From ca2081198432ebfeb83d31eaf9fc9edc9ceea24c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Guido=20G=C3=BCnther?= <agx@sigxcpu.org>
Date: Thu, 13 Aug 2015 14:19:50 +0200
Subject: [PATCH] Check if qemu-bridge-helper exists and is executable

Otherwise the error is just

    error: Failed to create domain from test1.xml
    error: failed to retrieve file descriptor for interface: Transport endpoint is not connected

since we don't get a sensible error after the fork.

(cherry picked from commit 151ba022939dad1e562c4156cb62e7a3ade6a7f5)
---
 src/qemu/qemu_command.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 2d222da5fd..d12eb54d13 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -296,6 +296,12 @@ static int qemuCreateInBridgePortWithHelper(virQEMUDriverConfigPtr cfg,
         return -1;
     }
 
+    if (!virFileIsExecutable(cfg->bridgeHelperName)) {
+        virReportSystemError(errno, _("'%s' is not a suitable bridge helper"),
+                             cfg->bridgeHelperName);
+        return -1;
+    }
+
     cmd = virCommandNew(cfg->bridgeHelperName);
     if (flags & VIR_NETDEV_TAP_CREATE_VNET_HDR)
         virCommandAddArgFormat(cmd, "--use-vnet");