[Qemu-devel] [RFC PATCH v2 15/16] Wire in BER visitors

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <address@hidden>

BER output visitor to be selected with env
BER input visitor recognized by file header

Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
 include/migration/migration.h |   2 +
 savevm.c                      | 105 +++++++++++++++++++++++++++++++-----------
 2 files changed, 80 insertions(+), 27 deletions(-)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index 8111125..5d500ec 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -27,6 +27,8 @@
 #define QEMU_VM_FILE_VERSION_COMPAT  0x00000002
 #define QEMU_VM_FILE_VERSION         0x00000003
 
+#define QEMU_VM_BER_FILE_MAGIC       0x7fcdc551
+
 #define QEMU_VM_EOF                  0x00
 #define QEMU_VM_SECTION_START        0x01
 #define QEMU_VM_SECTION_PART         0x02
diff --git a/savevm.c b/savevm.c
index 515dd77..2bbbcdc 100644
--- a/savevm.c
+++ b/savevm.c
@@ -24,6 +24,8 @@
 
 #include "config-host.h"
 #include "qemu-common.h"
+#include "qapi/qemu-file-ber-output-visitor.h"
+#include "qapi/qemu-file-ber-input-visitor.h"
 #include "qapi/qemu-file-binary-input-visitor.h"
 #include "qapi/qemu-file-binary-output-visitor.h"
 #include "hw/hw.h"
@@ -527,6 +529,34 @@ bool qemu_savevm_state_blocked(Error **errp)
     return false;
 }
 
+/* Return a visitor for use on the QEMUFile; visit_destroy should be
+ * called on it to clean it up.
+ */
+static Visitor *qemu_savevm_get_visitor(QEMUFile *f)
+{
+    char *formatvar = getenv("QEMUMIGFORMAT");
+
+    if (formatvar && (!strcmp(formatvar, "BER"))) {
+        QemuFileBEROutputVisitor *qfberov = 
qemu_file_ber_output_visitor_new(f);
+        Visitor *v = qemu_file_ber_output_get_visitor(qfberov);
+
+        qemu_file_set_tmp_visitor(f, v);
+        return v;
+    }
+
+    if (formatvar) {
+        error_report("QEMUMIGFORMAT set to unknown value '%s'", formatvar);
+        assert(0);
+    }
+
+    QemuFileBinOutputVisitor *qfbov = qemu_file_bin_output_visitor_new(f);
+    Visitor *v = qemu_file_bin_output_get_visitor(qfbov);
+
+    qemu_file_set_tmp_visitor(f, v);
+
+    return v;
+}
+
 void qemu_savevm_state_begin(QEMUFile *f,
                              const MigrationParams *params)
 {
@@ -534,10 +564,7 @@ void qemu_savevm_state_begin(QEMUFile *f,
     int ret;
     Error *local_err = NULL;
     SectionHeader sh;
-
-    QemuFileBinOutputVisitor *qfbov = qemu_file_bin_output_visitor_new(f);
-    Visitor *v = qemu_file_bin_output_get_visitor(qfbov);
-    qemu_file_set_tmp_visitor(f, v);
+    Visitor *v = qemu_savevm_get_visitor(f);
 
     trace_savevm_state_begin();
     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
@@ -789,13 +816,11 @@ static int qemu_savevm_state(QEMUFile *f)
 
 static int qemu_save_device_state(QEMUFile *f)
 {
+    Visitor *v = qemu_savevm_get_visitor(f);
     SaveStateEntry *se;
     Error *local_err;
     SectionHeader sh;
 
-    QemuFileBinOutputVisitor *qfbov = qemu_file_bin_output_visitor_new(f);
-    qemu_file_set_tmp_visitor(f, qemu_file_bin_output_get_visitor(qfbov));
-    Visitor *v = qemu_file_bin_output_get_visitor(qfbov);
     int32_t section_type;
 
     cpu_synchronize_all_states();
@@ -861,41 +886,65 @@ typedef struct LoadStateEntry {
     int version_id;
 } LoadStateEntry;
 
+/* Given a just opened input QEMUFile, peak at the header and figure
+ * out which visitor should be used for it.
+ * Return the visitor ready for use.
+ */
+static Visitor *pick_input_visitor(QEMUFile *f)
+{
+    uint32_t tmp32;
+
+    if (qemu_peek_buffer(f, (uint8_t *)&tmp32, 4, 0) != 4) {
+        fprintf(stderr, "Failed to read SaveVM header word\n");
+        return NULL;
+    }
+
+    tmp32 = be32_to_cpu(tmp32);
+
+    switch (tmp32) {
+    case QEMU_VM_FILE_MAGIC: {
+        QemuFileBinInputVisitor *qfbiv = qemu_file_bin_input_visitor_new(f);
+        Visitor *v = qemu_file_bin_input_get_visitor(qfbiv);
+        qemu_file_set_tmp_visitor(f, v);
+
+        return v;
+        }
+
+    case QEMU_VM_BER_FILE_MAGIC: {
+        QemuFileBERInputVisitor *qfberiv = qemu_file_ber_input_visitor_new(f);
+        Visitor *v = qemu_file_ber_input_get_visitor(qfberiv);
+        qemu_file_set_tmp_visitor(f, v);
+
+        return v;
+        }
+
+    default:
+        fprintf(stderr, "Invalid SaveVM header (0x%x)\n", tmp32);
+        return NULL;
+    }
+}
+
 int qemu_loadvm_state(QEMUFile *f)
 {
     QLIST_HEAD(, LoadStateEntry) loadvm_handlers =
         QLIST_HEAD_INITIALIZER(loadvm_handlers);
     LoadStateEntry *le, *new_le;
+    Visitor *v;
     Error *local_err = NULL;
     int32_t section_type;
-    unsigned int tmp;
     int ret;
 
     if (qemu_savevm_state_blocked(NULL)) {
         return -EINVAL;
     }
 
-    tmp = qemu_get_be32(f);
-    if (tmp != QEMU_VM_FILE_MAGIC) {
-        return -EINVAL;
-    }
-
-    tmp = qemu_get_be32(f);
-    if (tmp == QEMU_VM_FILE_VERSION_COMPAT) {
-        error_report("SaveVM v2 format is obsolete and don't work anymore");
+    v = pick_input_visitor(f);
+    if (!v) {
         return -ENOTSUP;
     }
-    if (tmp != QEMU_VM_FILE_VERSION) {
-        return -ENOTSUP;
-    }
-
-    /* TODO: Here we should be able to figure out if it's a binary file
-     * or what and open the right type of visitor
-     */
-    QemuFileBinInputVisitor *qfbiv = qemu_file_bin_input_visitor_new(f);
-    Visitor *v = qemu_file_bin_input_get_visitor(qfbiv);
-    qemu_file_set_tmp_visitor(f, v);
 
+    visit_start_sequence_compat(v, "file", VISIT_SEQ_COMPAT_FILE, NULL,
+                                &local_err);
     visit_start_sequence_compat(v, "top", VISIT_SEQ_COMPAT_BYTE0TERM,
                                 NULL, &local_err);
     while (visit_get_next_type(v, &section_type, NULL, "section", &local_err),
@@ -912,6 +961,7 @@ int qemu_loadvm_state(QEMUFile *f)
                       "secstart" : "secfull",
                   VISIT_SEQ_COMPAT_SECTION_HEADER, &sh, &local_err);
             if (local_err) {
+                error_report("%s", error_get_pretty(local_err));
                 ret = -EINVAL;
                 goto out;
             }
@@ -1001,6 +1051,7 @@ out:
     }
 
     visit_end_sequence_compat(v, "top", VISIT_SEQ_COMPAT_BYTE0TERM, 
&local_err);
+    visit_end_sequence_compat(v, "file", VISIT_SEQ_COMPAT_FILE, &local_err);
     if (local_err) {
         error_report("%s", error_get_pretty(local_err));
         ret = -EINVAL;
@@ -1010,7 +1061,7 @@ out:
         ret = qemu_file_get_error(f);
     }
 
-    qemu_file_bin_input_visitor_cleanup(qfbiv);
+    visit_destroy(v, &local_err);
     return ret;
 }
 
-- 
1.9.0