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From 2112c4a8297592045ac8ed8b0677e81208296364 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Thu, 23 Oct 2014 10:10:05 +0200
Subject: [PATCH 02/19] error: Add error_abort

Message-id: <1414059011-15516-3-git-send-email-kwolf@redhat.com>
Patchwork-id: 61836
O-Subject: [RHEL-7.1 qemu-kvm PATCH v2 2/8] error: Add error_abort
Bugzilla: 1088176
RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
RH-Acked-by: Markus Armbruster <armbru@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>

From: Peter Crosthwaite <peter.crosthwaite@xilinx.com>

Add a special Error * that can be passed to error handling APIs to
signal that any errors are fatal and should abort QEMU. There are two
advantages to this:

- allows for brevity when wishing to assert success of Error **
  accepting APIs. No need for this pattern:
        Error * local_err = NULL;
        api_call(foo, bar, &local_err);
        assert_no_error(local_err);
  This also removes the need for _nofail variants of APIs with
  asserting call sites now reduced to 1LOC.
- SIGABRT happens from within the offending API. When a fatal error
  occurs in an API call (when the caller is asserting sucess) failure
  often means the API itself is broken. With the abort happening in the
  API call now, the stack frames into the call are available at debug
  time. In the assert_no_error scheme the abort happens after the fact.

The exact semantic is that when an error is raised, if the argument
Error ** matches &error_abort, then the abort occurs immediately. The
error messaged is reported.

For error_propagate, if the destination error is &error_abort, then
the abort happens at propagation time.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
(cherry picked from commit 5d24ee70bcbcf578614193526bcd5ed30a8eb16c)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

Conflicts:
	util/error.c

Conflicts because RHEL 7 doesn't have error_set_win32().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/qapi/error.h |  6 ++++++
 util/error.c         | 17 ++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/include/qapi/error.h b/include/qapi/error.h
index ffd1cea..fc7f44a 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -82,4 +82,10 @@ void error_propagate(Error **dst_err, Error *local_err);
  */
 void error_free(Error *err);
 
+/**
+ * If passed to error_set and friends, abort().
+ */
+
+extern Error *error_abort;
+
 #endif
diff --git a/util/error.c b/util/error.c
index 53b0435..82658bb 100644
--- a/util/error.c
+++ b/util/error.c
@@ -23,6 +23,8 @@ struct Error
     ErrorClass err_class;
 };
 
+Error *error_abort;
+
 void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
 {
     Error *err;
@@ -40,6 +42,11 @@ void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
     va_end(ap);
     err->err_class = err_class;
 
+    if (errp == &error_abort) {
+        error_report("%s", error_get_pretty(err));
+        abort();
+    }
+
     *errp = err;
 }
 
@@ -68,6 +75,11 @@ void error_set_errno(Error **errp, int os_errno, ErrorClass err_class,
     va_end(ap);
     err->err_class = err_class;
 
+    if (errp == &error_abort) {
+        error_report("%s", error_get_pretty(err));
+        abort();
+    }
+
     *errp = err;
 }
 
@@ -112,7 +124,10 @@ void error_free(Error *err)
 
 void error_propagate(Error **dst_err, Error *local_err)
 {
-    if (dst_err && !*dst_err) {
+    if (local_err && dst_err == &error_abort) {
+        error_report("%s", error_get_pretty(local_err));
+        abort();
+    } else if (dst_err && !*dst_err) {
         *dst_err = local_err;
     } else if (local_err) {
         error_free(local_err);
-- 
1.8.3.1