$iso_path" boot/grub/grub.cfg 2>/dev/null | grep -n 'Memory Test\|memtest' || echo "  (no memtest lines in boot/grub/grub.cfg)"
 
             echo "-- ISO isolinux memtest lines --"
-            bsdtar -xOf "$iso_path" isolinux/live.cfg 2>/dev/null | grep -n 'Memory Test\|memtest' || echo "  (no memtest lines in isolinux/live.cfg)"
+            iso_extract_file "$iso_path" isolinux/live.cfg 2>/dev/null | grep -n 'Memory Test\|memtest' || echo "  (no memtest lines in isolinux/live.cfg)"
         fi
 
         echo "=== end memtest debug: ${phase} ==="
@@ -206,20 +245,20 @@ validate_iso_memtest() {
     echo "=== validating memtest in ISO ==="
 
     [ -f "$iso_path" ] || memtest_fail "ISO not found for validation: $iso_path" "$iso_path"
-    command -v bsdtar >/dev/null 2>&1 || memtest_fail "bsdtar is required for ISO validation" "$iso_path"
+    require_iso_reader "$iso_path"
 
-    bsdtar -tf "$iso_path" | grep -q '^boot/memtest86+x64\.bin$' || {
+    iso_list_files "$iso_path" | grep -q '^boot/memtest86+x64\.bin$' || {
         memtest_fail "memtest BIOS binary missing in ISO: boot/memtest86+x64.bin" "$iso_path"
     }
-    bsdtar -tf "$iso_path" | grep -q '^boot/memtest86+x64\.efi$' || {
+    iso_list_files "$iso_path" | grep -q '^boot/memtest86+x64\.efi$' || {
         memtest_fail "memtest EFI binary missing in ISO: boot/memtest86+x64.efi" "$iso_path"
     }
 
     grub_cfg="$(mktemp)"
     isolinux_cfg="$(mktemp)"
 
-    bsdtar -xOf "$iso_path" boot/grub/grub.cfg > "$grub_cfg" || memtest_fail "failed to extract boot/grub/grub.cfg from ISO" "$iso_path"
+    iso_extract_file "$iso_path" boot/grub/grub.cfg > "$grub_cfg" || memtest_fail "failed to extract boot/grub/grub.cfg from ISO" "$iso_path"
-    bsdtar -xOf "$iso_path" isolinux/live.cfg > "$isolinux_cfg" || memtest_fail "failed to extract isolinux/live.cfg from ISO" "$iso_path"
+    iso_extract_file "$iso_path" isolinux/live.cfg > "$isolinux_cfg" || memtest_fail "failed to extract isolinux/live.cfg from ISO" "$iso_path"
 
     grep -q 'Memory Test (memtest86+)' "$grub_cfg" || {
         memtest_fail "GRUB menu entry for memtest is missing" "$iso_path"