hid.c

/*******************************************************
 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 General 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 */
    IOHIDManagerSetDeviceMatching(hid_mgr, NULL);
    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