/* $NetBSD: rmtlib.c,v 1.4 1996/08/13 20:09:50 thorpej 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 #include #include #include #include #ifdef RMTIOCTL #include #include #endif #ifdef USE_REXEC #include #endif #include #include #include #include #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; { register int blen; void (*pstat)(); /* * 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(host, user) char *host; char *user; /* may be NULL */ { struct servent *rexecserv; 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) 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; 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/bin/rsh", "rsh", system, "-l", login, "/etc/rmt", (char *) 0); } else { execl("/usr/bin/rsh", "rsh", system, "/etc/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 */ sprintf(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]; 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) { 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; char *buf; unsigned int nbyte; { int rc; char buffer[BUFMAGIC]; void (*pstat)(); 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); rmtabort(fildes); errno = EIO; return(-1); } /* * _rmt_lseek --- perform an imitation lseek operation remotely */ static 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 */ #ifdef RMTIOCTL static _rmt_ioctl(fildes, op, arg) int fildes; unsigned long 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) { 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 * # 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 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) register char *path; { 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 rmtopen (path, oflag, mode) char *path; int oflag; int mode; { int fd; 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) char *path; int amode; { if (remdev (path)) { return (0); /* Let /etc/rmt find out */ } else { return (access (path, amode)); } } /* * Read from stream. Looks just like read(2) to caller. */ int rmtread (fildes, buf, nbyte) int fildes; char *buf; unsigned int nbyte; { 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. */ int rmtwrite (fildes, buf, nbyte) int fildes; char *buf; unsigned int nbyte; { 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. */ long rmtlseek (fildes, offset, whence) int fildes; long 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 rmtioctl (fildes, request, arg) int fildes; unsigned long request; char *arg; { 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; { 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) char *path; struct stat *buf; { 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) char *path; int mode; { if (remdev (path)) { return (rmtopen (path, 1 | O_CREAT, mode)); } else { return (creat (path, mode)); } } /* * Isrmt. Let a programmer know he has a remote device. */ int isrmt (fd) int fd; { return (fd >= REM_BIAS); } /* * Rmtfcntl. Do a remote fcntl operation. */ int rmtfcntl (fd, cmd, arg) int fd, cmd, arg; { 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) char *path; struct stat *buf; { if (remdev (path)) { errno = EOPNOTSUPP; return (-1); /* For now (fnf) */ } else { return (lstat (path, buf)); } }