[PATCH] blockjob: report a better error message

[Stefano Garzarella <sgarzare@redhat.com>]

When a block job fails, we report 'strerror(-job->job.ret)' error
message, also if the job set an error object.
Let's report a better error message using 'error_get_pretty(job->job.err)'.

If an error object was not set, strerror(-job->ret) is used as fallback,
as explained in include/qemu/job.h:

typedef struct Job {
    ...
    /**
     * Error object for a failed job.
     * If job->ret is nonzero and an error object was not set, it will be set
     * to strerror(-job->ret) during job_completed.
     */
    Error *err;
}

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 blockjob.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/blockjob.c b/blockjob.c
index f2feff051d..a696f3408d 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -319,7 +319,8 @@ BlockJobInfo *block_job_query(BlockJob *job, Error **errp)
     info->auto_finalize = job->job.auto_finalize;
     info->auto_dismiss  = job->job.auto_dismiss;
     info->has_error = job->job.ret != 0;
-    info->error     = job->job.ret ? g_strdup(strerror(-job->job.ret)) : NULL;
+    info->error     = job->job.ret ?
+                        g_strdup(error_get_pretty(job->job.err)) : NULL;
     return info;
 }
 
@@ -356,7 +357,7 @@ static void block_job_event_completed(Notifier *n, void *opaque)
     }
 
     if (job->job.ret < 0) {
-        msg = strerror(-job->job.ret);
+        msg = error_get_pretty(job->job.err);
     }
 
     qapi_event_send_block_job_completed(job_type(&job->job),
-- 
2.29.2