pipe.c

   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) 2004-2007 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                 if (dup2(to_child_pipe[0], STDIN_FILENO) < 0 ||
 137                     close(to_child_pipe[1]) < 0 ||
 138                     close(from_child_pipe[0]) < 0 ||
 139                     dup2(from_child_pipe[1], STDOUT_FILENO) < 0) {
 140                         rsyserr(FERROR, errno, "Failed to dup/close");
 141                         exit_cleanup(RERR_IPC);
 142                 }
 143                 if (to_child_pipe[0] != STDIN_FILENO)
 144                         close(to_child_pipe[0]);
 145                 if (from_child_pipe[1] != STDOUT_FILENO)
 146                         close(from_child_pipe[1]);
 147 #ifdef ICONV_CONST
 148                 setup_iconv();
 149 #endif
 150                 child_main(argc, argv);
 151         }
 152
 153         /* Let the client side handle this. */
 154         if (logfile_name) {
 155                 logfile_name = NULL;
 156                 logfile_close();
 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 }