Merge branch 'patch-1' of https://github.com/dtrebbien/util-linux

[thirdparty/util-linux.git] / sys-utils / eject.c

/*
 * Copyright (C) 1994-2005 Jeff Tranter (tranter@pobox.com)
 * Copyright (C) 2012 Karel Zak <kzak@redhat.com>
 * Copyright (C) Michal Luscon <mluscon@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <limits.h>
#include <err.h>
#include <stdarg.h>

#include <getopt.h>
#include <errno.h>
#include <regex.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <sys/mtio.h>
#include <linux/cdrom.h>
#include <linux/fd.h>
#include <sys/mount.h>
#include <scsi/scsi.h>
#include <scsi/sg.h>
#include <scsi/scsi_ioctl.h>
#include <sys/time.h>

#include <libmount.h>

#include "c.h"
#include "closestream.h"
#include "nls.h"
#include "strutils.h"
#include "xalloc.h"
#include "pathnames.h"
#include "sysfs.h"

#define EJECT_DEFAULT_DEVICE "/dev/cdrom"


/* Used by the toggle_tray() function. If ejecting the tray takes this
 * time or less, the tray was probably already ejected, so we close it
 * again.
 */
#define TRAY_WAS_ALREADY_OPEN_USECS  200000     /* about 0.2 seconds */

/* eject(1) is able to eject only 'removable' devices (attribute in /sys)
 * _or_ devices connected by hotplug subsystem.
 */
static const char * const hotplug_subsystems[] = {
        "usb",
        "ieee1394",
        "pcmcia",
        "mmc",
        "ccw"
};

/* Global Variables */
static int a_option; /* command flags and arguments */
static int c_option;
static int d_option;
static int f_option;
static int F_option;
static int n_option;
static int q_option;
static int r_option;
static int s_option;
static int t_option;
static int T_option;
static int X_option;
static int v_option;
static int x_option;
static int p_option;
static int m_option;
static int M_option;
static int i_option;
static int a_arg;
static int i_arg;
static long int c_arg;
static long int x_arg;

struct libmnt_table *mtab;
struct libmnt_cache *cache;

static void vinfo(const char *fmt, va_list va)
{
        fprintf(stdout, "%s: ", program_invocation_short_name);
        vprintf(fmt, va);
        fputc('\n', stdout);
}

static inline void verbose(const char *fmt, ...)
{
        va_list va;

        if (!v_option)
                return;

        va_start(va, fmt);
        vinfo(fmt, va);
        va_end(va);
}

static inline void info(const char *fmt, ...)
{
        va_list va;
        va_start(va, fmt);
        vinfo(fmt, va);
        va_end(va);
}

static void __attribute__ ((__noreturn__)) usage(FILE * out)
{
        fputs(USAGE_HEADER, out);

        fprintf(out,
                _(" %s [options] [<device>|<mountpoint>]\n"), program_invocation_short_name);

        fputs(USAGE_OPTIONS, out);
        fputs(_(" -a, --auto <on|off>         turn auto-eject feature on or off\n"
                " -c, --changerslot <slot>    switch discs on a CD-ROM changer\n"
                " -d, --default               display default device\n"
                " -f, --floppy                eject floppy\n"
                " -F, --force                 don't care about device type\n"
                " -i, --manualeject <on|off>  toggle manual eject protection on/off\n"
                " -m, --no-unmount            do not unmount device even if it is mounted\n"
                " -M, --no-partitions-unmount do not unmount another partitions\n"
                " -n, --noop                  don't eject, just show device found\n"
                " -p, --proc                  use /proc/mounts instead of /etc/mtab\n"
                " -q, --tape                  eject tape\n"
                " -r, --cdrom                 eject CD-ROM\n"
                " -s, --scsi                  eject SCSI device\n"
                " -t, --trayclose             close tray\n"
                " -T, --traytoggle            toggle tray\n"
                " -v, --verbose               enable verbose output\n"
                " -x, --cdspeed <speed>       set CD-ROM max speed\n"
                " -X, --listspeed             list CD-ROM available speeds\n"),
                out);

        fputs(USAGE_SEPARATOR, out);
        fputs(USAGE_HELP, out);
        fputs(USAGE_VERSION, out);

        fputs(_("\nBy default tries -r, -s, -f, and -q in order until success.\n"), out);
        fprintf(out, USAGE_MAN_TAIL("eject(1)"));

        exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}


/* Handle command line options. */
static void parse_args(int argc, char **argv, char **device)
{
        static const struct option long_opts[] =
        {
                {"auto",        required_argument, NULL, 'a'},
                {"cdrom",       no_argument,       NULL, 'r'},
                {"cdspeed",     required_argument, NULL, 'x'},
                {"changerslot", required_argument, NULL, 'c'},
                {"default",     no_argument,       NULL, 'd'},
                {"floppy",      no_argument,       NULL, 'f'},
                {"force",       no_argument,       NULL, 'F'},
                {"help",        no_argument,       NULL, 'h'},
                {"listspeed",   no_argument,       NULL, 'X'},
                {"manualeject", required_argument, NULL, 'i'},
                {"noop",        no_argument,       NULL, 'n'},
                {"no-unmount",  no_argument,       NULL, 'm'},
                {"no-partitions-unmount", no_argument, NULL, 'M' },
                {"proc",        no_argument,       NULL, 'p'},
                {"scsi",        no_argument,       NULL, 's'},
                {"tape",        no_argument,       NULL, 'q'},
                {"trayclose",   no_argument,       NULL, 't'},
                {"traytoggle",  no_argument,       NULL, 'T'},
                {"verbose",     no_argument,       NULL, 'v'},
                {"version",     no_argument,       NULL, 'V'},
                {0, 0, 0, 0}
        };
        int c;

        while ((c = getopt_long(argc, argv,
                                "a:c:i:x:dfFhnqrstTXvVpmM", long_opts, NULL)) != -1) {
                switch (c) {
                case 'a':
                        a_option = 1;
                        if (!strcmp(optarg, "0") || !strcmp(optarg, "off"))
                                a_arg = 0;
                        else if (!strcmp(optarg, "1") || !strcmp(optarg, "on"))
                                a_arg = 1;
                        else
                                errx(EXIT_FAILURE, _("invalid argument to --auto/-a option"));
                        break;
                case 'c':
                        c_option = 1;
                        c_arg = strtoul_or_err(optarg, _("invalid argument to --changerslot/-c option"));
                        break;
                case 'x':
                        x_option = 1;
                        x_arg = strtoul_or_err(optarg, _("invalid argument to --cdspeed/-x option"));
                        break;
                case 'd':
                        d_option = 1;
                        break;
                case 'f':
                        f_option = 1;
                        break;
                case 'F':
                        F_option = 1;
                        break;
                case 'h':
                        usage(stdout);
                        break;
                case 'i':
                        i_option = 1;
                        if (!strcmp(optarg, "0") || !strcmp(optarg, "off"))
                                i_arg = 0;
                        else if (!strcmp(optarg, "1") || !strcmp(optarg, "on"))
                                i_arg = 1;
                        else
                                errx(EXIT_FAILURE, _("invalid argument to --manualeject/-i option"));
                        break;
                case 'm':
                        m_option = 1;
                        break;
                case 'M':
                        M_option = 1;
                        break;
                case 'n':
                        n_option = 1;
                        break;
                case 'p':
                        p_option = 1;
                        break;
                case 'q':
                        q_option = 1;
                        break;
                case 'r':
                        r_option = 1;
                        break;
                case 's':
                        s_option = 1;
                        break;
                case 't':
                        t_option = 1;
                        break;
                case 'T':
                        T_option = 1;
                        break;
                case 'X':
                        X_option = 1;
                        break;
                case 'v':
                        v_option = 1;
                        break;
                case 'V':
                        printf(UTIL_LINUX_VERSION);
                        exit(EXIT_SUCCESS);
                        break;
                default:
                case '?':
                        usage(stderr);
                        break;
                }
        }

        /* check for a single additional argument */
        if ((argc - optind) > 1)
                errx(EXIT_FAILURE, _("too many arguments"));

        if ((argc - optind) == 1)
                *device = xstrdup(argv[optind]);
}

/*
 * Given name, such as foo, see if any of the following exist:
 *
 * foo (if foo starts with '.' or '/')
 * /dev/foo
 *
 * If found, return the full path. If not found, return 0.
 * Returns pointer to dynamically allocated string.
 */
static char *find_device(const char *name)
{
        if (!name)
                return NULL;

        if ((*name == '.' || *name == '/') && access(name, F_OK) == 0)
                return xstrdup(name);
        else {
                char buf[PATH_MAX];

                snprintf(buf, sizeof(buf), "/dev/%s", name);
                if (access(buf, F_OK) == 0)
                        return xstrdup(buf);
        }

        return NULL;
}

/* Set or clear auto-eject mode. */
static void auto_eject(int fd, int on)
{
        int status = -1;

#if defined(CDROM_SET_OPTIONS) && defined(CDROM_CLEAR_OPTIONS)
        if (on)
                status = ioctl(fd, CDROM_SET_OPTIONS, CDO_AUTO_EJECT);
        else
                status = ioctl(fd, CDROM_CLEAR_OPTIONS, CDO_AUTO_EJECT);
#else
        errno = ENOSYS;
#endif
        if (status < 0)
                err(EXIT_FAILURE,_("CD-ROM auto-eject command failed"));
}

/*
 * Stops CDROM from opening on manual eject pressing the button.
 * This can be useful when you carry your laptop
 * in your bag while it's on and no CD inserted in it's drive.
 * Implemented as found in Documentation/ioctl/cdrom.txt
 *
 * TODO: Maybe we should check this also:
 * EDRIVE_CANT_DO_THIS   Door lock function not supported.
 * EBUSY                 Attempt to unlock when multiple users
 *                       have the drive open and not CAP_SYS_ADMIN
 */
static void manual_eject(int fd, int on)
{
        if (ioctl(fd, CDROM_LOCKDOOR, on) < 0)
                err(EXIT_FAILURE, _("CD-ROM lock door command failed"));

        if (on)
                info(_("CD-Drive may NOT be ejected with device button"));
        else
                info(_("CD-Drive may be ejected with device button"));
}

/*
 * Changer select. CDROM_SELECT_DISC is preferred, older kernels used
 * CDROMLOADFROMSLOT.
 */
static void changer_select(int fd, int slot)
{
#ifdef CDROM_SELECT_DISC
        if (ioctl(fd, CDROM_SELECT_DISC, slot) < 0)
                err(EXIT_FAILURE, _("CD-ROM select disc command failed"));

#elif defined CDROMLOADFROMSLOT
        if (ioctl(fd, CDROMLOADFROMSLOT, slot) != 0)
                err(EXIT_FAILURE, _("CD-ROM load from slot command failed"));
#else
        warnx(_("IDE/ATAPI CD-ROM changer not supported by this kernel\n") );
#endif
}

/*
 * Close tray. Not supported by older kernels.
 */
static void close_tray(int fd)
{
        int status;

#if defined(CDROMCLOSETRAY) || defined(CDIOCCLOSE)
#if defined(CDROMCLOSETRAY)
        status = ioctl(fd, CDROMCLOSETRAY);
#elif defined(CDIOCCLOSE)
        status = ioctl(fd, CDIOCCLOSE);
#endif
        if (status != 0)
                err(EXIT_FAILURE, _("CD-ROM tray close command failed"));
#else
        warnx(_("CD-ROM tray close command not supported by this kernel\n"));
#endif
}

/*
 * Eject using CDROMEJECT ioctl.
 */
static int eject_cdrom(int fd)
{
#if defined(CDROMEJECT)
        return ioctl(fd, CDROMEJECT) >= 0;
#elif defined(CDIOCEJECT)
        return ioctl(fd, CDIOCEJECT) >= 0;
#else
        warnx(_("CD-ROM eject unsupported"));
        errno = ENOSYS;
        return 0;
#endif
}

/*
 * Toggle tray.
 *
 * Written by Benjamin Schwenk <benjaminschwenk@yahoo.de> and
 * Sybren Stuvel <sybren@thirdtower.com>
 *
 * Not supported by older kernels because it might use
 * CloseTray().
 *
 */
static void toggle_tray(int fd)
{
        struct timeval time_start, time_stop;
        int time_elapsed;

#ifdef CDROM_DRIVE_STATUS
        /* First ask the CDROM for info, otherwise fall back to manual.  */
        switch (ioctl(fd, CDROM_DRIVE_STATUS)) {
        case CDS_TRAY_OPEN:
                close_tray(fd);
                return;

        case CDS_NO_DISC:
        case CDS_DISC_OK:
                if (!eject_cdrom(fd))
                        err(EXIT_FAILURE, _("CD-ROM eject command failed"));
                return;
        case CDS_NO_INFO:
                warnx(_("no CD-ROM information available"));
                return;
        case CDS_DRIVE_NOT_READY:
                warnx(_("CD-ROM drive is not ready"));
                return;
        default:
                abort();
        }
#endif

        /* Try to open the CDROM tray and measure the time therefor
         * needed.  In my experience the function needs less than 0.05
         * seconds if the tray was already open, and at least 1.5 seconds
         * if it was closed.  */
        gettimeofday(&time_start, NULL);

        /* Send the CDROMEJECT command to the device. */
        if (!eject_cdrom(fd))
                err(EXIT_FAILURE, _("CD-ROM eject command failed"));

        /* Get the second timestamp, to measure the time needed to open
         * the tray.  */
        gettimeofday(&time_stop, NULL);

        time_elapsed = (time_stop.tv_sec * 1000000 + time_stop.tv_usec) -
                (time_start.tv_sec * 1000000 + time_start.tv_usec);

        /* If the tray "opened" too fast, we can be nearly sure, that it
         * was already open. In this case, close it now. Else the tray was
         * closed before. This would mean that we are done.  */
        if (time_elapsed < TRAY_WAS_ALREADY_OPEN_USECS)
                close_tray(fd);
}

/*
 * Select Speed of CD-ROM drive.
 * Thanks to Roland Krivanek (krivanek@fmph.uniba.sk)
 * http://dmpc.dbp.fmph.uniba.sk/~krivanek/cdrom_speed/
 */
static void select_speed(int fd, int speed)
{
#ifdef CDROM_SELECT_SPEED
        if (ioctl(fd, CDROM_SELECT_SPEED, speed) != 0)
                err(EXIT_FAILURE, _("CD-ROM select speed command failed"));
#else
        warnx(_("CD-ROM select speed command not supported by this kernel"));
#endif
}

/*
 * Read Speed of CD-ROM drive. From Linux 2.6.13, the current speed
 * is correctly reported
 */
static int read_speed(const char *devname)
{
        int drive_number = -1;
        char *name;
        FILE *f;

        f = fopen(_PATH_PROC_CDROMINFO, "r");
        if (!f)
                err(EXIT_FAILURE, _("cannot open %s"), _PATH_PROC_CDROMINFO);

        name = strrchr(devname, '/') + 1;

        while (name && !feof(f)) {
                char line[512];
                char *str;

                if (!fgets(line, sizeof(line), f))
                        break;

                /* find drive number in line "drive name" */
                if (drive_number == -1) {
                        if (strncmp(line, "drive name:", 11) == 0) {
                                str = strtok(&line[11], "\t ");
                                drive_number = 0;
                                while (str && strncmp(name, str, strlen(name)) != 0) {
                                        drive_number++;
                                        str = strtok(NULL, "\t ");
                                        if (!str)
                                                errx(EXIT_FAILURE,
                                                     _("%s: failed to finding CD-ROM name"),
                                                     _PATH_PROC_CDROMINFO);
                                }
                        }
                /* find line "drive speed" and read the correct speed */
                } else {
                        if (strncmp(line, "drive speed:", 12) == 0) {
                                int i;

                                str = strtok(&line[12], "\t ");
                                for (i = 1; i < drive_number; i++)
                                        str = strtok(NULL, "\t ");

                                if (!str)
                                        errx(EXIT_FAILURE,
                                                _("%s: failed to read speed"),
                                                _PATH_PROC_CDROMINFO);
                                fclose(f);
                                return atoi(str);
                        }
                }
        }

        errx(EXIT_FAILURE, _("failed to read speed"));
}

/*
 * List Speed of CD-ROM drive.
 */
static void list_speeds(const char *name, int fd)
{
#ifdef CDROM_SELECT_SPEED
        int max_speed, curr_speed = 0, prev_speed;

        select_speed(fd, 0);
        max_speed = read_speed(name);

        while (curr_speed < max_speed) {
                prev_speed = curr_speed;
                select_speed(fd, prev_speed + 1);
                curr_speed = read_speed(name);
                if (curr_speed > prev_speed)
                        printf("%d ", curr_speed);
                else
                        curr_speed = prev_speed + 1;
        }

        printf("\n");
#else
        warnx(_("CD-ROM select speed command not supported by this kernel"));
#endif
}

/*
 * Eject using SCSI SG_IO commands. Return 1 if successful, 0 otherwise.
 */
static int eject_scsi(int fd)
{
        int status, k;
        sg_io_hdr_t io_hdr;
        unsigned char allowRmBlk[6] = {ALLOW_MEDIUM_REMOVAL, 0, 0, 0, 0, 0};
        unsigned char startStop1Blk[6] = {START_STOP, 0, 0, 0, 1, 0};
        unsigned char startStop2Blk[6] = {START_STOP, 0, 0, 0, 2, 0};
        unsigned char inqBuff[2];
        unsigned char sense_buffer[32];

        if ((ioctl(fd, SG_GET_VERSION_NUM, &k) < 0) || (k < 30000)) {
                verbose(_("not an sg device, or old sg driver"));
                return 0;
        }

        memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
        io_hdr.interface_id = 'S';
        io_hdr.cmd_len = 6;
        io_hdr.mx_sb_len = sizeof(sense_buffer);
        io_hdr.dxfer_direction = SG_DXFER_NONE;
        io_hdr.dxfer_len = 0;
        io_hdr.dxferp = inqBuff;
        io_hdr.sbp = sense_buffer;
        io_hdr.timeout = 10000;

        io_hdr.cmdp = allowRmBlk;
        status = ioctl(fd, SG_IO, (void *)&io_hdr);
        if (status < 0)
                return 0;

        io_hdr.cmdp = startStop1Blk;
        status = ioctl(fd, SG_IO, (void *)&io_hdr);
        if (status < 0)
                return 0;

        io_hdr.cmdp = startStop2Blk;
        status = ioctl(fd, SG_IO, (void *)&io_hdr);
        if (status < 0)
                return 0;

        /* force kernel to reread partition table when new disc inserted */
        status = ioctl(fd, BLKRRPART);
        return 1;
}

/*
 * Eject using FDEJECT ioctl. Return 1 if successful, 0 otherwise.
 */
static int eject_floppy(int fd)
{
        return ioctl(fd, FDEJECT) >= 0;
}


/*
 * Rewind and eject using tape ioctl. Return 1 if successful, 0 otherwise.
 */
static int eject_tape(int fd)
{
        struct mtop op = { .mt_op = MTOFFL, .mt_count = 0 };

        return ioctl(fd, MTIOCTOP, &op) >= 0;
}


/* umount a device. */
static void umount_one(const char *name)
{
        int status;

        if (!name)
                return;

        verbose(_("%s: unmounting"), name);

        switch (fork()) {
        case 0: /* child */
                if (setgid(getgid()) < 0)
                        err(EXIT_FAILURE, _("cannot set group id"));

                if (setuid(getuid()) < 0)
                        err(EXIT_FAILURE, _("cannot set user id"));

                if (p_option)
                        execl("/bin/umount", "/bin/umount", name, "-n", NULL);
                else
                        execl("/bin/umount", "/bin/umount", name, NULL);

                errx(EXIT_FAILURE, _("unable to exec /bin/umount of `%s'"), name);

        case -1:
                warn( _("unable to fork"));
                break;

        default: /* parent */
                wait(&status);
                if (WIFEXITED(status) == 0)
                        errx(EXIT_FAILURE,
                             _("unmount of `%s' did not exit normally"), name);

                if (WEXITSTATUS(status) != 0)
                        errx(EXIT_FAILURE, _("unmount of `%s' failed\n"), name);
                break;
        }
}

/* Open a device file. */
static int open_device(const char *name)
{
        int fd = open(name, O_RDWR|O_NONBLOCK);

        if (fd < 0)
                fd = open(name, O_RDONLY|O_NONBLOCK);
        if (fd == -1)
                err(EXIT_FAILURE, _("cannot open %s"), name);
        return fd;
}

/*
 * See if device has been mounted by looking in mount table.  If so, set
 * device name and mount point name, and return 1, otherwise return 0.
 */
static int device_get_mountpoint(char **devname, char **mnt)
{
        struct libmnt_fs *fs;
        int rc;

        *mnt = NULL;

        if (!mtab) {
                mtab = mnt_new_table();
                if (!mtab)
                        err(EXIT_FAILURE, _("failed to initialize libmount table"));

                cache = mnt_new_cache();
                mnt_table_set_cache(mtab, cache);

                if (p_option)
                        rc = mnt_table_parse_file(mtab, _PATH_PROC_MOUNTINFO);
                else
                        rc = mnt_table_parse_mtab(mtab, NULL);
                if (rc)
                        err(EXIT_FAILURE, _("failed to parse mount table"));
        }

        fs = mnt_table_find_source(mtab, *devname, MNT_ITER_BACKWARD);
        if (!fs) {
                /* maybe 'devname' is mountpoint rather than a real device */
                fs = mnt_table_find_target(mtab, *devname, MNT_ITER_BACKWARD);
                if (fs) {
                        free(*devname);
                        *devname = xstrdup(mnt_fs_get_source(fs));
                }
        }

        if (fs)
                *mnt = xstrdup(mnt_fs_get_target(fs));
        return *mnt ? 0 : -1;
}

static char *get_disk_devname(const char *device)
{
        struct stat st;
        dev_t diskno = 0;
        char diskname[128];

        if (stat(device, &st) != 0)
                return NULL;

        /* get whole-disk devno */
        if (sysfs_devno_to_wholedisk(st.st_rdev, diskname,
                                sizeof(diskname), &diskno) != 0)
                return NULL;

        return st.st_rdev == diskno ? NULL : find_device(diskname);
}

static int umount_partitions(const char *disk, int checkonly)
{
        struct sysfs_cxt cxt = UL_SYSFSCXT_EMPTY;
        dev_t devno;
        DIR *dir = NULL;
        struct dirent *d;
        int count = 0;

        devno = sysfs_devname_to_devno(disk, NULL);
        if (sysfs_init(&cxt, devno, NULL) != 0)
                return 0;

        /* open /sys/block/<wholedisk> */
        if (!(dir = sysfs_opendir(&cxt, NULL)))
                goto done;

        /* scan for partition subdirs */
        while ((d = readdir(dir))) {
                if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
                        continue;

                if (sysfs_is_partition_dirent(dir, d, disk)) {
                        char *mnt = NULL;
                        char *dev = find_device(d->d_name);

                        if (dev && device_get_mountpoint(&dev, &mnt) == 0) {
                                verbose(_("%s: mounted on %s"), dev, mnt);
                                if (!checkonly)
                                        umount_one(mnt);
                                count++;
                        }
                        free(dev);
                        free(mnt);
                }
        }

done:
        if (dir)
                closedir(dir);
        sysfs_deinit(&cxt);

        return count;
}

static int is_hotpluggable_subsystem(const char *name)
{
        size_t i;

        for (i = 0; i < ARRAY_SIZE(hotplug_subsystems); i++)
                if (strcmp(name, hotplug_subsystems[i]) == 0)
                        return 1;

        return 0;
}

#define SUBSYSTEM_LINKNAME      "/subsystem"

/*
 * For example:
 *
 * chain: /sys/dev/block/../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/ \
 *                           1-1.2:1.0/host65/target65:0:0/65:0:0:0/block/sdb
 *
 * The function check if <chain>/subsystem symlink exists, if yes then returns
 * basename of the readlink result, and remove the last subdirectory from the
 * <chain> path.
 */
static char *get_subsystem(char *chain, char *buf, size_t bufsz)
{
        size_t len;
        char *p;

        if (!chain || !*chain)
                return NULL;

        len = strlen(chain);
        if (len + sizeof(SUBSYSTEM_LINKNAME) > PATH_MAX)
                return NULL;

        do {
                ssize_t sz;

                /* append "/subsystem" to the path */
                memcpy(chain + len, SUBSYSTEM_LINKNAME, sizeof(SUBSYSTEM_LINKNAME));

                /* try if subsystem symlink exists */
                sz = readlink(chain, buf, bufsz - 1);

                /* remove last subsystem from chain */
                chain[len] = '\0';
                p = strrchr(chain, '/');
                if (p) {
                        *p = '\0';
                        len = p - chain;
                }

                if (sz > 0) {
                        /* we found symlink to subsystem, return basename */
                        buf[sz] = '\0';
                        return basename(buf);
                }

        } while (p);

        return NULL;
}

static int is_hotpluggable(const char* device)
{
        struct sysfs_cxt cxt = UL_SYSFSCXT_EMPTY;
        char devchain[PATH_MAX];
        char subbuf[PATH_MAX];
        dev_t devno;
        int rc = 0;
        ssize_t sz;
        char *sub;

        devno = sysfs_devname_to_devno(device, NULL);
        if (sysfs_init(&cxt, devno, NULL) != 0)
                return 0;

        /* check /sys/dev/block/<maj>:<min>/removable attribute */
        if (sysfs_read_int(&cxt, "removable", &rc) == 0 && rc == 1) {
                verbose(_("%s: is removable device"), device);
                goto done;
        }

        /* read /sys/dev/block/<maj>:<min> symlink */
        sz = sysfs_readlink(&cxt, NULL, devchain, sizeof(devchain));
        if (sz <= 0 || sz + sizeof(_PATH_SYS_DEVBLOCK "/") > sizeof(devchain))
                goto done;

        devchain[sz++] = '\0';

        /* create absolute patch from the link */
        memmove(devchain + sizeof(_PATH_SYS_DEVBLOCK "/") - 1, devchain, sz);
        memcpy(devchain, _PATH_SYS_DEVBLOCK "/",
               sizeof(_PATH_SYS_DEVBLOCK "/") - 1);

        while ((sub = get_subsystem(devchain, subbuf, sizeof(subbuf)))) {
                rc = is_hotpluggable_subsystem(sub);
                if (rc) {
                        verbose(_("%s: connected by hotplug subsystem: %s"),
                                device, sub);
                        break;
                }
        }

done:
        sysfs_deinit(&cxt);
        return rc;
}


/* handle -x option */
static void set_device_speed(char *name)
{
        int fd;

        if (!x_option)
                return;

        if (x_arg == 0)
                verbose(_("setting CD-ROM speed to auto"));
        else
                verbose(_("setting CD-ROM speed to %ldX"), x_arg);

        fd = open_device(name);
        select_speed(fd, x_arg);
        exit(EXIT_SUCCESS);
}


/* main program */
int main(int argc, char **argv)
{
        char *device = NULL;
        char *disk = NULL;
        char *mountpoint = NULL;
        int worked = 0;    /* set to 1 when successfully ejected */
        int fd;            /* file descriptor for device */

        setlocale(LC_ALL,"");
        bindtextdomain(PACKAGE, LOCALEDIR);
        textdomain(PACKAGE);
        atexit(close_stdout);

        /* parse the command line arguments */
        parse_args(argc, argv, &device);

        /* handle -d option */
        if (d_option) {
                info(_("default device: `%s'"), EJECT_DEFAULT_DEVICE);
                return EXIT_SUCCESS;
        }

        if (!device) {
                device = mnt_resolve_path(EJECT_DEFAULT_DEVICE, NULL);
                verbose(_("using default device `%s'"), device);
        } else {
                char *p;

                if (device[strlen(device)-1] == '/')
                        device[strlen(device)-1] = '\0';

                /* figure out full device or mount point name */
                p = find_device(device);
                if (p)
                        free(device);
                else
                        p = device;

                device = mnt_resolve_spec(p, NULL);
                free(p);
        }

        if (!device)
                errx(EXIT_FAILURE, _("%s: unable to find device"), device);

        verbose(_("device name is `%s'"), device);

        device_get_mountpoint(&device, &mountpoint);
        if (mountpoint)
                verbose(_("%s: mounted on %s"), device, mountpoint);
        else
                verbose(_("%s: not mounted"), device);

        disk = get_disk_devname(device);
        if (disk) {
                verbose(_("%s: disc device: %s (disk device will be used for eject)"), device, disk);
                free(device);
                device = disk;
                disk = NULL;
        } else {
                struct stat st;

                if (stat(device, &st) != 0 || !S_ISBLK(st.st_mode))
                        errx(EXIT_FAILURE, _("%s: not found mountpoint or device "
                                        "with the given name"), device);

                verbose(_("%s: is whole-disk device"), device);
        }

        if (F_option == 0 && is_hotpluggable(device) == 0)
                errx(EXIT_FAILURE, _("%s: is not hot-pluggable device"), device);

        /* handle -n option */
        if (n_option) {
                info(_("device is `%s'"), device);
                verbose(_("exiting due to -n/--noop option"));
                return EXIT_SUCCESS;
        }

        /* handle -i option */
        if (i_option) {
                fd = open_device(device);
                manual_eject(fd, i_arg);
                return EXIT_SUCCESS;
        }

        /* handle -a option */
        if (a_option) {
                if (a_arg)
                        verbose(_("%s: enabling auto-eject mode"), device);
                else
                        verbose(_("%s: disabling auto-eject mode"), device);
                fd = open_device(device);
                auto_eject(fd, a_arg);
                return EXIT_SUCCESS;
        }

        /* handle -t option */
        if (t_option) {
                verbose(_("%s: closing tray"), device);
                fd = open_device(device);
                close_tray(fd);
                set_device_speed(device);
                return EXIT_SUCCESS;
        }

        /* handle -T option */
        if (T_option) {
                verbose(_("%s: toggling tray"), device);
                fd = open_device(device);
                toggle_tray(fd);
                set_device_speed(device);
                return EXIT_SUCCESS;
        }

        /* handle -X option */
        if (X_option) {
                verbose(_("%s: listing CD-ROM speed"), device);
                fd = open_device(device);
                list_speeds(device, fd);
                return EXIT_SUCCESS;
        }

        /* handle -x option only */
        if (!c_option)
                set_device_speed(device);


        /*
         * Unmount all partitions if -m is not specified; or umount given
         * mountpoint if -M is specified, otherwise print error of another
         * partition is mounted.
         */
        if (!m_option) {
                int ct = umount_partitions(device, M_option);

                if (ct == 0 && mountpoint)
                        umount_one(mountpoint); /* probably whole-device */

                if (M_option) {
                        if (ct == 1 && mountpoint)
                                umount_one(mountpoint);
                        else if (ct)
                                errx(EXIT_FAILURE, _("error: %s: device in use"), device);
                }
        }

        /* handle -c option */
        if (c_option) {
                verbose(_("%s: selecting CD-ROM disc #%ld"), device, c_arg);
                fd = open_device(device);
                changer_select(fd, c_arg);
                set_device_speed(device);
                return EXIT_SUCCESS;
        }

        /* if user did not specify type of eject, try all four methods */
        if (r_option + s_option + f_option + q_option == 0)
                r_option = s_option = f_option = q_option = 1;

        /* open device */
        fd = open_device(device);

        /* try various methods of ejecting until it works */
        if (r_option) {
                verbose(_("%s: trying to eject using CD-ROM eject command"), device);
                worked = eject_cdrom(fd);
                verbose(worked ? _("CD-ROM eject command succeeded") :
                                 _("CD-ROM eject command failed"));
        }

        if (s_option && !worked) {
                verbose(_("%s: trying to eject using SCSI commands"), device);
                worked = eject_scsi(fd);
                verbose(worked ? _("SCSI eject succeeded") :
                                 _("SCSI eject failed"));
        }

        if (f_option && !worked) {
                verbose(_("%s: trying to eject using floppy eject command"), device);
                worked = eject_floppy(fd);
                verbose(worked ? _("floppy eject command succeeded") :
                                 _("floppy eject command failed"));
        }

        if (q_option && !worked) {
                verbose(_("%s: trying to eject using tape offline command"), device);
                worked = eject_tape(fd);
                verbose(worked ? _("tape offline command succeeded") :
                                 _("tape offline command failed"));
        }

        if (!worked)
                errx(EXIT_FAILURE, _("unable to eject"));

        /* cleanup */
        close(fd);
        free(device);
        free(mountpoint);

        mnt_free_table(mtab);
        mnt_free_cache(cache);

        return EXIT_SUCCESS;
}