I'm trying to rsync (with -a to preserve permissions) to a mount point on an NFS server, and it fails when copying a file that is read-only.  The problem is that do_mkstemp creates the temp file with the desired user permissions (either with open() or with fchmod().

SUSv3 says that the affect of chmod()/fchmod() on existing open file descriptors is implemtation defined; it also says:

    Any file descriptors currently open by any process on the file could
    possibly become invalid if the mode of the file is changed to a value which
    would deny access to that process. One situation where this could occur is
    on a stateless file system. This behavior will not occur in a conforming
    environment.

I guess I have a non-conforming environment (I'm talking to a unfs3 server).

If I remove HAVE_FCHMOD, it still doesn't work, because the call to open() includes the read-only permissions as well (a case I don't really see referenced in SUSv3 right off).

The following patch makes sure that the user always has write permission to the temp file:

diff -urN rsync-2.6.9-dist/syscall.c rsync-2.6.9/syscall.c
--- rsync-2.6.9-dist/syscall.c  2007-10-19 20:49:29.000000000 -0500
+++ rsync-2.6.9/syscall.c       2007-10-19 20:53:02.000000000 -0500
@@ -190,6 +190,7 @@
 {
        RETURN_ERROR_IF(dry_run, 0);
        RETURN_ERROR_IF(read_only, EROFS);
+       perms |= S_IWUSR;
 
 #if defined HAVE_SECURE_MKSTEMP && defined HAVE_FCHMOD && (!defined HAVE_OPEN64 || defined HAVE_MKSTEMP64)
        {