From 4470d66ddc7a41c8efee2f307a2dece3227f5515 Mon Sep 17 00:00:00 2001
From: Christopher Faylor <me@cgf.cx>
Date: Fri, 23 Jun 2006 00:19:39 +0000
Subject: [PATCH] * fhandler_fifo.cc (fhandler_fifo::open): Release process
 lock and grab a system-wide mutex to prevent a deadlock and a race. * sync.h
 (lock_process): Make fhandler_fifo a friend. * smallprint.c
 (__small_vsprintf): Cosmetic change.

---
 winsup/cygwin/ChangeLog        |  8 ++++++
 winsup/cygwin/fhandler_fifo.cc | 45 +++++++++++++++++++++++++++++++++-
 winsup/cygwin/smallprint.c     |  4 +--
 winsup/cygwin/sync.h           |  3 ++-
 4 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index af6c3dd13..a0c0fd9f4 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,11 @@
+2006-06-22  Christopher Faylor  <cgf@timesys.com>
+
+	* fhandler_fifo.cc (fhandler_fifo::open): Release process lock and grab
+	a system-wide mutex to prevent a deadlock and a race.
+	* sync.h (lock_process): Make fhandler_fifo a friend.
+
+	* smallprint.c (__small_vsprintf): Cosmetic change.
+
 2006-06-15  Corinna Vinschen  <corinna@vinschen.de>
 
 	* cygwin.din: Export __srget_r, __swbuf_r.
diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index 14292671a..8f1a58477 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -1,6 +1,6 @@
 /* fhandler_fifo.cc - See fhandler.h for a description of the fhandler classes.
 
-   Copyright 2002, 2003, 2004, 2005 Red Hat, Inc.
+   Copyright 2002, 2003, 2004, 2005, 2006 Red Hat, Inc.
 
    This file is part of Cygwin.
 
@@ -141,10 +141,48 @@ out:
   return res;
 }
 
+#define FIFO_PREFIX "_cygfifo_"
+
 int
 fhandler_fifo::open (int flags, mode_t)
 {
   int res = 1;
+  char mutex[CYG_MAX_PATH];
+  char *emutex = mutex + CYG_MAX_PATH;
+  char *p, *p1;
+
+  /* Generate a semi-unique name to associate with this fifo but try to ensure
+     that it is no larger than CYG_MAX_PATH */
+  for (p = mutex, p1 = strchr (get_name (), '\0');
+       --p1 >= get_name () && p < emutex ; p++)
+    *p = (*p1 == '/') ? '_' : *p1;
+  strncpy (p, FIFO_PREFIX, emutex - p);
+  mutex[CYG_MAX_PATH - 1] = '\0';
+
+  /* Create a mutex lock access to this fifo to prevent a race by two processes
+     trying to figure out if they own the fifo or if they should create it. */
+  HANDLE h = CreateMutex (&sec_none_nih, false, mutex);
+  if (!h)
+    {
+      __seterrno ();
+      system_printf ("couldn't open fifo mutex '%s', %E", mutex);
+      res = 0;
+      goto out;
+    }
+
+  lock_process::locker.release ();	/* Since we may be a while, release the
+					   process lock that is held when we
+					   open an fd. */
+  /* FIXME? Need to wait for signal here?
+     This shouldn't block for long, but... */
+  DWORD resw = WaitForSingleObject (h, INFINITE);
+  lock_process::locker.acquire ();	/* Restore the lock */
+  if (resw != WAIT_OBJECT_0 && resw != WAIT_ABANDONED_0)
+    {
+      __seterrno ();
+      system_printf ("Wait for fifo mutex '%s' failed, %E", mutex);
+      goto out;
+    }
 
   set_io_handle (NULL);
   set_output_handle (NULL);
@@ -174,6 +212,11 @@ fhandler_fifo::open (int flags, mode_t)
     }
 
 out:
+  if (h)
+    {
+      ReleaseMutex (h);
+      CloseHandle (h);
+    }
   debug_printf ("returning %d, errno %d", res, get_errno ());
   return res;
 }
diff --git a/winsup/cygwin/smallprint.c b/winsup/cygwin/smallprint.c
index 851e1414c..37c70ee60 100644
--- a/winsup/cygwin/smallprint.c
+++ b/winsup/cygwin/smallprint.c
@@ -1,6 +1,6 @@
 /* smallprint.c: small print routines for WIN32
 
-   Copyright 1996, 1998, 2000, 2001, 2002 Red Hat, Inc.
+   Copyright 1996, 1998, 2000, 2001, 2002, 2003, 2005, 2006 Red Hat, Inc.
 
 This file is part of Cygwin.
 
@@ -159,7 +159,7 @@ __small_vsprintf (char *dst, const char *fmt, va_list ap)
 		    s = tmp;
 		  goto fillin;
 		case '.':
-		  n = strtol (fmt, (char **)&fmt, 10);
+		  n = strtol (fmt, (char **) &fmt, 10);
 		  if (*fmt++ != 's')
 		    goto endfor;
 		case 's':
diff --git a/winsup/cygwin/sync.h b/winsup/cygwin/sync.h
index f8019a8fe..8fd01df3a 100644
--- a/winsup/cygwin/sync.h
+++ b/winsup/cygwin/sync.h
@@ -1,6 +1,6 @@
 /* sync.h: Header file for cygwin synchronization primitives.
 
-   Copyright 1999, 2000, 2001, 2002, 2003, 2004 Red Hat, Inc.
+   Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Red Hat, Inc.
 
    Written by Christopher Faylor <cgf@cygnus.com>
 
@@ -66,6 +66,7 @@ public:
       locker.release ();
   }
   friend class dtable;
+  friend class fhandler_fifo;
 };
 
 #endif /*_SYNC_H*/