[newlib-cygwin] Cygwin: disable creating directories below /dev/mqueue

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=fd3fb7a1479009507bbd050c845f18497c7117a0

commit fd3fb7a1479009507bbd050c845f18497c7117a0
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Tue May 25 22:05:13 2021 +0200

    Cygwin: disable creating directories below /dev/mqueue
    
    ...as on Linux.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/fhandler.h         | 1 +
 winsup/cygwin/fhandler_mqueue.cc | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 8208a0356..4c475184e 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -3151,6 +3151,7 @@ public:
 
   void fixup_after_fork (HANDLE);
 
+  int mkdir (mode_t);
   void __reg3 read (void *, size_t&);
   off_t lseek (off_t, int);
   int __reg2 fstat (struct stat *);
diff --git a/winsup/cygwin/fhandler_mqueue.cc b/winsup/cygwin/fhandler_mqueue.cc
index f074474d7..f3201883d 100644
--- a/winsup/cygwin/fhandler_mqueue.cc
+++ b/winsup/cygwin/fhandler_mqueue.cc
@@ -368,6 +368,13 @@ fhandler_mqueue::get_proc_fd_name (char *buf)
   return strcpy (buf, strrchr (get_name (), '/'));
 }
 
+int
+fhandler_mqueue::mkdir (mode_t mode)
+{
+  set_errno (EPERM);
+  return -1;
+}
+
 /* Do what fhandler_virtual does for read/lseek */
 bool
 fhandler_mqueue::fill_filebuf ()