path: root/options.c

/*  -*- c-file-style: "linux" -*-
    
    Copyright (C) 1998-2001 by Andrew Tridgell <tridge@samba.org>
    Copyright (C) 2000-2001 by Martin Pool <mbp@samba.org>
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "rsync.h"
#include "popt.h"

int make_backups = 0;
int whole_file = 0;
int copy_links = 0;
int preserve_links = 0;
int preserve_hard_links = 0;
int preserve_perms = 0;
int preserve_devices = 0;
int preserve_uid = 0;
int preserve_gid = 0;
int preserve_times = 0;
int update_only = 0;
int cvs_exclude = 0;
int dry_run=0;
int local_server=0;
int ignore_times=0;
int delete_mode=0;
int delete_excluded=0;
int one_file_system=0;
int remote_version=0;
int sparse_files=0;
int do_compression=0;
int am_root=0;
int orig_umask=0;
int relative_paths=0;
int numeric_ids = 0;
int force_delete = 0;
int io_timeout = 0;
int io_error = 0;
int read_only = 0;
int module_id = -1;
int am_server = 0;
int am_sender=0;
int recurse = 0;
int am_daemon=0;
int do_stats=0;
int do_progress=0;
int keep_partial=0;
int safe_symlinks=0;
int copy_unsafe_links=0;
int block_size=BLOCK_SIZE;
int size_only=0;
int bwlimit=0;
int delete_after=0;
int only_existing=0;
int max_delete=0;
int ignore_errors=0;
#ifdef _WIN32
int modify_window=2;
#else
int modify_window=0;
#endif
int blocking_io=0;

char *backup_suffix = BACKUP_SUFFIX;
char *tmpdir = NULL;
char *compare_dest = NULL;
char *config_file = RSYNCD_CONF;
char *shell_cmd = NULL;
char *log_format = NULL;
char *password_file = NULL;
char *rsync_path = RSYNC_NAME;
char *backup_dir = NULL;
int rsync_port = RSYNC_PORT;

int verbose = 0;
int quiet = 0;
int always_checksum = 0;
int list_only = 0;

static int modify_window_set;


struct in_addr socket_address = {INADDR_ANY};


static void print_rsync_version(int f)
{
        char const *got_socketpair = "no ";
        char const *hardlinks = "no ";
        char const *links = "no ";

#ifdef HAVE_SOCKETPAIR
        got_socketpair = "";
#endif

#if SUPPORT_HARD_LINKS
        hardlinks = "";
#endif

#if SUPPORT_LINKS
        links = "";
#endif

        rprintf(f, "%s  version %s  protocol version %d\n",
                RSYNC_NAME, VERSION, PROTOCOL_VERSION);
        rprintf(f,
                "Copyright (C) 1996-2001 by Andrew Tridgell, Paul Mackerras and others\n");
        rprintf(f, "Capabilities: %d-bit files, %ssocketpairs, "
                "%shard links, %ssymlinks\n\n",
                sizeof(int64) * 8,
                got_socketpair,
                hardlinks, links);

#ifdef NO_INT64
        rprintf(f, "WARNING: no 64-bit integers on this platform!\n");
#endif
}


void usage(enum logcode F)
{
  print_rsync_version(F);

  rprintf(F,"rsync is a file transfer program capable of efficient remote update\nvia a fast differencing algorithm.\n\n");

  rprintf(F,"Usage: rsync [OPTION]... SRC [SRC]... [USER@]HOST:DEST\n");
  rprintf(F,"  or   rsync [OPTION]... [USER@]HOST:SRC DEST\n");
  rprintf(F,"  or   rsync [OPTION]... SRC [SRC]... DEST\n");
  rprintf(F,"  or   rsync [OPTION]... [USER@]HOST::SRC [DEST]\n");
  rprintf(F,"  or   rsync [OPTION]... SRC [SRC]... [USER@]HOST::DEST\n");
  rprintf(F,"  or   rsync [OPTION]... rsync://[USER@]HOST[:PORT]/SRC [DEST]\n");
  rprintf(F,"SRC on single-colon remote HOST will be expanded by remote shell\n");
  rprintf(F,"SRC on server remote HOST may contain shell wildcards or multiple\n");
  rprintf(F,"  sources separated by space as long as they have same top-level\n");
  rprintf(F,"\nOptions\n");
  rprintf(F," -v, --verbose               increase verbosity\n");
  rprintf(F," -q, --quiet                 decrease verbosity\n");
  rprintf(F," -c, --checksum              always checksum\n");
  rprintf(F," -a, --archive               archive mode\n");
  rprintf(F," -r, --recursive             recurse into directories\n");
  rprintf(F," -R, --relative              use relative path names\n");
  rprintf(F," -b, --backup                make backups (default %s suffix)\n",BACKUP_SUFFIX);
  rprintf(F,"     --backup-dir            make backups into this directory\n");
  rprintf(F,"     --suffix=SUFFIX         override backup suffix\n");  
  rprintf(F," -u, --update                update only (don't overwrite newer files)\n");
  rprintf(F," -l, --links                 preserve soft links\n");
  rprintf(F," -L, --copy-links            treat soft links like regular files\n");
  rprintf(F,"     --copy-unsafe-links     copy links outside the source tree\n");
  rprintf(F,"     --safe-links            ignore links outside the destination tree\n");
  rprintf(F," -H, --hard-links            preserve hard links\n");
  rprintf(F," -p, --perms                 preserve permissions\n");
  rprintf(F," -o, --owner                 preserve owner (root only)\n");
  rprintf(F," -g, --group                 preserve group\n");
  rprintf(F," -D, --devices               preserve devices (root only)\n");
  rprintf(F," -t, --times                 preserve times\n");  
  rprintf(F," -S, --sparse                handle sparse files efficiently\n");
  rprintf(F," -n, --dry-run               show what would have been transferred\n");
  rprintf(F," -W, --whole-file            copy whole files, no incremental checks\n");
  rprintf(F," -x, --one-file-system       don't cross filesystem boundaries\n");
  rprintf(F," -B, --block-size=SIZE       checksum blocking size (default %d)\n",BLOCK_SIZE);  
  rprintf(F," -e, --rsh=COMMAND           specify rsh replacement\n");
  rprintf(F,"     --rsync-path=PATH       specify path to rsync on the remote machine\n");
  rprintf(F," -C, --cvs-exclude           auto ignore files in the same way CVS does\n");
  rprintf(F,"     --existing              only update files that already exist\n");
  rprintf(F,"     --delete                delete files that don't exist on the sending side\n");
  rprintf(F,"     --delete-excluded       also delete excluded files on the receiving side\n");
  rprintf(F,"     --delete-after          delete after transferring, not before\n");
  rprintf(F,"     --ignore-errors         delete even if there are IO errors\n");
  rprintf(F,"     --max-delete=NUM        don't delete more than NUM files\n");
  rprintf(F,"     --partial               keep partially transferred files\n");
  rprintf(F,"     --force                 force deletion of directories even if not empty\n");
  rprintf(F,"     --numeric-ids           don't map uid/gid values by user/group name\n");
  rprintf(F,"     --timeout=TIME          set IO timeout in seconds\n");
  rprintf(F," -I, --ignore-times          don't exclude files that match length and time\n");
  rprintf(F,"     --size-only             only use file size when determining if a file should be transferred\n");
  rprintf(F,"     --modify-window=NUM     Timestamp window (seconds) for file match (default=%d)\n",modify_window);
  rprintf(F," -T  --temp-dir=DIR          create temporary files in directory DIR\n");
  rprintf(F,"     --compare-dest=DIR      also compare destination files relative to DIR\n");
  rprintf(F," -P                          equivalent to --partial --progress\n");
  rprintf(F," -z, --compress              compress file data\n");
  rprintf(F,"     --exclude=PATTERN       exclude files matching PATTERN\n");
  rprintf(F,"     --exclude-from=FILE     exclude patterns listed in FILE\n");
  rprintf(F,"     --include=PATTERN       don't exclude files matching PATTERN\n");
  rprintf(F,"     --include-from=FILE     don't exclude patterns listed in FILE\n");
  rprintf(F,"     --version               print version number\n");  
  rprintf(F,"     --daemon                run as a rsync daemon\n");  
  rprintf(F,"     --address               bind to the specified address\n");  
  rprintf(F,"     --config=FILE           specify alternate rsyncd.conf file\n");  
  rprintf(F,"     --port=PORT             specify alternate rsyncd port number\n");
  rprintf(F,"     --blocking-io           use blocking IO for the remote shell\n");  
  rprintf(F,"     --stats                 give some file transfer stats\n");  
  rprintf(F,"     --progress              show progress during transfer\n");  
  rprintf(F,"     --log-format=FORMAT     log file transfers using specified format\n");  
  rprintf(F,"     --password-file=FILE    get password from FILE\n");
  rprintf(F,"     --bwlimit=KBPS          limit I/O bandwidth, KBytes per second\n");
  rprintf(F," -h, --help                  show this help screen\n");

  rprintf(F,"\n");

  rprintf(F,"\nPlease see the rsync(1) and rsyncd.conf(5) man pages for full documentation\n");
  rprintf(F,"See http://rsync.samba.org/ for updates, bug reports, and answers\n");
}

enum {OPT_VERSION = 1000, OPT_SUFFIX, OPT_SENDER, OPT_SERVER, OPT_EXCLUDE,
      OPT_EXCLUDE_FROM, OPT_DELETE, OPT_DELETE_EXCLUDED, OPT_NUMERIC_IDS,
      OPT_RSYNC_PATH, OPT_FORCE, OPT_TIMEOUT, OPT_DAEMON, OPT_CONFIG, OPT_PORT,
      OPT_INCLUDE, OPT_INCLUDE_FROM, OPT_STATS, OPT_PARTIAL, OPT_PROGRESS,
      OPT_COPY_UNSAFE_LINKS, OPT_SAFE_LINKS, OPT_COMPARE_DEST,
      OPT_LOG_FORMAT, OPT_PASSWORD_FILE, OPT_SIZE_ONLY, OPT_ADDRESS,
      OPT_DELETE_AFTER, OPT_EXISTING, OPT_MAX_DELETE, OPT_BACKUP_DIR, 
      OPT_IGNORE_ERRORS, OPT_BWLIMIT, OPT_BLOCKING_IO,
      OPT_MODIFY_WINDOW};

static struct poptOption long_options[] = {
  /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  {"version",          0,  POPT_ARG_NONE,   0,             OPT_VERSION},
  {"suffix",           0,  POPT_ARG_STRING, &backup_suffix},
  {"rsync-path",       0,  POPT_ARG_STRING, &rsync_path},
  {"password-file",    0,  POPT_ARG_STRING, &password_file},
  {"ignore-times",    'I', POPT_ARG_NONE,   &ignore_times},
  {"size-only",        0,  POPT_ARG_NONE,   &size_only},
  {"modify-window",    0,  POPT_ARG_INT,    &modify_window, OPT_MODIFY_WINDOW},
  {"one-file-system", 'x', POPT_ARG_NONE,   &one_file_system},
  {"delete",           0,  POPT_ARG_NONE,   &delete_mode},
  {"existing",         0,  POPT_ARG_NONE,   &only_existing},
  {"delete-after",     0,  POPT_ARG_NONE,   &delete_after},
  {"delete-excluded",  0,  POPT_ARG_NONE,   0,              OPT_DELETE_EXCLUDED},
  {"force",            0,  POPT_ARG_NONE,   &force_delete},
  {"numeric-ids",      0,  POPT_ARG_NONE,   &numeric_ids},
  {"exclude",          0,  POPT_ARG_STRING, 0,              OPT_EXCLUDE},
  {"include",          0,  POPT_ARG_STRING, 0,              OPT_INCLUDE},
  {"exclude-from",     0,  POPT_ARG_STRING, 0,              OPT_EXCLUDE_FROM},
  {"include-from",     0,  POPT_ARG_STRING, 0,              OPT_INCLUDE_FROM},
  {"safe-links",       0,  POPT_ARG_NONE,   &safe_symlinks},
  {"help",            'h', POPT_ARG_NONE,   0,              'h'},
  {"backup",          'b', POPT_ARG_NONE,   &make_backups},
  {"dry-run",         'n', POPT_ARG_NONE,   &dry_run},
  {"sparse",          'S', POPT_ARG_NONE,   &sparse_files},
  {"cvs-exclude",     'C', POPT_ARG_NONE,   &cvs_exclude},
  {"update",          'u', POPT_ARG_NONE,   &update_only},
  {"links",           'l', POPT_ARG_NONE,   &preserve_links},
  {"copy-links",      'L', POPT_ARG_NONE,   &copy_links},
  {"whole",           'W', POPT_ARG_NONE,   &whole_file},
  {"copy-unsafe-links", 0, POPT_ARG_NONE,   &copy_unsafe_links},
  {"perms",           'p', POPT_ARG_NONE,   &preserve_perms},
  {"owner",           'o', POPT_ARG_NONE,   &preserve_uid},
  {"group",           'g', POPT_ARG_NONE,   &preserve_gid},
  {"devices",         'D', POPT_ARG_NONE,   &preserve_devices},
  {"times",           't', POPT_ARG_NONE,   &preserve_times},
  {"checksum",        'c', POPT_ARG_NONE,   &always_checksum},
  {"verbose",         'v', POPT_ARG_NONE,   0,               'v'},
  {"quiet",           'q', POPT_ARG_NONE,   0,               'q'},
  {"archive",         'a', POPT_ARG_NONE,   0,               'a'}, 
  {"server",           0,  POPT_ARG_NONE,   &am_server},
  {"sender",           0,  POPT_ARG_NONE,   0,               OPT_SENDER},
  {"recurse",         'r', POPT_ARG_NONE,   &recurse},
  {"relative",        'R', POPT_ARG_NONE,   &relative_paths},
  {"rsh",             'e', POPT_ARG_STRING, &shell_cmd},
  {"block-size",      'B', POPT_ARG_INT,    &block_size},
  {"max-delete",       0,  POPT_ARG_INT,    &max_delete},
  {"timeout",          0,  POPT_ARG_INT,    &io_timeout},
  {"temp-dir",        'T', POPT_ARG_STRING, &tmpdir},
  {"compare-dest",     0,  POPT_ARG_NONE,   &compare_dest},
  /* TODO: Should this take an optional int giving the compression level? */
  {"compress",        'z', POPT_ARG_NONE,   &do_compression},
  {"daemon",           0,  POPT_ARG_NONE,   &am_daemon},
  {"stats",            0,  POPT_ARG_NONE,   &do_stats},
  {"progress",         0,  POPT_ARG_NONE,   &do_progress},
  {"partial",          0,  POPT_ARG_NONE,   &keep_partial},
  {"ignore-errors",    0,  POPT_ARG_NONE,   &ignore_errors},
  {"blocking-io",      0,  POPT_ARG_NONE,   &blocking_io},
  {0,                 'P', POPT_ARG_NONE,   0,               'P'},
  {"config",           0,  POPT_ARG_STRING, &config_file},
  {"port",             0,  POPT_ARG_INT,    &rsync_port},
  {"log-format",       0,  POPT_ARG_STRING, &log_format},
  {"bwlimit",          0,  POPT_ARG_INT,    &bwlimit},
  {"address",          0,  POPT_ARG_STRING, 0,               OPT_ADDRESS},
  {"backup-dir",       0,  POPT_ARG_STRING, &backup_dir},
  {"hard-links",      'H', POPT_ARG_NONE,   &preserve_hard_links},
  {0,0,0,0}
};


static char err_buf[100];


void option_error(void)
{
	if (err_buf[0]) {
		rprintf(FLOG, "%s", err_buf);
		rprintf(FERROR, "%s: %s", RSYNC_NAME, err_buf);
	} else {
		rprintf(FLOG,"Error parsing options - unsupported option?\n");
		rprintf(FERROR,"Error parsing options - unsupported option?\n");
	}
}

/* check to see if we should refuse this option */
static int check_refuse_options(char *ref, int opt)
{
	int i, len;
	char *p;
	const char *name;

	for (i=0; long_options[i].longName; i++) {
		if (long_options[i].val == opt) break;
	}
	
	if (!long_options[i].longName) return 0;

	name = long_options[i].longName;
	len = strlen(name);

	while ((p = strstr(ref,name))) {
		if ((p==ref || p[-1]==' ') &&
		    (p[len] == ' ' || p[len] == 0)) {
			snprintf(err_buf,sizeof(err_buf),
				 "The '%s' option is not supported by this server\n", name);
			return 1;
		}
		ref += len;
	}
	return 0;
}


static int count_args(char const **argv)
{
        int i = 0;

        while (argv[i] != NULL)
                i++;
        
        return i;
}


/* Process command line arguments.  Called on both local and remote.
 * Returns if all options are OK, otherwise fills in err_buf and
 * returns 0. */
int parse_arguments(int *argc, const char ***argv, int frommain)
{
	int opt;
	char *ref = lp_refuse_options(module_id);
        poptContext pc;

        /* TODO: Call poptReadDefaultConfig; handle errors. */

        /* The context leaks in case of an error, but if there's a
         * problem we always exit anyhow. */
        pc = poptGetContext(RSYNC_NAME, *argc, *argv, long_options, 0);

	while ((opt = poptGetNextOpt(pc)) != -1) {
		if (ref) {
			if (check_refuse_options(ref, opt)) return 0;
		}

                /* most options are handled automatically by popt;
                 * only special cases are returned and listed here. */

		switch (opt) {
		case OPT_VERSION:
                        print_rsync_version(FINFO);
			exit_cleanup(0);
			
		case OPT_MODIFY_WINDOW:
                        /* The value has already been set by popt, but
                         * we need to remember that we're using a
                         * non-default setting. */
			modify_window_set = 1;
			break;
			
		case OPT_DELETE_EXCLUDED:
			delete_excluded = 1;
			delete_mode = 1;
			break;

		case OPT_EXCLUDE:
			add_exclude(poptGetOptArg(pc), 0);
			break;

		case OPT_INCLUDE:
			add_exclude(poptGetOptArg(pc), 1);
			break;

		case OPT_EXCLUDE_FROM:
			add_exclude_file(poptGetOptArg(pc), 1, 0);
			break;

		case OPT_INCLUDE_FROM:
			add_exclude_file(poptGetOptArg(pc), 1, 1);
			break;

		case 'h':
			usage(FINFO);
			exit_cleanup(0);

		case 'H':
#if SUPPORT_HARD_LINKS
			preserve_hard_links=1;
#else
                        /* FIXME: Don't say "server" if this is
                         * happening on the client. */
                        /* FIXME: Why do we have the duplicated
                         * rprintf?  Everybody who gets this message
                         * ought to send it to the client and also to
                         * the logs. */
			snprintf(err_buf,sizeof(err_buf),
                                 "hard links are not supported on this %s\n",
				 am_server ? "server" : "client");
			rprintf(FERROR,"ERROR: hard links not supported on this platform\n");
			return 0;
#endif /* SUPPORT_HARD_LINKS */
			break;

		case 'v':
			verbose++;
			break;

		case 'q':
			if (frommain) quiet++;
			break;

		case 'a':
			recurse=1;
#if SUPPORT_LINKS
			preserve_links=1;
#endif
			preserve_perms=1;
			preserve_times=1;
			preserve_gid=1;
			preserve_uid=1;
			preserve_devices=1;
			break;

		case OPT_SENDER:
			if (!am_server) {
				usage(FERROR);
				exit_cleanup(RERR_SYNTAX);
			}
			am_sender = 1;
			break;

		case 'P':
			do_progress = 1;
			keep_partial = 1;
			break;

		case OPT_ADDRESS:
			{
				struct in_addr *ia;
				if ((ia = ip_address(optarg))) {
					socket_address = *ia;
				}
			}
			break;

		default:
                        /* FIXME: If --daemon is specified, then errors for later
                         * parameters seem to disappear. */
                        snprintf(err_buf, sizeof(err_buf),
                                 "%s%s: %s\n",
                                 am_server ? "on remote machine: " : "",
                                 poptBadOption(pc, POPT_BADOPTION_NOALIAS),
                                 poptStrerror(opt));
                        return 0;
		}
	}

        *argv = poptGetArgs(pc);
        if (*argv)
                *argc = count_args(*argv);
        else
                *argc = 0;

	return 1;
}


/* Construct a filtered list of options to pass through from the
 * client to the server */
void server_options(char **args,int *argc)
{
	int ac = *argc;
	static char argstr[50];
	static char bsize[30];
	static char iotime[30];
	static char mdelete[30];
	static char mwindow[30];
	static char bw[50];

	int i, x;

	args[ac++] = "--server";

	if (!am_sender)
		args[ac++] = "--sender";

	x = 1;
	argstr[0] = '-';
	for (i=0;i<verbose;i++)
		argstr[x++] = 'v';

	/* the -q option is intentionally left out */
	if (make_backups)
		argstr[x++] = 'b';
	if (update_only)
		argstr[x++] = 'u';
	if (dry_run)
		argstr[x++] = 'n';
	if (preserve_links)
		argstr[x++] = 'l';
	if (copy_links)
		argstr[x++] = 'L';
	if (whole_file)
		argstr[x++] = 'W';
	if (preserve_hard_links)
		argstr[x++] = 'H';
	if (preserve_uid)
		argstr[x++] = 'o';
	if (preserve_gid)
		argstr[x++] = 'g';
	if (preserve_devices)
		argstr[x++] = 'D';
	if (preserve_times)
		argstr[x++] = 't';
	if (preserve_perms)
		argstr[x++] = 'p';
	if (recurse)
		argstr[x++] = 'r';
	if (always_checksum)
		argstr[x++] = 'c';
	if (cvs_exclude)
		argstr[x++] = 'C';
	if (ignore_times)
		argstr[x++] = 'I';
	if (relative_paths)
		argstr[x++] = 'R';
	if (one_file_system)
		argstr[x++] = 'x';
	if (sparse_files)
		argstr[x++] = 'S';
	if (do_compression)
		argstr[x++] = 'z';

	/* this is a complete hack - blame Rusty 

	   this is a hack to make the list_only (remote file list)
	   more useful */
	if (list_only && !recurse) 
		argstr[x++] = 'r';

	argstr[x] = 0;

	if (x != 1) args[ac++] = argstr;

	if (block_size != BLOCK_SIZE) {
		snprintf(bsize,sizeof(bsize),"-B%d",block_size);
		args[ac++] = bsize;
	}    

	if (max_delete && am_sender) {
		snprintf(mdelete,sizeof(mdelete),"--max-delete=%d",max_delete);
		args[ac++] = mdelete;
	}    

	if (io_timeout) {
		snprintf(iotime,sizeof(iotime),"--timeout=%d",io_timeout);
		args[ac++] = iotime;
	}    

	if (bwlimit) {
		snprintf(bw,sizeof(bw),"--bwlimit=%d",bwlimit);
		args[ac++] = bw;
	}

	if (strcmp(backup_suffix, BACKUP_SUFFIX)) {
		args[ac++] = "--suffix";
		args[ac++] = backup_suffix;
	}

	if (delete_mode && !delete_excluded)
		args[ac++] = "--delete";

	if (delete_excluded)
		args[ac++] = "--delete-excluded";

	if (size_only)
		args[ac++] = "--size-only";

	if (modify_window_set) {
	        snprintf(mwindow,sizeof(mwindow),"--modify-window=%d",
			 modify_window);
		args[ac++] = mwindow;
	}

	if (keep_partial)
		args[ac++] = "--partial";

	if (force_delete)
		args[ac++] = "--force";

	if (delete_after)
		args[ac++] = "--delete-after";

	if (ignore_errors)
		args[ac++] = "--ignore-errors";

	if (copy_unsafe_links)
		args[ac++] = "--copy-unsafe-links";

	if (safe_symlinks)
		args[ac++] = "--safe-links";

	if (numeric_ids)
		args[ac++] = "--numeric-ids";

	if (only_existing && am_sender)
		args[ac++] = "--existing";

	if (tmpdir) {
		args[ac++] = "--temp-dir";
		args[ac++] = tmpdir;
	}

	if (backup_dir && am_sender) {
		/* only the receiver needs this option, if we are the sender
		 *   then we need to send it to the receiver.
		 */
		args[ac++] = "--backup-dir";
		args[ac++] = backup_dir;
	}

	if (compare_dest && am_sender) {
		/* the server only needs this option if it is not the sender,
		 *   and it may be an older version that doesn't know this
		 *   option, so don't send it if client is the sender.
		 */
		args[ac++] = "--compare-dest";
		args[ac++] = compare_dest;
	}


	*argc = ac;
}