A patch from Stefan Müller to add the --downdate option, which works
in the opposite manner as --update.

--- old/generator.c
+++ new/generator.c
@@ -53,6 +53,7 @@ extern int ignore_errors;
 extern int remove_sent_files;
 extern int delay_updates;
 extern int update_only;
+extern int downdate_only;
 extern int ignore_existing;
 extern int ignore_non_existing;
 extern int inplace;
@@ -1133,6 +1134,13 @@ static void recv_generator(char *fname, 
 		return;
 	}
 
+	if (downdate_only && statret == 0
+	    && cmp_time(st.st_mtime, file->modtime) < 0) {
+		if (verbose > 1)
+			rprintf(FINFO, "%s is older\n", fname);
+		return;
+	}
+
 	fnamecmp = fname;
 	fnamecmp_type = FNAMECMP_FNAME;
 
@@ -1430,7 +1438,7 @@ void generate_files(int f_out, struct fi
 	phase++;
 	csum_length = SUM_LENGTH;
 	max_size = min_size = ignore_existing = ignore_non_existing = 0;
-	update_only = always_checksum = size_only = 0;
+	downdate_only = update_only = always_checksum = size_only = 0;
 	ignore_times = 1;
 	if (append_mode)  /* resend w/o append mode */
 		append_mode = -1; /* ... but only longer files */
--- old/options.c
+++ new/options.c
@@ -56,6 +56,7 @@ int preserve_gid = 0;
 int preserve_times = 0;
 int omit_dir_times = 0;
 int update_only = 0;
+int downdate_only = 0;
 int cvs_exclude = 0;
 int dry_run = 0;
 int do_xfers = 1;
@@ -291,6 +292,7 @@ void usage(enum logcode F)
   rprintf(F,"     --backup-dir=DIR        make backups into hierarchy based in DIR\n");
   rprintf(F,"     --suffix=SUFFIX         set backup suffix (default %s w/o --backup-dir)\n",BACKUP_SUFFIX);
   rprintf(F," -u, --update                skip files that are newer on the receiver\n");
+  rprintf(F," -w, --downdate              skip files that are older on the receiver\n");
   rprintf(F,"     --inplace               update destination files in-place (SEE MAN PAGE)\n");
   rprintf(F,"     --append                append data onto shorter files\n");
   rprintf(F," -d, --dirs                  transfer directories without recursing\n");
@@ -461,6 +463,7 @@ static struct poptOption long_options[] 
   {"size-only",        0,  POPT_ARG_NONE,   &size_only, 0, 0, 0 },
   {"one-file-system", 'x', POPT_ARG_NONE,   0, 'x', 0, 0 },
   {"update",          'u', POPT_ARG_NONE,   &update_only, 0, 0, 0 },
+  {"downdate",        'w', POPT_ARG_NONE,   &downdate_only, 0, 0, 0 },
   {"existing",         0,  POPT_ARG_NONE,   &ignore_non_existing, 0, 0, 0 },
   {"ignore-non-existing",0,POPT_ARG_NONE,   &ignore_non_existing, 0, 0, 0 },
   {"ignore-existing",  0,  POPT_ARG_NONE,   &ignore_existing, 0, 0, 0 },