From 4c78f9561d3a9e09484e1391194d9de7bf8060ab Mon Sep 17 00:00:00 2001
From: "emellor@ewan" <emellor@ewan>
Date: Thu, 6 Oct 2005 10:13:11 +0100
Subject: [PATCH] Raise an exception if an error appears on the pipes to our
 children, and make sure that the child's pipes are closed even under that
 exception.  Move the handling of POLLHUP to the end of the loop, so that we
 guarantee to read any remaining data from the child if POLLHUP and POLLIN
 appear at the same time.

Signed-off-by: Ewan Mellor <ewan@xensource.com>
---
 tools/python/xen/xend/XendCheckpoint.py | 66 +++++++++++++++----------
 1 file changed, 39 insertions(+), 27 deletions(-)

diff --git a/tools/python/xen/xend/XendCheckpoint.py b/tools/python/xen/xend/XendCheckpoint.py
index 144cd134ef..ab8ba6fb4e 100644
--- a/tools/python/xen/xend/XendCheckpoint.py
+++ b/tools/python/xen/xend/XendCheckpoint.py
@@ -116,6 +116,7 @@ def restore(xd, fd):
 
     assert dominfo.store_channel
     assert dominfo.console_channel
+    assert dominfo.getDomainPath()
 
     try:
         l = read_exact(fd, sizeof_unsigned_long,
@@ -138,6 +139,11 @@ def restore(xd, fd):
             if m:
                 store_mfn = int(m.group(2))
                 dominfo.setStoreRef(store_mfn)
+                log.debug("IntroduceDomain %d %d %d %s",
+                          dominfo.getDomid(),
+                          store_mfn,
+                          dominfo.store_channel.port1,
+                          dominfo.getDomainPath())
                 IntroduceDomain(dominfo.getDomid(),
                                 store_mfn,
                                 dominfo.store_channel.port1,
@@ -161,34 +167,40 @@ def forkHelper(cmd, fd, inputHandler, closeToChild):
     if closeToChild:
         child.tochild.close()
 
-    fds = [child.fromchild.fileno(),
-           child.childerr.fileno()]
-    p = select.poll()
-    map(p.register, fds)
-    while len(fds) > 0:
-        r = p.poll()
-        for (fd, event) in r:
-            if event & select.POLLHUP or event & select.POLLERR:
-                fds.remove(fd)
-                p.unregister(fd)
-                continue
-            if not event & select.POLLIN:
-                continue
-            if fd == child.childerr.fileno():
-                lasterr = child.childerr.readline().rstrip()
-                log.error('%s', lasterr)
-            else:
-                l = child.fromchild.readline().rstrip()
-                while l:
-                    log.debug('%s', l)
-                    inputHandler(l, child.tochild)
-                    try:
+    try:
+        fds = [child.fromchild.fileno(),
+               child.childerr.fileno()]
+        p = select.poll()
+        map(p.register, fds)
+        while len(fds) > 0:
+            r = p.poll()
+            for (fd, event) in r:
+                if event & select.POLLIN:
+                    if fd == child.childerr.fileno():
+                        lasterr = child.childerr.readline().rstrip()
+                        log.error('%s', lasterr)
+                    else:
                         l = child.fromchild.readline().rstrip()
-                    except:
-                        l = None
-
-    child.fromchild.close()
-    child.childerr.close()
+                        while l:
+                            log.debug('%s', l)
+                            inputHandler(l, child.tochild)
+                            try:
+                                l = child.fromchild.readline().rstrip()
+                            except:
+                                l = None
+
+                if event & select.POLLERR:
+                    raise XendError('Error reading from child process for %s',
+                                    cmd)
+
+                if event & select.POLLHUP:
+                    fds.remove(fd)
+                    p.unregister(fd)
+    finally:
+        child.fromchild.close()
+        child.childerr.close()
+        if not closeToChild:
+            child.tochild.close()
 
     if child.wait() >> 8 == 127:
         lasterr = "popen failed"
-- 
2.30.2