From 408a4aeed4d87396028a5975bd6e4e1f244bd8a0 Mon Sep 17 00:00:00 2001
From: Thilo Fromm <thilofromm@microsoft.com>
Date: Thu, 8 Oct 2026 16:30:43 +0200
Subject: [PATCH] qemu_template: fix -S flag when '-- -snapshot' was provided

This change fixes a corner case in #4310 when the new '-S' option
introduced in that PR was not provided, but the classic '-- -snapshot'
pass-through option is used. Since the PR explicitly sets 'snapshot=off'
on all disks individually, and since per-disk options override global
options, '-- -snapshot' is effectively ignored.

Signed-off-by: Thilo Fromm <thilofromm@microsoft.com>
---
 build_library/qemu_template.sh | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/build_library/qemu_template.sh b/build_library/qemu_template.sh
index 1e58e9257b8..1fc6140aa18 100755
--- a/build_library/qemu_template.sh
+++ b/build_library/qemu_template.sh
@@ -22,7 +22,7 @@ SAFE_ARGS=0
 FORWARDED_PORTS=""
 PRIMARY_DISK_OPTS=""
 DISKS=()
-SNAPSHOT="off"
+SNAPSHOT=""
 USAGE="Usage: $0 [-a authorized_keys] [--] [qemu options...]
 Options:
     -i FILE     File containing an Ignition config
@@ -133,7 +133,7 @@ while [ $# -ge 1 ]; do
             VM_INITRD="$2"
             shift 2 ;;
         -S|-snapshot)
-            SNAPSHOT="on"
+            SNAPSHOT=",snapshot=on"
             shift ;;
         -v|-verbose)
             set -x
@@ -276,14 +276,14 @@ if [ -n "${CONFIG_DRIVE}" ]; then
 fi
 
 if [ -n "${CONFIG_IMAGE}" ]; then
-    set -- -drive if=virtio,file="${CONFIG_IMAGE}",snapshot="${SNAPSHOT}" "$@"
+    set -- -drive if=virtio,file="${CONFIG_IMAGE}${SNAPSHOT}" "$@"
 fi
 
 if [ -n "${VM_IMAGE}" ]; then
     if [[ ,${PRIMARY_DISK_OPTS}, = *,drive=* || ,${PRIMARY_DISK_OPTS}, = *,bootindex=* ]]; then
         die "Can't override drive or bootindex options for primary disk"
     fi
-    set -- -drive if=none,id=blk,file="${VM_IMAGE}",snapshot="${SNAPSHOT}" \
+    set -- -drive if=none,id=blk,file="${VM_IMAGE}${SNAPSHOT}" \
         -device virtio-blk-pci,drive=blk,bootindex=1${PRIMARY_DISK_OPTS:+,}${PRIMARY_DISK_OPTS:-} "$@"
 fi
 
@@ -299,7 +299,7 @@ for disk in "${DISKS[@]}"; do
         disk_opts=
     fi
     set -- \
-        -drive "if=none,id=${disk_id},file=${disk_path},snapshot=${SNAPSHOT}" \
+        -drive "if=none,id=${disk_id},file=${disk_path}${SNAPSHOT}" \
         -device "virtio-blk-pci,drive=${disk_id}${disk_opts:+,}${disk_opts:-}" \
         "${@}"
 done
@@ -324,7 +324,7 @@ fi
 if [ -n "${VM_PFLASH_RO}" ] && [ -n "${VM_PFLASH_RW}" ]; then
     set -- \
         -drive if=pflash,unit=0,file="${VM_PFLASH_RO}",format=qcow2,readonly=on \
-        -drive if=pflash,unit=1,file="${VM_PFLASH_RW}",format=qcow2,snapshot="${SNAPSHOT}" "$@"
+        -drive if=pflash,unit=1,file="${VM_PFLASH_RW}",format=qcow2"${SNAPSHOT}" "$@"
 fi
 
 if [ -n "${IGNITION_CONFIG_FILE}" ]; then