[Qemu-devel] [PATCH v2 2/3] error: allow local errors to trigger abort

[Michael S. Tsirkin]

It's a common idiom:

    Error *local_err = NULL;
    ....
    foo(&local_err);
    ...
    if (local_err) {
        error_propagate(errp, local_err);
        return;
    }

Unfortunately it means that call to foo(&local_err) will
not abort even if errp is set to error_abort.

Instead, we get an abort at error_propagate which is too late,
that is, the quality of the stack trace is degraded in that it no longer
pinpoints the actual cause of failure.

To fix, add an API to check errp and set local_err to error_abort
if errp is error_abort.

Signed-off-by: Michael S. Tsirkin <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
 include/qapi/error.h | 5 +++++
 util/error.c         | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/include/qapi/error.h b/include/qapi/error.h
index f44c451..8246a62 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -88,6 +88,11 @@ const char *error_get_pretty(Error *err);
 void error_report_err(Error *);
 
 /**
+ * Init a local error. It must be propagated to errp using error_propagate.
+ */
+Error *error_init_local(Error **errp);
+
+/**
  * Propagate an error to an indirect pointer to an error.  This function will
  * always transfer ownership of the error reference and handles the case where
  * dst_err is NULL correctly.  Errors after the first are discarded.
diff --git a/util/error.c b/util/error.c
index e10cb34..7f5b134 100644
--- a/util/error.c
+++ b/util/error.c
@@ -28,6 +28,11 @@ static bool error_is_abort(Error **errp)
     return errp && *errp == error_abort;
 }
 
+Error *error_init_local(Error **errp)
+{
+    return error_is_abort(errp) ? *errp : NULL;
+}
+
 void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
 {
     Error *err;
-- 
MST