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Dogcows Code - chaz/tar/blob - src/rtapelib.c
1 /* Functions for communicating with a remote tape drive.
2 Copyright (C) 1988, 1992 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
18 /* The man page rmt(8) for /etc/rmt documents the remote mag tape
19 protocol which rdump and rrestore use. Unfortunately, the man
20 page is *WRONG*. The author of the routines I'm including originally
21 wrote his code just based on the man page, and it didn't work, so he
22 went to the rdump source to figure out why. The only thing he had to
23 change was to check for the 'F' return code in addition to the 'E',
24 and to separate the various arguments with \n instead of a space. I
25 personally don't think that this is much of a problem, but I wanted to
26 point it out. -- Arnold Robbins
28 Originally written by Jeff Lee, modified some by Arnold Robbins.
29 Redone as a library that can replace open, read, write, etc., by
30 Fred Fish, with some additional work by Arnold Robbins.
31 Modified to make all rmtXXX calls into macros for speed by Jay Fenlason.
32 Use -DHAVE_NETDB_H for rexec code, courtesy of Dan Kegel, srs!dan. */
35 #include <sys/types.h>
38 #ifdef HAVE_SYS_MTIO_H
39 #include <sys/ioctl.h>
63 /* Maximum size of a fully qualified host name. */
64 #define MAXHOSTLEN 257
66 /* Size of buffers for reading and writing commands to rmt.
67 (An arbitrary limit.) */
71 #define RETSIGTYPE void
74 /* Maximum number of simultaneous remote tape connections.
75 (Another arbitrary limit.) */
78 /* Return the parent's read side of remote tape connection FILDES. */
79 #define READ(fildes) (from_rmt[fildes][0])
81 /* Return the parent's write side of remote tape connection FILDES. */
82 #define WRITE(fildes) (to_rmt[fildes][1])
84 /* The pipes for receiving data from remote tape drives. */
85 static int from_rmt
[MAXUNIT
][2] = {-1, -1, -1, -1, -1, -1, -1, -1};
87 /* The pipes for sending data to remote tape drives. */
88 static int to_rmt
[MAXUNIT
][2] = {-1, -1, -1, -1, -1, -1, -1, -1};
90 /* Temporary variable used by macros in rmt.h. */
93 /* Close remote tape connection FILDES. */
96 _rmt_shutdown (fildes
)
99 close (READ (fildes
));
100 close (WRITE (fildes
));
105 /* Attempt to perform the remote tape command specified in BUF
106 on remote tape connection FILDES.
107 Return 0 if successful, -1 on error. */
110 command (fildes
, buf
)
115 RETSIGTYPE (*pipe_handler
) ();
117 /* Save the current pipe handler and try to make the request. */
119 pipe_handler
= signal (SIGPIPE
, SIG_IGN
);
120 buflen
= strlen (buf
);
121 if (write (WRITE (fildes
), buf
, buflen
) == buflen
)
123 signal (SIGPIPE
, pipe_handler
);
127 /* Something went wrong. Close down and go home. */
129 signal (SIGPIPE
, pipe_handler
);
130 _rmt_shutdown (fildes
);
135 /* Read and return the status from remote tape connection FILDES.
136 If an error occurred, return -1 and set errno. */
144 char buffer
[CMDBUFSIZE
];
146 /* Read the reply command line. */
148 for (i
= 0, cp
= buffer
; i
< CMDBUFSIZE
; i
++, cp
++)
150 if (read (READ (fildes
), cp
, 1) != 1)
152 _rmt_shutdown (fildes
);
165 _rmt_shutdown (fildes
);
170 /* Check the return status. */
172 for (cp
= buffer
; *cp
; cp
++)
176 if (*cp
== 'E' || *cp
== 'F')
178 errno
= atoi (cp
+ 1);
179 /* Skip the error message line. */
180 while (read (READ (fildes
), &c
, 1) == 1)
185 _rmt_shutdown (fildes
);
190 /* Check for mis-synced pipes. */
194 _rmt_shutdown (fildes
);
199 /* Got an `A' (success) response. */
200 return atoi (cp
+ 1);
204 /* Execute /etc/rmt as user USER on remote system HOST using rexec.
205 Return a file descriptor of a bidirectional socket for stdin and stdout.
206 If USER is NULL, or an empty string, use the current username.
208 By default, this code is not used, since it requires that
209 the user have a .netrc file in his/her home directory, or that the
210 application designer be willing to have rexec prompt for login and
211 password info. This may be unacceptable, and .rhosts files for use
212 with rsh are much more common on BSD systems. */
215 _rmt_rexec (host
, user
)
219 struct servent
*rexecserv
;
220 int save_stdin
= dup (fileno (stdin
));
221 int save_stdout
= dup (fileno (stdout
));
222 int tape_fd
; /* Return value. */
224 /* When using cpio -o < filename, stdin is no longer the tty.
225 But the rexec subroutine reads the login and the passwd on stdin,
226 to allow remote execution of the command.
227 So, reopen stdin and stdout on /dev/tty before the rexec and
228 give them back their original value after. */
229 if (freopen ("/dev/tty", "r", stdin
) == NULL
)
230 freopen ("/dev/null", "r", stdin
);
231 if (freopen ("/dev/tty", "w", stdout
) == NULL
)
232 freopen ("/dev/null", "w", stdout
);
234 rexecserv
= getservbyname ("exec", "tcp");
235 if (NULL
== rexecserv
)
237 fprintf (stderr
, "exec/tcp: service not available");
240 if (user
!= NULL
&& *user
== '\0')
242 tape_fd
= rexec (&host
, rexecserv
->s_port
, user
, NULL
,
243 "/etc/rmt", (int *) NULL
);
245 fdopen (save_stdin
, "r");
247 fdopen (save_stdout
, "w");
251 #endif /* HAVE_NETDB_H */
253 /* Open a magtape device on the system specified in PATH, as the given user.
254 PATH has the form `[user@]system:/dev/????'.
255 If COMPAT is defined, it can also have the form `system[.user]:/dev/????'.
257 OFLAG is O_RDONLY, O_WRONLY, etc.
258 MODE is ignored; 0666 is always used.
260 If successful, return the remote tape pipe number plus BIAS.
261 On error, return -1. */
264 __rmt_open (path
, oflag
, mode
, bias
)
271 char buffer
[CMDBUFSIZE
]; /* Command buffer. */
272 char system
[MAXHOSTLEN
]; /* The remote host name. */
273 char device
[CMDBUFSIZE
]; /* The remote device name. */
274 char login
[CMDBUFSIZE
]; /* The remote user name. */
275 char *sys
, *dev
, *user
; /* For copying into the above buffers. */
281 /* Find an unused pair of file descriptors. */
283 for (i
= 0; i
< MAXUNIT
; i
++)
284 if (READ (i
) == -1 && WRITE (i
) == -1)
293 /* Pull apart the system and device, and optional user.
294 Don't munge the original string. */
307 if (*(path
- 1) == '@')
309 /* Saw user part of user@host. Start over. */
310 strcpy (user
, system
);
320 else if (*(path
- 1) == '.')
340 /* Execute the remote command using rexec. */
341 READ (i
) = WRITE (i
) = _rmt_rexec (system
, login
);
344 #else /* !HAVE_NETDB_H */
345 /* Set up the pipes for the `rsh' command, and fork. */
347 if (pipe (to_rmt
[i
]) == -1 || pipe (from_rmt
[i
]) == -1)
359 close (to_rmt
[i
][0]);
360 close (to_rmt
[i
][1]);
363 dup (from_rmt
[i
][1]);
364 close (from_rmt
[i
][0]);
365 close (from_rmt
[i
][1]);
372 execl ("/usr/ucb/rsh", "rsh", system
, "-l", login
,
373 "/etc/rmt", (char *) 0);
374 execl ("/usr/bin/remsh", "remsh", system
, "-l", login
,
375 "/etc/rmt", (char *) 0);
376 execl ("/usr/bin/rsh", "rsh", system
, "-l", login
,
377 "/etc/rmt", (char *) 0);
378 execl ("/usr/bsd/rsh", "rsh", system
, "-l", login
,
379 "/etc/rmt", (char *) 0);
380 execl ("/usr/bin/nsh", "nsh", system
, "-l", login
,
381 "/etc/rmt", (char *) 0);
385 execl ("/usr/ucb/rsh", "rsh", system
,
386 "/etc/rmt", (char *) 0);
387 execl ("/usr/bin/remsh", "remsh", system
,
388 "/etc/rmt", (char *) 0);
389 execl ("/usr/bin/rsh", "rsh", system
,
390 "/etc/rmt", (char *) 0);
391 execl ("/usr/bsd/rsh", "rsh", system
,
392 "/etc/rmt", (char *) 0);
393 execl ("/usr/bin/nsh", "nsh", system
,
394 "/etc/rmt", (char *) 0);
397 /* Bad problems if we get here. */
399 perror ("cannot execute remote shell");
404 close (to_rmt
[i
][0]);
405 close (from_rmt
[i
][1]);
406 #endif /* !HAVE_NETDB_H */
408 /* Attempt to open the tape device. */
410 sprintf (buffer
, "O%s\n%d\n", device
, oflag
);
411 if (command (i
, buffer
) == -1 || status (i
) == -1)
417 /* Close remote tape connection FILDES and shut down.
418 Return 0 if successful, -1 on error. */
426 if (command (fildes
, "C\n") == -1)
429 rc
= status (fildes
);
430 _rmt_shutdown (fildes
);
434 /* Read up to NBYTE bytes into BUF from remote tape connection FILDES.
435 Return the number of bytes read on success, -1 on error. */
438 __rmt_read (fildes
, buf
, nbyte
)
444 char buffer
[CMDBUFSIZE
];
446 sprintf (buffer
, "R%d\n", nbyte
);
447 if (command (fildes
, buffer
) == -1 || (rc
= status (fildes
)) == -1)
450 for (i
= 0; i
< rc
; i
+= nbyte
, buf
+= nbyte
)
452 nbyte
= read (READ (fildes
), buf
, rc
);
455 _rmt_shutdown (fildes
);
464 /* Write NBYTE bytes from BUF to remote tape connection FILDES.
465 Return the number of bytes written on success, -1 on error. */
468 __rmt_write (fildes
, buf
, nbyte
)
473 char buffer
[CMDBUFSIZE
];
474 RETSIGTYPE (*pipe_handler
) ();
476 sprintf (buffer
, "W%d\n", nbyte
);
477 if (command (fildes
, buffer
) == -1)
480 pipe_handler
= signal (SIGPIPE
, SIG_IGN
);
481 if (write (WRITE (fildes
), buf
, nbyte
) == nbyte
)
483 signal (SIGPIPE
, pipe_handler
);
484 return status (fildes
);
488 signal (SIGPIPE
, pipe_handler
);
489 _rmt_shutdown (fildes
);
494 /* Perform an imitation lseek operation on remote tape connection FILDES.
495 Return the new file offset if successful, -1 if on error. */
498 __rmt_lseek (fildes
, offset
, whence
)
503 char buffer
[CMDBUFSIZE
];
505 sprintf (buffer
, "L%ld\n%d\n", offset
, whence
);
506 if (command (fildes
, buffer
) == -1)
509 return status (fildes
);
512 /* Perform a raw tape operation on remote tape connection FILDES.
513 Return the results of the ioctl, or -1 on error. */
517 __rmt_ioctl (fildes
, op
, arg
)
523 char buffer
[CMDBUFSIZE
];
532 /* MTIOCTOP is the easy one. Nothing is transfered in binary. */
533 sprintf (buffer
, "I%d\n%d\n", ((struct mtop
*) arg
)->mt_op
,
534 ((struct mtop
*) arg
)->mt_count
);
535 if (command (fildes
, buffer
) == -1)
537 return status (fildes
); /* Return the count. */
540 /* Grab the status and read it directly into the structure.
541 This assumes that the status buffer is not padded
542 and that 2 shorts fit in a long without any word
543 alignment problems; i.e., the whole struct is contiguous.
544 NOTE - this is probably NOT a good assumption. */
546 if (command (fildes
, "S") == -1 || (rc
= status (fildes
)) == -1)
549 for (; rc
> 0; rc
-= cnt
, arg
+= cnt
)
551 cnt
= read (READ (fildes
), arg
, rc
);
554 _rmt_shutdown (fildes
);
560 /* Check for byte position. mt_type is a small integer field
561 (normally) so we will check its magnitude. If it is larger than
562 256, we will assume that the bytes are swapped and go through
563 and reverse all the bytes. */
565 if (((struct mtget
*) arg
)->mt_type
< 256)
568 for (cnt
= 0; cnt
< rc
; cnt
+= 2)
571 arg
[cnt
] = arg
[cnt
+ 1];
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