Category : C Source Code
Archive   : GTAK201S.ZIP
Filename : RTAPE_LB.C

/* Remote tape emulator subroutines.
Copyright (C) 1988 Free Software Foundation

This file is part of GNU Tar.

GNU Tar 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 1, or (at your option)
any later version.

GNU Tar 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 GNU Tar; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */

/* JF: modified to make all rmtXXX calls into macros for speed */

#ifndef lint
static char *RCSid = "$Header: h:/SRC.SSB/tar/1.10/rtape_lb.c,v 1.2 1992/09/02 20:09:08 ak Exp $";
#endif

/*
* $Log: rtape_lb.c,v $
* Revision 1.2 1992/09/02 20:09:08 ak
* Version AK200
* - Tape access
* - Quick file access
* - OS/2 extended attributes
* - Some OS/2 fixes
* - Some fixes of Kai Uwe Rommel
*
* Revision 1.7 89/03/23 14:09:51 root
* Fix from [email protected] for use w/compat. ADR.
*
* Revision 1.6 88/10/25 17:04:29 root
* rexec code and a bug fix from srs!dan, miscellanious cleanup. ADR.
*
* Revision 1.5 88/10/25 16:30:17 root
* Fix from [email protected] for getting user@host:dev right. ADR.
*
* Revision 1.4 87/10/30 10:36:12 root
* Made 4.2 syntax a compile time option. ADR.
*
* Revision 1.3 87/04/22 11:16:48 root
* Two fixes from [email protected] to correctly
* do fd biasing and rmt protocol on 'S' command. ADR.
*
* Revision 1.2 86/10/09 16:38:53 root
* Changed to reflect 4.3BSD rcp syntax. ADR.
*
* Revision 1.1 86/10/09 16:17:35 root
* Initial revision
*
*/

/*
* rmt --- remote tape emulator subroutines
*
* Originally written by Jeff Lee, modified some by Arnold Robbins
*
* WARNING: The man page rmt(8) for /etc/rmt documents the remote mag
* tape protocol which rdump and rrestore use. Unfortunately, the man
* page is *WRONG*. The author of the routines I'm including originally
* wrote his code just based on the man page, and it didn't work, so he
* went to the rdump source to figure out why. The only thing he had to
* change was to check for the 'F' return code in addition to the 'E',
* and to separate the various arguments with \n instead of a space. I
* personally don't think that this is much of a problem, but I wanted to
* point it out.
* -- Arnold Robbins
*
* Redone as a library that can replace open, read, write, etc, by
* Fred Fish, with some additional work by Arnold Robbins.
*/

/* Use -DUSE_REXEC for rexec code, courtesy of Dan Kegel, srs!dan */

#if defined(USG) && !defined(HAVE_MTIO)
#define NO_RMTIOCTL
#endif

#include
#include
#include

#ifndef NO_RMTIOCTL
#include
#include
#endif

#ifdef USE_REXEC
#include
#endif

#include
#include
#include

#define BUFMAGIC 64 /* a magic number for buffer sizes */

/*
* MAXUNIT --- Maximum number of remote tape file units
*/
#define MAXUNIT 4

/*
* READ --- Return the number of the read side file descriptor
* WRITE --- Return the number of the write side file descriptor
*/
#define READ(fd) (Ctp[fd][0])
#define WRITE(fd) (Ptc[fd][1])

static int Ctp[MAXUNIT][2] = { -1, -1, -1, -1, -1, -1, -1, -1 };
static int Ptc[MAXUNIT][2] = { -1, -1, -1, -1, -1, -1, -1, -1 };

extern int errno;

char *__rmt_path;

/*
* _rmt_panic --- close off a remote tape connection
*/

static void _rmt_panic(fildes)
int fildes;
{
close(READ(fildes));
close(WRITE(fildes));
READ(fildes) = -1;
WRITE(fildes) = -1;
}



/*
* command --- attempt to perform a remote tape command
*/

static int command(fildes, buf)
int fildes;
char *buf;
{
register int blen;
#ifdef SIGNAL_VOID
void (*pstat)();
#else
int (*pstat)();
#endif

/*
* save current pipe status and try to make the request
*/

blen = strlen(buf);
pstat = signal(SIGPIPE, SIG_IGN);
if (write(WRITE(fildes), buf, blen) == blen)
{
signal(SIGPIPE, pstat);
return(0);
}

/*
* something went wrong. close down and go home
*/

signal(SIGPIPE, pstat);
_rmt_panic(fildes);

errno = EIO;
return(-1);
}



/*
* status --- retrieve the status from the pipe
*/

static int status(fildes)
int fildes;
{
int i;
char c, *cp;
char buffer[BUFMAGIC];

/*
* read the reply command line
*/

for (i = 0, cp = buffer; i < BUFMAGIC; i++, cp++)
{
if (read(READ(fildes), cp, 1) != 1)
{
_rmt_panic(fildes);
errno = EIO;
return(-1);
}
if (*cp == '\n')
{
*cp = 0;
break;
}
}

if (i == BUFMAGIC)
{
_rmt_panic(fildes);
errno = EIO;
return(-1);
}

/*
* check the return status
*/

for (cp = buffer; *cp; cp++)
if (*cp != ' ')
break;

if (*cp == 'E' || *cp == 'F')
{
errno = atoi(cp + 1);
while (read(READ(fildes), &c, 1) == 1)
if (c == '\n')
break;

if (*cp == 'F')
_rmt_panic(fildes);

return(-1);
}

/*
* check for mis-synced pipes
*/

if (*cp != 'A')
{
_rmt_panic(fildes);
errno = EIO;
return(-1);
}

return(atoi(cp + 1));
}

#ifdef USE_REXEC

/*
* _rmt_rexec
*
* execute /etc/rmt on a remote system using rexec().
* Return file descriptor of bidirectional socket for stdin and stdout
* If username is NULL, or an empty string, uses current username.
*
* ADR: By default, this code is not used, since it requires that
* the user have a .netrc file in his/her home directory, or that the
* application designer be willing to have rexec prompt for login and
* password info. This may be unacceptable, and .rhosts files for use
* with rsh are much more common on BSD systems.
*/

static int
_rmt_rexec(host, user)
char *host;
char *user; /* may be NULL */
{
struct servent *rexecserv;
int save_stdin = dup(fileno(stdin));
int save_stdout = dup(fileno(stdout));
int tape_fd; /* Return value. */

/*
* When using cpio -o < filename, stdin is no longer the tty.
* But the rexec subroutine reads the login and the passwd on stdin,
* to allow remote execution of the command.
* So, reopen stdin and stdout on /dev/tty before the rexec and
* give them back their original value after.
*/
if (freopen("/dev/tty", "r", stdin) == NULL)
freopen("/dev/null", "r", stdin);
if (freopen("/dev/tty", "w", stdout) == NULL)
freopen("/dev/null", "w", stdout);

rexecserv = getservbyname("exec", "tcp");
if (NULL == rexecserv) {
fprintf (stderr, "? exec/tcp: service not available.");
exit (-1);
}
if ((user != NULL) && *user == '\0')
user = (char *) NULL;
tape_fd = rexec (&host, rexecserv->s_port, user, NULL,
"/etc/rmt", (int *)NULL);
fclose(stdin);
fdopen(save_stdin, "r");
fclose(stdout);
fdopen(save_stdout, "w");

return tape_fd;
}
#endif /* USE_REXEC */

/*
* _rmt_open --- open a magtape device on system specified, as given user
*
* file name has the form [user@]system:/dev/????
#ifdef COMPAT
* file name has the form system[.user]:/dev/????
#endif
*/

#define MAXHOSTLEN 257 /* BSD allows very long host names... */

int __rmt_open (path, oflag, mode, bias)
char *path;
int oflag;
int mode;
int bias;
{
int i, rc;
char buffer[BUFMAGIC];
char system[MAXHOSTLEN];
char device[BUFMAGIC];
char login[BUFMAGIC];
char *sys, *dev, *user;

sys = system;
dev = device;
user = login;

/*
* first, find an open pair of file descriptors
*/

for (i = 0; i < MAXUNIT; i++)
if (READ(i) == -1 && WRITE(i) == -1)
break;

if (i == MAXUNIT)
{
errno = EMFILE;
return(-1);
}

/*
* pull apart system and device, and optional user
* don't munge original string
* if COMPAT is defined, also handle old (4.2) style person.site notation.
*/

while (*path != '@'
#ifdef COMPAT
&& *path != '.'
#endif
&& *path != ':') {
*sys++ = *path++;
}
*sys = '\0';
path++;

if (*(path - 1) == '@')
{
(void) strcpy (user, system); /* saw user part of user@host */
sys = system; /* start over */
while (*path != ':') {
*sys++ = *path++;
}
*sys = '\0';
path++;
}
#ifdef COMPAT
else if (*(path - 1) == '.')
{
while (*path != ':') {
*user++ = *path++;
}
*user = '\0';
path++;
}
#endif
else
*user = '\0';

while (*path) {
*dev++ = *path++;
}
*dev = '\0';

#ifdef USE_REXEC
/*
* Execute the remote command using rexec
*/
READ(i) = WRITE(i) = _rmt_rexec(system, login);
if (READ(i) < 0)
return -1;
#else
/*
* setup the pipes for the 'rsh' command and fork
*/

if (pipe(Ptc[i]) == -1 || pipe(Ctp[i]) == -1)
return(-1);

if ((rc = fork()) == -1)
return(-1);

if (rc == 0)
{
close(0);
dup(Ptc[i][0]);
close(Ptc[i][0]); close(Ptc[i][1]);
close(1);
dup(Ctp[i][1]);
close(Ctp[i][0]); close(Ctp[i][1]);
(void) setuid (getuid ());
(void) setgid (getgid ());
if (*login)
{
execl("/usr/ucb/rsh", "rsh", system, "-l", login,
"/etc/rmt", (char *) 0);
execl("/usr/bin/remsh", "remsh", system, "-l", login,
"/etc/rmt", (char *) 0);
execl("/usr/bin/rsh", "rsh", system, "-l", login,
"/etc/rmt", (char *) 0);
execl("/usr/bsd/rsh", "rsh", system, "-l", login,
"/etc/rmt", (char *)0);
execl("/usr/bin/nsh", "nsh", system, "-l", login,
"/etc/rmt", (char *)0);
}
else
{
execl("/usr/ucb/rsh", "rsh", system,
"/etc/rmt", (char *) 0);
execl("/usr/bin/remsh", "remsh", system,
"/etc/rmt", (char *) 0);
execl("/usr/bin/rsh", "rsh", system,
"/etc/rmt", (char *) 0);
execl("/usr/bsd/rsh", "rsh", system,
"/etc/rmt", (char *) 0);
execl("/usr/bin/nsh", "nsh", system,
"/etc/rmt", (char *)0);
}

/*
* bad problems if we get here
*/

perror("remote shell exec");
exit(1);
}

close(Ptc[i][0]); close(Ctp[i][1]);
#endif

/*
* now attempt to open the tape device
*/

sprintf(buffer, "O%s\n%d\n", device, oflag);
if (command(i, buffer) == -1 || status(i) == -1)
return(-1);

return(i+bias);
}



/*
* _rmt_close --- close a remote magtape unit and shut down
*/

int __rmt_close(fildes)
int fildes;
{
int rc;

if (command(fildes, "C\n") != -1)
{
rc = status(fildes);

_rmt_panic(fildes);
return(rc);
}

return(-1);
}



/*
* _rmt_read --- read a buffer from a remote tape
*/

int __rmt_read(fildes, buf, nbyte)
int fildes;
char *buf;
unsigned int nbyte;
{
int rc, i;
char buffer[BUFMAGIC];

sprintf(buffer, "R%d\n", nbyte);
if (command(fildes, buffer) == -1 || (rc = status(fildes)) == -1)
return(-1);

for (i = 0; i < rc; i += nbyte, buf += nbyte)
{
nbyte = read(READ(fildes), buf, rc);
if (nbyte <= 0)
{
_rmt_panic(fildes);
errno = EIO;
return(-1);
}
}

return(rc);
}



/*
* _rmt_write --- write a buffer to the remote tape
*/

int __rmt_write(fildes, buf, nbyte)
int fildes;
char *buf;
unsigned int nbyte;
{
char buffer[BUFMAGIC];
#ifdef SIGNAL_VOID
void (*pstat)();
#else
int (*pstat)();
#endif

sprintf(buffer, "W%d\n", nbyte);
if (command(fildes, buffer) == -1)
return(-1);

pstat = signal(SIGPIPE, SIG_IGN);
if (write(WRITE(fildes), buf, nbyte) == nbyte)
{
signal (SIGPIPE, pstat);
return(status(fildes));
}

signal (SIGPIPE, pstat);
_rmt_panic(fildes);
errno = EIO;
return(-1);
}



/*
* _rmt_lseek --- perform an imitation lseek operation remotely
*/

long __rmt_lseek(fildes, offset, whence)
int fildes;
long offset;
int whence;
{
char buffer[BUFMAGIC];

sprintf(buffer, "L%d\n%d\n", offset, whence);
if (command(fildes, buffer) == -1)
return(-1);

return(status(fildes));
}


/*
* _rmt_ioctl --- perform raw tape operations remotely
*/

#ifndef NO_RMTIOCTL
__rmt_ioctl(fildes, op, arg)
int fildes, op;
char *arg;
{
char c;
int rc, cnt;
char buffer[BUFMAGIC];

/*
* MTIOCOP is the easy one. nothing is transfered in binary
*/

if (op == MTIOCTOP)
{
sprintf(buffer, "I%d\n%d\n", ((struct mtop *) arg)->mt_op,
((struct mtop *) arg)->mt_count);
if (command(fildes, buffer) == -1)
return(-1);
return(status(fildes));
}

/*
* we can only handle 2 ops, if not the other one, punt
*/

if (op != MTIOCGET)
{
errno = EINVAL;
return(-1);
}

/*
* grab the status and read it directly into the structure
* this assumes that the status buffer is (hopefully) not
* padded and that 2 shorts fit in a long without any word
* alignment problems, ie - the whole struct is contiguous
* NOTE - this is probably NOT a good assumption.
*/

if (command(fildes, "S") == -1 || (rc = status(fildes)) == -1)
return(-1);

for (; rc > 0; rc -= cnt, arg += cnt)
{
cnt = read(READ(fildes), arg, rc);
if (cnt <= 0)
{
_rmt_panic(fildes);
errno = EIO;
return(-1);
}
}

/*
* now we check for byte position. mt_type is a small integer field
* (normally) so we will check its magnitude. if it is larger than
* 256, we will assume that the bytes are swapped and go through
* and reverse all the bytes
*/

if (((struct mtget *) arg)->mt_type < 256)
return(0);

for (cnt = 0; cnt < rc; cnt += 2)
{
c = arg[cnt];
arg[cnt] = arg[cnt+1];
arg[cnt+1] = c;
}

return(0);
}
#endif /* NO_RMTIOCTL */