Fix crash using bogus arch in QEMU

ChangeLog

+Fri Jan 30 16:12:22 GMT 2009 Daniel P. Berrange <berrange@redhat.com>
+
+	Fix crash when using bogus arch type
+	* src/capabilities.c, src/capabilities.h: Add method to query
+	for supported arch+ostype combo
+	* src/domain_conf.c: Validate requested arch+ostype against
+	supported capabilities
+	* src/qemu_conf.c: Sanity check to avoid deferencing NULL
+	machine type
+
 Fri Jan 30 16:58:22 GMT 2009 Daniel P. Berrange <berrange@redhat.com>
 
 	Misc QEMU driver startup fixes

src/capabilities.c

@@ -432,6 +432,30 @@ virCapabilitiesSupportsGuestOSType(virCapsPtr caps,
 }
 
 
+/**
+ * virCapabilitiesSupportsGuestOSType:
+ * @caps: capabilities to query
+ * @ostype: OS type to search for (eg 'hvm', 'xen')
+ * @arch: Architecture to search for (eg, 'i686', 'x86_64')
+ *
+ * Returns non-zero if the capabilities support the
+ * requested operating system type
+ */
+extern int
+virCapabilitiesSupportsGuestArch(virCapsPtr caps,
+                                 const char *ostype,
+                                 const char *arch)
+{
+    int i;
+    for (i = 0 ; i < caps->nguests ; i++) {
+        if (STREQ(caps->guests[i]->ostype, ostype) &&
+            STREQ(caps->guests[i]->arch.name, arch))
+            return 1;
+    }
+    return 0;
+}
+
+
 /**
  * virCapabilitiesDefaultGuestArch:
  * @caps: capabilities to query

src/capabilities.h

@@ -162,6 +162,12 @@ virCapabilitiesAddGuestFeature(virCapsGuestPtr guest,
 extern int
 virCapabilitiesSupportsGuestOSType(virCapsPtr caps,
                                    const char *ostype);
+extern int
+virCapabilitiesSupportsGuestArch(virCapsPtr caps,
+                                 const char *ostype,
+                                 const char *arch);
+
+
 extern const char *
 virCapabilitiesDefaultGuestArch(virCapsPtr caps,
                                 const char *ostype);

src/domain_conf.c

@@ -2038,7 +2038,14 @@ static virDomainDefPtr virDomainDefParseXML(virConnectPtr conn,
     }
 
     def->os.arch = virXPathString(conn, "string(./os/type[1]/@arch)", ctxt);
-    if (!def->os.arch) {
+    if (def->os.arch) {
+        if (!virCapabilitiesSupportsGuestArch(caps, def->os.type, def->os.arch)) {
+            virDomainReportError(conn, VIR_ERR_INTERNAL_ERROR,
+                                 _("os type '%s' & arch '%s' combination is not supported"),
+                                 def->os.type, def->os.arch);
+            goto error;
+        }
+    } else {
         const char *defaultArch = virCapabilitiesDefaultGuestArch(caps, def->os.type);
         if (defaultArch == NULL) {
             virDomainReportError(conn, VIR_ERR_INTERNAL_ERROR,

src/qemu_conf.c

@@ -837,8 +837,16 @@ int qemudBuildCommandLine(virConnectPtr conn,
 
     ADD_ARG_LIT(emulator);
     ADD_ARG_LIT("-S");
-    ADD_ARG_LIT("-M");
-    ADD_ARG_LIT(vm->def->os.machine);
+
+    /* This should *never* be NULL, since we always provide
+     * a machine in the capabilities data for QEMU. So this
+     * check is just here as a safety in case the unexpected
+     * happens */
+    if (vm->def->os.machine) {
+        ADD_ARG_LIT("-M");
+        ADD_ARG_LIT(vm->def->os.machine);
+    }
+
     if (disableKQEMU)
         ADD_ARG_LIT("-no-kqemu");
     ADD_ARG_LIT("-m");