From 105071cc70a454680e6bf11e2d9d7b73c7ce7491 Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Thu, 3 Apr 2014 19:50:31 +0300
Subject: [PATCH] vmstate: add VMS_MUST_EXIST

Can be used to verify a required field exists or validate
state in some other way.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 5bf81c8d63db0216a4d29dc87f9ce530bb791dd1)
---
 include/migration/vmstate.h |  1 +
 vmstate.c                   | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index e7e1705..de970ab 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -100,6 +100,7 @@ enum VMStateFlags {
     VMS_MULTIPLY         = 0x200,  /* multiply "size" field by field_size */
     VMS_VARRAY_UINT8     = 0x400,  /* Array with size in uint8_t field*/
     VMS_VARRAY_UINT32    = 0x800,  /* Array with size in uint32_t field*/
+    VMS_MUST_EXIST       = 0x1000, /* Field must exist in input */
 };
 
 typedef struct {
diff --git a/vmstate.c b/vmstate.c
index b689f2f..d856319 100644
--- a/vmstate.c
+++ b/vmstate.c
@@ -78,6 +78,10 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                     return ret;
                 }
             }
+        } else if (field->flags & VMS_MUST_EXIST) {
+            fprintf(stderr, "Input validation failed: %s/%s\n",
+                    vmsd->name, field->name);
+            return -1;
         }
         field++;
     }
@@ -138,6 +142,12 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                     field->info->put(f, addr, size);
                 }
             }
+        } else {
+            if (field->flags & VMS_MUST_EXIST) {
+                fprintf(stderr, "Output state validation failed: %s/%s\n",
+                        vmsd->name, field->name);
+                assert(!(field->flags & VMS_MUST_EXIST));
+            }
         }
         field++;
     }