[PATCH 2/3] migration: Use error_setg instead of error_report

[Arun Menon <armenon@redhat.com>]

- This is an incremental step in converting vmstate
  loading code to report error via Error object.
- error_report() has been replaced with error_setg();
  and in places where error has been already set,
  error_prepend() is used to not lose information.

Signed-off-by: Arun Menon <armenon@redhat.com>
---
 migration/migration.c |  8 +++++++-
 migration/savevm.c    | 56 ++++++++++++++++++++++++++++++++-------------------
 migration/vmstate.c   | 20 +++++++++---------
 3 files changed, 52 insertions(+), 32 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 5cabb4e7307323159241ff35781db7f1c665a75b..86e16a284286928aedd47e65e7756d27e82e811c 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -903,7 +903,13 @@ process_incoming_migration_co(void *opaque)
     }
 
     if (ret < 0) {
-        error_setg(&local_err, "load of migration failed: %s", strerror(-ret));
+        if (local_err) {
+            error_prepend(&local_err, "load of migration failed: %s: ",
+                          strerror(-ret));
+        } else {
+            error_setg(&local_err, "load of migration failed: %s",
+                       strerror(-ret));
+        }
         goto fail;
     }
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 9bcc0935781b73e209dc57945f9dbb381283cad5..dd7b722f51143eacdc621c343a1334e6056bb268 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2689,8 +2689,8 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type, Error **errp)
     /* Read section start */
     section_id = qemu_get_be32(f);
     if (!qemu_get_counted_string(f, idstr)) {
-        error_report("Unable to read ID string for section %u",
-                     section_id);
+        error_setg(errp, "Unable to read ID string for section %u",
+                   section_id);
         return -EINVAL;
     }
     instance_id = qemu_get_be32(f);
@@ -2698,8 +2698,8 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type, Error **errp)
 
     ret = qemu_file_get_error(f);
     if (ret) {
-        error_report("%s: Failed to read instance/version ID: %d",
-                     __func__, ret);
+        error_setg(errp, "%s: Failed to read instance/version ID: %d",
+                   __func__, ret);
         return ret;
     }
 
@@ -2708,17 +2708,17 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type, Error **errp)
     /* Find savevm section */
     se = find_se(idstr, instance_id);
     if (se == NULL) {
-        error_report("Unknown savevm section or instance '%s' %"PRIu32". "
-                     "Make sure that your current VM setup matches your "
-                     "saved VM setup, including any hotplugged devices",
-                     idstr, instance_id);
+        error_setg(errp, "Unknown savevm section or instance '%s' %"PRIu32". "
+                   "Make sure that your current VM setup matches your "
+                   "saved VM setup, including any hotplugged devices",
+                   idstr, instance_id);
         return -EINVAL;
     }
 
     /* Validate version */
     if (version_id > se->version_id) {
-        error_report("savevm: unsupported version %d for '%s' v%d",
-                     version_id, idstr, se->version_id);
+        error_setg(errp, "savevm: unsupported version %d for '%s' v%d",
+                   version_id, idstr, se->version_id);
         return -EINVAL;
     }
     se->load_version_id = version_id;
@@ -2726,7 +2726,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, uint8_t type, Error **errp)
 
     /* Validate if it is a device's state */
     if (xen_enabled() && se->is_ram) {
-        error_report("loadvm: %s RAM loading not allowed on Xen", idstr);
+        error_setg(errp, "loadvm: %s RAM loading not allowed on Xen", idstr);
         return -EINVAL;
     }
 
@@ -2767,8 +2767,8 @@ qemu_loadvm_section_part_end(QEMUFile *f, uint8_t type, Error **errp)
 
     ret = qemu_file_get_error(f);
     if (ret) {
-        error_report("%s: Failed to read section ID: %d",
-                     __func__, ret);
+        error_setg(errp, "%s: Failed to read section ID: %d",
+                   __func__, ret);
         return ret;
     }
 
@@ -2779,7 +2779,7 @@ qemu_loadvm_section_part_end(QEMUFile *f, uint8_t type, Error **errp)
         }
     }
     if (se == NULL) {
-        error_report("Unknown savevm section %d", section_id);
+        error_setg(errp, "Unknown savevm section %d", section_id);
         return -EINVAL;
     }
 
@@ -2814,23 +2814,27 @@ static int qemu_loadvm_state_header(QEMUFile *f, Error **errp)
 
     v = qemu_get_be32(f);
     if (v != QEMU_VM_FILE_MAGIC) {
-        error_report("Not a migration stream");
+        error_setg(errp, "Not a migration stream magic %x != %x",
+                   v, QEMU_VM_FILE_MAGIC);
         return -EINVAL;
     }
 
     v = qemu_get_be32(f);
     if (v == QEMU_VM_FILE_VERSION_COMPAT) {
-        error_report("SaveVM v2 format is obsolete and don't work anymore");
+        error_setg(errp, "SaveVM v2 format is obsolete and don't work anymore");
         return -ENOTSUP;
     }
     if (v != QEMU_VM_FILE_VERSION) {
-        error_report("Unsupported migration stream version");
+        error_setg(errp, "Unsupported migration stream version %x != %x",
+                   v, QEMU_VM_FILE_VERSION);
         return -ENOTSUP;
     }
 
     if (migrate_get_current()->send_configuration) {
-        if (qemu_get_byte(f) != QEMU_VM_CONFIGURATION) {
-            error_report("Configuration section missing");
+        v = qemu_get_byte(f);
+        if (v != QEMU_VM_CONFIGURATION) {
+            error_setg(errp, "Configuration section missing, %x != %x",
+                       v, QEMU_VM_CONFIGURATION);
             return -EINVAL;
         }
         ret = vmstate_load_state(f, &vmstate_configuration, &savevm_state, 0,
@@ -3434,7 +3438,12 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
     ret = qemu_loadvm_state(f, errp);
     qemu_fclose(f);
     if (ret < 0) {
-        error_setg(errp, "loading Xen device state failed");
+        if (*errp) {
+            ERRP_GUARD();
+            error_prepend(errp, "loading Xen device state failed: ");
+        } else {
+            error_setg(errp, "loading Xen device state failed");
+        }
     }
     migration_incoming_state_destroy();
 }
@@ -3511,7 +3520,12 @@ bool load_snapshot(const char *name, const char *vmstate,
     bdrv_drain_all_end();
 
     if (ret < 0) {
-        error_setg(errp, "Error %d while loading VM state", ret);
+        if (*errp) {
+            ERRP_GUARD();
+            error_prepend(errp, "Error %d while loading VM state: ", ret);
+        } else {
+            error_setg(errp, "Error %d while loading VM state", ret);
+        }
         return false;
     }
 
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 177c563ff103ada2e494c14173fa773d52adb800..3f8c3d3c1dcfe14d70bab1f43b827244eb4bb385 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -139,16 +139,16 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
 
     trace_vmstate_load_state(vmsd->name, version_id);
     if (version_id > vmsd->version_id) {
-        error_report("%s: incoming version_id %d is too new "
-                     "for local version_id %d",
-                     vmsd->name, version_id, vmsd->version_id);
+        error_setg(errp, "%s: incoming version_id %d is too new "
+                   "for local version_id %d",
+                   vmsd->name, version_id, vmsd->version_id);
         trace_vmstate_load_state_end(vmsd->name, "too new", -EINVAL);
         return -EINVAL;
     }
     if  (version_id < vmsd->minimum_version_id) {
-        error_report("%s: incoming version_id %d is too old "
-                     "for local minimum version_id  %d",
-                     vmsd->name, version_id, vmsd->minimum_version_id);
+        error_setg(errp, "%s: incoming version_id %d is too old "
+                   "for local minimum version_id  %d",
+                   vmsd->name, version_id, vmsd->minimum_version_id);
         trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL);
         return -EINVAL;
     }
@@ -213,15 +213,15 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                 }
                 if (ret < 0) {
                     qemu_file_set_error(f, ret);
-                    error_report("Failed to load %s:%s", vmsd->name,
-                                 field->name);
+                    error_setg(errp, "Failed to load %s:%s", vmsd->name,
+                               field->name);
                     trace_vmstate_load_field_error(field->name, ret);
                     return ret;
                 }
             }
         } else if (field->flags & VMS_MUST_EXIST) {
-            error_report("Input validation failed: %s/%s",
-                         vmsd->name, field->name);
+            error_setg(errp, "Input validation failed: %s/%s",
+                       vmsd->name, field->name);
             return -1;
         }
         field++;

-- 
2.49.0