virfdstream: Check for thread error more frequently

When the I/O thread quits (e.g. due to an I/O error, lseek()
error, whatever), any subsequent virFDStream API should return
error too. Moreover, when invoking stream event callback, we must
set the VIR_STREAM_EVENT_ERROR flag so that the callback knows
something bad happened.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/util/virfdstream.c

@@ -312,6 +312,9 @@ static void virFDStreamEvent(int watch ATTRIBUTE_UNUSED,
         return;
     }
 
+    if (fdst->threadErr)
+        events |= VIR_STREAM_EVENT_ERROR;
+
     cb = fdst->cb;
     cbopaque = fdst->opaque;
     ff = fdst->ff;
@@ -791,10 +794,10 @@ static int virFDStreamWrite(virStreamPtr st, const char *bytes, size_t nbytes)
     if (fdst->thread) {
         char *buf;
 
-        if (fdst->threadQuit) {
+        if (fdst->threadQuit || fdst->threadErr) {
             virReportSystemError(EBADF, "%s",
                                  _("cannot write to stream"));
-            return -1;
+            goto cleanup;
         }
 
         if (VIR_ALLOC(msg) < 0 ||
@@ -870,7 +873,7 @@ static int virFDStreamRead(virStreamPtr st, char *bytes, size_t nbytes)
         virFDStreamMsgPtr msg = NULL;
 
         while (!(msg = fdst->msg)) {
-            if (fdst->threadQuit) {
+            if (fdst->threadQuit || fdst->threadErr) {
                 if (nbytes) {
                     virReportSystemError(EBADF, "%s",
                                          _("stream is not open"));
@@ -971,6 +974,13 @@ virFDStreamSendHole(virStreamPtr st,
          * the thread to do the lseek() for us. Under no
          * circumstances we can do the lseek() ourselves here. We
          * might mess up file position for the thread. */
+
+        if (fdst->threadQuit || fdst->threadErr) {
+            virReportSystemError(EBADF, "%s",
+                                 _("stream is not open"));
+            goto cleanup;
+        }
+
         if (fdst->threadDoRead) {
             msg = fdst->msg;
             if (msg->type != VIR_FDSTREAM_MSG_TYPE_HOLE) {
@@ -1025,6 +1035,9 @@ virFDStreamInData(virStreamPtr st,
     if (fdst->thread) {
         virFDStreamMsgPtr msg;
 
+        if (fdst->threadErr)
+            goto cleanup;
+
         while (!(msg = fdst->msg)) {
             if (fdst->threadQuit) {
                 *inData = *length = 0;