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NetBSD/lib/librmt/rmtlib.c

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/* $NetBSD: rmtlib.c,v 1.13 1999/09/20 04:48:05 lukem Exp $ */
/*
* 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.
*/
/*
* MAXUNIT --- Maximum number of remote tape file units
*
* READ --- Return the number of the read side file descriptor
* WRITE --- Return the number of the write side file descriptor
*/
#define RMTIOCTL 1
/* #define USE_REXEC 1 */ /* rexec code courtesy of Dan Kegel, srs!dan */
#include <sys/types.h>
#include <sys/stat.h>
#ifdef RMTIOCTL
#include <sys/ioctl.h>
#include <sys/mtio.h>
#endif
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef USE_REXEC
#include <netdb.h>
#endif
#define __RMTLIB_PRIVATE
#include <rmt.h> /* get prototypes for remapped functions */
#ifdef __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
#include "pathnames.h"
static int _rmt_close __P((int));
static int _rmt_ioctl __P((int, unsigned long, char *));
static off_t _rmt_lseek __P((int, off_t, int));
static int _rmt_open __P((const char *, int, int));
static int _rmt_read __P((int, char *, unsigned int));
static int _rmt_write __P((int, const void *, unsigned int));
static int command __P((int, char *));
static int remdev __P((const char *));
static void rmtabort __P((int));
static int status __P((int));
int isrmt __P((int));
#define BUFMAGIC 64 /* a magic number for buffer sizes */
#define MAXUNIT 4
#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} };
/*
* rmtabort --- close off a remote tape connection
*/
static void
rmtabort(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;
{
int blen;
void (*pstat) __P((int));
_DIAGASSERT(buf != NULL);
/*
* 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);
rmtabort(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)
{
rmtabort(fildes);
errno = EIO;
return(-1);
}
if (*cp == '\n')
{
*cp = 0;
break;
}
}
if (i == BUFMAGIC)
{
rmtabort(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')
rmtabort(fildes);
return(-1);
}
/*
* check for mis-synced pipes
*/
if (*cp != 'A')
{
rmtabort(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 __P((const char *, const char *));
static int
_rmt_rexec(host, user)
const char *host;
const char *user; /* may be NULL */
{
struct servent *rexecserv;
_DIAGASSERT(host != NULL);
/* user may be NULL */
rexecserv = getservbyname("exec", "tcp");
if (NULL == rexecserv) {
fprintf (stderr, "? exec/tcp: service not available.");
exit (-1);
}
if ((user != NULL) && *user == '\0')
user = (char *) NULL;
return rexec (&host, rexecserv->s_port, user, NULL,
"/etc/rmt", (int *)NULL);
}
#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... */
static int
_rmt_open(path, oflag, mode)
const char *path;
int oflag;
int mode;
{
int i, rc;
char buffer[BUFMAGIC];
char system[MAXHOSTLEN];
char device[BUFMAGIC];
char login[BUFMAGIC];
char *sys, *dev, *user;
_DIAGASSERT(path != NULL);
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)strncpy(user, system, sizeof(login) - 1);
/* 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)
{
char *rshpath, *rsh;
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 ((rshpath = getenv("RCMD_CMD")) == NULL)
rshpath = _PATH_RSH;
if ((rsh = strrchr(rshpath, '/')) == NULL)
rsh = rshpath;
else
rsh++;
if (*login)
{
execl(rshpath, rsh, system, "-l", login,
_PATH_RMT, (char *) 0);
}
else
{
execl(rshpath, rsh, system,
_PATH_RMT, (char *) 0);
}
/*
* bad problems if we get here
*/
perror("exec");
exit(1);
}
close(Ptc[i][0]); close(Ctp[i][1]);
#endif
/*
* now attempt to open the tape device
*/
(void)snprintf(buffer, sizeof(buffer), "O%s\n%d\n", device, oflag);
if (command(i, buffer) == -1 || status(i) == -1)
return(-1);
return(i);
}
/*
* _rmt_close --- close a remote magtape unit and shut down
*/
static int
_rmt_close(fildes)
int fildes;
{
int rc;
if (command(fildes, "C\n") != -1)
{
rc = status(fildes);
rmtabort(fildes);
return(rc);
}
return(-1);
}
/*
* _rmt_read --- read a buffer from a remote tape
*/
static int
_rmt_read(fildes, buf, nbyte)
int fildes;
char *buf;
unsigned int nbyte;
{
int rc, i;
char buffer[BUFMAGIC];
_DIAGASSERT(buf != NULL);
(void)snprintf(buffer, sizeof 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)
{
rmtabort(fildes);
errno = EIO;
return(-1);
}
}
return(rc);
}
/*
* _rmt_write --- write a buffer to the remote tape
*/
static int
_rmt_write(fildes, buf, nbyte)
int fildes;
const void *buf;
unsigned int nbyte;
{
char buffer[BUFMAGIC];
void (*pstat) __P((int));
_DIAGASSERT(buf != NULL);
(void)snprintf(buffer, sizeof 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);
rmtabort(fildes);
errno = EIO;
return(-1);
}
/*
* _rmt_lseek --- perform an imitation lseek operation remotely
*/
static off_t
_rmt_lseek(fildes, offset, whence)
int fildes;
off_t offset;
int whence;
{
char buffer[BUFMAGIC];
(void)snprintf(buffer, sizeof buffer, "L%qd\n%d\n", (long long)offset,
whence);
if (command(fildes, buffer) == -1)
return(-1);
return(status(fildes));
}
/*
* _rmt_ioctl --- perform raw tape operations remotely
*/
#ifdef RMTIOCTL
static int
_rmt_ioctl(fildes, op, arg)
int fildes;
unsigned long op;
char *arg;
{
char c;
int rc, cnt;
char buffer[BUFMAGIC];
_DIAGASSERT(arg != NULL);
/*
* MTIOCOP is the easy one. nothing is transfered in binary
*/
if (op == MTIOCTOP)
{
(void)snprintf(buffer, sizeof 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)
{
rmtabort(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 /* RMTIOCTL */
/*
* Added routines to replace open(), close(), lseek(), ioctl(), etc.
* The preprocessor can be used to remap these the rmtopen(), etc
* thus minimizing source changes:
*
* #ifdef <something>
* # define access rmtaccess
* # define close rmtclose
* # define creat rmtcreat
* # define dup rmtdup
* # define fcntl rmtfcntl
* # define fstat rmtfstat
* # define ioctl rmtioctl
* # define isatty rmtisatty
* # define lseek rmtlseek
* # define lstat rmtlstat
* # define open rmtopen
* # define read rmtread
* # define stat rmtstat
* # define write rmtwrite
* #endif
*
* -- Fred Fish
*
* ADR --- I set up a <rmt.h> include file for this
*
*/
/*
* Note that local vs remote file descriptors are distinquished
* by adding a bias to the remote descriptors. This is a quick
* and dirty trick that may not be portable to some systems.
*/
#define REM_BIAS 128
/*
* Test pathname to see if it is local or remote. A remote device
* is any string that contains ":/dev/". Returns 1 if remote,
* 0 otherwise.
*/
static int
remdev(path)
const char *path;
{
_DIAGASSERT(path != NULL);
if ((path = strchr (path, ':')) != NULL)
{
if (strncmp (path + 1, "/dev/", 5) == 0)
{
return (1);
}
}
return (0);
}
/*
* Open a local or remote file. Looks just like open(2) to
* caller.
*/
int
#ifdef __STDC__
rmtopen(const char *path, int oflag, ...)
#else
rmtopen(va_alist)
va_decl
#endif
{
mode_t mode;
int fd;
va_list ap;
#if __STDC__
va_start(ap, oflag);
#else
const char *path;
int oflag;
va_start(ap);
path = va_arg(ap, const char *);
oflag = va_arg(ap, int);
#endif
mode = va_arg(ap, mode_t);
va_end(ap);
_DIAGASSERT(path != NULL);
if (remdev (path))
{
fd = _rmt_open (path, oflag, mode);
return (fd == -1) ? -1 : (fd + REM_BIAS);
}
else
{
return (open (path, oflag, mode));
}
}
/*
* Test pathname for specified access. Looks just like access(2)
* to caller.
*/
int
rmtaccess(path, amode)
const char *path;
int amode;
{
_DIAGASSERT(path != NULL);
if (remdev (path))
{
return (0); /* Let /etc/rmt find out */
}
else
{
return (access (path, amode));
}
}
/*
* Isrmt. Let a programmer know he has a remote device.
*/
int
isrmt(fd)
int fd;
{
return (fd >= REM_BIAS);
}
/*
* Read from stream. Looks just like read(2) to caller.
*/
ssize_t
rmtread(fildes, buf, nbyte)
int fildes;
void *buf;
size_t nbyte;
{
_DIAGASSERT(buf != NULL);
if (isrmt (fildes))
{
return (_rmt_read (fildes - REM_BIAS, buf, nbyte));
}
else
{
return (read (fildes, buf, nbyte));
}
}
/*
* Write to stream. Looks just like write(2) to caller.
*/
ssize_t
rmtwrite(fildes, buf, nbyte)
int fildes;
const void *buf;
size_t nbyte;
{
_DIAGASSERT(buf != NULL);
if (isrmt (fildes))
{
return (_rmt_write (fildes - REM_BIAS, buf, nbyte));
}
else
{
return (write (fildes, buf, nbyte));
}
}
/*
* Perform lseek on file. Looks just like lseek(2) to caller.
*/
off_t
rmtlseek(fildes, offset, whence)
int fildes;
off_t offset;
int whence;
{
if (isrmt (fildes))
{
return (_rmt_lseek (fildes - REM_BIAS, offset, whence));
}
else
{
return (lseek (fildes, offset, whence));
}
}
/*
* Close a file. Looks just like close(2) to caller.
*/
int
rmtclose(fildes)
int fildes;
{
if (isrmt (fildes))
{
return (_rmt_close (fildes - REM_BIAS));
}
else
{
return (close (fildes));
}
}
/*
* Do ioctl on file. Looks just like ioctl(2) to caller.
*/
int
#ifdef __STDC__
rmtioctl(int fildes, unsigned long request, ...)
#else
rmtioctl(va_alist)
va_decl
#endif
{
char *arg;
va_list ap;
#if __STDC__
va_start(ap, request);
#else
int fildes;
unsigned long request;
va_start(ap);
filedes = va_arg(ap, int);
request = va_arg(ap, unsigned long);
#endif
arg = va_arg(ap, char *);
va_end(ap);
/* XXX: arg may be NULL ? */
if (isrmt (fildes))
{
#ifdef RMTIOCTL
return (_rmt_ioctl (fildes - REM_BIAS, request, arg));
#else
errno = EOPNOTSUPP;
return (-1); /* For now (fnf) */
#endif
}
else
{
return (ioctl (fildes, request, arg));
}
}
/*
* Duplicate an open file descriptor. Looks just like dup(2)
* to caller.
*/
int
rmtdup(fildes)
int fildes;
{
if (isrmt (fildes))
{
errno = EOPNOTSUPP;
return (-1); /* For now (fnf) */
}
else
{
return (dup (fildes));
}
}
/*
* Get file status. Looks just like fstat(2) to caller.
*/
int
rmtfstat(fildes, buf)
int fildes;
struct stat *buf;
{
_DIAGASSERT(buf != NULL);
if (isrmt (fildes))
{
errno = EOPNOTSUPP;
return (-1); /* For now (fnf) */
}
else
{
return (fstat (fildes, buf));
}
}
/*
* Get file status. Looks just like stat(2) to caller.
*/
int
rmtstat(path, buf)
const char *path;
struct stat *buf;
{
_DIAGASSERT(path != NULL);
_DIAGASSERT(buf != NULL);
if (remdev (path))
{
errno = EOPNOTSUPP;
return (-1); /* For now (fnf) */
}
else
{
return (stat (path, buf));
}
}
/*
* Create a file from scratch. Looks just like creat(2) to the caller.
*/
int
rmtcreat(path, mode)
const char *path;
mode_t mode;
{
_DIAGASSERT(path != NULL);
if (remdev (path))
{
return (rmtopen (path, 1 | O_CREAT, mode));
}
else
{
return (creat (path, mode));
}
}
/*
* Rmtfcntl. Do a remote fcntl operation.
*/
int
#ifdef __STDC__
rmtfcntl(int fd, int cmd, ...)
#else
rmtfcntl(va_alist)
va_decl
#endif
{
void *arg;
va_list ap;
#if __STDC__
va_start(ap, cmd);
#else
int fd, cmd;
va_start(ap);
fd = va_arg(ap, int);
cmd = va_arg(ap, int);
#endif
arg = va_arg(ap, void *);
va_end(ap);
/* XXX: arg may be NULL ? */
if (isrmt (fd))
{
errno = EOPNOTSUPP;
return (-1);
}
else
{
return (fcntl (fd, cmd, arg));
}
}
/*
* Rmtisatty. Do the isatty function.
*/
int
rmtisatty(fd)
int fd;
{
if (isrmt (fd))
return (0);
else
return (isatty (fd));
}
/*
* Get file status, even if symlink. Looks just like lstat(2) to caller.
*/
int
rmtlstat(path, buf)
const char *path;
struct stat *buf;
{
_DIAGASSERT(path != NULL);
_DIAGASSERT(buf != NULL);
if (remdev (path))
{
errno = EOPNOTSUPP;
return (-1); /* For now (fnf) */
}
else
{
return (lstat (path, buf));
}
}
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