[PATCH v2 01/15] qemu: Handle quirks of 'device' field of BLOCK_IO_ERROR event in monitor code

[Peter Krempa <pkrempa@xxxxxxxxxx>]

BLOCK_IO_ERROR's 'device' field is an empty string in case when it isn't
applicable as it was originally mandatory in the qemu API docs.

Move the logic that convert's empty string back to NULL from
'qemuProcessHandleIOError()' to 'qemuMonitorJSONHandleIOError()'

This also fixes a hypothetical NULL-dereference if qemu would indeed
report an IO error without the 'device' field present.

Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
 src/qemu/qemu_monitor_json.c | 9 ++++++++-
 src/qemu/qemu_process.c      | 3 ---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 9f417d27c6..5ca76d2d80 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -708,8 +708,15 @@ qemuMonitorJSONHandleIOError(qemuMonitor *mon, virJSONValue *data)
         action = "ignore";
     }

-    if ((device = virJSONValueObjectGetString(data, "device")) == NULL)
+    if ((device = virJSONValueObjectGetString(data, "device")) == NULL) {
         VIR_WARN("missing device in disk io error event");
+    } else {
+        /* 'device' was documented as mandatory in the qemu event, but later became
+         * optional, in which case an empty string is sent by qemu. Convert it back
+         * to NULL */
+        if (*device == '\0')
+            device = NULL;
+    }

     nodename = virJSONValueObjectGetString(data, "node-name");

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 34a755a49a..edcd8ac3a8 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -840,9 +840,6 @@ qemuProcessHandleIOError(qemuMonitor *mon G_GNUC_UNUSED,
     virObjectLock(vm);
     priv = QEMU_DOMAIN_PRIVATE(vm);

-    if (*diskAlias == '\0')
-        diskAlias = NULL;
-
     if (diskAlias)
         disk = qemuProcessFindDomainDiskByAliasOrQOM(vm, diskAlias, NULL);
     else if (nodename)
-- 
2.48.1