[PATCH 03/25] conf: refactor virDomainBlkioDeviceParseXML to remove possible NULL dereference

[Laine Stump <laine@xxxxxxxxxx>]

virDomainBlkioDeviceParseXML() has multiple cases of sending the
return from xmlNodeGetContent() directly to virStrToLong_xx() without
checking for NULL. Although it is *very* rare for xmlNodeGetContent()
to return NULL (possibly it only happens in an OOM condition? The
documentation is unclear), it could happen, and the refactor in this
patch manages to eliminate several lines of repeated code while adding
in a (single) check for NULL.

Signed-off-by: Laine Stump <laine@xxxxxxxxxx>
---
 src/conf/domain_conf.c | 39 +++++++++++++++------------------------
 1 file changed, 15 insertions(+), 24 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 1916b51d38..8cde1cd0e8 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -1628,73 +1628,64 @@ virDomainBlkioDeviceParseXML(xmlNodePtr root,
                              virBlkioDevicePtr dev)
 {
     xmlNodePtr node;
-    g_autofree char *c = NULL;
+    g_autofree char *path = NULL;
 
     node = root->children;
     while (node) {
-        if (node->type == XML_ELEMENT_NODE) {
-            if (virXMLNodeNameEqual(node, "path") && !dev->path) {
-                dev->path = (char *)xmlNodeGetContent(node);
+        g_autofree char *c = NULL;
+
+        if (node->type == XML_ELEMENT_NODE &&
+            (c = (char *)xmlNodeGetContent(node))) {
+            if (virXMLNodeNameEqual(node, "path") && !path) {
+                path = g_steal_pointer(&c);
             } else if (virXMLNodeNameEqual(node, "weight")) {
-                c = (char *)xmlNodeGetContent(node);
                 if (virStrToLong_ui(c, NULL, 10, &dev->weight) < 0) {
                     virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                    _("could not parse weight %s"),
                                    c);
-                        goto error;
+                    return -1;
                 }
-                VIR_FREE(c);
             } else if (virXMLNodeNameEqual(node, "read_bytes_sec")) {
-                c = (char *)xmlNodeGetContent(node);
                 if (virStrToLong_ull(c, NULL, 10, &dev->rbps) < 0) {
                     virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                    _("could not parse read bytes sec %s"),
                                    c);
-                    goto error;
+                    return -1;
                 }
-                VIR_FREE(c);
             } else if (virXMLNodeNameEqual(node, "write_bytes_sec")) {
-                c = (char *)xmlNodeGetContent(node);
                 if (virStrToLong_ull(c, NULL, 10, &dev->wbps) < 0) {
                     virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                    _("could not parse write bytes sec %s"),
                                    c);
-                    goto error;
+                    return -1;
                 }
-                VIR_FREE(c);
             } else if (virXMLNodeNameEqual(node, "read_iops_sec")) {
-                c = (char *)xmlNodeGetContent(node);
                 if (virStrToLong_ui(c, NULL, 10, &dev->riops) < 0) {
                     virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                    _("could not parse read iops sec %s"),
                                    c);
-                    goto error;
+                    return -1;
                 }
-                VIR_FREE(c);
             } else if (virXMLNodeNameEqual(node, "write_iops_sec")) {
-                c = (char *)xmlNodeGetContent(node);
                 if (virStrToLong_ui(c, NULL, 10, &dev->wiops) < 0) {
                     virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                                    _("could not parse write iops sec %s"),
                                    c);
-                    goto error;
+                    return -1;
                 }
-                VIR_FREE(c);
             }
         }
         node = node->next;
     }
-    if (!dev->path) {
+
+    if (!path) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                        _("missing per-device path"));
         return -1;
     }
 
+    dev->path = g_steal_pointer(&path);
     return 0;
-
- error:
-    VIR_FREE(dev->path);
-    return -1;
 }
 
 
-- 
2.25.4