/*
 * 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 <libudev.h>

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

#include <getopt.h>

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

enum unbind_status {
        UNBIND_ST_OK,
        UNBIND_ST_USBIP_HOST,
        UNBIND_ST_FAILED
};

static const char usbip_bind_usage_string[] =
        "usbip bind <args>\n"
        "    -b, --busid=<busid>    Bind " USBIP_HOST_DRV_NAME ".ko to device "
        "on <busid>\n";

void usbip_bind_usage(void)
{
        printf("usage: %s", usbip_bind_usage_string);
}

/* call at unbound state */
static int bind_usbip(char *busid)
{
        char attr_name[] = "bind";
        char bind_attr_path[SYSFS_PATH_MAX];
        int rc = -1;

        snprintf(bind_attr_path, sizeof(bind_attr_path), "%s/%s/%s/%s/%s/%s",
                 SYSFS_MNT_PATH, SYSFS_BUS_NAME, SYSFS_BUS_TYPE,
                 SYSFS_DRIVERS_NAME, USBIP_HOST_DRV_NAME, attr_name);

        rc = write_sysfs_attribute(bind_attr_path, busid, strlen(busid));
        if (rc < 0) {
                err("error binding device %s to driver: %s", busid,
                    strerror(errno));
                return -1;
        }

        return 0;
}

/* buggy driver may cause dead lock */
static int unbind_other(char *busid)
{
        enum unbind_status status = UNBIND_ST_OK;

        char attr_name[] = "unbind";
        char unbind_attr_path[SYSFS_PATH_MAX];
        int rc = -1;

        struct udev *udev;
        struct udev_device *dev;
        const char *driver;
        const char *bDevClass;

        /* Create libudev context. */
        udev = udev_new();

        /* Get the device. */
        dev = udev_device_new_from_subsystem_sysname(udev, "usb", busid);
        if (!dev) {
                dbg("unable to find device with bus ID %s", busid);
                goto err_close_busid_dev;
        }

        /* Check what kind of device it is. */
        bDevClass  = udev_device_get_sysattr_value(dev, "bDeviceClass");
        if (!bDevClass) {
                dbg("unable to get bDevClass device attribute");
                goto err_close_busid_dev;
        }

        if (!strncmp(bDevClass, "09", strlen(bDevClass))) {
                dbg("skip unbinding of hub");
                goto err_close_busid_dev;
        }

        /* Get the device driver. */
        driver = udev_device_get_driver(dev);
        if (!driver) {
                /* No driver bound to this device. */
                goto out;
        }

        if (!strncmp(USBIP_HOST_DRV_NAME, driver,
                                strlen(USBIP_HOST_DRV_NAME))) {
                /* Already bound to usbip-host. */
                status = UNBIND_ST_USBIP_HOST;
                goto out;
        }

        /* Unbind device from driver. */
        snprintf(unbind_attr_path, sizeof(unbind_attr_path), "%s/%s/%s/%s/%s/%s",
                 SYSFS_MNT_PATH, SYSFS_BUS_NAME, SYSFS_BUS_TYPE,
                 SYSFS_DRIVERS_NAME, driver, attr_name);

        rc = write_sysfs_attribute(unbind_attr_path, busid, strlen(busid));
        if (rc < 0) {
                err("error unbinding device %s from driver", busid);
                goto err_close_busid_dev;
        }

        goto out;

err_close_busid_dev:
        status = UNBIND_ST_FAILED;
out:
        udev_device_unref(dev);
        udev_unref(udev);

        return status;
}

static int bind_device(char *busid)
{
        int rc;
        struct udev *udev;
        struct udev_device *dev;
        const char *devpath;

        /* Check whether the device with this bus ID exists. */
        udev = udev_new();
        dev = udev_device_new_from_subsystem_sysname(udev, "usb", busid);
        if (!dev) {
                err("device with the specified bus ID does not exist");
                return -1;
        }
        devpath = udev_device_get_devpath(dev);
        udev_unref(udev);

        /* If the device is already attached to vhci_hcd - bail out */
        if (strstr(devpath, USBIP_VHCI_DRV_NAME)) {
                err("bind loop detected: device: %s is attached to %s\n",
                    devpath, USBIP_VHCI_DRV_NAME);
                return -1;
        }

        rc = unbind_other(busid);
        if (rc == UNBIND_ST_FAILED) {
                err("could not unbind driver from device on busid %s", busid);
                return -1;
        } else if (rc == UNBIND_ST_USBIP_HOST) {
                err("device on busid %s is already bound to %s", busid,
                    USBIP_HOST_DRV_NAME);
                return -1;
        }

        rc = modify_match_busid(busid, 1);
        if (rc < 0) {
                err("unable to bind device on %s", busid);
                return -1;
        }

        rc = bind_usbip(busid);
        if (rc < 0) {
                err("could not bind device to %s", USBIP_HOST_DRV_NAME);
                modify_match_busid(busid, 0);
                return -1;
        }

        info("bind device on busid %s: complete", busid);

        return 0;
}

int usbip_bind(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 = bind_device(optarg);
                        goto out;
                default:
                        goto err_out;
                }
        }

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