storagefile: Add externalDataStoreRaw member

Add the plumbing to track a qcow2 external data file path in
virStorageSource
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

src/util/virstoragefile.c

@@ -202,6 +202,7 @@ qedGetBackingStore(char **, int *, const char *, size_t);
 
 #define QCOW2_HDR_EXTENSION_END 0
 #define QCOW2_HDR_EXTENSION_BACKING_FORMAT 0xE2792ACA
+#define QCOW2_HDR_EXTENSION_DATA_FILE 0x44415441
 
 #define QCOW2v3_HDR_FEATURES_INCOMPATIBLE (QCOW2_HDR_TOTAL_SIZE)
 #define QCOW2v3_HDR_FEATURES_COMPATIBLE (QCOW2v3_HDR_FEATURES_INCOMPATIBLE+8)
@@ -429,7 +430,8 @@ cowGetBackingStore(char **res,
 static int
 qcow2GetExtensions(const char *buf,
                    size_t buf_size,
-                   int *backingFormat)
+                   int *backingFormat,
+                   char **externalDataStoreRaw)
 {
     size_t offset;
     size_t extension_start;
@@ -505,6 +507,9 @@ qcow2GetExtensions(const char *buf,
         switch (magic) {
         case QCOW2_HDR_EXTENSION_BACKING_FORMAT: {
             VIR_AUTOFREE(char *) tmp = NULL;
+            if (!backingFormat)
+                break;
+
             if (VIR_ALLOC_N(tmp, len + 1) < 0)
                 return -1;
             memcpy(tmp, buf + offset, len);
@@ -516,6 +521,19 @@ qcow2GetExtensions(const char *buf,
             break;
         }
 
+        case QCOW2_HDR_EXTENSION_DATA_FILE: {
+            if (!externalDataStoreRaw)
+                break;
+
+            if (VIR_ALLOC_N(*externalDataStoreRaw, len + 1) < 0)
+                return -1;
+            memcpy(*externalDataStoreRaw, buf + offset, len);
+            (*externalDataStoreRaw)[len] = '\0';
+            VIR_DEBUG("parsed externalDataStoreRaw='%s'",
+                      *externalDataStoreRaw);
+            break;
+        }
+
         case QCOW2_HDR_EXTENSION_END:
             goto done;
         }
@@ -567,7 +585,7 @@ qcowXGetBackingStore(char **res,
     memcpy(*res, buf + offset, size);
     (*res)[size] = '\0';
 
-    if (qcow2GetExtensions(buf, buf_size, format) < 0)
+    if (qcow2GetExtensions(buf, buf_size, format, NULL) < 0)
         return BACKING_STORE_INVALID;
 
     return BACKING_STORE_OK;
@@ -2259,6 +2277,7 @@ virStorageSourceCopy(const virStorageSource *src,
         VIR_STRDUP(def->volume, src->volume) < 0 ||
         VIR_STRDUP(def->relPath, src->relPath) < 0 ||
         VIR_STRDUP(def->backingStoreRaw, src->backingStoreRaw) < 0 ||
+        VIR_STRDUP(def->externalDataStoreRaw, src->externalDataStoreRaw) < 0 ||
         VIR_STRDUP(def->snapshot, src->snapshot) < 0 ||
         VIR_STRDUP(def->configFile, src->configFile) < 0 ||
         VIR_STRDUP(def->nodeformat, src->nodeformat) < 0 ||
@@ -2534,6 +2553,7 @@ virStorageSourceClear(virStorageSourcePtr def)
     virStorageSourceSeclabelsClear(def);
     virStoragePermsFree(def->perms);
     VIR_FREE(def->timestamps);
+    VIR_FREE(def->externalDataStoreRaw);
 
     virStorageNetHostDefFree(def->nhosts, def->hosts);
     virStorageAuthDefFree(def->auth);

src/util/virstoragefile.h

@@ -302,6 +302,8 @@ struct _virStorageSource {
     /* Name of the child backing store recorded in metadata of the
      * current file.  */
     char *backingStoreRaw;
+    /* Name of the child data file recorded in metadata of the current file. */
+    char *externalDataStoreRaw;
 
     /* metadata that allows identifying given storage source */
     char *nodeformat;  /* name of the format handler object */