usbip_unbind.c

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/*
 * Copyright (C) 2011 matt mooney <[email protected]>
 *               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;
}