From 92082c21d1baaf5105f2d4cfcf9ec1b0f63bd13f Mon Sep 17 00:00:00 2001
From: David Rose <david@ddrose.com>
Date: Sat, 19 Oct 2002 02:27:54 +0000
Subject: [PATCH] handle open_write() correctly on windows

---
 dtool/src/dtoolutil/filename.cxx | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/dtool/src/dtoolutil/filename.cxx b/dtool/src/dtoolutil/filename.cxx
index 40e19be38e..319e5719e0 100644
--- a/dtool/src/dtoolutil/filename.cxx
+++ b/dtool/src/dtoolutil/filename.cxx
@@ -1204,6 +1204,17 @@ open_write(ofstream &stream) const {
 
   int open_mode = ios::out;
 
+#ifdef WIN32_VC
+  // Windows insists on having this set to prevent the file from being
+  // truncated when we open it.  Makes ios::trunc kind of pointless,
+  // doesn't it?  On the other hand, setting ios::in also seems to
+  // imply ios::nocreate (!), so we should only set this if the file
+  // already exists.
+  if (exists()) {
+    open_mode |= ios::in;
+  }
+#endif
+
 #ifdef HAVE_IOS_BINARY
   // For some reason, some systems (like Irix) don't define
   // ios::binary.