# HG changeset patch
# User Adrian Buehlmann <adrian@cadifra.com>
# Date 1295132041 -3600
# Node ID 764441ecbf2ecd9d7479494ba70afbc6985acbfd
# Parent  5ccdca7df211eb326832d72537da1f21c081f6bb
osutil: treat open modes 'w' and 'a' as 'w+' and 'a+' in posixfile

to work around http://support.microsoft.com/kb/899149.

Also, Microsoft's documentation of the CreateFile Windows API says (quote):

  When an application creates a file across a network, it is better to use
  GENERIC_READ | GENERIC_WRITE for dwDesiredAccess than to use
  GENERIC_WRITE alone. The resulting code is faster, because the
  redirector can use the cache manager and send fewer SMBs with more data.
  This combination also avoids an issue where writing to a file across a
  network can occasionally return ERROR_ACCESS_DENIED.

diff -r 5ccdca7df211 -r 764441ecbf2e mercurial/osutil.c
--- a/mercurial/osutil.c	Tue Jan 04 06:29:08 2011 +0100
+++ b/mercurial/osutil.c	Sat Jan 15 23:54:01 2011 +0100
@@ -436,7 +436,14 @@
 	}
 	else
 		flags = _O_TEXT;
-	if (plus) {
+	if (m0 == 'r' && !plus) {
+		flags |= _O_RDONLY;
+		access = GENERIC_READ;
+	} else {
+		/*
+		work around http://support.microsoft.com/kb/899149 and
+		set _O_RDWR for 'w' and 'a', even if mode has no '+'
+		*/
 		flags |= _O_RDWR;
 		access = GENERIC_READ | GENERIC_WRITE;
 		fpmode[fppos++] = '+';
@@ -446,25 +453,13 @@
 	switch (m0) {
 	case 'r':
 		creation = OPEN_EXISTING;
-		if (!plus) {
-			flags |= _O_RDONLY;
-			access = GENERIC_READ;
-		}
 		break;
 	case 'w':
 		creation = CREATE_ALWAYS;
-		if (!plus) {
-			access = GENERIC_WRITE;
-			flags |= _O_WRONLY;
-		}
 		break;
 	case 'a':
 		creation = OPEN_ALWAYS;
 		flags |= _O_APPEND;
-		if (!plus) {
-			flags |= _O_WRONLY;
-			access = GENERIC_WRITE;
-		}
 		break;
 	default:
 		PyErr_Format(PyExc_ValueError,