[libvirt] [PATCH v2] Fix Memory Leak in virQEMUCapsInitGuestFromBinary()

[Nehal J Wani]

While running qemucaps2xmltest, it was found that valgrind pointed out
the following memory leaks:

==29896== 0 bytes in 1 blocks are definitely lost in loss record 1 of 65
==29896==    at 0x4A0577B: calloc (vg_replace_malloc.c:593)
==29896==    by 0x4C6B45E: virAllocN (viralloc.c:191)
==29896==    by 0x4232A9: virQEMUCapsGetMachineTypesCaps (qemu_capabilities.c:1999)
==29896==    by 0x4234E7: virQEMUCapsInitGuestFromBinary (qemu_capabilities.c:789)
==29896==    by 0x41F10B: testQemuCapsXML (qemucaps2xmltest.c:118)
==29896==    by 0x41FFD1: virtTestRun (testutils.c:201)
==29896==    by 0x41EE7A: mymain (qemucaps2xmltest.c:203)
==29896==    by 0x42074D: virtTestMain (testutils.c:789)
==29896==    by 0x3E6CE1ED1C: (below main) (libc-start.c:226)
==29896== 
==29896== 0 bytes in 1 blocks are definitely lost in loss record 2 of 65
==29896==    at 0x4A0577B: calloc (vg_replace_malloc.c:593)
==29896==    by 0x4C6B45E: virAllocN (viralloc.c:191)
==29896==    by 0x4232A9: virQEMUCapsGetMachineTypesCaps (qemu_capabilities.c:1999)
==29896==    by 0x4234E7: virQEMUCapsInitGuestFromBinary (qemu_capabilities.c:789)
==29896==    by 0x41F10B: testQemuCapsXML (qemucaps2xmltest.c:118)
==29896==    by 0x41FFD1: virtTestRun (testutils.c:201)
==29896==    by 0x41EEA3: mymain (qemucaps2xmltest.c:204)
==29896==    by 0x42074D: virtTestMain (testutils.c:789)
==29896==    by 0x3E6CE1ED1C: (below main) (libc-start.c:226)

---
 src/qemu/qemu_capabilities.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 7673592..aef8bc1 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -789,6 +789,10 @@ virQEMUCapsInitGuestFromBinary(virCapsPtr caps,
     if (virQEMUCapsGetMachineTypesCaps(qemubinCaps, &nmachines, &machines) < 0)
         goto cleanup;
 
+    /* Free unneeded memory given by malloc(0) */
+    if (!nmachines)
+        VIR_FREE(machines);
+
     /* We register kvm as the base emulator too, since we can
      * just give -no-kvm to disable acceleration if required */
     if ((guest = virCapabilitiesAddGuest(caps,
-- 
1.7.1