/* Copyright (C) 1988 Free Software Foundation GNU tar is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY. No author or distributor accepts responsibility to anyone for the consequences of using it or for whether it serves any particular purpose or works at all, unless he says so in writing. Refer to the GNU tar General Public License for full details. Everyone is granted permission to copy, modify and redistribute GNU tar, but only under the conditions described in the GNU tar General Public License. A copy of this license is supposed to have been given to you along with GNU tar so you can know your rights and responsibilities. It should be in a file named COPYING. Among other things, the copyright notice and this notice must be preserved on all copies. In other words, go ahead and share GNU tar, but don't try to stop anyone else from sharing it farther. Help stamp out software hoarding! */ #ifndef lint static char *RCSid = "$Header: rmtlib.c,v 1.6 88/10/25 17:04:29 root Locked $"; #endif /* JF: modified to make all rmtXXX calls into macros for speed */ /* * $Log: rmtlib.c,v $ * 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 jeff@gatech.edu 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 parmelee@wayback.cs.cornell.edu 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. */ /* * 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 #ifdef RMTIOCTL #include #include #endif #ifdef USE_REXEC #include #endif #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 }; 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; int (*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); _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; 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... */ 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 (*user) { execl("/usr/ucb/rsh", "rsh", system, "-l", login, "/etc/rmt", (char *) 0); execl("/usr/bin/remsh", "remsh", 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); } /* * 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+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]; int (*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); _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 */ #ifdef 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 /* RMTIOCTL */