From 0fe4aa149f35fcca9d4029d5be8a0f3967d46fd5 Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Mon, 29 May 2017 16:29:36 +0200
Subject: [PATCH] fdstream: Report error from the I/O thread

Problem with our error reporting is that the error object is a
thread local variable. That means if there's an error reported
within the I/O thread it gets logged and everything, but later
when the event loop aborts the stream it doesn't see the original
error. So we are left with some generic error. We can do better
if we copy the error message between the threads.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
---
 daemon/stream.c        | 18 ++++++++++++------
 src/util/virfdstream.c |  9 ++++++---
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/daemon/stream.c b/daemon/stream.c
index 1d5b50ad76..5077ac8b0a 100644
--- a/daemon/stream.c
+++ b/daemon/stream.c
@@ -231,17 +231,23 @@ daemonStreamEvent(virStreamPtr st, int events, void *opaque)
         int ret;
         virNetMessagePtr msg;
         virNetMessageError rerr;
+        virErrorPtr origErr = virSaveLastError();
 
         memset(&rerr, 0, sizeof(rerr));
         stream->closed = true;
         virStreamEventRemoveCallback(stream->st);
         virStreamAbort(stream->st);
-        if (events & VIR_STREAM_EVENT_HANGUP)
-            virReportError(VIR_ERR_RPC,
-                           "%s", _("stream had unexpected termination"));
-        else
-            virReportError(VIR_ERR_RPC,
-                           "%s", _("stream had I/O failure"));
+        if (origErr && origErr->code != VIR_ERR_OK) {
+            virSetError(origErr);
+            virFreeError(origErr);
+        } else {
+            if (events & VIR_STREAM_EVENT_HANGUP)
+                virReportError(VIR_ERR_RPC,
+                               "%s", _("stream had unexpected termination"));
+            else
+                virReportError(VIR_ERR_RPC,
+                               "%s", _("stream had I/O failure"));
+        }
 
         msg = virNetMessageNew(false);
         if (!msg) {
diff --git a/src/util/virfdstream.c b/src/util/virfdstream.c
index bd2355d17f..f54ba15aee 100644
--- a/src/util/virfdstream.c
+++ b/src/util/virfdstream.c
@@ -106,7 +106,7 @@ struct virFDStreamData {
     /* Thread data */
     virThreadPtr thread;
     virCond threadCond;
-    int threadErr;
+    virErrorPtr threadErr;
     bool threadQuit;
     bool threadAbort;
     bool threadDoRead;
@@ -123,6 +123,7 @@ virFDStreamDataDispose(void *obj)
     virFDStreamDataPtr fdst = obj;
 
     VIR_DEBUG("obj=%p", fdst);
+    virFreeError(fdst->threadErr);
     virFDStreamMsgQueueFree(&fdst->msg);
 }
 
@@ -312,8 +313,10 @@ static void virFDStreamEvent(int watch ATTRIBUTE_UNUSED,
         return;
     }
 
-    if (fdst->threadErr)
+    if (fdst->threadErr) {
         events |= VIR_STREAM_EVENT_ERROR;
+        virSetError(fdst->threadErr);
+    }
 
     cb = fdst->cb;
     cbopaque = fdst->opaque;
@@ -641,7 +644,7 @@ virFDStreamThread(void *opaque)
     return;
 
  error:
-    fdst->threadErr = errno;
+    fdst->threadErr = virSaveLastError();
     goto cleanup;
 }