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