[libvirt] [PATCH] qemu: Don't try to parse -help for new QEMU

[Jiri Denemark]

Since QEMU 1.2.0, we switched to QMP probing instead of parsing -help
(and other commands, such as -cpu ?) output. However, if QMP probing
failed, we still tried starting QEMU with various options and parsing
the output, which was guaranteed to fail because the output changed.
Let's just refuse parsing -help for QEMU >= 1.2.0.

https://bugzilla.redhat.com/show_bug.cgi?id=1160318
Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
---
 src/qemu/qemu_capabilities.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 74a3b24..bef96d5 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -1384,6 +1384,16 @@ int virQEMUCapsParseHelpStr(const char *qemu,
 
     *version = (major * 1000 * 1000) + (minor * 1000) + micro;
 
+    /* Refuse to parse -help output for QEMU releases >= 1.2.0 that should be
+     * using QMP probing.
+     */
+    if (*version > 1002000) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("QEMU %u.%u.%u is too new for help parsing"),
+                       major, minor, micro);
+        goto cleanup;
+    }
+
     if (virQEMUCapsComputeCmdFlags(help, *version, *is_kvm, *kvm_version,
                                    qemuCaps, check_yajl) < 0)
         goto cleanup;
-- 
2.1.3