[PATCH 11/14] Cygwin: FIFO: fix clone

Ken Brown kbrown@cornell.edu
Sun Apr 14 19:16:00 GMT 2019


After copyto is called, make the new fhandler's pipe_name point to the
new fhandler's pipe_name_buf, which is a *copy* of the old fhandler's
pipe_name_buf.  Previously, get_pipe_name would return the wrong
result after a clone/dup, causing create_pipe_instance and open_pipe
to fail.

Also, stop the listen_client thread when cloning.  Otherwise the
thread can keep accepting connections that the cloned fhandler won't
know about.

Do this via a new method fhandler_fifo::stop_listen_client, extracted
from fhandler_fifo::close.
---
 winsup/cygwin/fhandler.h       |  6 ++++++
 winsup/cygwin/fhandler_fifo.cc | 20 +++++++++++++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 1e26c651f..aea02c2b3 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -1280,6 +1280,7 @@ class fhandler_fifo: public fhandler_base
   int disconnect_and_reconnect (int);
   int add_client_handler ();
   bool listen_client ();
+  int stop_listen_client ();
 public:
   fhandler_fifo ();
   bool hit_eof ();
@@ -1326,7 +1327,12 @@ public:
   {
     void *ptr = (void *) ccalloc (malloc_type, 1, sizeof (fhandler_fifo));
     fhandler_fifo *fhf = new (ptr) fhandler_fifo (ptr);
+    /* We don't want our client list to change any more. */
+    stop_listen_client ();
     copyto (fhf);
+    /* fhf->pipe_name_buf is a *copy* of this->pipe_name_buf, but
+       fhf->pipe_name.Buffer == this->pipe_name_buf. */
+    fhf->pipe_name.Buffer = fhf->pipe_name_buf;
     for (int i = 0; i < nhandlers; i++)
       fhf->fc_handler[i].fh = fc_handler[i].fh->clone ();
     return fhf;
diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index d4d2b3883..a3ecbeb4a 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -812,9 +812,9 @@ fifo_client_handler::close ()
 }
 
 int
-fhandler_fifo::close ()
+fhandler_fifo::stop_listen_client ()
 {
-  int res = 0;
+  int ret = 0;
   HANDLE evt = InterlockedExchangePointer (&lct_termination_evt, NULL);
   HANDLE thr = InterlockedExchangePointer (&listen_client_thr, NULL);
   if (thr)
@@ -825,19 +825,29 @@ fhandler_fifo::close ()
       DWORD err;
       GetExitCodeThread (thr, &err);
       if (err)
-	debug_printf ("listen_client_thread exited with code %d", err);
+	{
+	  ret = -1;
+	  debug_printf ("listen_client_thread exited with error, %E");
+	}
       CloseHandle (thr);
     }
   if (evt)
     CloseHandle (evt);
+  return ret;
+}
+
+int
+fhandler_fifo::close ()
+{
+  int ret = stop_listen_client ();
   if (read_ready)
     CloseHandle (read_ready);
   if (write_ready)
     CloseHandle (write_ready);
   for (int i = 0; i < nhandlers; i++)
     if (fc_handler[i].close () < 0)
-      res = -1;
-  return fhandler_base::close () || res;
+      ret = -1;
+  return fhandler_base::close () || ret;
 }
 
 int
-- 
2.17.0



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