/*
 * Copyright (C) 2011 matt mooney <mfm@muteddisk.com>
 *               2005-2007 Takahiro Hirofuchi
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <sysfs/libsysfs.h>

#include <errno.h>
#include <stdio.h>
#include <string.h>

#include <getopt.h>

#include "usbip_common.h"
#include "utils.h"
#include "usbip.h"

static const char usbip_unbind_usage_string[] =
        "usbip unbind <args>\n"
        "    -b, --busid=<busid>    Unbind " USBIP_HOST_DRV_NAME ".ko from "
        "device on <busid>\n";

void usbip_unbind_usage(void)
{
        printf("usage: %s", usbip_unbind_usage_string);
}

static int unbind_device(char *busid)
{
        char bus_type[] = "usb";
        struct sysfs_driver *usbip_host_drv;
        struct sysfs_device *dev;
        struct dlist *devlist;
        int verified = 0;
        int rc, ret = -1;

        char attr_name[] = "bConfigurationValue";
        char sysfs_mntpath[SYSFS_PATH_MAX];
        char busid_attr_path[SYSFS_PATH_MAX];
        struct sysfs_attribute *busid_attr;
        char *val = NULL;
        int len;

        /* verify the busid device is using usbip-host */
        usbip_host_drv = sysfs_open_driver(bus_type, USBIP_HOST_DRV_NAME);
        if (!usbip_host_drv) {
                err("could not open %s driver: %s", USBIP_HOST_DRV_NAME,
                    strerror(errno));
                return -1;
        }

        devlist = sysfs_get_driver_devices(usbip_host_drv);
        if (!devlist) {
                err("%s is not in use by any devices", USBIP_HOST_DRV_NAME);
                goto err_close_usbip_host_drv;
        }

        dlist_for_each_data(devlist, dev, struct sysfs_device) {
                if (!strncmp(busid, dev->name, strlen(busid)) &&
                    !strncmp(dev->driver_name, USBIP_HOST_DRV_NAME,
                             strlen(USBIP_HOST_DRV_NAME))) {
                        verified = 1;
                        break;
                }
        }

        if (!verified) {
                err("device on busid %s is not using %s", busid,
                    USBIP_HOST_DRV_NAME);
                goto err_close_usbip_host_drv;
        }

        /*
         * NOTE: A read and write of an attribute value of the device busid
         * refers to must be done to start probing. That way a rebind of the
         * default driver for the device occurs.
         *
         * This seems very hackish and adds a lot of pointless code. I think it
         * should be done in the kernel by the driver after del_match_busid is
         * finished!
         */

        rc = sysfs_get_mnt_path(sysfs_mntpath, SYSFS_PATH_MAX);
        if (rc < 0) {
                err("sysfs must be mounted: %s", strerror(errno));
                return -1;
        }

        snprintf(busid_attr_path, sizeof(busid_attr_path), "%s/%s/%s/%s/%s/%s",
                 sysfs_mntpath, SYSFS_BUS_NAME, bus_type, SYSFS_DEVICES_NAME,
                 busid, attr_name);

        /* read a device attribute */
        busid_attr = sysfs_open_attribute(busid_attr_path);
        if (!busid_attr) {
                err("could not open %s/%s: %s", busid, attr_name,
                    strerror(errno));
                return -1;
        }

        if (sysfs_read_attribute(busid_attr) < 0) {
                err("problem reading attribute: %s", strerror(errno));
                goto err_out;
        }

        len = busid_attr->len;
        val = malloc(len);
        *val = *busid_attr->value;
        sysfs_close_attribute(busid_attr);

        /* notify driver of unbind */
        rc = modify_match_busid(busid, 0);
        if (rc < 0) {
                err("unable to unbind device on %s", busid);
                goto err_out;
        }

        /* write the device attribute */
        busid_attr = sysfs_open_attribute(busid_attr_path);
        if (!busid_attr) {
                err("could not open %s/%s: %s", busid, attr_name,
                    strerror(errno));
                return -1;
        }

        rc = sysfs_write_attribute(busid_attr, val, len);
        if (rc < 0) {
                err("problem writing attribute: %s", strerror(errno));
                goto err_out;
        }
        sysfs_close_attribute(busid_attr);

        ret = 0;
        printf("unbind device on busid %s: complete\n", busid);

err_out:
        free(val);
err_close_usbip_host_drv:
        sysfs_close_driver(usbip_host_drv);

        return ret;
}

int usbip_unbind(int argc, char *argv[])
{
        static const struct option opts[] = {
                { "busid", required_argument, NULL, 'b' },
                { NULL,    0,                 NULL,  0  }
        };

        int opt;
        int ret = -1;

        for (;;) {
                opt = getopt_long(argc, argv, "b:", opts, NULL);

                if (opt == -1)
                        break;

                switch (opt) {
                case 'b':
                        ret = unbind_device(optarg);
                        goto out;
                default:
                        goto err_out;
                }
        }

err_out:
        usbip_unbind_usage();
out:
        return ret;
}