third_party/libusb/src/libusb/os/linux

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This source file includes following definitions.
set_fd_cloexec_nb
linux_netlink_start_event_monitor
linux_netlink_stop_event_monitor
netlink_message_parse
linux_netlink_parse
linux_netlink_read_message
linux_netlink_event_thread_main
linux_netlink_hotplug_poll
/* -*- Mode: C; c-basic-offset:8 ; indent-tabs-mode:t -*- */
/*
 * Linux usbfs backend for libusb
 * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
 * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
 * Copyright (c) 2013 Nathan Hjelm <hjelmn@mac.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "config.h"
#include "libusb.h"
#include "libusbi.h"
#include "linux_usbfs.h"

#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

#ifdef HAVE_ASM_TYPES_H
#include <asm/types.h>
#endif

#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif

#include <arpa/inet.h>

#ifdef HAVE_LINUX_NETLINK_H
#include <linux/netlink.h>
#endif

#ifdef HAVE_LINUX_FILTER_H
#include <linux/filter.h>
#endif

#define KERNEL 1

static int linux_netlink_socket = -1;
static int netlink_control_pipe[2] = { -1, -1 };
static pthread_t libusb_linux_event_thread;

static void *linux_netlink_event_thread_main(void *arg);

struct sockaddr_nl snl = { .nl_family=AF_NETLINK, .nl_groups=KERNEL };

static int set_fd_cloexec_nb (int fd)
{
        int flags;

#if defined(FD_CLOEXEC)
        flags = fcntl (linux_netlink_socket, F_GETFD);
        if (0 > flags) {
                return -1;
        }

        if (!(flags & FD_CLOEXEC)) {
                fcntl (linux_netlink_socket, F_SETFD, flags | FD_CLOEXEC);
        }
#endif

        flags = fcntl (linux_netlink_socket, F_GETFL);
        if (0 > flags) {
                return -1;
        }

        if (!(flags & O_NONBLOCK)) {
                fcntl (linux_netlink_socket, F_SETFL, flags | O_NONBLOCK);
        }

        return 0;
}

int linux_netlink_start_event_monitor(void)
{
        int socktype = SOCK_RAW;
        int ret;

        snl.nl_groups = KERNEL;

#if defined(SOCK_CLOEXEC)
        socktype |= SOCK_CLOEXEC;
#endif
#if defined(SOCK_NONBLOCK)
        socktype |= SOCK_NONBLOCK;
#endif

        linux_netlink_socket = socket(PF_NETLINK, socktype, NETLINK_KOBJECT_UEVENT);
        if (-1 == linux_netlink_socket && EINVAL == errno) {
                linux_netlink_socket = socket(PF_NETLINK, SOCK_RAW, NETLINK_KOBJECT_UEVENT);
        }

        if (-1 == linux_netlink_socket) {
                return LIBUSB_ERROR_OTHER;
        }

        ret = set_fd_cloexec_nb (linux_netlink_socket);
        if (0 != ret) {
                close (linux_netlink_socket);
                linux_netlink_socket = -1;
                return LIBUSB_ERROR_OTHER;
        }

        ret = bind(linux_netlink_socket, (struct sockaddr *) &snl, sizeof(snl));
        if (0 != ret) {
                close(linux_netlink_socket);
                return LIBUSB_ERROR_OTHER;
        }

        /* TODO -- add authentication */
        /* setsockopt(linux_netlink_socket, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)); */

        ret = usbi_pipe(netlink_control_pipe);
        if (ret) {
                usbi_err(NULL, "could not create netlink control pipe");
                close(linux_netlink_socket);
                return LIBUSB_ERROR_OTHER;
        }

        ret = pthread_create(&libusb_linux_event_thread, NULL, linux_netlink_event_thread_main, NULL);
        if (0 != ret) {
                close(netlink_control_pipe[0]);
                close(netlink_control_pipe[1]);
                close(linux_netlink_socket);
                return LIBUSB_ERROR_OTHER;
        }

        return LIBUSB_SUCCESS;
}

int linux_netlink_stop_event_monitor(void)
{
        int r;
        char dummy = 1;

        if (-1 == linux_netlink_socket) {
                /* already closed. nothing to do */
                return LIBUSB_SUCCESS;
        }

        /* Write some dummy data to the control pipe and
         * wait for the thread to exit */
        r = usbi_write(netlink_control_pipe[1], &dummy, sizeof(dummy));
        if (r <= 0) {
                usbi_warn(NULL, "netlink control pipe signal failed");
        }
        pthread_join(libusb_linux_event_thread, NULL);

        close(linux_netlink_socket);
        linux_netlink_socket = -1;

        /* close and reset control pipe */
        close(netlink_control_pipe[0]);
        close(netlink_control_pipe[1]);
        netlink_control_pipe[0] = -1;
        netlink_control_pipe[1] = -1;

        return LIBUSB_SUCCESS;
}

static const char *netlink_message_parse (const char *buffer, size_t len, const char *key)
{
        size_t keylen = strlen(key);
        size_t offset;

        for (offset = 0 ; offset < len && '\0' != buffer[offset] ; offset += strlen(buffer + offset) + 1) {
                if (0 == strncmp(buffer + offset, key, keylen) &&
                    '=' == buffer[offset + keylen]) {
                        return buffer + offset + keylen + 1;
                }
        }

        return NULL;
}

/* parse parts of netlink message common to both libudev and the kernel */
static int linux_netlink_parse(char *buffer, size_t len, int *detached, const char **sys_name,
                               uint8_t *busnum, uint8_t *devaddr) {
        const char *tmp;
        int i;

        errno = 0;

        *sys_name = NULL;
        *detached = 0;
        *busnum   = 0;
        *devaddr  = 0;

        tmp = netlink_message_parse((const char *) buffer, len, "ACTION");
        if (tmp == NULL)
                return -1;
        if (0 == strcmp(tmp, "remove")) {
                *detached = 1;
        } else if (0 != strcmp(tmp, "add")) {
                usbi_dbg("unknown device action %s", tmp);
                return -1;
        }

        /* check that this is a usb message */
        tmp = netlink_message_parse(buffer, len, "SUBSYSTEM");
        if (NULL == tmp || 0 != strcmp(tmp, "usb")) {
                /* not usb. ignore */
                return -1;
        }

        tmp = netlink_message_parse(buffer, len, "BUSNUM");
        if (NULL == tmp) {
                /* no bus number (likely a usb interface). ignore*/
                return -1;
        }

        *busnum = (uint8_t)(strtoul(tmp, NULL, 10) & 0xff);
        if (errno) {
                errno = 0;
                return -1;
        }

        tmp = netlink_message_parse(buffer, len, "DEVNUM");
        if (NULL == tmp) {
                return -1;
        }

        *devaddr = (uint8_t)(strtoul(tmp, NULL, 10) & 0xff);
        if (errno) {
                errno = 0;
                return -1;
        }

        tmp = netlink_message_parse(buffer, len, "DEVPATH");
        if (NULL == tmp) {
                return -1;
        }

        for (i = strlen(tmp) - 1 ; i ; --i) {
                if ('/' ==tmp[i]) {
                        *sys_name = tmp + i + 1;
                        break;
                }
        }

        /* found a usb device */
        return 0;
}

static int linux_netlink_read_message(void)
{
        unsigned char buffer[1024];
        struct iovec iov = {.iov_base = buffer, .iov_len = sizeof(buffer)};
        struct msghdr meh = { .msg_iov=&iov, .msg_iovlen=1,
                             .msg_name=&snl, .msg_namelen=sizeof(snl) };
        const char *sys_name = NULL;
        uint8_t busnum, devaddr;
        int detached, r;
        size_t len;

        /* read netlink message */
        memset(buffer, 0, sizeof(buffer));
        len = recvmsg(linux_netlink_socket, &meh, 0);
        if (len < 32) {
                if (errno != EAGAIN)
                        usbi_dbg("error recieving message from netlink");
                return -1;
        }

        /* TODO -- authenticate this message is from the kernel or udevd */

        r = linux_netlink_parse(buffer, len, &detached, &sys_name,
                                &busnum, &devaddr);
        if (r)
                return r;

        usbi_dbg("netlink hotplug found device busnum: %hhu, devaddr: %hhu, sys_name: %s, removed: %s",
                 busnum, devaddr, sys_name, detached ? "yes" : "no");

        /* signal device is available (or not) to all contexts */
        if (detached)
                linux_device_disconnected(busnum, devaddr, sys_name);
        else
                linux_hotplug_enumerate(busnum, devaddr, sys_name);

        return 0;
}

static void *linux_netlink_event_thread_main(void *arg)
{
        char dummy;
        int r;
        struct pollfd fds[] = {
                { .fd = netlink_control_pipe[0],
                  .events = POLLIN },
                { .fd = linux_netlink_socket,
                  .events = POLLIN },
        };

        /* silence compiler warning */
        (void) arg;

        while (poll(fds, 2, -1) >= 0) {
                if (fds[0].revents & POLLIN) {
                        /* activity on control pipe, read the byte and exit */
                        r = usbi_read(netlink_control_pipe[0], &dummy, sizeof(dummy));
                        if (r <= 0) {
                                usbi_warn(NULL, "netlink control pipe read failed");
                        }
                        break;
                }
                if (fds[1].revents & POLLIN) {
                        usbi_mutex_static_lock(&linux_hotplug_lock);
                        linux_netlink_read_message();
                        usbi_mutex_static_unlock(&linux_hotplug_lock);
                }
        }

        return NULL;
}

void linux_netlink_hotplug_poll(void)
{
        int r;

        usbi_mutex_static_lock(&linux_hotplug_lock);
        do {
                r = linux_netlink_read_message();
        } while (r == 0);
        usbi_mutex_static_unlock(&linux_hotplug_lock);
}
/* [<][>][^][v][top][bottom][index][help] */
root/third_party/libusb/src/libusb/os/linux_netlink.c

DEFINITIONS
