From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 3 Jan 2012 17:40:55 +0000 (+0100)
Subject: virCommand: Properly handle POLLHUP
X-Git-Tag: v0.9.6.1~42
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e95df90dbb34d9ec92e4fd84cdc48f47da4b83e6;p=thirdparty%2Flibvirt.git

virCommand: Properly handle POLLHUP

It is a good practise to set revents to zero before doing any poll().
Moreover, we should check if event we waited for really occurred or
if any of fds we were polling on didn't encountered hangup.
(cherry picked from commit 06b9c5b9231ef4dbd4b5ff69564305cd4f814879)
---

diff --git a/src/util/command.c b/src/util/command.c
index d390478029..e444f237c9 100644
--- a/src/util/command.c
+++ b/src/util/command.c
@@ -1604,16 +1604,19 @@ virCommandProcessIO(virCommandPtr cmd)
         if (infd != -1) {
             fds[nfds].fd = infd;
             fds[nfds].events = POLLOUT;
+            fds[nfds].revents = 0;
             nfds++;
         }
         if (outfd != -1) {
             fds[nfds].fd = outfd;
             fds[nfds].events = POLLIN;
+            fds[nfds].revents = 0;
             nfds++;
         }
         if (errfd != -1) {
             fds[nfds].fd = errfd;
             fds[nfds].events = POLLIN;
+            fds[nfds].revents = 0;
             nfds++;
         }
 
@@ -1629,8 +1632,8 @@ virCommandProcessIO(virCommandPtr cmd)
         }
 
         for (i = 0; i < nfds ; i++) {
-            if (fds[i].fd == errfd ||
-                fds[i].fd == outfd) {
+            if (fds[i].revents & POLLIN &&
+                (fds[i].fd == errfd || fds[i].fd == outfd)) {
                 char data[1024];
                 char **buf;
                 size_t *len;
@@ -1668,7 +1671,10 @@ virCommandProcessIO(virCommandPtr cmd)
                     memcpy(*buf + *len, data, done);
                     *len += done;
                 }
-            } else {
+            }
+
+            if (fds[i].revents & POLLOUT &&
+                fds[i].fd == infd) {
                 int done;
 
                 /* Coverity 5.3.0 can't see that we only get here if
@@ -1693,6 +1699,18 @@ virCommandProcessIO(virCommandPtr cmd)
                 }
             }
 
+            if (fds[i].revents & (POLLHUP | POLLERR)) {
+                if (fds[i].fd == errfd) {
+                    VIR_DEBUG("hangup on stderr");
+                    errfd = -1;
+                } else if (fds[i].fd == outfd) {
+                    VIR_DEBUG("hangup on stdout");
+                    outfd = -1;
+                } else {
+                    VIR_DEBUG("hangup on stdin");
+                    infd = -1;
+                }
+            }
         }
     }