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From 264a2066904d31c46860e0bac8790d57e6498b80 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones@redhat.com>
Date: Thu, 16 Jul 2015 15:41:54 +0200
Subject: [PATCH 1/5] block/curl: Don't lose original error when a connection
 fails.

Message-id: <1437061314-4775-1-git-send-email-rjones@redhat.com>
Patchwork-id: 67043
O-Subject: [RHEL-7.2 qemu-kvm PATCH v3] block/curl: Don't lose original error when a connection fails.
Bugzilla: 1235812
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

From: "Richard W.M. Jones" <rjones@redhat.com>

Currently if qemu is connected to a curl source (eg. web server), and
the web server fails / times out / dies, you always see a bogus EIO
"Input/output error".

For example, choose a large file located on any local webserver which
you control:

  $ qemu-img convert -p http://example.com/large.iso /tmp/test

Once it starts copying the file, stop the webserver and you will see
qemu-img fail with:

  qemu-img: error while reading sector 61440: Input/output error

This patch does two things: Firstly print the actual error from curl
so it doesn't get lost.  Secondly, change EIO to EPROTO.  EPROTO is a
POSIX.1 compatible errno which more accurately reflects that there was
a protocol error, rather than some kind of hardware failure.

After this patch is applied, the error changes to:

  $ qemu-img convert -p http://example.com/large.iso /tmp/test
  qemu-img: curl: transfer closed with 469989 bytes remaining to read
  qemu-img: error while reading sector 16384: Protocol error

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>

BZ: https://bugzilla.redhat.com/1235812
Brew: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=9529354
Upstream-status: 796a060bc0fab40953997976a2e30d9d6235bc7b
---
 block/curl.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/curl.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/block/curl.c b/block/curl.c
index 3088329..dfa8cee 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -22,6 +22,7 @@
  * THE SOFTWARE.
  */
 #include "qemu-common.h"
+#include "qemu/error-report.h"
 #include "block/block_int.h"
 #include "qapi/qmp/qbool.h"
 #include <curl/curl.h>
@@ -294,6 +295,18 @@ static void curl_multi_check_completion(BDRVCURLState *s)
             /* ACBs for successful messages get completed in curl_read_cb */
             if (msg->data.result != CURLE_OK) {
                 int i;
+                static int errcount = 100;
+
+                /* Don't lose the original error message from curl, since
+                 * it contains extra data.
+                 */
+                if (errcount > 0) {
+                    error_report("curl: %s", state->errmsg);
+                    if (--errcount == 0) {
+                        error_report("curl: further errors suppressed");
+                    }
+                }
+
                 for (i = 0; i < CURL_NUM_ACB; i++) {
                     CURLAIOCB *acb = state->acb[i];
 
@@ -301,7 +314,7 @@ static void curl_multi_check_completion(BDRVCURLState *s)
                         continue;
                     }
 
-                    acb->common.cb(acb->common.opaque, -EIO);
+                    acb->common.cb(acb->common.opaque, -EPROTO);
                     qemu_aio_release(acb);
                     state->acb[i] = NULL;
                 }
-- 
1.8.3.1