Adding third party library hidapi

third_party/hidapi/hidapi_mac.c

Index: third_party/hidapi/hidapi_mac.c
diff --git a/third_party/hidapi/hidapi_mac.c b/third_party/hidapi/hidapi_mac.c
new file mode 100644
index 0000000000000000000000000000000000000000..73a8d28044e29d25ee21fe6d28cb5c283e747fc8
--- /dev/null
+++ b/third_party/hidapi/hidapi_mac.c
@@ -0,0 +1,1112 @@
+/*******************************************************
+ 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