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rsync

    1: /*
    2:  * Routines used to setup various kinds of inter-process pipes.
    3:  *
    4:  * Copyright (C) 1996-2000 Andrew Tridgell
    5:  * Copyright (C) 1996 Paul Mackerras
    6:  * Copyright (C) 2001, 2002 Martin Pool <mbp@samba.org>
    7:  * Copyright (C) 2004-2009 Wayne Davison
    8:  *
    9:  * This program is free software; you can redistribute it and/or modify
   10:  * it under the terms of the GNU General Public License as published by
   11:  * the Free Software Foundation; either version 3 of the License, or
   12:  * (at your option) any later version.
   13:  *
   14:  * This program is distributed in the hope that it will be useful,
   15:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   16:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   17:  * GNU General Public License for more details.
   18:  *
   19:  * You should have received a copy of the GNU General Public License along
   20:  * with this program; if not, visit the http://fsf.org website.
   21:  */
   22: 
   23: #include "rsync.h"
   24: 
   25: extern int am_sender;
   26: extern int am_server;
   27: extern int blocking_io;
   28: extern int filesfrom_fd;
   29: extern mode_t orig_umask;
   30: extern char *logfile_name;
   31: extern struct chmod_mode_struct *chmod_modes;
   32: 
   33: /**
   34:  * Create a child connected to us via its stdin/stdout.
   35:  *
   36:  * This is derived from CVS code
   37:  *
   38:  * Note that in the child STDIN is set to blocking and STDOUT
   39:  * is set to non-blocking. This is necessary as rsh relies on stdin being blocking
   40:  *  and ssh relies on stdout being non-blocking
   41:  *
   42:  * If blocking_io is set then use blocking io on both fds. That can be
   43:  * used to cope with badly broken rsh implementations like the one on
   44:  * Solaris.
   45:  **/
   46: pid_t piped_child(char **command, int *f_in, int *f_out)
   47: {
   48: 	pid_t pid;
   49: 	int to_child_pipe[2];
   50: 	int from_child_pipe[2];
   51: 
   52: 	if (verbose >= 2)
   53: 		print_child_argv("opening connection using:", command);
   54: 
   55: 	if (fd_pair(to_child_pipe) < 0 || fd_pair(from_child_pipe) < 0) {
   56: 		rsyserr(FERROR, errno, "pipe");
   57: 		exit_cleanup(RERR_IPC);
   58: 	}
   59: 
   60: 	pid = do_fork();
   61: 	if (pid == -1) {
   62: 		rsyserr(FERROR, errno, "fork");
   63: 		exit_cleanup(RERR_IPC);
   64: 	}
   65: 
   66: 	if (pid == 0) {
   67: 		if (dup2(to_child_pipe[0], STDIN_FILENO) < 0 ||
   68: 		    close(to_child_pipe[1]) < 0 ||
   69: 		    close(from_child_pipe[0]) < 0 ||
   70: 		    dup2(from_child_pipe[1], STDOUT_FILENO) < 0) {
   71: 			rsyserr(FERROR, errno, "Failed to dup/close");
   72: 			exit_cleanup(RERR_IPC);
   73: 		}
   74: 		if (to_child_pipe[0] != STDIN_FILENO)
   75: 			close(to_child_pipe[0]);
   76: 		if (from_child_pipe[1] != STDOUT_FILENO)
   77: 			close(from_child_pipe[1]);
   78: 		umask(orig_umask);
   79: 		set_blocking(STDIN_FILENO);
   80: 		if (blocking_io > 0)
   81: 			set_blocking(STDOUT_FILENO);
   82: 		execvp(command[0], command);
   83: 		rsyserr(FERROR, errno, "Failed to exec %s", command[0]);
   84: 		exit_cleanup(RERR_IPC);
   85: 	}
   86: 
   87: 	if (close(from_child_pipe[1]) < 0 || close(to_child_pipe[0]) < 0) {
   88: 		rsyserr(FERROR, errno, "Failed to close");
   89: 		exit_cleanup(RERR_IPC);
   90: 	}
   91: 
   92: 	*f_in = from_child_pipe[0];
   93: 	*f_out = to_child_pipe[1];
   94: 
   95: 	return pid;
   96: }
   97: 
   98: /* This function forks a child which calls child_main().  First,
   99:  * however, it has to establish communication paths to and from the
  100:  * newborn child.  It creates two socket pairs -- one for writing to
  101:  * the child (from the parent) and one for reading from the child
  102:  * (writing to the parent).  Since that's four socket ends, each
  103:  * process has to close the two ends it doesn't need.  The remaining
  104:  * two socket ends are retained for reading and writing.  In the
  105:  * child, the STDIN and STDOUT file descriptors refer to these
  106:  * sockets.  In the parent, the function arguments f_in and f_out are
  107:  * set to refer to these sockets. */
  108: pid_t local_child(int argc, char **argv, int *f_in, int *f_out,
  109: 		  int (*child_main)(int, char*[]))
  110: {
  111: 	pid_t pid;
  112: 	int to_child_pipe[2];
  113: 	int from_child_pipe[2];
  114: 
  115: 	/* The parent process is always the sender for a local rsync. */
  116: 	assert(am_sender);
  117: 
  118: 	if (fd_pair(to_child_pipe) < 0 ||
  119: 	    fd_pair(from_child_pipe) < 0) {
  120: 		rsyserr(FERROR, errno, "pipe");
  121: 		exit_cleanup(RERR_IPC);
  122: 	}
  123: 
  124: 	pid = do_fork();
  125: 	if (pid == -1) {
  126: 		rsyserr(FERROR, errno, "fork");
  127: 		exit_cleanup(RERR_IPC);
  128: 	}
  129: 
  130: 	if (pid == 0) {
  131: 		am_sender = 0;
  132: 		am_server = 1;
  133: 		filesfrom_fd = -1;
  134: 		chmod_modes = NULL; /* Let the sending side handle this. */
  135: 
  136: 		/* Let the client side handle this. */
  137: 		if (logfile_name) {
  138: 			logfile_name = NULL;
  139: 			logfile_close();
  140: 		}
  141: 
  142: 		if (dup2(to_child_pipe[0], STDIN_FILENO) < 0 ||
  143: 		    close(to_child_pipe[1]) < 0 ||
  144: 		    close(from_child_pipe[0]) < 0 ||
  145: 		    dup2(from_child_pipe[1], STDOUT_FILENO) < 0) {
  146: 			rsyserr(FERROR, errno, "Failed to dup/close");
  147: 			exit_cleanup(RERR_IPC);
  148: 		}
  149: 		if (to_child_pipe[0] != STDIN_FILENO)
  150: 			close(to_child_pipe[0]);
  151: 		if (from_child_pipe[1] != STDOUT_FILENO)
  152: 			close(from_child_pipe[1]);
  153: #ifdef ICONV_CONST
  154: 		setup_iconv();
  155: #endif
  156: 		child_main(argc, argv);
  157: 	}
  158: 
  159: 	if (close(from_child_pipe[1]) < 0 ||
  160: 	    close(to_child_pipe[0]) < 0) {
  161: 		rsyserr(FERROR, errno, "Failed to close");
  162: 		exit_cleanup(RERR_IPC);
  163: 	}
  164: 
  165: 	*f_in = from_child_pipe[0];
  166: 	*f_out = to_child_pipe[1];
  167: 
  168: 	return pid;
  169: }