/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * BSD 3 Clause License
 *
 * Copyright (c) 2007, The Storage Networking Industry Association.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *      - Redistributions of source code must retain the above copyright
 *        notice, this list of conditions and the following disclaimer.
 *
 *      - 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.
 *
 *      - Neither the name of The Storage Networking Industry Association (SNIA)
 *        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 COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
 */
/* Copyright (c) 2007, The Storage Networking Industry Association. */
/* Copyright (c) 1996, 1997 PDC, Network Appliance. All Rights Reserved */
/* Copyright 2014 Nexenta Systems, Inc.  All rights reserved. */

#include <sys/param.h>
#include <fcntl.h>
#include <sys/mtio.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "ndmpd_common.h"
#include "ndmpd.h"

static void tape_open_send_reply(ndmp_connection_t *connection, int err);
static void unbuffered_read(ndmpd_session_t *session, char *buf, long wanted,
    ndmp_tape_read_reply *reply);
static boolean_t validmode(int mode);
static void common_tape_open(ndmp_connection_t *connection, char *devname,
    int ndmpmode);
static void common_tape_close(ndmp_connection_t *connection);

/*
 * Configurable delay & time when the tape is
 * busy during opening the tape.
 */
int ndmp_tape_open_retries = 5;
int ndmp_tape_open_delay = 1000;

/*
 * A few words about EOT (end-of-tape) and EOM handling on tapes with SVR4
 * semantic:
 *
 * We adhere to terminology as used in st driver.  EOT means end of recorded
 * data on a tape. This is different from EOM (somewhere referred to as LEOT)
 * which is the end of tape medium. EOT is meaningful only for reads while EOM
 * is meaningful only for writes. It's not possible to read after EOT (fails
 * with EIO), but it's possible to write data after EOM. EOM returned by st
 * driver on modern tape drives is just indication that the physical end of
 * tape medium is nearing and that writer should write just the necessary
 * minimum and stop writing. When physical end of tape is reached all writes
 * return EIO. If EOM is crossed during read operation then st driver doesn't
 * bother to report it to client and that's alright because reads don't care
 * where medium physically ends but they care about meaningful data recorded on
 * the tape and as long as there are such data reads should continue to work.
 *
 * When reading EOT is signalled by st driver by two empty consecutive reads
 * (with FSF done between them).  When writing EOM is signalled by empty write
 * (a write which writes zero bytes). Following writes succeed until physical
 * end of tape is reached in which case EIO is returned.
 */

/*
 * ************************************************************************
 * NDMP V2 HANDLERS
 * ************************************************************************
 */

/*
 * ndmpd_tape_open_v2
 *
 * This handler opens the specified tape device.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
void
ndmpd_tape_open_v2(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_open_request_v2 *request = (ndmp_tape_open_request_v2 *) body;
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        char adptnm[SCSI_MAX_NAME];
        int mode;
        int sid, lun;
        int err;
        scsi_adapter_t *sa;
        int devid;

        err = NDMP_NO_ERR;

        if (session->ns_tape.td_fd != -1 || session->ns_scsi.sd_is_open != -1) {
                NDMP_LOG(LOG_INFO,
                    "Connection already has a tape or scsi device open");
                err = NDMP_DEVICE_OPENED_ERR;
        } else if (request->mode != NDMP_TAPE_READ_MODE &&
            request->mode != NDMP_TAPE_WRITE_MODE &&
            request->mode != NDMP_TAPE_RAW1_MODE) {
                err = NDMP_ILLEGAL_ARGS_ERR;
        }

        if ((sa = scsi_get_adapter(0)) != NULL) {
                NDMP_LOG(LOG_DEBUG,
                    "Adapter device opened: %s", request->device.name);
                (void) strlcpy(adptnm, request->device.name, SCSI_MAX_NAME-2);
                adptnm[SCSI_MAX_NAME-1] = '\0';
                sid = lun = -1;
        }
        /* try to get the scsi id etc.... */
        if (sa) {
                scsi_find_sid_lun(sa, request->device.name, &sid, &lun);
                if (ndmp_open_list_find(request->device.name, sid, lun) == 0 &&
                    (devid = tape_open(request->device.name,
                    O_RDWR | O_NDELAY)) < 0) {
                        NDMP_LOG(LOG_ERR, "Failed to open device %s: %m.",
                            request->device.name);
                        err = NDMP_NO_DEVICE_ERR;
                }
                else
                        (void) close(devid);
        } else {
                NDMP_LOG(LOG_ERR, "%s: No such tape device.",
                    request->device.name);
                err = NDMP_NO_DEVICE_ERR;
        }
        if (err != NDMP_NO_ERR) {
                tape_open_send_reply(connection, err);
                return;
        }

        switch (ndmp_open_list_add(connection, adptnm, sid, lun, devid)) {
        case 0:
                err = NDMP_NO_ERR;
                break;
        case EBUSY:
                err = NDMP_DEVICE_BUSY_ERR;
                break;
        case ENOMEM:
                err = NDMP_NO_MEM_ERR;
                break;
        default:
                err = NDMP_IO_ERR;
        }
        if (err != NDMP_NO_ERR) {
                tape_open_send_reply(connection, err);
                return;
        }

        /*
         * According to Connectathon 2001, the 0x7fffffff is a secret
         * code between "Workstartion Solutions" and * net_app.
         * If mode is set to this value, tape_open() won't fail if
         * the tape device is not ready.
         */
        if (request->mode != NDMP_TAPE_RAW1_MODE &&
            !is_tape_unit_ready(adptnm, 0)) {
                (void) ndmp_open_list_del(adptnm, sid, lun);
                tape_open_send_reply(connection, NDMP_NO_TAPE_LOADED_ERR);
                return;
        }

        mode = (request->mode == NDMP_TAPE_READ_MODE) ? O_RDONLY : O_RDWR;
        mode |= O_NDELAY;
        if ((session->ns_tape.td_fd = open(request->device.name, mode)) < 0) {
                        NDMP_LOG(LOG_ERR, "Failed to open tape device %s: %m.",
                            request->device.name);
                        switch (errno) {
                        case EACCES:
                                err = NDMP_WRITE_PROTECT_ERR;
                                break;
                        case ENXIO:
                        case ENOENT:
                                err = NDMP_NO_DEVICE_ERR;
                                break;
                        case EBUSY:
                                err = NDMP_DEVICE_BUSY_ERR;
                                break;
                        default:
                                err = NDMP_IO_ERR;
                        }

                        (void) ndmp_open_list_del(adptnm, sid, lun);
                        tape_open_send_reply(connection, err);
                        return;
                }

        session->ns_tape.td_mode = request->mode;
        session->ns_tape.td_sid = sid;
        session->ns_tape.td_lun = lun;
        (void) strlcpy(session->ns_tape.td_adapter_name, adptnm, SCSI_MAX_NAME);
        session->ns_tape.td_record_count = 0;

        NDMP_LOG(LOG_DEBUG, "Tape is opened fd: %d", session->ns_tape.td_fd);

        tape_open_send_reply(connection, NDMP_NO_ERR);
}


/*
 * ndmpd_tape_close_v2
 *
 * This handler closes the currently open tape device.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
/*ARGSUSED*/
void
ndmpd_tape_close_v2(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_close_reply reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_close reply");
                return;
        }
        common_tape_close(connection);

}

/*
 * ndmpd_tape_get_state_v2
 *
 * This handler handles the tape_get_state request.
 * Status information for the currently open tape device is returned.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
/*ARGSUSED*/
void
ndmpd_tape_get_state_v2(ndmp_connection_t *connection, void *body)

{
        ndmp_tape_get_state_reply_v2 reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        struct mtget mtstatus;
        struct mtdrivetype_request dtpr;
        struct mtdrivetype dtp;

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_get_state reply");
                return;
        }

        if (ioctl(session->ns_tape.td_fd, MTIOCGET, &mtstatus) < 0) {
                NDMP_LOG(LOG_ERR, "Failed to get status from tape: %m.");
                NDMP_LOG(LOG_DEBUG, "ioctl(MTIOCGET) error: %m.");
                reply.error = NDMP_IO_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_get_state reply");
                return;
        }

        dtpr.size = sizeof (struct mtdrivetype);
        dtpr.mtdtp = &dtp;
        if (ioctl(session->ns_tape.td_fd, MTIOCGETDRIVETYPE, &dtpr) == -1) {
                NDMP_LOG(LOG_ERR,
                    "Failed to get drive type information from tape: %m.");
                NDMP_LOG(LOG_DEBUG, "ioctl(MTIOCGETDRIVETYPE) error: %m.");
                reply.error = NDMP_IO_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_get_state reply");
                return;
        }

        reply.flags = 0;

        reply.file_num = mtstatus.mt_fileno;
        reply.soft_errors = 0;
        reply.block_size = dtp.bsize;
        if (dtp.bsize == 0)
                reply.blockno = mtstatus.mt_blkno;
        else
                reply.blockno = mtstatus.mt_blkno *
                    (session->ns_mover.md_record_size / dtp.bsize);

        reply.soft_errors = 0;
        reply.total_space = long_long_to_quad(0);       /* not supported */
        reply.space_remain = long_long_to_quad(0);      /* not supported */

        NDMP_LOG(LOG_DEBUG,
            "flags: 0x%x, file_num: %d, block_size: %d, blockno: %d",
            reply.flags, reply.file_num, reply.block_size, reply.blockno);

        reply.error = NDMP_NO_ERR;
        ndmp_send_reply(connection, (void *) &reply,
            "sending tape_get_state reply");
}


/*
 * ndmpd_tape_mtio_v2
 *
 * This handler handles tape_mtio requests.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
void
ndmpd_tape_mtio_v2(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_mtio_request *request = (ndmp_tape_mtio_request *) body;
        ndmp_tape_mtio_reply reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);

        struct mtop tapeop;
        struct mtget mtstatus;
        int retry = 0;
        int rc;

        reply.resid_count = 0;

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_mtio reply");
                return;
        }

        reply.error = NDMP_NO_ERR;
        switch (request->tape_op) {
        case NDMP_MTIO_FSF:
                tapeop.mt_op = MTFSF;
                break;
        case NDMP_MTIO_BSF:
                tapeop.mt_op = MTBSF;
                break;
        case NDMP_MTIO_FSR:
                tapeop.mt_op = MTFSR;
                break;
        case NDMP_MTIO_BSR:
                tapeop.mt_op = MTBSR;
                break;
        case NDMP_MTIO_REW:
                tapeop.mt_op = MTREW;
                break;
        case NDMP_MTIO_EOF:
                if (session->ns_tape.td_mode == NDMP_TAPE_READ_MODE)
                        reply.error = NDMP_PERMISSION_ERR;
                tapeop.mt_op = MTWEOF;
                break;
        case NDMP_MTIO_OFF:
                tapeop.mt_op = MTOFFL;
                break;

        case NDMP_MTIO_TUR: /* test unit ready */

                if (is_tape_unit_ready(session->ns_tape.td_adapter_name,
                    session->ns_tape.td_fd) == 0)
                        /* tape not ready ? */
                        reply.error = NDMP_NO_TAPE_LOADED_ERR;
                break;

        default:
                reply.error = NDMP_ILLEGAL_ARGS_ERR;
        }

        if (reply.error == NDMP_NO_ERR && request->tape_op != NDMP_MTIO_TUR) {
                tapeop.mt_count = request->count;

                do {
                        NS_UPD(twait, trun);
                        errno = 0;
                        rc = ioctl(session->ns_tape.td_fd, MTIOCTOP, &tapeop);
                        NS_UPD(trun, twait);
                        NDMP_LOG(LOG_DEBUG,
                            "ioctl MTIO rc:%d, cmd:%d, retry:%d, error: %d",
                            rc, tapeop.mt_op, retry, errno);
                } while (rc < 0 && errno == EIO &&
                    retry++ < 5);

                /*
                 * Ignore I/O errors since these usually are the result of
                 * attempting to position past the beginning or end of the tape.
                 * The residual count will be returned and can be used to
                 * determine that the call was not completely successful.
                 */
                if (rc < 0) {
                        NDMP_LOG(LOG_ERR,
                            "Failed to send command to tape: %m.");
                        NDMP_LOG(LOG_DEBUG, "ioctl(MTIOCTOP) error: %m.");

                        /* MTWEOF doesnt have residual count */
                        if (tapeop.mt_op == MTWEOF)
                                reply.error = NDMP_IO_ERR;
                        else
                                reply.error = NDMP_NO_ERR;
                        reply.resid_count = tapeop.mt_count;
                        ndmp_send_reply(connection, (void *)&reply,
                            "sending tape_mtio reply");
                        return;
                }

                if (request->tape_op != NDMP_MTIO_REW &&
                    request->tape_op != NDMP_MTIO_OFF) {
                        if (ioctl(session->ns_tape.td_fd, MTIOCGET,
                            &mtstatus) < 0) {
                                NDMP_LOG(LOG_ERR,
                                    "Failed to send command to tape: %m.");
                                NDMP_LOG(LOG_DEBUG,
                                    "ioctl(MTIOCGET) error: %m.");
                                reply.error = NDMP_IO_ERR;
                                ndmp_send_reply(connection, (void *)&reply,
                                    "sending tape_mtio reply");

                                return;
                        }

                        reply.resid_count = labs(mtstatus.mt_resid);
                }
        }

        NDMP_LOG(LOG_DEBUG, "resid_count: %d",
            reply.resid_count);
        ndmp_send_reply(connection, (void *) &reply, "sending tape_mtio reply");
}


/*
 * ndmpd_tape_read_v2
 *
 * This handler handles tape_read requests.
 * This interface is a non-buffered interface. Each read request
 * maps directly to a read to the tape device. It is the responsibility
 * of the NDMP client to issue read requests with a length that is at
 * least as large as the record size used write the tape. The tape driver
 * always reads a full record. Data is discarded if the read request is
 * smaller than the record size.
 * It is the responsibility of the NDMP client to ensure that the
 * length is a multiple of the tape block size if the tape device
 * is in fixed block mode.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
void
ndmpd_tape_read_v2(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_read_request *request = (ndmp_tape_read_request *) body;
        ndmp_tape_read_reply reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        char *buf;

        reply.data_in.data_in_len = 0;

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_read reply");
                return;
        }
        if (request->count == 0) {
                reply.error = NDMP_NO_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_read reply");
                return;
        }
        if ((buf = ndmp_malloc(request->count)) == 0) {
                reply.error = NDMP_NO_MEM_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_read reply");
                return;
        }

        unbuffered_read(session, buf, request->count, &reply);

        ndmp_send_reply(connection, (void *) &reply, "sending tape_read reply");
        (void) free(buf);
}


/*
 * ndmpd_tape_execute_cdb_v2
 *
 * This handler handles tape_execute_cdb requests.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
void
ndmpd_tape_execute_cdb_v2(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_execute_cdb_request *request;
        ndmp_tape_execute_cdb_reply reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);

        request = (ndmp_tape_execute_cdb_request *) body;

        if (session->ns_tape.td_fd == -1) {
                (void) memset((void *) &reply, 0, sizeof (reply));

                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_execute_cdb reply");
        } else {
                ndmp_execute_cdb(session, session->ns_tape.td_adapter_name,
                    session->ns_tape.td_sid, session->ns_tape.td_lun,
                    (ndmp_execute_cdb_request *)request);
        }
}


/*
 * ************************************************************************
 * NDMP V3 HANDLERS
 * ************************************************************************
 */

/*
 * ndmpd_tape_open_v3
 *
 * This handler opens the specified tape device.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
void
ndmpd_tape_open_v3(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_open_request_v3 *request = (ndmp_tape_open_request_v3 *)body;

        common_tape_open(connection, request->device, request->mode);
}


/*
 * ndmpd_tape_get_state_v3
 *
 * This handler handles the ndmp_tape_get_state_request.
 * Status information for the currently open tape device is returned.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
/*ARGSUSED*/
void
ndmpd_tape_get_state_v3(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_get_state_reply_v3 reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        struct mtdrivetype_request dtpr;
        struct mtdrivetype dtp;
        struct mtget mtstatus;

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_get_state reply");
                return;
        }

        if (ioctl(session->ns_tape.td_fd, MTIOCGET, &mtstatus) == -1) {
                NDMP_LOG(LOG_ERR, "Failed to get status from tape: %m.");
                NDMP_LOG(LOG_DEBUG, "ioctl(MTIOCGET) error: %m.");

                reply.error = NDMP_IO_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_get_state reply");
                return;
        }

        dtpr.size = sizeof (struct mtdrivetype);
        dtpr.mtdtp = &dtp;
        if (ioctl(session->ns_tape.td_fd, MTIOCGETDRIVETYPE, &dtpr) == -1) {
                NDMP_LOG(LOG_ERR,
                    "Failed to get drive type information from tape: %m.");
                NDMP_LOG(LOG_DEBUG, "ioctl(MTIOCGETDRIVETYPE) error: %m.");

                reply.error = NDMP_IO_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_get_state reply");
                return;
        }

        reply.flags = 0;

        reply.file_num = mtstatus.mt_fileno;
        reply.soft_errors = 0;
        reply.block_size = dtp.bsize;
        if (dtp.bsize == 0)
                reply.blockno = mtstatus.mt_blkno;
        else
                reply.blockno = mtstatus.mt_blkno *
                    (session->ns_mover.md_record_size / dtp.bsize);
        reply.total_space = long_long_to_quad(0); /* not supported */
        reply.space_remain = long_long_to_quad(0); /* not supported */
        reply.partition = 0; /* not supported */

        reply.soft_errors = 0;
        reply.total_space = long_long_to_quad(0LL);
        reply.space_remain = long_long_to_quad(0LL);

        reply.invalid = NDMP_TAPE_STATE_SOFT_ERRORS_INVALID |
            NDMP_TAPE_STATE_TOTAL_SPACE_INVALID |
            NDMP_TAPE_STATE_SPACE_REMAIN_INVALID |
            NDMP_TAPE_STATE_PARTITION_INVALID;


        NDMP_LOG(LOG_DEBUG, "f 0x%x, fnum %d, bsize %d, bno: %d",
            reply.flags, reply.file_num, reply.block_size, reply.blockno);

        reply.error = NDMP_NO_ERR;
        ndmp_send_reply(connection, (void *) &reply,
            "sending tape_get_state reply");
}

/*
 * tape_is_at_bot
 *
 * Returns 1 if tape is at BOT, 0 on error or not at BOT.
 *
 */
int
tape_is_at_bot(ndmpd_session_t *session)
{
        struct mtget mtstatus;

        if (ioctl(session->ns_tape.td_fd, MTIOCGET, &mtstatus) == 0 &&
            mtstatus.mt_fileno == 0 && mtstatus.mt_blkno == 0)
                return (1);

        return (0);
}

/*
 * If we are at the beginning of a file (block # is zero) and read returns
 * zero bytes then this has to be end of recorded data on the tape. Repeated
 * reads at EOT return EIO. In both cases (zero read and EIO read) this
 * function should be used to test if we are at EOT.
 *
 * Returns 1 if tape is at BOF, 0 on error or not at BOF.
 */
int
tape_is_at_bof(ndmpd_session_t *session)
{
        struct mtget mtstatus;

        if ((ioctl(session->ns_tape.td_fd, MTIOCGET, &mtstatus) == 0) &&
            (mtstatus.mt_fileno > 0) && (mtstatus.mt_blkno == 0))
                return (1);

        return (0);
}

/*
 * Skips forward over a file mark and then back before the file mark. Why is
 * this needed? There are two reasons for it:
 *
 * 1) Because NDMPv4 spec requires that when EOF is encountered, the tape
 * position should remain on BOT side of the file mark. When st driver reaches
 * end of file get-position mtioctl reports position before file mark, however
 * the file mark has already been read and the real position is thus after the
 * file mark (real position as reported for example by uscsi commands). Thus we
 * need to do FSF, which does nothing but only updates file & block counter in
 * st driver and then BSF, which sets the position before the file mark. Thus
 * current position as reported by scsi and mtioctl will be in sync.
 *
 * 2) st driver returns EIO for repeated reads at EOF while according to NDMP
 * spec we should continue to return zero bytes until FSF is done. By skipping
 * forward and backward, st driver will return zero bytes for the next read
 * again and we don't need to specifically handle this case.
 */
void
fm_dance(ndmpd_session_t *session)
{
        (void) ndmp_mtioctl(session->ns_tape.td_fd, MTFSF, 1);
        (void) ndmp_mtioctl(session->ns_tape.td_fd, MTBSF, 1);
}

/*
 * ndmpd_tape_write_v3
 *
 * This handler handles tape_write requests.  This interface is a non-buffered
 * interface. Each write request maps directly to a write to the tape device.
 * It is the responsibility of the NDMP client to pad the data to the desired
 * record size.  It is the responsibility of the NDMP client to ensure that the
 * length is a multiple of the tape block size if the tape device is in fixed
 * block mode.
 *
 * A logical end of tape will return number of bytes written less than
 * requested, and one more request to write will give 0 and NDMP_EOM_ERR,
 * followed by NDMP_NO_ERR until NDMP_IO_ERR when physical end of tape is
 * reached.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 */
void ndmpd_tape_write_v3(ndmp_connection_t *connection, void *body) {
        ndmp_tape_write_request *request = (ndmp_tape_write_request *)body;
        ndmp_tape_write_reply reply; ndmpd_session_t *session =
                ndmp_get_client_data(connection); ssize_t n;

        reply.count = 0;

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_write reply");
                return;
        }
        if (session->ns_tape.td_mode == NDMP_TAPE_READ_MODE) {
                NDMP_LOG(LOG_INFO, "Tape device opened in read-only mode");
                reply.error = NDMP_PERMISSION_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_write reply");
                return;
        }
        if (request->data_out.data_out_len == 0) {
                reply.error = NDMP_NO_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_write reply");
                return;
        }

        /*
         * V4 suggests that this should not be accepted
         * when mover is in listen or active state
         */
        if (session->ns_protocol_version == NDMPV4 &&
            (session->ns_mover.md_state == NDMP_MOVER_STATE_LISTEN ||
            session->ns_mover.md_state == NDMP_MOVER_STATE_ACTIVE)) {

                reply.error = NDMP_DEVICE_BUSY_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_write reply");
                return;
        }

        n = write(session->ns_tape.td_fd, request->data_out.data_out_val,
            request->data_out.data_out_len);

        if (n < 0) {
                NDMP_LOG(LOG_ERR, "Tape write error: %m.");
                reply.error = NDMP_IO_ERR;
        } else if (n == 0) {
                NDMP_LOG(LOG_INFO, "EOM detected");
                reply.error = NDMP_EOM_ERR;
        } else {
                NS_ADD(wtape, n);
                reply.count = n;
                reply.error = NDMP_NO_ERR;

                if (n < request->data_out.data_out_len)
                        NDMP_LOG(LOG_DEBUG,
                                "EOM is coming (partial write of %d bytes)", n);
        }

        ndmp_send_reply(connection, (void *) &reply,
            "sending tape_write reply");
}

/*
 * ndmpd_tape_read_v3
 *
 * This handler handles tape_read requests.  This interface is a non-buffered
 * interface. Each read request maps directly to a read to the tape device. It
 * is the responsibility of the NDMP client to issue read requests with a
 * length that is at least as large as the record size used write the tape. The
 * tape driver always reads a full record. Data is discarded if the read
 * request is smaller than the record size.  It is the responsibility of the
 * NDMP client to ensure that the length is a multiple of the tape block size
 * if the tape device is in fixed block mode.
 *
 * A logical end of tape will return less bytes than requested, and one more
 * request to read will give 0 and NDMP_EOM_ERR.  All subsequent reads will
 * return NDMP_EOM_ERR until the tape is repositioned.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 */
void
ndmpd_tape_read_v3(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_read_request *request = (ndmp_tape_read_request *) body;
        ndmp_tape_read_reply reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        char *buf;
        int n;

        reply.data_in.data_in_len = 0;

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_read reply");
                return;
        }
        if (request->count == 0) {
                reply.error = NDMP_NO_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_read reply");
                return;
        }

        /*
         * V4 suggests that this should not be accepted
         * when mover is in listen or active state
         */
        if (session->ns_protocol_version == NDMPV4 &&
            (session->ns_mover.md_state == NDMP_MOVER_STATE_LISTEN ||
            session->ns_mover.md_state == NDMP_MOVER_STATE_ACTIVE)) {

                reply.error = NDMP_DEVICE_BUSY_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_read reply");
                return;
        }

        if ((buf = ndmp_malloc(request->count)) == NULL) {
                reply.error = NDMP_NO_MEM_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_read reply");
                return;
        }

        n = read(session->ns_tape.td_fd, buf, request->count);
        if (n < 0) {
                /*
                 * This fix is for Symantec during importing
                 * of spanned data between the tapes.
                 */
                if (errno == ENOSPC) {
                        reply.error = NDMP_EOF_ERR;
                }
                /*
                 * If at beginning of file and read fails with EIO, then it's
                 * repeated attempt to read at EOT.
                 */
                else if (errno == EIO && tape_is_at_bof(session)) {
                        NDMP_LOG(LOG_DEBUG, "Repeated read at EOT");
                        reply.error = NDMP_EOM_ERR;
                }
                /*
                 * According to NDMPv4 spec preferred error code when
                 * trying to read from blank tape is NDMP_EOM_ERR.
                 */
                else if (errno == EIO && tape_is_at_bot(session)) {
                        NDMP_LOG(LOG_ERR, "Blank tape detected, returning EOM");
                        reply.error = NDMP_EOM_ERR;
                } else {
                        NDMP_LOG(LOG_ERR, "Tape read error: %m.");
                        reply.error = NDMP_IO_ERR;
                }
        } else if (n == 0) {
                if (tape_is_at_bof(session)) {
                        NDMP_LOG(LOG_DEBUG, "EOT detected");
                        reply.error = NDMP_EOM_ERR;
                } else {
                        /* reposition the tape to BOT side of FM */
                        fm_dance(session);
                        NDMP_LOG(LOG_DEBUG, "EOF detected");
                        reply.error = NDMP_EOF_ERR;
                }
        } else {
                session->ns_tape.td_pos += n;
                reply.data_in.data_in_len = n;
                reply.data_in.data_in_val = buf;
                reply.error = NDMP_NO_ERR;
                NS_ADD(rtape, n);
        }

        ndmp_send_reply(connection, (void *) &reply, "sending tape_read reply");
        free(buf);
}


/*
 * ************************************************************************
 * NDMP V4 HANDLERS
 * ************************************************************************
 */

/*
 * ndmpd_tape_get_state_v4
 *
 * This handler handles the ndmp_tape_get_state_request.
 * Status information for the currently open tape device is returned.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
/*ARGSUSED*/
void
ndmpd_tape_get_state_v4(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_get_state_reply_v4 reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        struct mtget mtstatus;
        struct mtdrivetype_request dtpr;
        struct mtdrivetype dtp;

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_get_state reply");
                return;
        }

        /*
         * Need code to detect NDMP_TAPE_STATE_NOREWIND
         */

        if (ioctl(session->ns_tape.td_fd, MTIOCGET, &mtstatus) == -1) {
                NDMP_LOG(LOG_ERR,
                    "Failed to get status information from tape: %m.");
                NDMP_LOG(LOG_DEBUG, "ioctl(MTIOCGET) error: %m.");

                reply.error = NDMP_IO_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_get_state reply");
                return;
        }

        dtpr.size = sizeof (struct mtdrivetype);
        dtpr.mtdtp = &dtp;
        if (ioctl(session->ns_tape.td_fd, MTIOCGETDRIVETYPE, &dtpr) == -1) {
                NDMP_LOG(LOG_ERR,
                    "Failed to get drive type information from tape: %m.");
                NDMP_LOG(LOG_DEBUG, "ioctl(MTIOCGETDRIVETYPE) error: %m.");

                reply.error = NDMP_IO_ERR;
                ndmp_send_reply(connection, (void *)&reply,
                    "sending tape_get_state reply");
                return;
        }

        reply.flags = NDMP_TAPE_NOREWIND;

        reply.file_num = mtstatus.mt_fileno;
        reply.soft_errors = 0;
        reply.block_size = dtp.bsize;

        if (dtp.bsize == 0)
                reply.blockno = mtstatus.mt_blkno;
        else
                reply.blockno = mtstatus.mt_blkno /
                    (session->ns_mover.md_record_size / dtp.bsize);

        reply.total_space = long_long_to_quad(0LL); /* not supported */
        reply.space_remain = long_long_to_quad(0LL); /* not supported */
        reply.soft_errors = 0;
        reply.unsupported = NDMP_TAPE_STATE_SOFT_ERRORS_INVALID |
            NDMP_TAPE_STATE_TOTAL_SPACE_INVALID |
            NDMP_TAPE_STATE_SPACE_REMAIN_INVALID |
            NDMP_TAPE_STATE_PARTITION_INVALID;

        NDMP_LOG(LOG_DEBUG, "f 0x%x, fnum %d, bsize %d, bno: %d",
            reply.flags, reply.file_num, reply.block_size, reply.blockno);

        reply.error = NDMP_NO_ERR;
        ndmp_send_reply(connection, (void *) &reply,
            "sending tape_get_state reply");
}
/*
 * ndmpd_tape_close_v4
 *
 * This handler (v4) closes the currently open tape device.
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   body       (input) - request message body.
 *
 * Returns:
 *   void
 */
/*ARGSUSED*/
void
ndmpd_tape_close_v4(ndmp_connection_t *connection, void *body)
{
        ndmp_tape_close_reply reply;
        ndmpd_session_t *session = ndmp_get_client_data(connection);

        if (session->ns_tape.td_fd == -1) {
                NDMP_LOG(LOG_ERR, "Tape device is not open.");
                reply.error = NDMP_DEV_NOT_OPEN_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_close reply");
                return;
        }

        /*
         * V4 suggests that this should not be accepted
         * when mover is in listen or active state
         */
        if (session->ns_mover.md_state == NDMP_MOVER_STATE_LISTEN ||
            session->ns_mover.md_state == NDMP_MOVER_STATE_ACTIVE) {

                reply.error = NDMP_DEVICE_BUSY_ERR;
                ndmp_send_reply(connection, (void *) &reply,
                    "sending tape_close reply");
                return;
        }

        common_tape_close(connection);
}


/*
 * ************************************************************************
 * LOCALS
 * ************************************************************************
 */
/*
 * tape_open_send_reply
 *
 * Send a reply to the tape open message
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   err (input) - NDMP error
 *
 * Returns:
 *   void
 */
static void
tape_open_send_reply(ndmp_connection_t *connection, int err)
{
        ndmp_tape_open_reply reply;

        reply.error = err;
        ndmp_send_reply(connection, (void *) &reply, "sending tape_open reply");
}

/*
 * unbuffered_read
 *
 * Perform tape read without read-ahead
 *
 * Parameters:
 *   session (input) - session handle
 *   bp (output) - read buffer
 *   wanted (input) - number of bytes wanted
 *   reply (output) - tape read reply message
 *
 * Returns:
 *   void
 */
static void
unbuffered_read(ndmpd_session_t *session, char *buf, long wanted,
    ndmp_tape_read_reply *reply)
{
        int n, len;

        n = read(session->ns_tape.td_fd, buf, wanted);
        if (n < 0) {
                /*
                 * This fix is for Symantec during importing
                 * of spanned data between the tapes.
                 */
                if (errno == ENOSPC) {
                        reply->error = NDMP_EOF_ERR;
                } else {
                        NDMP_LOG(LOG_ERR, "Tape read error: %m.");
                        reply->error = NDMP_IO_ERR;
                }
        } else if (n == 0) {
                NDMP_LOG(LOG_DEBUG, "NDMP_EOF_ERR");

                reply->error = NDMP_EOF_ERR;

                (void) ndmp_mtioctl(session->ns_tape.td_fd, MTFSF, 1);

                len = strlen(NDMP_EOM_MAGIC);
                (void) memset(buf, 0, len);
                n = read(session->ns_tape.td_fd, buf, len);
                buf[len] = '\0';

                NDMP_LOG(LOG_DEBUG, "Checking EOM: nread %d [%s]", n, buf);

                (void) ndmp_mtioctl(session->ns_tape.td_fd, MTBSF, 1);

                if (strncmp(buf, NDMP_EOM_MAGIC, len) != 0)
                        (void) ndmp_mtioctl(session->ns_tape.td_fd, MTFSF, 1);
        } else {
                session->ns_tape.td_pos += n;
                reply->data_in.data_in_len = n;
                reply->data_in.data_in_val = buf;
                reply->error = NDMP_NO_ERR;
                NS_ADD(rtape, n);
        }
}


/*
 * validmode
 *
 * Check the tape read mode is valid
 */
static boolean_t
validmode(int mode)
{
        boolean_t rv;

        switch (mode) {
        case NDMP_TAPE_READ_MODE:
        case NDMP_TAPE_WRITE_MODE:
        case NDMP_TAPE_RAW1_MODE:
        case NDMP_TAPE_RAW2_MODE:
                rv = TRUE;
                break;
        default:
                rv = FALSE;
        }

        return (rv);
}


/*
 * common_tape_open
 *
 * Generic function for opening the tape for all versions
 *
 * Parameters:
 *   connection (input) - connection handle.
 *   devname (input) - tape device name to open.
 *   ndmpmode (input) - mode of opening (read, write, raw)
 *
 * Returns:
 *   void
 */
static void
common_tape_open(ndmp_connection_t *connection, char *devname, int ndmpmode)
{
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        char adptnm[SCSI_MAX_NAME];
        int err;
        int mode;
        int sid, lun;
        scsi_adapter_t *sa;
        int devid;

        err = NDMP_NO_ERR;

        if (session->ns_tape.td_fd != -1 || session->ns_scsi.sd_is_open != -1) {
                NDMP_LOG(LOG_INFO,
                    "Connection already has a tape or scsi device open");
                err = NDMP_DEVICE_OPENED_ERR;
        } else if (!validmode(ndmpmode))
                err = NDMP_ILLEGAL_ARGS_ERR;
        if ((sa = scsi_get_adapter(0)) != NULL) {
                NDMP_LOG(LOG_DEBUG, "Adapter device opened: %s", devname);
                (void) strlcpy(adptnm, devname, SCSI_MAX_NAME-2);
                adptnm[SCSI_MAX_NAME-1] = '\0';
                sid = lun = -1;
        }
        if (sa) {
                scsi_find_sid_lun(sa, devname, &sid, &lun);
                if (ndmp_open_list_find(devname, sid, lun) == 0 &&
                    (devid = open(devname, O_RDWR | O_NDELAY)) < 0) {
                        NDMP_LOG(LOG_ERR,
                            "Failed to open device %s: %m.", devname);
                        err = NDMP_NO_DEVICE_ERR;
                } else {
                        (void) close(devid);
                }
        } else {
                NDMP_LOG(LOG_ERR, "%s: No such tape device.", devname);
                err = NDMP_NO_DEVICE_ERR;
        }

        if (err != NDMP_NO_ERR) {
                tape_open_send_reply(connection, err);
                return;
        }

        /*
         * If tape is not opened in raw mode and tape is not loaded
         * return error.
         */
        if (ndmpmode != NDMP_TAPE_RAW1_MODE &&
            ndmpmode != NDMP_TAPE_RAW2_MODE &&
            !is_tape_unit_ready(adptnm, 0)) {
                tape_open_send_reply(connection, NDMP_NO_TAPE_LOADED_ERR);
                return;
        }

        mode = (ndmpmode == NDMP_TAPE_READ_MODE) ? O_RDONLY : O_RDWR;
        mode |= O_NDELAY;
        session->ns_tape.td_fd = open(devname, mode);
        if (session->ns_protocol_version == NDMPV4 &&
            session->ns_tape.td_fd < 0 &&
            ndmpmode == NDMP_TAPE_RAW_MODE && errno == EACCES) {
                /*
                 * V4 suggests that if the tape is open in raw mode
                 * and could not be opened with write access, it should
                 * be opened read only instead.
                 */
                ndmpmode = NDMP_TAPE_READ_MODE;
                session->ns_tape.td_fd = open(devname, O_RDONLY);
        }
        if (session->ns_tape.td_fd < 0) {
                NDMP_LOG(LOG_ERR, "Failed to open tape device %s: %m.",
                    devname);
                switch (errno) {
                case EACCES:
                        err = NDMP_WRITE_PROTECT_ERR;
                        break;
                case ENOENT:
                        err = NDMP_NO_DEVICE_ERR;
                        break;
                case EBUSY:
                        err = NDMP_DEVICE_BUSY_ERR;
                        break;
                case EPERM:
                        err = NDMP_PERMISSION_ERR;
                        break;
                default:
                        err = NDMP_IO_ERR;
                }

                tape_open_send_reply(connection, err);
                return;
        }

        switch (ndmp_open_list_add(connection,
            adptnm, sid, lun, session->ns_tape.td_fd)) {
        case 0:
                err = NDMP_NO_ERR;
                break;
        case EBUSY:
                err = NDMP_DEVICE_BUSY_ERR;
                break;
        case ENOMEM:
                err = NDMP_NO_MEM_ERR;
                break;
        default:
                err = NDMP_IO_ERR;
        }
        if (err != NDMP_NO_ERR) {
                tape_open_send_reply(connection, err);
                return;
        }

        session->ns_tape.td_mode = ndmpmode;
        session->ns_tape.td_sid = sid;
        session->ns_tape.td_lun = lun;
        (void) strlcpy(session->ns_tape.td_adapter_name, adptnm, SCSI_MAX_NAME);
        session->ns_tape.td_record_count = 0;

        NDMP_LOG(LOG_DEBUG, "Tape is opened fd: %d", session->ns_tape.td_fd);

        tape_open_send_reply(connection, NDMP_NO_ERR);
}


/*
 * common_tape_close
 *
 * Generic function for closing the tape
 *
 * Parameters:
 *   connection (input) - connection handle.
 *
 * Returns:
 *   void
 */
static void
common_tape_close(ndmp_connection_t *connection)
{
        ndmpd_session_t *session = ndmp_get_client_data(connection);
        ndmp_tape_close_reply reply;

        (void) ndmp_open_list_del(session->ns_tape.td_adapter_name,
            session->ns_tape.td_sid, session->ns_tape.td_lun);
        (void) close(session->ns_tape.td_fd);
        session->ns_tape.td_fd = -1;
        session->ns_tape.td_sid = 0;
        session->ns_tape.td_lun = 0;
        (void) memset(session->ns_tape.td_adapter_name, 0,
            sizeof (session->ns_tape.td_adapter_name));
        session->ns_tape.td_record_count = 0;

        reply.error = NDMP_NO_ERR;
        ndmp_send_reply(connection, (void *) &reply,
            "sending tape_close reply");
}

/*
 * tape_open
 *
 * Will try to open the tape with the given flags and
 * path using the given retries and delay intervals
 */
int
tape_open(char *path, int flags)
{
        int fd;
        int i = 0;

        while ((fd = open(path, flags)) == -1 &&
            i++ < ndmp_tape_open_retries) {
                if (errno != EBUSY)
                        break;
                (void) usleep(ndmp_tape_open_delay);
        }
        return (fd);
}