commit 5004f121bc572c58d9721bf7bf3c3a1988720ba8
Author: Michal Privoznik <mprivozn@redhat.com>
Date:   Mon Jun 5 13:22:23 2017 +0200

    virFDStreamThread: Make sure we won't exceed @length
    
    There's a problem with current streams after I switched them from
    iohelper to thread implementation. Previously, iohelper made sure
    not to exceed specified @length resulting in the pipe EOF
    appearing at the exact right moment (the pipe was used to tunnel
    the data from the iohelper to the daemon). Anyway, when switching
    to thread I had to write the I/O code from scratch. Whilst doing
    that I took an inspiration from the iohelper code, but since the
    usage of pipe switched to slightly different meaning, there was
    no 1:1 relationship between the codes.
    
    Moreover, after introducing VIR_FDSTREAM_MSG_TYPE_HOLE, the
    condition that should made sure we won't exceed @length was
    completely wrong.
    
    The fix is to:
    
    a) account for holes for @length
    b) cap not just data sections but holes too (if @length would be
    exceeded)
    
    For this purpose, the condition needs to be brought closer to the
    code that handles holes and data sections.
    
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

Index: libvirt-3.4.0/src/util/virfdstream.c
===================================================================
--- libvirt-3.4.0.orig/src/util/virfdstream.c
+++ libvirt-3.4.0/src/util/virfdstream.c
@@ -420,6 +420,8 @@ virFDStreamThreadDoRead(virFDStreamDataP
                         const int fdout,
                         const char *fdinname,
                         const char *fdoutname,
+                        size_t length,
+                        size_t total,
                         size_t *dataLen,
                         size_t buflen)
 {
@@ -433,10 +435,18 @@ virFDStreamThreadDoRead(virFDStreamDataP
         if (virFileInData(fdin, &inData, &sectionLen) < 0)
             goto error;
 
+        if (length &&
+            sectionLen > length - total)
+            sectionLen = length - total;
+
         if (inData)
             *dataLen = sectionLen;
     }
 
+    if (length &&
+        buflen > length - total)
+        buflen = length - total;
+
     if (VIR_ALLOC(msg) < 0)
         goto error;
 
@@ -578,13 +588,6 @@ virFDStreamThread(void *opaque)
     while (1) {
         ssize_t got;
 
-        if (length &&
-            (length - total) < buflen)
-            buflen = length - total;
-
-        if (buflen == 0)
-            break; /* End of requested data from client */
-
         while (doRead == (fdst->msg != NULL) &&
                !fdst->threadQuit) {
             if (virCondWait(&fdst->threadCond, &fdst->parent.lock)) {
@@ -608,6 +611,7 @@ virFDStreamThread(void *opaque)
             got = virFDStreamThreadDoRead(fdst, sparse,
                                           fdin, fdout,
                                           fdinname, fdoutname,
+                                          length, total,
                                           &dataLen, buflen);
         else
             got = virFDStreamThreadDoWrite(fdst, sparse,