migration: Check field save returns

Check the return values from vmstate_save_state for fields and also the
return values from 'put' for fields that use that.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170925112917.21340-4-dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/migration/vmstate.c b/migration/vmstate.c
index ae8abd3c32..848e8448c6 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -347,6 +347,7 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
             }
             for (i = 0; i < n_elems; i++) {
                 void *curr_elem = first_elem + size * i;
+                ret = 0;
 
                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
                 old_offset = qemu_ftell_fast(f);
@@ -357,11 +358,19 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                 if (!curr_elem && size) {
                     /* if null pointer write placeholder and do not follow */
                     assert(field->flags & VMS_ARRAY_OF_POINTER);
-                    vmstate_info_nullptr.put(f, curr_elem, size, NULL, NULL);
+                    ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
+                                                   NULL);
                 } else if (field->flags & VMS_STRUCT) {
-                    vmstate_save_state(f, field->vmsd, curr_elem, vmdesc_loop);
+                    ret = vmstate_save_state(f, field->vmsd, curr_elem,
+                                             vmdesc_loop);
                 } else {
-                    field->info->put(f, curr_elem, size, field, vmdesc_loop);
+                    ret = field->info->put(f, curr_elem, size, field,
+                                     vmdesc_loop);
+                }
+                if (ret) {
+                    error_report("Save of field %s/%s failed",
+                                 vmsd->name, field->name);
+                    return ret;
                 }
 
                 written_bytes = qemu_ftell_fast(f) - old_offset;