/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1983, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * rmt
 */
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/mtio.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static int      tape = -1;

static char     *record;
static int      maxrecsize = -1;

#define SSIZE   64
static char     device[SSIZE];
static char     count[SSIZE], mode[SSIZE], pos[SSIZE], op[SSIZE];

static char     resp[BUFSIZ];

static FILE     *debug;
#define DEBUG(f)        if (debug) fprintf(debug, f)
#define DEBUG1(f,a)     if (debug) fprintf(debug, f, a)
#define DEBUG2(f,a1,a2) if (debug) fprintf(debug, f, a1, a2)

static char     *checkbuf(char *, int);
static void      error(int);
static void      getstring(char *);

int
main(int argc, char **argv)
{
        int rval;
        char c;
        int n, i, cc;

        argc--, argv++;
        if (argc > 0) {
                debug = fopen(*argv, "w");
                if (debug == NULL) {
                        DEBUG1("rmtd: error to open %s\n", *argv);
                        exit(1);
                }
                (void)setbuf(debug, (char *)0);
        }
top:
        errno = 0;
        rval = 0;
        if (read(STDIN_FILENO, &c, 1) != 1)
                exit(0);
        switch (c) {

        case 'O':
                if (tape >= 0)
                        (void) close(tape);
                getstring(device);
                getstring(mode);
                DEBUG2("rmtd: O %s %s\n", device, mode);
                /*
                 * XXX the rmt protocol does not provide a means to
                 * specify the permission bits; allow rw for everyone,
                 * as modified by the users umask
                 */
                tape = open(device, atoi(mode), 0666);
                if (tape < 0)
                        goto ioerror;
                goto respond;

        case 'C':
                DEBUG("rmtd: C\n");
                getstring(device);              /* discard */
                if (close(tape) < 0)
                        goto ioerror;
                tape = -1;
                goto respond;

        case 'L':
                getstring(count);
                getstring(pos);
                DEBUG2("rmtd: L %s %s\n", count, pos);
                rval = lseek(tape, (off_t)strtoll(count, NULL, 10), atoi(pos));
                if (rval < 0)
                        goto ioerror;
                goto respond;

        case 'W':
                getstring(count);
                n = atoi(count);
                DEBUG1("rmtd: W %s\n", count);
                record = checkbuf(record, n);
                for (i = 0; i < n; i += cc) {
                        cc = read(STDIN_FILENO, &record[i], n - i);
                        if (cc <= 0) {
                                DEBUG("rmtd: premature eof\n");
                                exit(2);
                        }
                }
                rval = write(tape, record, n);
                if (rval < 0)
                        goto ioerror;
                goto respond;

        case 'R':
                getstring(count);
                DEBUG1("rmtd: R %s\n", count);
                n = atoi(count);
                record = checkbuf(record, n);
                rval = read(tape, record, n);
                if (rval < 0)
                        goto ioerror;
                (void)sprintf(resp, "A%d\n", rval);
                (void)write(STDOUT_FILENO, resp, strlen(resp));
                (void)write(STDOUT_FILENO, record, rval);
                goto top;

        case 'I':
                getstring(op);
                getstring(count);
                DEBUG2("rmtd: I %s %s\n", op, count);
                { struct mtop mtop;
                  mtop.mt_op = atoi(op);
                  mtop.mt_count = atoi(count);
                  if (ioctl(tape, MTIOCTOP, (char *)&mtop) < 0)
                        goto ioerror;
                  rval = mtop.mt_count;
                }
                goto respond;

        case 'S':               /* status */
                DEBUG("rmtd: S\n");
                { struct mtget mtget;
                  if (ioctl(tape, MTIOCGET, (char *)&mtget) < 0)
                        goto ioerror;
                  rval = sizeof (mtget);
                  if (rval > 24)        /* original mtget structure size */
                        rval = 24;
                  (void)sprintf(resp, "A%d\n", rval);
                  (void)write(STDOUT_FILENO, resp, strlen(resp));
                  (void)write(STDOUT_FILENO, (char *)&mtget, rval);
                  goto top;
                }

        case 'V':               /* version */
                getstring(op);
                DEBUG1("rmtd: V %s\n", op);
                rval = 2;
                goto respond;

        default:
                DEBUG1("rmtd: garbage command %c\n", c);
                exit(3);
        }
respond:
        DEBUG1("rmtd: A %d\n", rval);
        (void)sprintf(resp, "A%d\n", rval);
        (void)write(STDOUT_FILENO, resp, strlen(resp));
        goto top;
ioerror:
        error(errno);
        goto top;
}

void
getstring(char *bp)
{
        int i;
        char *cp = bp;

        for (i = 0; i < SSIZE; i++) {
                if (read(STDIN_FILENO, cp+i, 1) != 1)
                        exit(0);
                if (cp[i] == '\n')
                        break;
        }
        cp[i] = '\0';
}

static char *
checkbuf(char *rec, int size)
{

        if (size <= maxrecsize)
                return (rec);
        if (rec != NULL)
                free(rec);
        rec = malloc(size);
        if (rec == NULL) {
                DEBUG("rmtd: cannot allocate buffer space\n");
                exit(4);
        }
        maxrecsize = size;
        while (size > 1024 &&
               setsockopt(0, SOL_SOCKET, SO_RCVBUF, &size, sizeof (size)) < 0)
                size -= 1024;
        return (rec);
}

static void
error(int num)
{

        DEBUG2("rmtd: E %d (%s)\n", num, strerror(num));
        (void)snprintf(resp, sizeof(resp), "E%d\n%s\n", num, strerror(num));
        (void)write(STDOUT_FILENO, resp, strlen(resp));
}