[libvirt] [PATCH] tests: avoid null pointer dereference

[Eric Blake <eblake redhat com>]

Unlikely to hit in real life, but clang noticed it.

* tests/commandtest.c (test4): Avoid unlink(NULL) on OOM.
---

Much like a similar patch I sent for qemu_driver, but this time
the unlink(NULL) is much harder to trigger.

 tests/commandtest.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/tests/commandtest.c b/tests/commandtest.c
index fa0061c..e8d8858 100644
--- a/tests/commandtest.c
+++ b/tests/commandtest.c
@@ -240,7 +240,8 @@ static int test4(const void *unused ATTRIBUTE_UNUSED)

 cleanup:
     virCommandFree(cmd);
-    unlink(pidfile);
+    if (pidfile)
+        unlink(pidfile);
     VIR_FREE(pidfile);
     return ret;
 }
-- 
1.7.4.4