/* -*- Mode: C; indent-tabs-mode:t ; c-basic-offset:8 -*- */
/*
* Hotplug functions for libusb
* Copyright © 2012-2013 Nathan Hjelm <hjelmn@mac.com>
* Copyright © 2012-2013 Peter Stuge <peter@stuge.se>
*
* 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 <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <assert.h>
#include "libusbi.h"
#include "hotplug.h"
/**
* @defgroup libusb_hotplug Device hotplug event notification
* This page details how to use the libusb hotplug interface, where available.
*
* Be mindful that not all platforms currently implement hotplug notification and
* that you should first call on \ref libusb_has_capability() with parameter
* \ref LIBUSB_CAP_HAS_HOTPLUG to confirm that hotplug support is available.
*
* \page libusb_hotplug Device hotplug event notification
*
* \section hotplug_intro Introduction
*
* Version 1.0.16, \ref LIBUSB_API_VERSION >= 0x01000102, has added support
* for hotplug events on <b>some</b> platforms (you should test if your platform
* supports hotplug notification by calling \ref libusb_has_capability() with
* parameter \ref LIBUSB_CAP_HAS_HOTPLUG).
*
* This interface allows you to request notification for the arrival and departure
* of matching USB devices.
*
* To receive hotplug notification you register a callback by calling
* \ref libusb_hotplug_register_callback(). This function will optionally return
* a callback handle that can be passed to \ref libusb_hotplug_deregister_callback().
*
* A callback function must return an int (0 or 1) indicating whether the callback is
* expecting additional events. Returning 0 will rearm the callback and 1 will cause
* the callback to be deregistered. Note that when callbacks are called from
* libusb_hotplug_register_callback() because of the \ref LIBUSB_HOTPLUG_ENUMERATE
* flag, the callback return value is ignored, iow you cannot cause a callback
* to be deregistered by returning 1 when it is called from
* libusb_hotplug_register_callback().
*
* Callbacks for a particular context are automatically deregistered by libusb_exit().
*
* As of 1.0.16 there are two supported hotplug events:
* - LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED: A device has arrived and is ready to use
* - LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT: A device has left and is no longer available
*
* A hotplug event can listen for either or both of these events.
*
* Note: If you receive notification that a device has left and you have any
* a libusb_device_handles for the device it is up to you to call libusb_close()
* on each device handle to free up any remaining resources associated with the device.
* Once a device has left any libusb_device_handle associated with the device
* are invalid and will remain so even if the device comes back.
*
* When handling a LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED event it is considered
* safe to call any libusb function that takes a libusb_device. It also safe to
* open a device and submit asynchronous transfers. However, most other functions
* that take a libusb_device_handle are <b>not</b> safe to call. Examples of such
* functions are any of the \ref libusb_syncio "synchronous API" functions or the blocking
* functions that retrieve various \ref libusb_desc "USB descriptors". These functions must
* be used outside of the context of the hotplug callback.
*
* When handling a LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT event the only safe function
* is libusb_get_device_descriptor().
*
* The following code provides an example of the usage of the hotplug interface:
\code
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <libusb.h>
static int count = 0;
int hotplug_callback(struct libusb_context *ctx, struct libusb_device *dev,
libusb_hotplug_event event, void *user_data) {
static libusb_device_handle *dev_handle = NULL;
struct libusb_device_descriptor desc;
int rc;
(void)libusb_get_device_descriptor(dev, &desc);
if (LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED == event) {
rc = libusb_open(dev, &dev_handle);
if (LIBUSB_SUCCESS != rc) {
printf("Could not open USB device\n");
}
} else if (LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT == event) {
if (dev_handle) {
libusb_close(dev_handle);
dev_handle = NULL;
}
} else {
printf("Unhandled event %d\n", event);
}
count++;
return 0;
}
int main (void) {
libusb_hotplug_callback_handle callback_handle;
int rc;
libusb_init(NULL);
rc = libusb_hotplug_register_callback(NULL, LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED |
LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT, 0, 0x045a, 0x5005,
LIBUSB_HOTPLUG_MATCH_ANY, hotplug_callback, NULL,
&callback_handle);
if (LIBUSB_SUCCESS != rc) {
printf("Error creating a hotplug callback\n");
libusb_exit(NULL);
return EXIT_FAILURE;
}
while (count < 2) {
libusb_handle_events_completed(NULL, NULL);
nanosleep(&(struct timespec){0, 10000000UL}, NULL);
}
libusb_hotplug_deregister_callback(NULL, callback_handle);
libusb_exit(NULL);
return 0;
}
\endcode
*/
static int usbi_hotplug_match_cb(struct libusb_context *ctx,
struct libusb_device *dev, libusb_hotplug_event event,
struct libusb_hotplug_callback *hotplug_cb)
{
if (!(hotplug_cb->flags & event)) {
return 0;
}
if ((hotplug_cb->flags & USBI_HOTPLUG_VENDOR_ID_VALID) &&
hotplug_cb->vendor_id != dev->device_descriptor.idVendor) {
return 0;
}
if ((hotplug_cb->flags & USBI_HOTPLUG_PRODUCT_ID_VALID) &&
hotplug_cb->product_id != dev->device_descriptor.idProduct) {
return 0;
}
if ((hotplug_cb->flags & USBI_HOTPLUG_DEV_CLASS_VALID) &&
hotplug_cb->dev_class != dev->device_descriptor.bDeviceClass) {
return 0;
}
return hotplug_cb->cb(ctx, dev, event, hotplug_cb->user_data);
}
void usbi_hotplug_match(struct libusb_context *ctx, struct libusb_device *dev,
libusb_hotplug_event event)
{
struct libusb_hotplug_callback *hotplug_cb, *next;
int ret;
usbi_mutex_lock(&ctx->hotplug_cbs_lock);
list_for_each_entry_safe(hotplug_cb, next, &ctx->hotplug_cbs, list, struct libusb_hotplug_callback) {
if (hotplug_cb->flags & USBI_HOTPLUG_NEEDS_FREE) {
/* process deregistration in usbi_hotplug_deregister() */
continue;
}
usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
ret = usbi_hotplug_match_cb(ctx, dev, event, hotplug_cb);
usbi_mutex_lock(&ctx->hotplug_cbs_lock);
if (ret) {
list_del(&hotplug_cb->list);
free(hotplug_cb);
}
}
usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
}
void usbi_hotplug_notification(struct libusb_context *ctx, struct libusb_device *dev,
libusb_hotplug_event event)
{
int pending_events;
struct libusb_hotplug_message *message = calloc(1, sizeof(*message));
if (!message) {
usbi_err(ctx, "error allocating hotplug message");
return;
}
message->event = event;
message->device = dev;
/* Take the event data lock and add this message to the list.
* Only signal an event if there are no prior pending events. */
usbi_mutex_lock(&ctx->event_data_lock);
pending_events = usbi_pending_events(ctx);
list_add_tail(&message->list, &ctx->hotplug_msgs);
if (!pending_events)
usbi_signal_event(ctx);
usbi_mutex_unlock(&ctx->event_data_lock);
}
int API_EXPORTED libusb_hotplug_register_callback(libusb_context *ctx,
libusb_hotplug_event events, libusb_hotplug_flag flags,
int vendor_id, int product_id, int dev_class,
libusb_hotplug_callback_fn cb_fn, void *user_data,
libusb_hotplug_callback_handle *callback_handle)
{
struct libusb_hotplug_callback *new_callback;
/* check for sane values */
if ((!events || (~(LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED | LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT) & events)) ||
(flags && (~LIBUSB_HOTPLUG_ENUMERATE & flags)) ||
(LIBUSB_HOTPLUG_MATCH_ANY != vendor_id && (~0xffff & vendor_id)) ||
(LIBUSB_HOTPLUG_MATCH_ANY != product_id && (~0xffff & product_id)) ||
(LIBUSB_HOTPLUG_MATCH_ANY != dev_class && (~0xff & dev_class)) ||
!cb_fn) {
return LIBUSB_ERROR_INVALID_PARAM;
}
/* check for hotplug support */
if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
return LIBUSB_ERROR_NOT_SUPPORTED;
}
USBI_GET_CONTEXT(ctx);
new_callback = calloc(1, sizeof(*new_callback));
if (!new_callback) {
return LIBUSB_ERROR_NO_MEM;
}
new_callback->flags = (uint8_t)events;
if (LIBUSB_HOTPLUG_MATCH_ANY != vendor_id) {
new_callback->flags |= USBI_HOTPLUG_VENDOR_ID_VALID;
new_callback->vendor_id = (uint16_t)vendor_id;
}
if (LIBUSB_HOTPLUG_MATCH_ANY != product_id) {
new_callback->flags |= USBI_HOTPLUG_PRODUCT_ID_VALID;
new_callback->product_id = (uint16_t)product_id;
}
if (LIBUSB_HOTPLUG_MATCH_ANY != dev_class) {
new_callback->flags |= USBI_HOTPLUG_DEV_CLASS_VALID;
new_callback->dev_class = (uint8_t)dev_class;
}
new_callback->cb = cb_fn;
new_callback->user_data = user_data;
usbi_mutex_lock(&ctx->hotplug_cbs_lock);
/* protect the handle by the context hotplug lock */
new_callback->handle = ctx->next_hotplug_cb_handle++;
/* handle the unlikely case of overflow */
if (ctx->next_hotplug_cb_handle < 0)
ctx->next_hotplug_cb_handle = 1;
list_add(&new_callback->list, &ctx->hotplug_cbs);
usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
usbi_dbg("new hotplug cb %p with handle %d", new_callback, new_callback->handle);
if ((flags & LIBUSB_HOTPLUG_ENUMERATE) && (events & LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED)) {
ssize_t i, len;
struct libusb_device **devs;
len = libusb_get_device_list(ctx, &devs);
if (len < 0) {
libusb_hotplug_deregister_callback(ctx,
new_callback->handle);
return (int)len;
}
for (i = 0; i < len; i++) {
usbi_hotplug_match_cb(ctx, devs[i],
LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED,
new_callback);
}
libusb_free_device_list(devs, 1);
}
if (callback_handle)
*callback_handle = new_callback->handle;
return LIBUSB_SUCCESS;
}
void API_EXPORTED libusb_hotplug_deregister_callback(struct libusb_context *ctx,
libusb_hotplug_callback_handle callback_handle)
{
struct libusb_hotplug_callback *hotplug_cb;
int deregistered = 0;
/* check for hotplug support */
if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
return;
}
USBI_GET_CONTEXT(ctx);
usbi_dbg("deregister hotplug cb %d", callback_handle);
usbi_mutex_lock(&ctx->hotplug_cbs_lock);
list_for_each_entry(hotplug_cb, &ctx->hotplug_cbs, list, struct libusb_hotplug_callback) {
if (callback_handle == hotplug_cb->handle) {
/* Mark this callback for deregistration */
hotplug_cb->flags |= USBI_HOTPLUG_NEEDS_FREE;
deregistered = 1;
}
}
usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
if (deregistered) {
int pending_events;
usbi_mutex_lock(&ctx->event_data_lock);
pending_events = usbi_pending_events(ctx);
ctx->event_flags |= USBI_EVENT_HOTPLUG_CB_DEREGISTERED;
if (!pending_events)
usbi_signal_event(ctx);
usbi_mutex_unlock(&ctx->event_data_lock);
}
}
void usbi_hotplug_deregister(struct libusb_context *ctx, int forced)
{
struct libusb_hotplug_callback *hotplug_cb, *next;
usbi_mutex_lock(&ctx->hotplug_cbs_lock);
list_for_each_entry_safe(hotplug_cb, next, &ctx->hotplug_cbs, list, struct libusb_hotplug_callback) {
if (forced || (hotplug_cb->flags & USBI_HOTPLUG_NEEDS_FREE)) {
usbi_dbg("freeing hotplug cb %p with handle %d", hotplug_cb,
hotplug_cb->handle);
list_del(&hotplug_cb->list);
free(hotplug_cb);
}
}
usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
}