[newlib-cygwin] Cygwin: FIFO: avoid hang after exec

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=230c5df2dfddeb83d31b16f791a079871ba224e8

commit 230c5df2dfddeb83d31b16f791a079871ba224e8
Author: Ken Brown <kbrown@cornell.edu>
Date:   Thu Apr 18 15:39:52 2019 +0000

    Cygwin: FIFO: avoid hang after exec
    
    Define fhandler:fifo::fixup_after_exec, which sets listen_client_thr
    and lct_termination_evt to NULL.  This forces the listen_client thread
    to restart on the first attempt to read after an exec.  Previously the
    exec'd process could hang in fhandler_fifo::raw_read.

Diff:
---
 winsup/cygwin/fhandler.h       | 1 +
 winsup/cygwin/fhandler_fifo.cc | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 8fb176b..da007ee 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -1301,6 +1301,7 @@ public:
   ssize_t __reg3 raw_write (const void *ptr, size_t ulen);
   bool arm (HANDLE h);
   void fixup_after_fork (HANDLE);
+  void fixup_after_exec ();
   int __reg2 fstatvfs (struct statvfs *buf);
   void clear_readahead ()
   {
diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index 1d02adb..bc9c239 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -943,6 +943,15 @@ fhandler_fifo::fixup_after_fork (HANDLE parent)
 }
 
 void
+fhandler_fifo::fixup_after_exec ()
+{
+  fhandler_base::fixup_after_exec ();
+  listen_client_thr = NULL;
+  lct_termination_evt = NULL;
+  fifo_client_unlock ();
+}
+
+void
 fhandler_fifo::set_close_on_exec (bool val)
 {
   fhandler_base::set_close_on_exec (val);