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/*******************************************************
 HIDAPI - Multi-Platform library for
 communication with HID devices.

 Alan Ott
 Signal 11 Software

 2010-07-03

 Copyright 2010, All Rights Reserved.

 At the discretion of the user of this library,
 this software may be licensed under the terms of the
 GNU Public License v3, a BSD-Style license, or the
 original HIDAPI license as outlined in the LICENSE.txt,
 LICENSE-gpl3.txt, LICENSE-bsd.txt, and LICENSE-orig.txt
 files located at the root of the source distribution.
 These files may also be found in the public source
 code repository located at:
        http://github.com/signal11/hidapi .
********************************************************/

/* See Apple Technical Note TN2187 for details on IOHidManager. */

#include <IOKit/hid/IOHIDManager.h>
#include <IOKit/hid/IOHIDKeys.h>
#include <CoreFoundation/CoreFoundation.h>
#include <wchar.h>
#include <locale.h>
#include <pthread.h>
#include <sys/time.h>
#include <unistd.h>

#include "hidapi.h"

/* Barrier implementation because Mac OSX doesn't have pthread_barrier.
   It also doesn't have clock_gettime(). So much for POSIX and SUSv2.
   This implementation came from Brent Priddy and was posted on
   StackOverflow. It is used with his permission. */
typedef int pthread_barrierattr_t;
typedef struct pthread_barrier {
    pthread_mutex_t mutex;
    pthread_cond_t cond;
    int count;
    int trip_count;
} pthread_barrier_t;

static int pthread_barrier_init(pthread_barrier_t *barrier, const pthread_barrierattr_t *attr, unsigned int count)
{
        if(count == 0) {
                errno = EINVAL;
                return -1;
        }

        if(pthread_mutex_init(&barrier->mutex, 0) < 0) {
                return -1;
        }
        if(pthread_cond_init(&barrier->cond, 0) < 0) {
                pthread_mutex_destroy(&barrier->mutex);
                return -1;
        }
        barrier->trip_count = count;
        barrier->count = 0;

        return 0;
}

static int pthread_barrier_destroy(pthread_barrier_t *barrier)
{
        pthread_cond_destroy(&barrier->cond);
        pthread_mutex_destroy(&barrier->mutex);
        return 0;
}

static int pthread_barrier_wait(pthread_barrier_t *barrier)
{
        pthread_mutex_lock(&barrier->mutex);
        ++(barrier->count);
        if(barrier->count >= barrier->trip_count)
        {
                barrier->count = 0;
                pthread_cond_broadcast(&barrier->cond);
                pthread_mutex_unlock(&barrier->mutex);
                return 1;
        }
        else
        {
                pthread_cond_wait(&barrier->cond, &(barrier->mutex));
                pthread_mutex_unlock(&barrier->mutex);
                return 0;
        }
}

static int return_data(hid_device *dev, unsigned char *data, size_t length);

/* Linked List of input reports received from the device. */
struct input_report {
        uint8_t *data;
        size_t len;
        struct input_report *next;
};

struct hid_device_ {
        IOHIDDeviceRef device_handle;
        int blocking;
        int uses_numbered_reports;
        int disconnected;
        CFStringRef run_loop_mode;
        CFRunLoopRef run_loop;
        CFRunLoopSourceRef source;
        uint8_t *input_report_buf;
        CFIndex max_input_report_len;
        struct input_report *input_reports;

        pthread_t thread;
        pthread_mutex_t mutex; /* Protects input_reports */
        pthread_cond_t condition;
        pthread_barrier_t barrier; /* Ensures correct startup sequence */
        pthread_barrier_t shutdown_barrier; /* Ensures correct shutdown sequence */
        int shutdown_thread;
};

static hid_device *new_hid_device(void)
{
        hid_device *dev = calloc(1, sizeof(hid_device));
        dev->device_handle = NULL;
        dev->blocking = 1;
        dev->uses_numbered_reports = 0;
        dev->disconnected = 0;
        dev->run_loop_mode = NULL;
        dev->run_loop = NULL;
        dev->source = NULL;
        dev->input_report_buf = NULL;
        dev->input_reports = NULL;
        dev->shutdown_thread = 0;

        /* Thread objects */
        pthread_mutex_init(&dev->mutex, NULL);
        pthread_cond_init(&dev->condition, NULL);
        pthread_barrier_init(&dev->barrier, NULL, 2);
        pthread_barrier_init(&dev->shutdown_barrier, NULL, 2);

        return dev;
}

static void free_hid_device(hid_device *dev)
{
        if (!dev)
                return;

        /* Delete any input reports still left over. */
        struct input_report *rpt = dev->input_reports;
        while (rpt) {
                struct input_report *next = rpt->next;
                free(rpt->data);
                free(rpt);
                rpt = next;
        }

        /* Free the string and the report buffer. The check for NULL
           is necessary here as CFRelease() doesn't handle NULL like
           free() and others do. */
        if (dev->run_loop_mode)
                CFRelease(dev->run_loop_mode);
        if (dev->source)
                CFRelease(dev->source);
        free(dev->input_report_buf);

        /* Clean up the thread objects */
        pthread_barrier_destroy(&dev->shutdown_barrier);
        pthread_barrier_destroy(&dev->barrier);
        pthread_cond_destroy(&dev->condition);
        pthread_mutex_destroy(&dev->mutex);

        /* Free the structure itself. */
        free(dev);
}

static  IOHIDManagerRef hid_mgr = 0x0;


#if 0
static void register_error(hid_device *device, const char *op)
{

}
#endif


static int32_t get_int_property(IOHIDDeviceRef device, CFStringRef key)
{
        CFTypeRef ref;
        int32_t value;

        ref = IOHIDDeviceGetProperty(device, key);
        if (ref) {
                if (CFGetTypeID(ref) == CFNumberGetTypeID()) {
                        CFNumberGetValue((CFNumberRef) ref, kCFNumberSInt32Type, &value);
                        return value;
                }
        }
        return 0;
}

static unsigned short get_vendor_id(IOHIDDeviceRef device)
{
        return get_int_property(device, CFSTR(kIOHIDVendorIDKey));
}

static unsigned short get_product_id(IOHIDDeviceRef device)
{
        return get_int_property(device, CFSTR(kIOHIDProductIDKey));
}

static int32_t get_location_id(IOHIDDeviceRef device)
{
        return get_int_property(device, CFSTR(kIOHIDLocationIDKey));
}

static int32_t get_max_report_length(IOHIDDeviceRef device)
{
        return get_int_property(device, CFSTR(kIOHIDMaxInputReportSizeKey));
}

static int get_string_property(IOHIDDeviceRef device, CFStringRef prop, wchar_t *buf, size_t len)
{
        CFStringRef str;

        if (!len)
                return 0;

        str = IOHIDDeviceGetProperty(device, prop);

        buf[0] = 0;

        if (str) {
                CFIndex str_len = CFStringGetLength(str);
                CFRange range;
                CFIndex used_buf_len;
                CFIndex chars_copied;

                len --;

                range.location = 0;
                range.length = ((size_t)str_len > len)? len: (size_t)str_len;
                chars_copied = CFStringGetBytes(str,
                        range,
                        kCFStringEncodingUTF32LE,
                        (char)'?',
                        FALSE,
                        (UInt8*)buf,
                        len * sizeof(wchar_t),
                        &used_buf_len);

                if (chars_copied == len)
                        buf[len] = 0; /* len is decremented above */
                else
                        buf[chars_copied] = 0;

                return 0;
        }
        else
                return -1;

}

static int get_string_property_utf8(IOHIDDeviceRef device, CFStringRef prop, char *buf, size_t len)
{
        CFStringRef str;
        if (!len)
                return 0;

        str = IOHIDDeviceGetProperty(device, prop);

        buf[0] = 0;

        if (str) {
                len--;

                CFIndex str_len = CFStringGetLength(str);
                CFRange range;
                range.location = 0;
                range.length = str_len;
                CFIndex used_buf_len;
                CFIndex chars_copied;
                chars_copied = CFStringGetBytes(str,
                        range,
                        kCFStringEncodingUTF8,
                        (char)'?',
                        FALSE,
                        (UInt8*)buf,
                        len,
                        &used_buf_len);

                if (used_buf_len == len)
                        buf[len] = 0; /* len is decremented above */
                else
                        buf[used_buf_len] = 0;

                return used_buf_len;
        }
        else
                return 0;
}


static int get_serial_number(IOHIDDeviceRef device, wchar_t *buf, size_t len)
{
        return get_string_property(device, CFSTR(kIOHIDSerialNumberKey), buf, len);
}

static int get_manufacturer_string(IOHIDDeviceRef device, wchar_t *buf, size_t len)
{
        return get_string_property(device, CFSTR(kIOHIDManufacturerKey), buf, len);
}

static int get_product_string(IOHIDDeviceRef device, wchar_t *buf, size_t len)
{
        return get_string_property(device, CFSTR(kIOHIDProductKey), buf, len);
}


/* Implementation of wcsdup() for Mac. */
static wchar_t *dup_wcs(const wchar_t *s)
{
        size_t len = wcslen(s);
        wchar_t *ret = malloc((len+1)*sizeof(wchar_t));
        wcscpy(ret, s);

        return ret;
}


static int make_path(IOHIDDeviceRef device, char *buf, size_t len)
{
        int res;
        unsigned short vid, pid;
        char transport[32];
        int32_t location;

        buf[0] = '\0';

        res = get_string_property_utf8(
                device, CFSTR(kIOHIDTransportKey),
                transport, sizeof(transport));

        if (!res)
                return -1;

        location = get_location_id(device);
        vid = get_vendor_id(device);
        pid = get_product_id(device);

        res = snprintf(buf, len, "%s_%04hx_%04hx_%x",
                       transport, vid, pid, location);


        buf[len-1] = '\0';
        return res+1;
}

/* Initialize the IOHIDManager. Return 0 for success and -1 for failure. */
static int init_hid_manager(void)
{
        /* Initialize all the HID Manager Objects */
        hid_mgr = IOHIDManagerCreate(kCFAllocatorDefault, kIOHIDOptionsTypeNone);
        if (hid_mgr) {
                IOHIDManagerSetDeviceMatching(hid_mgr, NULL);
                IOHIDManagerScheduleWithRunLoop(hid_mgr, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
                return 0;
        }

        return -1;
}

/* Initialize the IOHIDManager if necessary. This is the public function, and
   it is safe to call this function repeatedly. Return 0 for success and -1
   for failure. */
int HID_API_EXPORT hid_init(void)
{
        if (!hid_mgr) {
                return init_hid_manager();
        }

        /* Already initialized. */
        return 0;
}

int HID_API_EXPORT hid_exit(void)
{
        if (hid_mgr) {
                /* Close the HID manager. */
                IOHIDManagerClose(hid_mgr, kIOHIDOptionsTypeNone);
                CFRelease(hid_mgr);
                hid_mgr = NULL;
        }

        return 0;
}

static void process_pending_events(void) {
        SInt32 res;
        do {
                res = CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.001, FALSE);
        } while(res != kCFRunLoopRunFinished && res != kCFRunLoopRunTimedOut);
}

struct hid_device_info  HID_API_EXPORT *hid_enumerate(unsigned short vendor_id, unsigned short product_id)
{
        struct hid_device_info *root = NULL; /* return object */
        struct hid_device_info *cur_dev = NULL;
        CFIndex num_devices;
        int i;

        /* Set up the HID Manager if it hasn't been done */
        if (hid_init() < 0)
                return NULL;

        /* give the IOHIDManager a chance to update itself */
        process_pending_events();

        /* Get a list of the Devices */
        CFSetRef device_set = IOHIDManagerCopyDevices(hid_mgr);

        /* Convert the list into a C array so we can iterate easily. */
        num_devices = CFSetGetCount(device_set);
        IOHIDDeviceRef *device_array = calloc(num_devices, sizeof(IOHIDDeviceRef));
        CFSetGetValues(device_set, (const void **) device_array);

        /* Iterate over each device, making an entry for it. */
        for (i = 0; i < num_devices; i++) {
                unsigned short dev_vid;
                unsigned short dev_pid;
                #define BUF_LEN 256
                wchar_t buf[BUF_LEN];
                char cbuf[BUF_LEN];

                IOHIDDeviceRef dev = device_array[i];

        if (!dev) {
            continue;
        }
                dev_vid = get_vendor_id(dev);
                dev_pid = get_product_id(dev);

                /* Check the VID/PID against the arguments */
                if ((vendor_id == 0x0 || vendor_id == dev_vid) &&
                    (product_id == 0x0 || product_id == dev_pid)) {
                        struct hid_device_info *tmp;
                        size_t len;

                        /* VID/PID match. Create the record. */
                        tmp = malloc(sizeof(struct hid_device_info));
                        if (cur_dev) {
                                cur_dev->next = tmp;
                        }
                        else {
                                root = tmp;
                        }
                        cur_dev = tmp;

                        /* Get the Usage Page and Usage for this device. */
                        cur_dev->usage_page = get_int_property(dev, CFSTR(kIOHIDPrimaryUsagePageKey));
                        cur_dev->usage = get_int_property(dev, CFSTR(kIOHIDPrimaryUsageKey));

                        /* Fill out the record */
                        cur_dev->next = NULL;
                        len = make_path(dev, cbuf, sizeof(cbuf));
                        cur_dev->path = strdup(cbuf);

                        /* Serial Number */
                        get_serial_number(dev, buf, BUF_LEN);
                        cur_dev->serial_number = dup_wcs(buf);

                        /* Manufacturer and Product strings */
                        get_manufacturer_string(dev, buf, BUF_LEN);
                        cur_dev->manufacturer_string = dup_wcs(buf);
                        get_product_string(dev, buf, BUF_LEN);
                        cur_dev->product_string = dup_wcs(buf);

                        /* VID/PID */
                        cur_dev->vendor_id = dev_vid;
                        cur_dev->product_id = dev_pid;

                        /* Release Number */
                        cur_dev->release_number = get_int_property(dev, CFSTR(kIOHIDVersionNumberKey));

                        /* Interface Number (Unsupported on Mac)*/
                        cur_dev->interface_number = -1;
                }
        }

        free(device_array);
        CFRelease(device_set);

        return root;
}

void  HID_API_EXPORT hid_free_enumeration(struct hid_device_info *devs)
{
        /* This function is identical to the Linux version. Platform independent. */
        struct hid_device_info *d = devs;
        while (d) {
                struct hid_device_info *next = d->next;
                free(d->path);
                free(d->serial_number);
                free(d->manufacturer_string);
                free(d->product_string);
                free(d);
                d = next;
        }
}

hid_device * HID_API_EXPORT hid_open(unsigned short vendor_id, unsigned short product_id, const wchar_t *serial_number)
{
        /* This function is identical to the Linux version. Platform independent. */
        struct hid_device_info *devs, *cur_dev;
        const char *path_to_open = NULL;
        hid_device * handle = NULL;

        devs = hid_enumerate(vendor_id, product_id);
        cur_dev = devs;
        while (cur_dev) {
                if (cur_dev->vendor_id == vendor_id &&
                    cur_dev->product_id == product_id) {
                        if (serial_number) {
                                if (wcscmp(serial_number, cur_dev->serial_number) == 0) {
                                        path_to_open = cur_dev->path;
                                        break;
                                }
                        }
                        else {
                                path_to_open = cur_dev->path;
                                break;
                        }
                }
                cur_dev = cur_dev->next;
        }

        if (path_to_open) {
                /* Open the device */
                handle = hid_open_path(path_to_open);
        }

        hid_free_enumeration(devs);

        return handle;
}

static void hid_device_removal_callback(void *context, IOReturn result,
                                        void *sender)
{
        /* Stop the Run Loop for this device. */
        hid_device *d = context;

        d->disconnected = 1;
        CFRunLoopStop(d->run_loop);
}

/* The Run Loop calls this function for each input report received.
   This function puts the data into a linked list to be picked up by
   hid_read(). */
static void hid_report_callback(void *context, IOReturn result, void *sender,
                         IOHIDReportType report_type, uint32_t report_id,
                         uint8_t *report, CFIndex report_length)
{
        struct input_report *rpt;
        hid_device *dev = context;

        /* Make a new Input Report object */
        rpt = calloc(1, sizeof(struct input_report));
        rpt->data = calloc(1, report_length);
        memcpy(rpt->data, report, report_length);
        rpt->len = report_length;
        rpt->next = NULL;

        /* Lock this section */
        pthread_mutex_lock(&dev->mutex);

        /* Attach the new report object to the end of the list. */
        if (dev->input_reports == NULL) {
                /* The list is empty. Put it at the root. */
                dev->input_reports = rpt;
        }
        else {
                /* Find the end of the list and attach. */
                struct input_report *cur = dev->input_reports;
                int num_queued = 0;
                while (cur->next != NULL) {
                        cur = cur->next;
                        num_queued++;
                }
                cur->next = rpt;

                /* Pop one off if we've reached 30 in the queue. This
                   way we don't grow forever if the user never reads
                   anything from the device. */
                if (num_queued > 30) {
                        return_data(dev, NULL, 0);
                }
        }

        /* Signal a waiting thread that there is data. */
        pthread_cond_signal(&dev->condition);

        /* Unlock */
        pthread_mutex_unlock(&dev->mutex);

}

/* This gets called when the read_thred's run loop gets signaled by
   hid_close(), and serves to stop the read_thread's run loop. */
static void perform_signal_callback(void *context)
{
        hid_device *dev = context;
        CFRunLoopStop(dev->run_loop); /*TODO: CFRunLoopGetCurrent()*/
}

static void *read_thread(void *param)
{
        hid_device *dev = param;
        SInt32 code;

        /* Move the device's run loop to this thread. */
        IOHIDDeviceScheduleWithRunLoop(dev->device_handle, CFRunLoopGetCurrent(), dev->run_loop_mode);

        /* Create the RunLoopSource which is used to signal the
           event loop to stop when hid_close() is called. */
        CFRunLoopSourceContext ctx;
        memset(&ctx, 0, sizeof(ctx));
        ctx.version = 0;
        ctx.info = dev;
        ctx.perform = &perform_signal_callback;
        dev->source = CFRunLoopSourceCreate(kCFAllocatorDefault, 0/*order*/, &ctx);
        CFRunLoopAddSource(CFRunLoopGetCurrent(), dev->source, dev->run_loop_mode);

        /* Store off the Run Loop so it can be stopped from hid_close()
           and on device disconnection. */
        dev->run_loop = CFRunLoopGetCurrent();

        /* Notify the main thread that the read thread is up and running. */
        pthread_barrier_wait(&dev->barrier);

        /* Run the Event Loop. CFRunLoopRunInMode() will dispatch HID input
           reports into the hid_report_callback(). */
        while (!dev->shutdown_thread && !dev->disconnected) {
                code = CFRunLoopRunInMode(dev->run_loop_mode, 1000/*sec*/, FALSE);
                /* Return if the device has been disconnected */
                if (code == kCFRunLoopRunFinished) {
                        dev->disconnected = 1;
                        break;
                }


                /* Break if The Run Loop returns Finished or Stopped. */
                if (code != kCFRunLoopRunTimedOut &&
                    code != kCFRunLoopRunHandledSource) {
                        /* There was some kind of error. Setting
                           shutdown seems to make sense, but
                           there may be something else more appropriate */
                        dev->shutdown_thread = 1;
                        break;
                }
        }

        /* Now that the read thread is stopping, Wake any threads which are
           waiting on data (in hid_read_timeout()). Do this under a mutex to
           make sure that a thread which is about to go to sleep waiting on
           the condition acutally will go to sleep before the condition is
           signaled. */
        pthread_mutex_lock(&dev->mutex);
        pthread_cond_broadcast(&dev->condition);
        pthread_mutex_unlock(&dev->mutex);

        /* Wait here until hid_close() is called and makes it past
           the call to CFRunLoopWakeUp(). This thread still needs to
           be valid when that function is called on the other thread. */
        pthread_barrier_wait(&dev->shutdown_barrier);

        return NULL;
}

hid_device * HID_API_EXPORT hid_open_path(const char *path)
{
        int i;
        hid_device *dev = NULL;
        CFIndex num_devices;

        dev = new_hid_device();

        /* Set up the HID Manager if it hasn't been done */
        if (hid_init() < 0)
                return NULL;

        /* give the IOHIDManager a chance to update itself */
        process_pending_events();

        CFSetRef device_set = IOHIDManagerCopyDevices(hid_mgr);

        num_devices = CFSetGetCount(device_set);
        IOHIDDeviceRef *device_array = calloc(num_devices, sizeof(IOHIDDeviceRef));
        CFSetGetValues(device_set, (const void **) device_array);
        for (i = 0; i < num_devices; i++) {
                char cbuf[BUF_LEN];
                size_t len;
                IOHIDDeviceRef os_dev = device_array[i];

                len = make_path(os_dev, cbuf, sizeof(cbuf));
                if (!strcmp(cbuf, path)) {
                        /* Matched Paths. Open this Device. */
                        IOReturn ret = IOHIDDeviceOpen(os_dev, kIOHIDOptionsTypeSeizeDevice);
                        if (ret == kIOReturnSuccess) {
                                char str[32];

                                free(device_array);
                                CFRetain(os_dev);
                                CFRelease(device_set);
                                dev->device_handle = os_dev;

                                /* Create the buffers for receiving data */
                                dev->max_input_report_len = (CFIndex) get_max_report_length(os_dev);
                                dev->input_report_buf = calloc(dev->max_input_report_len, sizeof(uint8_t));

                                /* Create the Run Loop Mode for this device.
                                   printing the reference seems to work. */
                                sprintf(str, "HIDAPI_%p", os_dev);
                                dev->run_loop_mode =
                                        CFStringCreateWithCString(NULL, str, kCFStringEncodingASCII);

                                /* Attach the device to a Run Loop */
                                IOHIDDeviceRegisterInputReportCallback(
                                        os_dev, dev->input_report_buf, dev->max_input_report_len,
                                        &hid_report_callback, dev);
                                IOHIDDeviceRegisterRemovalCallback(dev->device_handle, hid_device_removal_callback, dev);

                                /* Start the read thread */
                                pthread_create(&dev->thread, NULL, read_thread, dev);

                                /* Wait here for the read thread to be initialized. */
                                pthread_barrier_wait(&dev->barrier);

                                return dev;
                        }
                        else {
                                goto return_error;
                        }
                }
        }

return_error:
        free(device_array);
        CFRelease(device_set);
        free_hid_device(dev);
        return NULL;
}

static int set_report(hid_device *dev, IOHIDReportType type, const unsigned char *data, size_t length)
{
        const unsigned char *data_to_send;
        size_t length_to_send;
        IOReturn res;

        /* Return if the device has been disconnected. */
        if (dev->disconnected)
                return -1;

        if (data[0] == 0x0) {
                /* Not using numbered Reports.
                   Don't send the report number. */
                data_to_send = data+1;
                length_to_send = length-1;
        }
        else {
                /* Using numbered Reports.
                   Send the Report Number */
                data_to_send = data;
                length_to_send = length;
        }

        if (!dev->disconnected) {
                res = IOHIDDeviceSetReport(dev->device_handle,
                                           type,
                                           data[0], /* Report ID*/
                                           data_to_send, length_to_send);

                if (res == kIOReturnSuccess) {
                        return length;
                }
                else
                        return -1;
        }

        return -1;
}

int HID_API_EXPORT hid_write(hid_device *dev, const unsigned char *data, size_t length)
{
        return set_report(dev, kIOHIDReportTypeOutput, data, length);
}

/* Helper function, so that this isn't duplicated in hid_read(). */
static int return_data(hid_device *dev, unsigned char *data, size_t length)
{
        /* Copy the data out of the linked list item (rpt) into the
           return buffer (data), and delete the liked list item. */
        struct input_report *rpt = dev->input_reports;
        size_t len = (length < rpt->len)? length: rpt->len;
        memcpy(data, rpt->data, len);
        dev->input_reports = rpt->next;
        free(rpt->data);
        free(rpt);
        return len;
}

static int cond_wait(const hid_device *dev, pthread_cond_t *cond, pthread_mutex_t *mutex)
{
        while (!dev->input_reports) {
                int res = pthread_cond_wait(cond, mutex);
                if (res != 0)
                        return res;

                /* A res of 0 means we may have been signaled or it may
                   be a spurious wakeup. Check to see that there's acutally
                   data in the queue before returning, and if not, go back
                   to sleep. See the pthread_cond_timedwait() man page for
                   details. */

                if (dev->shutdown_thread || dev->disconnected)
                        return -1;
        }

        return 0;
}

static int cond_timedwait(const hid_device *dev, pthread_cond_t *cond, pthread_mutex_t *mutex, const struct timespec *abstime)
{
        while (!dev->input_reports) {
                int res = pthread_cond_timedwait(cond, mutex, abstime);
                if (res != 0)
                        return res;

                /* A res of 0 means we may have been signaled or it may
                   be a spurious wakeup. Check to see that there's acutally
                   data in the queue before returning, and if not, go back
                   to sleep. See the pthread_cond_timedwait() man page for
                   details. */

                if (dev->shutdown_thread || dev->disconnected)
                        return -1;
        }

        return 0;

}

int HID_API_EXPORT hid_read_timeout(hid_device *dev, unsigned char *data, size_t length, int milliseconds)
{
        int bytes_read = -1;

        /* Lock the access to the report list. */
        pthread_mutex_lock(&dev->mutex);

        /* There's an input report queued up. Return it. */
        if (dev->input_reports) {
                /* Return the first one */
                bytes_read = return_data(dev, data, length);
                goto ret;
        }

        /* Return if the device has been disconnected. */
        if (dev->disconnected) {
                bytes_read = -1;
                goto ret;
        }

        if (dev->shutdown_thread) {
                /* This means the device has been closed (or there
                   has been an error. An error code of -1 should
                   be returned. */
                bytes_read = -1;
                goto ret;
        }

        /* There is no data. Go to sleep and wait for data. */

        if (milliseconds == -1) {
                /* Blocking */
                int res;
                res = cond_wait(dev, &dev->condition, &dev->mutex);
                if (res == 0)
                        bytes_read = return_data(dev, data, length);
                else {
                        /* There was an error, or a device disconnection. */
                        bytes_read = -1;
                }
        }
        else if (milliseconds > 0) {
                /* Non-blocking, but called with timeout. */
                int res;
                struct timespec ts;
                struct timeval tv;
                gettimeofday(&tv, NULL);
                TIMEVAL_TO_TIMESPEC(&tv, &ts);
                ts.tv_sec += milliseconds / 1000;
                ts.tv_nsec += (milliseconds % 1000) * 1000000;
                if (ts.tv_nsec >= 1000000000L) {
                        ts.tv_sec++;
                        ts.tv_nsec -= 1000000000L;
                }

                res = cond_timedwait(dev, &dev->condition, &dev->mutex, &ts);
                if (res == 0)
                        bytes_read = return_data(dev, data, length);
                else if (res == ETIMEDOUT)
                        bytes_read = 0;
                else
                        bytes_read = -1;
        }
        else {
                /* Purely non-blocking */
                bytes_read = 0;
        }

ret:
        /* Unlock */
        pthread_mutex_unlock(&dev->mutex);
        return bytes_read;
}

int HID_API_EXPORT hid_read(hid_device *dev, unsigned char *data, size_t length)
{
        return hid_read_timeout(dev, data, length, (dev->blocking)? -1: 0);
}

int HID_API_EXPORT hid_set_nonblocking(hid_device *dev, int nonblock)
{
        /* All Nonblocking operation is handled by the library. */
        dev->blocking = !nonblock;

        return 0;
}

int HID_API_EXPORT hid_send_feature_report(hid_device *dev, const unsigned char *data, size_t length)
{
        return set_report(dev, kIOHIDReportTypeFeature, data, length);
}

int HID_API_EXPORT hid_get_feature_report(hid_device *dev, unsigned char *data, size_t length)
{
        CFIndex len = length;
        IOReturn res;

        /* Return if the device has been unplugged. */
        if (dev->disconnected)
                return -1;

        res = IOHIDDeviceGetReport(dev->device_handle,
                                   kIOHIDReportTypeFeature,
                                   data[0], /* Report ID */
                                   data, &len);
        if (res == kIOReturnSuccess)
                return len;
        else
                return -1;
}


void HID_API_EXPORT hid_close(hid_device *dev)
{
        if (!dev)
                return;

        /* Disconnect the report callback before close. */
        if (!dev->disconnected) {
                IOHIDDeviceRegisterInputReportCallback(
                        dev->device_handle, dev->input_report_buf, dev->max_input_report_len,
                        NULL, dev);
                IOHIDDeviceRegisterRemovalCallback(dev->device_handle, NULL, dev);
                IOHIDDeviceUnscheduleFromRunLoop(dev->device_handle, dev->run_loop, dev->run_loop_mode);
                IOHIDDeviceScheduleWithRunLoop(dev->device_handle, CFRunLoopGetMain(), kCFRunLoopDefaultMode);
        }

        /* Cause read_thread() to stop. */
        dev->shutdown_thread = 1;

        /* Wake up the run thread's event loop so that the thread can exit. */
        CFRunLoopSourceSignal(dev->source);
        CFRunLoopWakeUp(dev->run_loop);

        /* Notify the read thread that it can shut down now. */
        pthread_barrier_wait(&dev->shutdown_barrier);

        /* Wait for read_thread() to end. */
        pthread_join(dev->thread, NULL);

        /* Close the OS handle to the device, but only if it's not
           been unplugged. If it's been unplugged, then calling
           IOHIDDeviceClose() will crash. */
        if (!dev->disconnected) {
                IOHIDDeviceClose(dev->device_handle, kIOHIDOptionsTypeSeizeDevice);
        }

        /* Clear out the queue of received reports. */
        pthread_mutex_lock(&dev->mutex);
        while (dev->input_reports) {
                return_data(dev, NULL, 0);
        }
        pthread_mutex_unlock(&dev->mutex);
        CFRelease(dev->device_handle);

        free_hid_device(dev);
}

int HID_API_EXPORT_CALL hid_get_manufacturer_string(hid_device *dev, wchar_t *string, size_t maxlen)
{
        return get_manufacturer_string(dev->device_handle, string, maxlen);
}

int HID_API_EXPORT_CALL hid_get_product_string(hid_device *dev, wchar_t *string, size_t maxlen)
{
        return get_product_string(dev->device_handle, string, maxlen);
}

int HID_API_EXPORT_CALL hid_get_serial_number_string(hid_device *dev, wchar_t *string, size_t maxlen)
{
        return get_serial_number(dev->device_handle, string, maxlen);
}

int HID_API_EXPORT_CALL hid_get_indexed_string(hid_device *dev, int string_index, wchar_t *string, size_t maxlen)
{
        /* TODO: */

        return 0;
}


HID_API_EXPORT const wchar_t * HID_API_CALL  hid_error(hid_device *dev)
{
        /* TODO: */

        return NULL;
}







#if 0
static int32_t get_usage(IOHIDDeviceRef device)
{
        int32_t res;
        res = get_int_property(device, CFSTR(kIOHIDDeviceUsageKey));
        if (!res)
                res = get_int_property(device, CFSTR(kIOHIDPrimaryUsageKey));
        return res;
}

static int32_t get_usage_page(IOHIDDeviceRef device)
{
        int32_t res;
        res = get_int_property(device, CFSTR(kIOHIDDeviceUsagePageKey));
        if (!res)
                res = get_int_property(device, CFSTR(kIOHIDPrimaryUsagePageKey));
        return res;
}

static int get_transport(IOHIDDeviceRef device, wchar_t *buf, size_t len)
{
        return get_string_property(device, CFSTR(kIOHIDTransportKey), buf, len);
}


int main(void)
{
        IOHIDManagerRef mgr;
        int i;

        mgr = IOHIDManagerCreate(kCFAllocatorDefault, kIOHIDOptionsTypeNone);
        IOHIDManagerSetDeviceMatching(mgr, NULL);
        IOHIDManagerOpen(mgr, kIOHIDOptionsTypeNone);

        CFSetRef device_set = IOHIDManagerCopyDevices(mgr);

        CFIndex num_devices = CFSetGetCount(device_set);
        IOHIDDeviceRef *device_array = calloc(num_devices, sizeof(IOHIDDeviceRef));
        CFSetGetValues(device_set, (const void **) device_array);

        for (i = 0; i < num_devices; i++) {
                IOHIDDeviceRef dev = device_array[i];
                printf("Device: %p\n", dev);
                printf("  %04hx %04hx\n", get_vendor_id(dev), get_product_id(dev));

                wchar_t serial[256], buf[256];
                char cbuf[256];
                get_serial_number(dev, serial, 256);


                printf("  Serial: %ls\n", serial);
                printf("  Loc: %ld\n", get_location_id(dev));
                get_transport(dev, buf, 256);
                printf("  Trans: %ls\n", buf);
                make_path(dev, cbuf, 256);
                printf("  Path: %s\n", cbuf);

        }

        return 0;
}
#endif