[patch] rsync over existing I/O connections (new feature)

[Tony Clayton]

Hello,

I wrote this patch that allows you to run rsync over an existing I/O
connection, instead of creating a new rsh or socket connection.

For example, I have a client and server that talk over ssh via a simple
custom protocol.  I want to use the existing ssh connection to transfer files,
but I want the flexibility of rsync to do it.  

With this patch, I can do the following in my client (assuming input fd of 0
and output fd of 1):

- send the server a START_RSYNC request on stdout (my protocol)
- receive a START_RSYNC_ACK reply on fd stdin (my protocol)
- clear the close-on-exec flags for the input and output (ssh) descriptors if
necessary using fcntl (probably not required if using stdin/stdout)
- fork/exec: rsync --partial --quiet --fd-in 0 --fd-out 1 :. myfile
- return to blocking I/O for stdin/stdout using fcntl (rsync uses non-blocking)
- continue on with my protocol 

And on the server, I do the following:

- receive START_RSYNC request from client (my protocol)
- send START_RSYNC_REPLY from client (my protocol)
- fork/exec: rsync -p --server --sender --quiet . /path/to/file/on/server
- return to blocking I/O for stdin/stdout using fcntl (rsync uses non-blocking)
- continue on with my protocol 


I find this extremely useful. Hopefully it's useful enough to others to get
added to the rsync codebase in one form or another so I don't have to keep
patching rsync.

This patch was made against rsync 2.5.4.

cheers,

Tony

rsync-2.5.4-force_fd.apc.patch
-----

diff -urN rsync-2.5.4-2/main.c rsync-2.5.4-2apc/main.c
--- rsync-2.5.4-2/main.c	Mon Sep 30 10:09:17 2002
+++ rsync-2.5.4-2apc/main.c	Thu Mar  6 15:29:27 2003
@@ -665,6 +665,8 @@
 	extern int whole_file;
 	extern int write_batch;
 	extern int read_batch;
+	extern int force_f_in;
+	extern int force_f_out;
 	int rc;
 
 	/* Don't clobber argv[] so that ps(1) can still show the right
@@ -770,9 +772,14 @@
 		list_only = 1;
 	}
 	
-	pid = do_cmd(shell_cmd,shell_machine,shell_user,shell_path,&f_in,&f_out);
+	if (force_f_in != -1) {
+	  ret = client_run(force_f_in, force_f_out, -1, argc, argv);
+	}
+	else {
+	  pid = do_cmd(shell_cmd,shell_machine,shell_user,shell_path,&f_in,&f_out);
 	
-	ret = client_run(f_in, f_out, pid, argc, argv);
+	  ret = client_run(f_in, f_out, pid, argc, argv);
+	}
 
 	fflush(stdout);
 	fflush(stderr);
diff -urN rsync-2.5.4-2/options.c rsync-2.5.4-2apc/options.c
--- rsync-2.5.4-2/options.c	Mon Sep 30 10:09:17 2002
+++ rsync-2.5.4-2apc/options.c	Thu Mar  6 15:34:59 2003
@@ -106,6 +106,9 @@
 int write_batch = 0;
 int read_batch = 0;
 
+int force_f_in = -1;
+int force_f_out = -1;
+
 char *backup_suffix = BACKUP_SUFFIX;
 char *tmpdir = NULL;
 char *compare_dest = NULL;
@@ -261,6 +264,7 @@
   rprintf(F,"     --bwlimit=KBPS          limit I/O bandwidth, KBytes per second\n");
   rprintf(F,"     --write-batch=PREFIX    write batch fileset starting with PREFIX\n");
   rprintf(F,"     --read-batch=PREFIX     read batch fileset starting with PREFIX\n");
+  rprintf(F,"     --fd-in=FD --fd-out=FD  use these open file descriptors for input and output\n");
   rprintf(F," -h, --help                  show this help screen\n");
 #ifdef INET6
   rprintf(F," -4                          prefer IPv4\n");
@@ -356,6 +360,8 @@
   {"hard-links",      'H', POPT_ARG_NONE,   &preserve_hard_links , 0, 0, 0 },
   {"read-batch",       0,  POPT_ARG_STRING, &batch_prefix, OPT_READ_BATCH, 0, 0 },
   {"write-batch",      0,  POPT_ARG_STRING, &batch_prefix, OPT_WRITE_BATCH, 0, 0 },
+  {"fd-in",            0,  POPT_ARG_INT,    &force_f_in , 0, 0, 0 },
+  {"fd-out",           0,  POPT_ARG_INT,    &force_f_out , 0, 0, 0 },
 #ifdef INET6
   {0,		      '4', POPT_ARG_VAL,    &default_af_hint,   AF_INET , 0, 0 },
   {0,		      '6', POPT_ARG_VAL,    &default_af_hint,   AF_INET6 , 0, 0 },
@@ -586,6 +592,20 @@
 	    return 0;
 	}
 
+	if ((force_f_in == -1) && (force_f_out != -1)) {
+	    snprintf(err_buf,sizeof(err_buf),
+		"fd-out can not be used without fd-in\n");
+	    rprintf(FERROR,"ERROR: fd-out can not be used without fd-in\n");
+	    return 0;
+	}
+	if ((force_f_out == -1) && (force_f_in != -1)) {
+	    snprintf(err_buf,sizeof(err_buf),
+		"fd-in can not be used without fd-out\n");
+	    rprintf(FERROR,"ERROR: fd-in can not be used without fd-out\n");
+	    return 0;
+	}
+
+
         *argv = poptGetArgs(pc);
         if (*argv)
                 *argc = count_args(*argv);