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>

diff --git a/tools/python/xen/xend/XendCheckpoint.py b/tools/python/xen/xend/XendCheckpoint.py
index 144cd134efbd396f1f1499b9d66f21c196f0f71c..ab8ba6fb4e0b34b8beb1c5948d24d83de90bff7d 100644 (file)
--- 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"