[libvirt] [PATCH] udev: fix crash in libudev logging

[Ján Tomko]

VIR_ERROR_INT calls virLogMessage(..., const char *fmt, ...).
Call virLogVMessage(..., const char *fmt, va_list list) instead,
since libudev called us with a va_list object, not a list of arguments.

https://bugzilla.redhat.com/show_bug.cgi?id=969152
---

Without the cast, I was getting:
node_device/node_device_udev.c: In function 'nodeStateInitialize':
node_device/node_device_udev.c:1684:5: error: argument 2 of 'udev_set_log_fn' might be a candidate for a format attribute [-Werror=missing-format-attribute]
node_device/node_device_udev.c: At top level:
cc1: error: unrecognized command line option "-Wno-unused-command-line-argument" [-Werror]

Is there a nicer way to get rid of it?

 src/libvirt_private.syms           |  1 +
 src/node_device/node_device_udev.c | 30 +++++++++++++++++++++---------
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index b93629f..d73a4d0 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1486,6 +1486,7 @@ virLogSetBufferSize;
 virLogSetDefaultPriority;
 virLogSetFromEnv;
 virLogUnlock;
+virLogVMessage;
 
 
 # util/virmacaddr.h
diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index 620cd58..ffcae16 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -348,15 +348,26 @@ static int udevGenerateDeviceName(struct udev_device *device,
 }
 
 
-static void udevLogFunction(struct udev *udev ATTRIBUTE_UNUSED,
-                            int priority ATTRIBUTE_UNUSED,
-                            const char *file,
-                            int line,
-                            const char *fn,
-                            const char *fmt,
-                            va_list args)
+typedef void (*udevLogFunctionPtr) (struct udev *udev,
+                                    int priority,
+                                    const char *file,
+                                    int line,
+                                    const char *fn,
+                                    const char *format,
+                                    va_list args);
+
+static void
+ATTRIBUTE_FMT_PRINTF(6,0)
+udevLogFunction(struct udev *udev ATTRIBUTE_UNUSED,
+                int priority ATTRIBUTE_UNUSED,
+                const char *file,
+                int line,
+                const char *fn,
+                const char *fmt,
+                va_list args)
 {
-    VIR_ERROR_INT(VIR_LOG_FROM_LIBRARY, file, line, fn, fmt, args);
+    virLogVMessage(VIR_LOG_FROM_LIBRARY, VIR_LOG_ERROR,
+                   file, line, fn, NULL, fmt, args);
 }
 
 
@@ -1672,7 +1683,8 @@ static int nodeStateInitialize(bool privileged ATTRIBUTE_UNUSED,
      * its return value.
      */
     udev = udev_new();
-    udev_set_log_fn(udev, udevLogFunction);
+    /* cast to get rid of missing-format-attribute warning */
+    udev_set_log_fn(udev, (udevLogFunctionPtr) udevLogFunction);
 
     priv->udev_monitor = udev_monitor_new_from_netlink(udev, "udev");
     if (priv->udev_monitor == NULL) {
-- 
1.8.1.5