src: add API to determine if current identity is a system identity

This is essentially a way to determine if the current identity
is that of another libvirt daemon.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

src/libvirt_private.syms

@@ -2411,6 +2411,7 @@ virIdentityGetUNIXGroupID;
 virIdentityGetUNIXUserID;
 virIdentityGetUserName;
 virIdentityGetX509DName;
+virIdentityIsCurrentElevated;
 virIdentityNew;
 virIdentityNewCopy;
 virIdentityRestoreHelper;

src/util/viridentity.c

@@ -366,6 +366,34 @@ virIdentity *virIdentityGetSystem(void)
 }
 
 
+/**
+ * virIdentityIsCurrentElevated:
+ *
+ * Determine if the current identity has elevated privileges.
+ * This indicates that it was invoked on behalf of the
+ * user by a libvirt daemon.
+ *
+ * Returns: true if elevated
+ */
+int virIdentityIsCurrentElevated(void)
+{
+    g_autoptr(virIdentity) current = virIdentityGetCurrent();
+    const char *currentToken = NULL;
+    int rv;
+
+    if (!current) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("No current identity"));
+        return -1;
+    }
+
+    rv = virIdentityGetSystemToken(current, &currentToken);
+    if (rv <= 0)
+        return rv;
+
+    return STREQ_NULLABLE(currentToken, systemToken);
+}
+
 /**
  * virIdentityNew:
  *

src/util/viridentity.h

@@ -35,6 +35,7 @@ virIdentity *virIdentityElevateCurrent(void);
 
 void virIdentityRestoreHelper(virIdentity **identptr);
 
+int virIdentityIsCurrentElevated(void);
 virIdentity *virIdentityGetSystem(void);
 
 virIdentity *virIdentityNew(void);