job: Add error message for failing jobs

So far we relied on job->ret and strerror() to produce an error message
for failed jobs. Not surprisingly, this tends to result in completely
useless messages.

This adds a Job.error field that can contain an error string for a
failing job, and a parameter to job_completed() that sets the field. As
a default, if NULL is passed, we continue to use strerror(job->ret).

All existing callers are changed to pass NULL. They can be improved in
separate patches.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/include/qemu/job.h b/include/qemu/job.h
index 8c8badf..1d82053 100644
--- a/include/qemu/job.h
+++ b/include/qemu/job.h
@@ -124,6 +124,9 @@ typedef struct Job {
     /** Estimated progress_current value at the completion of the job */
     int64_t progress_total;
 
+    /** Error string for a failed job (NULL if, and only if, job->ret == 0) */
+    char *error;
+
     /** ret code passed to job_completed. */
     int ret;
 
@@ -466,13 +469,15 @@ void job_transition_to_ready(Job *job);
 /**
  * @job: The job being completed.
  * @ret: The status code.
+ * @error: The error message for a failing job (only with @ret < 0). If @ret is
+ *         negative, but NULL is given for @error, strerror() is used.
  *
  * Marks @job as completed. If @ret is non-zero, the job transaction it is part
  * of is aborted. If @ret is zero, the job moves into the WAITING state. If it
  * is the last job to complete in its transaction, all jobs in the transaction
  * move from WAITING to PENDING.
  */
-void job_completed(Job *job, int ret);
+void job_completed(Job *job, int ret, Error *error);
 
 /** Asynchronously complete the specified @job. */
 void job_complete(Job *job, Error **errp);