migration: Add canary to VMSTATE_END_OF_LIST

We fairly regularly forget VMSTATE_END_OF_LIST markers off descriptions;
given that the current check is only for ->name being NULL, sometimes
we get unlucky and the code apparently works and no one spots the error.

Explicitly add a flag, VMS_END that should be set, and assert it is
set during the traversal.

Note: This can't go in until we update the copy of vmstate.h in slirp.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

2 files changed, 3 insertions, 0 deletions

diff --git a/migration/savevm.c b/migration/savevm.c
index 6d985ad..5c3e5b1 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -585,6 +585,7 @@ static void dump_vmstate_vmsd(FILE *out_file,
             field++;
             first = false;
         }
+        assert(field->flags == VMS_END);
         fprintf(out_file, "\n%*s]", indent, "");
     }
     if (vmsd->subsections != NULL) {
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 924494b..83ca4c7 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -154,6 +154,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
         }
         field++;
     }
+    assert(field->flags == VMS_END);
     ret = vmstate_subsection_load(f, vmsd, opaque);
     if (ret != 0) {
         return ret;
@@ -408,6 +409,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
         }
         field++;
     }
+    assert(field->flags == VMS_END);
 
     if (vmdesc) {
         json_writer_end_array(vmdesc);