src/libmtp.c

#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "libmtp.h"
#include "unicode.h"
#include "ptp.h"
#include "libusb-glue.h"

// Forward declarations of local functions
static int send_file_object(LIBMTP_mtpdevice_t *device, 
			    int const fd, uint64_t size,
			    LIBMTP_progressfunc_t const * const callback,
			    void const * const data);
static int delete_item(LIBMTP_mtpdevice_t *device, uint32_t item_id);
uint16_t map_mtp_type_to_ptp_type(LIBMTP_filetype_t intype);

// Map this libptp2 single-threaded callback to the LIBMTP callback type
// extern Progress_Callback* globalCallback;
// static Progress_Callback single_threaded_callback_helper;

static void *single_threaded_callback_data;
static LIBMTP_progressfunc_t *single_threaded_callback;

/**
 * This is a ugly workaround due to limitations in callback set by
 * libptp2...
 */
static int single_threaded_callback_helper(uint32_t sent, uint32_t total) {
  if (single_threaded_callback != NULL) {
    /* 
     * If the callback return anything else than 0, we should interrupt the processing,
     * but currently libptp2 does not offer anything meaningful here so we have to ignore
     * the return value.
     */
    (void) single_threaded_callback(sent, total, single_threaded_callback_data);
  }
  return 0;
}

/**
 * Initialize the library.
 */
void LIBMTP_Init(void)
{
  return;
}

/**
 * Get a list of the supported devices.
 *
 * @param devices a pointer to a pointer that will hold a device
 *        list after the call to this function, if it was
 *        successful.
 * @param numdevs a pointer to an integer that will hold the number
 *        of devices in the device list if the call was successful.
 * @return 0 if the list was successfull retrieved, any other
 *        value means failure.
 */
int LIBMTP_Get_Supported_Devices_List(LIBMTP_device_entry_t ** const devices, int * const numdevs)
{
  // Just dispatch to libusb glue file...
  return get_device_list(devices, numdevs);
}

/**
 * Get the first connected MTP device.
 * @return a device pointer.
 */
LIBMTP_mtpdevice_t *LIBMTP_Get_First_Device(void)
{
  uint8_t interface_number;
  PTPParams *params;
  PTP_USB *ptp_usb;
  PTPStorageIDs storageIDs;
  unsigned storageID = 0;
  PTPDevicePropDesc dpd;
  uint8_t batteryLevelMax = 100;
  uint16_t ret;
  LIBMTP_mtpdevice_t *tmpdevice;

  // Allocate a parameter block
  params = (PTPParams *) malloc(sizeof(PTPParams));
  ptp_usb = (PTP_USB *) malloc(sizeof(PTP_USB));
  ret = connect_first_device(params, ptp_usb, &interface_number);
  
  switch (ret)
    {
    case PTP_CD_RC_CONNECTED:
      printf("Connected to MTP device.\n");
      break;
    case PTP_CD_RC_NO_DEVICES:
      printf("No MTP devices.\n");
      return NULL;
    case PTP_CD_RC_ERROR_CONNECTING:
      printf("Connection error.\n");
      return NULL;
    }

  // get storage ID
  if (ptp_getstorageids (params, &storageIDs) == PTP_RC_OK) {
    if (storageIDs.n > 0)
      storageID = storageIDs.Storage[0];
    free(storageIDs.Storage);
  }
  
  // Make sure there are no handlers
  params->handles.Handler = NULL;

  // Just cache the device information for any later use.
  if (ptp_getdeviceinfo(params, &params->deviceinfo) != PTP_RC_OK) {
    goto error_handler;
  }
  
  // Get battery maximum level
  if (ptp_getdevicepropdesc(params, PTP_DPC_BatteryLevel, &dpd) != PTP_RC_OK) {
    printf("LIBMTP_Get_First_Device(): Unable to retrieve battery max level.\n");
    goto error_handler;
  }
  // if is NULL, just leave as default
  if (dpd.FORM.Range.MaximumValue.u8 != 0) {
    batteryLevelMax = dpd.FORM.Range.MaximumValue.u8;
  }
  ptp_free_devicepropdesc(&dpd);

  // OK everything got this far, so it is time to create a device struct!
  tmpdevice = (LIBMTP_mtpdevice_t *) malloc(sizeof(LIBMTP_mtpdevice_t));
  tmpdevice->interface_number = interface_number;
  tmpdevice->params = (void *) params;
  tmpdevice->usbinfo = (void *) ptp_usb;
  tmpdevice->storage_id = storageID;
  tmpdevice->maximum_battery_level = batteryLevelMax;

  return tmpdevice;
  
  // Then close it again.
 error_handler:
  close_device(ptp_usb, params, interface_number);
  // TODO: libgphoto2 does not seem to be able to free the deviceinfo
  // ptp_free_deviceinfo(&params->deviceinfo);
  if (params->handles.Handler != NULL) {
    free(params->handles.Handler);
  }
  return NULL;
}

/**
 * This closes and releases an allocated MTP device.
 * @param device a pointer to the MTP device to release.
 */
void LIBMTP_Release_Device(LIBMTP_mtpdevice_t *device)
{
  PTPParams *params = (PTPParams *) device->params;
  PTP_USB *ptp_usb = (PTP_USB*) device->usbinfo;

  close_device(ptp_usb, params, device->interface_number);
  // Free the device info and any handler
  // TODO: libgphoto2 does not seem to be able to free the deviceinfo
  // ptp_free_deviceinfo(&params->deviceinfo);
  if (params->handles.Handler != NULL) {
    free(params->handles.Handler);
  }
  free(device);
}

/**
 * This function dumps out a large chunk of textual information
 * provided from the PTP protocol and additionally some extra
 * MTP-specific information where applicable.
 * @param device a pointer to the MTP device to report info from.
 */
void LIBMTP_Dump_Device_Info(LIBMTP_mtpdevice_t *device)
{
  int i;
  PTPParams *params = (PTPParams *) device->params;
    
  /* Print out some verbose information */
  printf("Device info:\n");
  printf("   Manufacturer: %s\n", params->deviceinfo.Manufacturer);
  printf("   Model: %s\n", params->deviceinfo.Model);
  printf("   Device version: %s\n", params->deviceinfo.DeviceVersion);
  printf("   Serial number: %s\n", params->deviceinfo.SerialNumber);
  printf("   Vendor extension ID: 0x%08x\n", params->deviceinfo.VendorExtensionID);
  printf("   Vendor extension description: %s\n", params->deviceinfo.VendorExtensionDesc);
  printf("Supported operations:\n");
  for (i=0;i<params->deviceinfo.OperationsSupported_len;i++) {
    printf("   0x%04x\n", params->deviceinfo.OperationsSupported[i]);
  }
  printf("Events supported:\n");
  if (params->deviceinfo.EventsSupported_len == 0) {
    printf("   None.\n");
  } else {
    for (i=0;i<params->deviceinfo.EventsSupported_len;i++) {
      printf("   0x%04x\n", params->deviceinfo.EventsSupported[i]);
    }
  }
  printf("Device Properties Supported:\n");
  for (i=0;i<params->deviceinfo.DevicePropertiesSupported_len;i++) {
    char *propdesc = ptp_get_property_description(params, params->deviceinfo.DevicePropertiesSupported[i]);
    printf("   0x%04x: %s\n", params->deviceinfo.DevicePropertiesSupported[i],
	   (propdesc == NULL) ? "Unknown property" : propdesc);
  }
}

/**
 * This retrieves the model name (often equal to product name) 
 * of an MTP device.
 * @param device a pointer to the device to get the model name for.
 * @return a newly allocated UTF-8 string representing the model name.
 *         The string must be freed by the caller after use. If the call
 *         was unsuccessful this will contain NULL.
 */
char *LIBMTP_Get_Modelname(LIBMTP_mtpdevice_t *device)
{
  char *retmodel = NULL;
  PTPParams *params = (PTPParams *) device->params;
  
  if (params->deviceinfo.Model != NULL) {
    retmodel = strdup(params->deviceinfo.Model);
  }
  return retmodel;
}

/**
 * This retrieves the serial number of an MTP device.
 * @param device a pointer to the device to get the serial number for.
 * @return a newly allocated UTF-8 string representing the serial number.
 *         The string must be freed by the caller after use. If the call
 *         was unsuccessful this will contain NULL.
 */
char *LIBMTP_Get_Serialnumber(LIBMTP_mtpdevice_t *device)
{
  char *retnumber = NULL;
  PTPParams *params = (PTPParams *) device->params;
  
  if (params->deviceinfo.SerialNumber != NULL) {
    retnumber = strdup(params->deviceinfo.SerialNumber);
  }
  return retnumber;
}

/**
 * This retrieves the device version (hardware and firmware version) of an 
 * MTP device.
 * @param device a pointer to the device to get the device version for.
 * @return a newly allocated UTF-8 string representing the device version.
 *         The string must be freed by the caller after use. If the call
 *         was unsuccessful this will contain NULL.
 */
char *LIBMTP_Get_Deviceversion(LIBMTP_mtpdevice_t *device)
{
  char *retversion = NULL;
  PTPParams *params = (PTPParams *) device->params;
  
  if (params->deviceinfo.DeviceVersion != NULL) {
    retversion = strdup(params->deviceinfo.DeviceVersion);
  }
  return retversion;
}


/**
 * This retrieves the owners name of an MTP device.
 * @param device a pointer to the device to get the owner for.
 * @return a newly allocated UTF-8 string representing the owner. 
 *         The string must be freed by the caller after use.
 */
char *LIBMTP_Get_Ownername(LIBMTP_mtpdevice_t *device)
{
  PTPPropertyValue propval;
  char *retstring = NULL;
  PTPParams *params = (PTPParams *) device->params;

  if (ptp_getdevicepropvalue(params, 
			     PTP_DPC_MTP_Device_Friendly_Name, 
			     &propval, 
			     PTP_DTC_UNISTR) != PTP_RC_OK) {
    return NULL;
  }
  // Convert from UTF-16 to UTF-8
  retstring = ucs2_to_utf8((uint16_t *) propval.unistr);
  free(propval.unistr);
  return retstring;
}

/**
 * This function finds out how much storage space is currently used
 * and any additional storage information. Storage may be a hard disk
 * or flash memory or whatever.
 * @param device a pointer to the device to get the storage info for.
 * @param total a pointer to a variable that will hold the 
 *        total the total number of bytes available on this volume after
 *        the call.
 * @param free a pointer to a variable that will hold the number of 
 *        free bytes available on this volume right now after the call.
 * @param storage_description a description of the storage. This may 
 *        be NULL after the call even if it succeeded. If it is not NULL, 
 *        it must be freed by the callee after use.
 * @param volume_label a volume label or similar. This may be NULL after the
 *        call even if it succeeded. If it is not NULL, it must be
 *        freed by the callee after use.
 * @return 0 if the storage info was successfully retrieved, any other
 *        value means failure.
 */
int LIBMTP_Get_Storageinfo(LIBMTP_mtpdevice_t *device, uint64_t * const total, 
			uint64_t * const free, char ** const storage_description, 
			char ** const volume_label)
{
  PTPStorageInfo storageInfo;
  PTPParams *params = (PTPParams *) device->params;
  
  if (ptp_getstorageinfo(params, device->storage_id, &storageInfo) != PTP_RC_OK) {
    printf("LIBMTP_Get_Diskinfo(): failed to get disk info\n");
    *total = 0;
    *free = 0;
    *storage_description = NULL;
    *volume_label = NULL;
    return -1;
  }
  *total = storageInfo.MaxCapability;
  *free = storageInfo.FreeSpaceInBytes;
  *storage_description = storageInfo.StorageDescription;
  *volume_label = storageInfo.VolumeLabel;

  return 0;
}


/**
 * This function retrieves the current battery level on the device.
 * @param device a pointer to the device to get the battery level for.
 * @param maximum_level a pointer to a variable that will hold the 
 *        maximum level of the battery if the call was successful.
 * @param current_level a pointer to a variable that will hold the 
 *        current level of the battery if the call was successful.
 * @return 0 if the storage info was successfully retrieved, any other
 *        value means failure.
 */
int LIBMTP_Get_Batterylevel(LIBMTP_mtpdevice_t *device, 
			    uint8_t * const maximum_level, 
			    uint8_t * const current_level)
{
  PTPPropertyValue propval;
  uint16_t ret;
  PTPParams *params = (PTPParams *) device->params;

  ret = ptp_getdevicepropvalue(params, PTP_DPC_BatteryLevel, &propval, PTP_DTC_UINT8);
  if (ret != PTP_RC_OK) {
    *maximum_level = 0;
    *current_level = 0;
    return -1;
  }
  
  *maximum_level = device->maximum_battery_level;
  *current_level = propval.u8;
  
  return 0;
}

/**
 * This creates a new file metadata structure and allocates memory
 * for it. Notice that if you add strings to this structure they
 * will be freed by the corresponding <code>LIBMTP_destroy_file_t</code>
 * operation later, so be careful of using strdup() when assigning 
 * strings, e.g.:
 *
 * <pre>
 * LIBMTP_file_t *file = LIBMTP_new_file_t();
 * file->filename = strdup(namestr);
 * ....
 * LIBMTP_destroy_file_t(file);
 * </pre>
 *
 * @return a pointer to the newly allocated metadata structure.
 * @see LIBMTP_destroy_file_t()
 */
LIBMTP_file_t *LIBMTP_new_file_t(void)
{
  LIBMTP_file_t *new = (LIBMTP_file_t *) malloc(sizeof(LIBMTP_file_t));
  if (new == NULL) {
    return NULL;
  }
  new->filename = NULL;
  new->filesize = 0;
  new->filetype = LIBMTP_FILETYPE_UNKNOWN;
  new->next = NULL;
  return new;
}

/**
 * This destroys a file metadata structure and deallocates the memory
 * used by it, including any strings. Never use a file metadata 
 * structure again after calling this function on it.
 * @param file the file metadata to destroy.
 * @see LIBMTP_new_file_t()
 */
void LIBMTP_destroy_file_t(LIBMTP_file_t *file)
{
  if (file == NULL) {
    return;
  }
  if (file->filename != NULL)
    free(file->filename);
  free(file);
  return;
}

/**
 * This returns a long list of all files available
 * on the current MTP device. Typical usage:
 *
 * <pre>
 * LIBMTP_file_t *filelist;
 *
 * filelist = LIBMTP_Get_Filelisting(device);
 * while (filelist != NULL) {
 *   LIBMTP_file_t *tmp;
 *
 *   // Do something on each element in the list here...
 *   tmp = filelist;
 *   filelist = filelist->next;
 *   LIBMTP_destroy_file_t(tmp);
 * }
 * </pre>
 *
 * @param device a pointer to the device to get the file listing for.
 * @return a list of files that can be followed using the <code>next</code>
 *         field of the <code>LIBMTP_file_t</code> data structure.
 *         Each of the metadata tags must be freed after use, and may
 *         contain only partial metadata information, i.e. one or several
 *         fields may be NULL or 0.
 */
LIBMTP_file_t *LIBMTP_Get_Filelisting(LIBMTP_mtpdevice_t *device)
{
  uint32_t i = 0;
  LIBMTP_file_t *retfiles = NULL;
  LIBMTP_file_t *curfile = NULL;
  PTPParams *params = (PTPParams *) device->params;
  
  if (params->handles.Handler == NULL) {
    // Get all the handles if we haven't already done that
    if (ptp_getobjecthandles(params,
			     PTP_GOH_ALL_STORAGE, 
			     PTP_GOH_ALL_FORMATS, 
			     PTP_GOH_ALL_ASSOCS, 
			     &params->handles) != PTP_RC_OK) {
      printf("LIBMTP panic: Could not get object handles...\n");
      return NULL;
    }
  }
  
  for (i = 0; i < params->handles.n; i++) {

    LIBMTP_file_t *file;
    PTPObjectInfo oi;

    if (ptp_getobjectinfo(params, params->handles.Handler[i], &oi) == PTP_RC_OK) {
      // Allocate a new file type
      file = LIBMTP_new_file_t();

      file->parent_id = oi.ParentObject;
      
      switch (oi.ObjectFormat)
	{
	case PTP_OFC_WAV:
	  file->filetype = LIBMTP_FILETYPE_WAV;
	  break;
	case PTP_OFC_MP3:
	  file->filetype = LIBMTP_FILETYPE_MP3;
	  break;
	case PTP_OFC_MTP_WMA:
	  file->filetype = LIBMTP_FILETYPE_WMA;
	  break;
	case PTP_OFC_MTP_OGG:
	  file->filetype = LIBMTP_FILETYPE_OGG;
	  break;
	case PTP_OFC_MTP_MP4:
	  file->filetype = LIBMTP_FILETYPE_MP4;
	  break;
	case PTP_OFC_MTP_UndefinedAudio:
	  file->filetype = LIBMTP_FILETYPE_UNDEF_AUDIO;
	  break;
	case PTP_OFC_MTP_WMV:
	  file->filetype = LIBMTP_FILETYPE_WMV;
	  break;
	case PTP_OFC_AVI:
	  file->filetype = LIBMTP_FILETYPE_AVI;
	  break;
	case PTP_OFC_MPEG:
	  file->filetype = LIBMTP_FILETYPE_MPEG;
	  break;
	case PTP_OFC_ASF:
	  file->filetype = LIBMTP_FILETYPE_ASF;
	  break;
	case PTP_OFC_QT:
	  file->filetype = LIBMTP_FILETYPE_QT;
	  break;
	case PTP_OFC_MTP_UndefinedVideo:
	  file->filetype = LIBMTP_FILETYPE_UNDEF_VIDEO;
	  break;
	case PTP_OFC_JFIF: // or should this be PTP_OFC_EXIF_JPEG?
	  file->filetype = LIBMTP_FILETYPE_JFIF;
	  break;
	case PTP_OFC_TIFF:
	  file->filetype = LIBMTP_FILETYPE_TIFF;
	  break;
	case PTP_OFC_BMP:
	  file->filetype = LIBMTP_FILETYPE_BMP;
	  break;
	case PTP_OFC_GIF:
	  file->filetype = LIBMTP_FILETYPE_GIF;
	  break;
	case PTP_OFC_PICT:
	  file->filetype = LIBMTP_FILETYPE_PICT;
	  break;
	case PTP_OFC_PNG:
	  file->filetype = LIBMTP_FILETYPE_PNG;
	  break;
	case PTP_OFC_MTP_vCalendar2:
	  file->filetype = LIBMTP_FILETYPE_CALENDAR;
	  break;
	default:
	  file->filetype = LIBMTP_FILETYPE_UNKNOWN;
	  // printf("LIBMTP warning: \"%s\" has unknown filetype 0x%04X, association: 0x%04X, association desc: 0x%08X\n", oi.Filename, oi.ObjectFormat, oi.AssociationType, oi.AssociationDesc);
	}

      // Original file-specific properties
      file->filesize = oi.ObjectCompressedSize;
      if (oi.Filename != NULL) {
	file->filename = strdup(oi.Filename);
      }

      // This is some sort of unique ID so we can keep track of the track.
      file->item_id = params->handles.Handler[i];
      
      // Add track to a list that will be returned afterwards.
      if (retfiles == NULL) {
	retfiles = file;
	curfile = file;
      } else {
	curfile->next = file;
	curfile = file;
      }
      
      // Call listing callback
      // double progressPercent = (double)i*(double)100.0 / (double)params->handles.n;

    } else {
      printf("LIBMTP panic: Found a bad handle, trying to ignore it.\n");
    }

  } // Handle counting loop
  return retfiles;
}

/**
 * This creates a new track metadata structure and allocates memory
 * for it. Notice that if you add strings to this structure they
 * will be freed by the corresponding <code>LIBMTP_destroy_track_t</code>
 * operation later, so be careful of using strdup() when assigning 
 * strings, e.g.:
 *
 * <pre>
 * LIBMTP_track_t *track = LIBMTP_new_track_t();
 * track->title = strdup(titlestr);
 * ....
 * LIBMTP_destroy_track_t(track);
 * </pre>
 *
 * @return a pointer to the newly allocated metadata structure.
 * @see LIBMTP_destroy_track_t()
 */
LIBMTP_track_t *LIBMTP_new_track_t(void)
{
  LIBMTP_track_t *new = (LIBMTP_track_t *) malloc(sizeof(LIBMTP_track_t));
  if (new == NULL) {
    return NULL;
  }
  new->title = NULL;
  new->artist = NULL;
  new->album = NULL;
  new->genre = NULL;
  new->date = NULL;
  new->filename = NULL;
  new->duration = 0;
  new->tracknumber = 0;
  new->filesize = 0;
  new->filetype = LIBMTP_FILETYPE_UNKNOWN;
  new->next = NULL;
  return new;
}

/**
 * This destroys a track metadata structure and deallocates the memory
 * used by it, including any strings. Never use a track metadata 
 * structure again after calling this function on it.
 * @param track the track metadata to destroy.
 * @see LIBMTP_new_track_t()
 */
void LIBMTP_destroy_track_t(LIBMTP_track_t *track)
{
  if (track == NULL) {
    return;
  }
  if (track->title != NULL)
    free(track->title);
  if (track->artist != NULL)
    free(track->artist);
  if (track->album != NULL)
    free(track->album);
  if (track->genre != NULL)
    free(track->genre);
  if (track->date != NULL)
    free(track->date);
  if (track->filename != NULL)
    free(track->filename);
  free(track);
  return;
}

/**
 * This returns a long list of all tracks available
 * on the current MTP device. Typical usage:
 *
 * <pre>
 * LIBMTP_track_t *tracklist;
 *
 * tracklist = LIBMTP_Get_Tracklisting(device);
 * while (tracklist != NULL) {
 *   LIBMTP_track_t *tmp;
 *
 *   // Do something on each element in the list here...
 *   tmp = tracklist;
 *   tracklist = tracklist->next;
 *   LIBMTP_destroy_track_t(tmp);
 * }
 * </pre>
 *
 * @param device a pointer to the device to get the track listing for.
 * @return a list of tracks that can be followed using the <code>next</code>
 *         field of the <code>LIBMTP_track_t</code> data structure.
 *         Each of the metadata tags must be freed after use, and may
 *         contain only partial metadata information, i.e. one or several
 *         fields may be NULL or 0.
 */
LIBMTP_track_t *LIBMTP_Get_Tracklisting(LIBMTP_mtpdevice_t *device)
{
  uint32_t i = 0;
  LIBMTP_track_t *retracks = NULL;
  LIBMTP_track_t *curtrack = NULL;
  PTPParams *params = (PTPParams *) device->params;
  
  if (params->handles.Handler == NULL) {
    // Get all the handles if we haven't already done that
    if (ptp_getobjecthandles(params,
			     PTP_GOH_ALL_STORAGE, 
			     PTP_GOH_ALL_FORMATS, 
			     PTP_GOH_ALL_ASSOCS, 
			     &params->handles) != PTP_RC_OK) {
      printf("LIBMTP panic: Could not get object handles...\n");
      return NULL;
    }
  }
  
  for (i = 0; i < params->handles.n; i++) {

    LIBMTP_track_t *track;
    PTPObjectInfo oi;
    int ret;
    PTPPropertyValue propval;

    if (ptp_getobjectinfo(params, params->handles.Handler[i], &oi) == PTP_RC_OK) {
      
      // Ignore stuff we don't know how to handle...
      if ( oi.ObjectFormat != PTP_OFC_WAV && 
	   oi.ObjectFormat != PTP_OFC_MP3 && 
	   oi.ObjectFormat != PTP_OFC_MTP_WMA &&
	   oi.ObjectFormat != PTP_OFC_MTP_OGG && 
	   oi.ObjectFormat != PTP_OFC_MTP_MP4 &&
	   oi.ObjectFormat != PTP_OFC_MTP_UndefinedAudio ) {
	printf("Not a music track (format: %d), skipping...\n",oi.ObjectFormat);
	continue;
      }
      
      // Allocate a new track type
      track = LIBMTP_new_track_t();

      switch (oi.ObjectFormat)
	{
	case PTP_OFC_WAV:
	  track->filetype = LIBMTP_FILETYPE_WAV;
	  break;
	case PTP_OFC_MP3:
	  track->filetype = LIBMTP_FILETYPE_MP3;
	  break;
	case PTP_OFC_MTP_WMA:
	  track->filetype = LIBMTP_FILETYPE_WMA;
	  break;
	case PTP_OFC_MTP_OGG:
	  track->filetype = LIBMTP_FILETYPE_OGG;
	  break;
	case PTP_OFC_MTP_MP4:
	  track->filetype = LIBMTP_FILETYPE_MP4;
	  break;
	case PTP_OFC_MTP_UndefinedAudio:
	  track->filetype = LIBMTP_FILETYPE_UNDEF_AUDIO;
	  break;
	default:
	  track->filetype = LIBMTP_FILETYPE_UNKNOWN;
	}

      // Original file-specific properties
      track->filesize = oi.ObjectCompressedSize;
      if (oi.Filename != NULL) {
	track->filename = strdup(oi.Filename);
      }

      ret = ptp_mtp_getobjectpropvalue(params, params->handles.Handler[i], 
				       PTP_OPC_Name, 
				       &propval,
				       PTP_DTC_UNISTR);
      if (ret == PTP_RC_OK && propval.unistr != NULL) {
	track->title = ucs2_to_utf8(propval.unistr);
	free(propval.unistr);
      }

      ret = ptp_mtp_getobjectpropvalue(params, 
				       params->handles.Handler[i], 
				       PTP_OPC_Artist,
				       &propval,
				       PTP_DTC_UNISTR);
      if (ret == PTP_RC_OK && propval.unistr != NULL) {
	track->artist = ucs2_to_utf8(propval.unistr);
	free(propval.unistr);
      }

      ret = ptp_mtp_getobjectpropvalue(params, 
				       params->handles.Handler[i], 
				       PTP_OPC_Duration, 
				       &propval,
				       PTP_DTC_UINT32);
      if (ret == PTP_RC_OK) {
	track->duration = propval.u32;
      }

      ret = ptp_mtp_getobjectpropvalue(params, 
				       params->handles.Handler[i], 
				       PTP_OPC_Track, 
				       &propval,
				       PTP_DTC_UINT16);
      if (ret == PTP_RC_OK) {
	track->tracknumber = propval.u16;
      }

      ret = ptp_mtp_getobjectpropvalue(params,
				       params->handles.Handler[i], 
				       PTP_OPC_Genre, 
				       &propval,
				       PTP_DTC_UNISTR);
      if (ret == PTP_RC_OK && propval.unistr != NULL) {
	track->genre = ucs2_to_utf8(propval.unistr);
	free(propval.unistr);
      }

      ret = ptp_mtp_getobjectpropvalue(params, 
				       params->handles.Handler[i], 
				       PTP_OPC_AlbumName, 
				       &propval,
				       PTP_DTC_UNISTR);
      if (ret == PTP_RC_OK && propval.unistr != NULL) {
	track->album = ucs2_to_utf8(propval.unistr);
	free(propval.unistr);
      }

      ret = ptp_mtp_getobjectpropvalue(params, 
				       params->handles.Handler[i], 
				       PTP_OPC_OriginalReleaseDate, 
				       &propval,
				       PTP_DTC_STR);
      if (ret == PTP_RC_OK && propval.str != NULL) {
	track->date = propval.str;
      }
      
      // This is some sort of unique ID so we can keep track of the track.
      track->item_id = params->handles.Handler[i];
      
      // Add track to a list that will be returned afterwards.
      if (retracks == NULL) {
	retracks = track;
	curtrack = track;
      } else {
	curtrack->next = track;
	curtrack = track;
      }
      
      // Call listing callback
      // double progressPercent = (double)i*(double)100.0 / (double)params->handles.n;

    } else {
      printf("LIBMTP panic: Found a bad handle, trying to ignore it.\n");
    }

  } // Handle counting loop
  return retracks;
}


/**
 * This gets a file off the device to a local file identified
 * by a filename.
 * @param device a pointer to the device to get the track from.
 * @param id the file ID of the file to retrieve.
 * @param path a filename to use for the retrieved file.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 * @see LIBMTP_Get_File_To_File_Descriptor()
 */
int LIBMTP_Get_File_To_File(LIBMTP_mtpdevice_t *device, uint32_t const id, 
			 char const * const path, LIBMTP_progressfunc_t const * const callback,
			 void const * const data)
{
  int fd = -1;
  int ret;

  // Sanity check
  if (path == NULL) {
    printf("LIBMTP_Get_File_To_File(): Bad arguments, path was NULL\n");
    return -1;
  }

  // Open file
#ifdef __WIN32__
  if ( (fd = open(path, O_RDWR|O_CREAT|O_TRUNC|O_BINARY,S_IRWXU|S_IRGRP) == -1 ) {
#else
  if ( (fd = open(path, O_RDWR|O_CREAT|O_TRUNC,S_IRWXU|S_IRGRP)) == -1) {
#endif
    printf("LIBMTP_Get_File_To_File(): Could not create file \"%s\"\n", path);
    return -1;
  }
  
  ret = LIBMTP_Get_File_To_File_Descriptor(device, id, fd, callback, data);

  // Close file
  close(fd);
  
  return ret;
}

/**
 * This gets a file off the device to a file identified
 * by a file descriptor.
 * @param device a pointer to the device to get the file from.
 * @param id the file ID of the file to retrieve.
 * @param fd a local file descriptor to write the file to.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 * @see LIBMTP_Get_File_To_File()
 */
int LIBMTP_Get_File_To_File_Descriptor(LIBMTP_mtpdevice_t *device, 
					uint32_t const id, 
					int const fd, 
					LIBMTP_progressfunc_t const * const callback,
					void const * const data)
{
  PTPObjectInfo oi;
  void *image = NULL;
  int ret;
  PTPParams *params = (PTPParams *) device->params;
  ssize_t written;

  single_threaded_callback_data = (void *) data;
  single_threaded_callback = callback;
  // Disabled since the new ptp.c from libgphoto2 doesn't seem to have this anymore.
  // globalCallback = single_threaded_callback_helper;

  if (ptp_getobjectinfo(params, id, &oi) != PTP_RC_OK) {
    printf("LIBMTP_Get_File_To_File_Descriptor(): Could not get object info\n");
    return -1;
  }
  if (oi.ObjectFormat == PTP_OFC_Association) {
    printf("LIBMTP_Get_File_To_File_Descriptor(): Bad object format\n");
    return -1;
  }

  // Copy object to memory
  // We could use ptp_getpartialobject to make for progress bars etc.
  ret = ptp_getobject(params, id, (unsigned char **) &image);

  if (ret != PTP_RC_OK) {
    printf("LIBMTP_Get_File_To_File_Descriptor(): Could not get file from device (%d)\n", ret);
    return -1;
  }

  written = write(fd, image, oi.ObjectCompressedSize);
  if (written != oi.ObjectCompressedSize) {
    printf("LIBMTP_Get_File_To_File_Descriptor(): Could not write object properly\n");
  }

  return 0;
}

/**
 * This gets a track off the device to a file identified
 * by a filename. This is actually just a wrapper for the
 * \c LIBMTP_Get_Track_To_File() function.
 * @param device a pointer to the device to get the track from.
 * @param id the track ID of the track to retrieve.
 * @param path a filename to use for the retrieved track.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 * @see LIBMTP_Get_Track_To_File_Descriptor()
 */
int LIBMTP_Get_Track_To_File(LIBMTP_mtpdevice_t *device, uint32_t const id, 
			 char const * const path, LIBMTP_progressfunc_t const * const callback,
			 void const * const data)
{
  // This is just a wrapper
  return LIBMTP_Get_File_To_File(device, id, path, callback, data);
}

/**
 * This gets a track off the device to a file identified
 * by a file descriptor. This is actually just a wrapper for
 * the \c LIBMTP_Get_File_To_File_Descriptor() function.
 * @param device a pointer to the device to get the track from.
 * @param id the track ID of the track to retrieve.
 * @param fd a file descriptor to write the track to.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 * @see LIBMTP_Get_Track_To_File()
 */
int LIBMTP_Get_Track_To_File_Descriptor(LIBMTP_mtpdevice_t *device, 
					uint32_t const id, 
					int const fd, 
					LIBMTP_progressfunc_t const * const callback,
					void const * const data)
{
  // This is just a wrapper
  return LIBMTP_Get_File_To_File_Descriptor(device, id, fd, callback, data);
}

/**
 * This function sends a track from a local file to an
 * MTP device. A filename and a set of metadata must be
 * given as input.
 * @param device a pointer to the device to send the track to.
 * @param path the filename of a local file which will be sent.
 * @param metadata a track metadata set to be written along with the file.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 * @see LIBMTP_Send_Track_From_File_Descriptor()
 */
int LIBMTP_Send_Track_From_File(LIBMTP_mtpdevice_t *device, 
			 char const * const path, LIBMTP_track_t * const metadata,
                         LIBMTP_progressfunc_t const * const callback,
			 void const * const data)
{
  int fd;
  int ret;

  // Sanity check
  if (path == NULL) {
    printf("LIBMTP_Send_Track_From_File(): Bad arguments, path was NULL\n");
    return -1;
  }

  // Open file
#ifdef __WIN32__
  if ( (fd = open(path, O_RDONLY|O_BINARY) == -1 ) {
#else
  if ( (fd = open(path, O_RDONLY)) == -1) {
#endif
    printf("LIBMTP_Get_Track_To_File(): Could not open source file \"%s\"\n", path);
    return -1;
  }

  ret = LIBMTP_Send_Track_From_File_Descriptor(device, fd, metadata, callback, data);
  
  // Close file.
  close(fd);

  return ret;
}


/**
 * This is an internal function used by both the file and track 
 * send functions. This takes care of a created object and 
 * transfer the actual file contents to it.
 * @param device a pointer to the device to send the track to.
 * @param fd the filedescriptor for a local file which will be sent.
 * @param size the size of the file to be sent.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 */
int send_file_object(LIBMTP_mtpdevice_t *device, 
		      int const fd, uint64_t size,
		      LIBMTP_progressfunc_t const * const callback,
		      void const * const data)
{
  void *image = NULL;
  int ret;
  PTPParams *params = (PTPParams *) device->params;
  ssize_t readb;
  
  image = malloc(size);
  if (image == NULL) {
    printf("send_file_object(): Could not allocate memory.\n");
    return -1;
  }
  readb = read(fd, image, size);
  if (readb != size) {
    free(image);
    printf("send_file_object(): Could not read source file.\n");
    return -1;
  }
  ret = ptp_sendobject(params, image, size);
  free(image);
  if (ret != PTP_RC_OK) {
    printf("send_file_object(): Bad return code from ptp_sendobject(): %d.\n", ret);
    return -1;
  }
  return 0;

#if 0
  PTPContainer ptp;
  PTPUSBBulkContainerSend usbdata;
  uint16_t ret;
  uint8_t *buffer;
  uint64_t remain;
  int last_chunk_size = 0; // Size of the last chunk written to the OUT endpoint
  PTPParams *params = (PTPParams *) device->params;
  PTP_USB *ptp_usb = (PTP_USB*) device->usbinfo;

  // Nullify and configure PTP container
  memset(&ptp, 0, sizeof(ptp));
  ptp.Code = PTP_OC_SendObject;
  ptp.Nparam = 0;
  ptp.Transaction_ID = params->transaction_id++;
  ptp.SessionID = params->session_id;

  // Send request to send an object
  ret = params->sendreq_func(params, &ptp);
  if (ret != PTP_RC_OK) {
    ptp_perror(params, ret);
    printf("send_file_object: Could not send \"send object\" request\n");
    return -1;
  }

  // build appropriate USB container
  usbdata.length = htod32p(params,sizeof(usbdata) + size);
  usbdata.type = htod16p(params,PTP_USB_CONTAINER_DATA);
  usbdata.code = htod16p(params,PTP_OC_SendObject);
  usbdata.trans_id = htod32p(params,ptp.Transaction_ID);

  // Write request to USB
  ret = params->write_func((unsigned char *)&usbdata, sizeof(usbdata), params->data);
  if (ret != PTP_RC_OK) {
    printf("send_file_object: Error initializing sending object\n");
    ptp_perror(params, ret);
    return -1;
  }
	
  // This space will be used as a reading ring buffer for the transfers
  buffer = (uint8_t *) malloc(BLOCK_SIZE);
  if (buffer == NULL) {
    printf("send_file_object: Could not allocate send buffer\n");
    return -1;
  }
	
  remain = size;
  while (remain != 0) {
    int readsize = (remain > BLOCK_SIZE) ? BLOCK_SIZE : (int) remain;
    int bytesdone = (int) (size - remain);
    int readbytes;

    readbytes = read(fd, buffer, readsize);
    if (readbytes < readsize) {
      printf("send_file_object: error reading source file\n");
      printf("Wanted to read %d bytes but could only read %d.\n", readsize, readbytes);
      free(buffer);
      return -1;
    }
    
    if (callback != NULL) {
      // If the callback return anything else than 0, interrupt the processing
      int callret = callback(bytesdone, size, data);
      if (callret != 0) {
	printf("send_file_object: transfer interrupted by callback\n");
	free(buffer);
	return -1;
      }
    }
    
    // Write to USB
    ret = params->write_func(buffer, readsize, params->data);
    if (ret != PTP_RC_OK) {
      printf("send_file_object: error writing data chunk to object\n");
      ptp_perror(params, ret);
      free(buffer);
      return -1;
    }
    remain -= (uint64_t) readsize;
    // This is useful to keep track of last write
    last_chunk_size = readsize;
  }
  
  if (callback != NULL) {
    // This last call will not be able to abort execution and is just
    // done so progress bars go up to 100%
    (void) callback(size, size, data);
  }
  
  /*
   * Signal to USB that this is the last transfer if the last chunk
   * was exactly as large as the buffer.
   *
   * On Linux you need kernel 2.6.16 or newer for this to work under
   * USB 2.0 since the EHCI driver did not support zerolength writes
   * until then. (Using a UHCI port should be OK though.)
   */
  if (last_chunk_size == ptp_usb->outep_maxpacket) {
    ret = params->write_func(NULL, 0, params->data);
    if (ret!=PTP_RC_OK) {
      printf("send_file_object: error writing last zerolen data chunk for USB termination\n");
      ptp_perror(params, ret);
      free(buffer);
      return -1;
    }
  }

  // Get a response from device to make sure that the track was properly stored
  ret = params->getresp_func(params, &ptp);
  if (ret != PTP_RC_OK) {
    printf("send_file_object: error getting response from device\n");
    ptp_perror(params, ret);
    free(buffer);
    return -1;
  }

  // Free allocated buffer
  free(buffer);

  return 0;
#endif
}

/**
 * This function sends a track from a file descriptor to an
 * MTP device. A filename and a set of metadata must be
 * given as input.
 * @param device a pointer to the device to send the track to.
 * @param fd the filedescriptor for a local file which will be sent.
 * @param metadata a track metadata set to be written along with the file.
 *                 After this call the field <code>item_id</code>
 *                 will contain the new track ID.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 * @see LIBMTP_Send_Track_From_File()
 */
int LIBMTP_Send_Track_From_File_Descriptor(LIBMTP_mtpdevice_t *device, 
			 int const fd, LIBMTP_track_t * const metadata,
                         LIBMTP_progressfunc_t const * const callback,
			 void const * const data)
{
  uint32_t parenthandle = 0;
  uint16_t ret;
  uint32_t store = 0;
  int subcall_ret;
  PTPObjectInfo new_track;
  PTPParams *params = (PTPParams *) device->params;
  
  switch (metadata->filetype) {
  case LIBMTP_FILETYPE_WAV:
    new_track.ObjectFormat = PTP_OFC_WAV;
    break;
  case LIBMTP_FILETYPE_MP3:
    new_track.ObjectFormat = PTP_OFC_MP3;
    break;
  case LIBMTP_FILETYPE_WMA:
    new_track.ObjectFormat = PTP_OFC_MTP_WMA;
    break;
  case LIBMTP_FILETYPE_OGG:
    new_track.ObjectFormat = PTP_OFC_MTP_OGG;
    break;
  case LIBMTP_FILETYPE_MP4:
    new_track.ObjectFormat = PTP_OFC_MTP_MP4;
    break;
  case LIBMTP_FILETYPE_UNDEF_AUDIO:
    new_track.ObjectFormat = PTP_OFC_MTP_UndefinedAudio;
    break;
  default:
    printf("LIBMTP_Send_Track_From_File_Descriptor: unknown filetype.\n");
    new_track.ObjectFormat = PTP_OFC_Undefined;
  }
  new_track.Filename = metadata->filename;
  new_track.ObjectCompressedSize = metadata->filesize;

  // Create the object
  ret = ptp_sendobjectinfo(params, &store, &parenthandle, &metadata->item_id, &new_track);
  if (ret != PTP_RC_OK) {
    ptp_perror(params, ret);
    printf("LIBMTP_Send_Track_From_File_Descriptor: Could not send object info\n");
    return -1;
  }

  // Call main function to transfer the track
  subcall_ret = send_file_object(device, fd, metadata->filesize, callback, data);
  if (subcall_ret != 0) {
    printf("LIBMTP_Send_Track_From_File_Descriptor: error sending track object\n");
    (void) delete_item(device, metadata->item_id);
    return -1;
  }
    
  // Set track metadata for the new fine track
  subcall_ret = LIBMTP_Update_Track_Metadata(device, metadata);
  if (subcall_ret != 0) {
    printf("LIBMTP_Send_Track_From_File_Descriptor: error setting metadata for new track\n");
    (void) delete_item(device, metadata->item_id);
    return -1;
  }
  
  return 0;
}



/**
 * Returns the PTP filetype that maps to a certain MTP file type.
 * @param intype the MTP library interface type
 * @return the PTP (libgphoto2) interface type
 */
uint16_t map_mtp_type_to_ptp_type(LIBMTP_filetype_t intype)
{
  switch (intype) {
  case LIBMTP_FILETYPE_WAV:
    return PTP_OFC_WAV;
    break;
  case LIBMTP_FILETYPE_MP3:
    return PTP_OFC_MP3;
    break;
  case LIBMTP_FILETYPE_WMA:
    return PTP_OFC_MTP_WMA;
    break;
  case LIBMTP_FILETYPE_OGG:
    return PTP_OFC_MTP_OGG;
    break;
  case LIBMTP_FILETYPE_MP4:
    return PTP_OFC_MTP_MP4;
    break;
  case LIBMTP_FILETYPE_UNDEF_AUDIO:
    return PTP_OFC_MTP_UndefinedAudio;
    break;
  case LIBMTP_FILETYPE_WMV:
    return PTP_OFC_MTP_WMV;
    break;
  case LIBMTP_FILETYPE_AVI:
    return PTP_OFC_AVI;
    break;
  case LIBMTP_FILETYPE_MPEG:
    return PTP_OFC_MPEG;
    break;
  case LIBMTP_FILETYPE_ASF:
    return PTP_OFC_ASF;
    break;
  case LIBMTP_FILETYPE_QT:
    return PTP_OFC_QT;
    break;
  case LIBMTP_FILETYPE_UNDEF_VIDEO:
    return PTP_OFC_MTP_UndefinedVideo;
    break;
  case LIBMTP_FILETYPE_JFIF:
    return PTP_OFC_JFIF; // or should this be PTP_OFC_EXIF_JPEG?
    break;
  case LIBMTP_FILETYPE_TIFF:
    return PTP_OFC_TIFF;
    break;
  case LIBMTP_FILETYPE_BMP:
    return PTP_OFC_BMP;
    break;
  case LIBMTP_FILETYPE_GIF:
    return PTP_OFC_GIF;
    break;
  case LIBMTP_FILETYPE_PICT:
    return PTP_OFC_PICT;
    break;
  case LIBMTP_FILETYPE_PNG:
    return PTP_OFC_PNG;
    break;
  case LIBMTP_FILETYPE_CALENDAR:
    return PTP_OFC_MTP_vCalendar2;
    break;
  default:
    printf("LIBMTP_Send_File_From_File_Descriptor: unknown filetype.\n");
    return PTP_OFC_Undefined;
  }
}

/**
 * This function sends a generic file from a file descriptor to an
 * MTP device. A filename and a set of metadata must be
 * given as input.
 * @param device a pointer to the device to send the file to.
 * @param fd the filedescriptor for a local file which will be sent.
 * @param filedata a file strtuct to pass in info abou the file.
 *                 After this call the field <code>item_id</code>
 *                 will contain the new track ID.
 * @param callback a progress indicator function or NULL to ignore.
 * @param data a user-defined pointer that is passed along to
 *             the <code>progress</code> function in order to
 *             pass along some user defined data to the progress
 *             updates. If not used, set this to NULL.
 * @return 0 if the transfer was successful, any other value means 
 *           failure.
 * @see LIBMTP_Send_Track_From_File()
 */
int LIBMTP_Send_File_From_File_Descriptor(LIBMTP_mtpdevice_t *device, 
			 int const fd, LIBMTP_file_t * const filedata,
                         LIBMTP_progressfunc_t const * const callback,
			 void const * const data, uint32_t parenthandle)
{
  uint16_t ret;
  uint32_t store = 0;
  int subcall_ret;
  PTPObjectInfo new_file;
  PTPParams *params = (PTPParams *) device->params;
  
  new_file.Filename = filedata->filename;
  new_file.ObjectCompressedSize = filedata->filesize;
  new_file.ObjectFormat = map_mtp_type_to_ptp_type(filedata->filetype);

  // Create the object
  ret = ptp_sendobjectinfo(params, &store, &parenthandle, &filedata->item_id, &new_file);
  if (ret != PTP_RC_OK) {
    ptp_perror(params, ret);
    printf("LIBMTP_Send_File_From_File_Descriptor: Could not send object info\n");
    return -1;
  }

  // Call main function to transfer the track
  subcall_ret = send_file_object(device, fd, filedata->filesize, callback, data);
  if (subcall_ret != 0) {
    printf("LIBMTP_Send_File_From_File_Descriptor: error sending track object\n");
    (void) delete_item(device, filedata->item_id);
    return -1;
  }
    
  return 0;
}

/**
 * This function updates the MTP object metadata on a single file
 * identified by an object ID.
 * @param device a pointer to the device to update the track 
 *        metadata on.
 * @param metadata a track metadata set to be written to the file.
 *        notice that the <code>track_id</code> field of the
 *        metadata structure must be correct so that the
 *        function can update the right file. If some properties
 *        of this metadata are set to NULL (strings) or 0
 *        (numerical values) they will be discarded and the
 *        track will not be tagged with these blank values.
 * @return 0 on success, any other value means failure.
 */
int LIBMTP_Update_Track_Metadata(LIBMTP_mtpdevice_t *device, 
				 LIBMTP_track_t const * const metadata)
{
  uint16_t ret;
  PTPParams *params = (PTPParams *) device->params;
  PTPPropertyValue propval;

  // Update title
  if (metadata->title != NULL) {
    propval.unistr = utf8_to_ucs2((const unsigned char *) metadata->title);
    ret = ptp_mtp_setobjectpropvalue(params, metadata->item_id, PTP_OPC_Name, &propval, PTP_DTC_UNISTR);
    free(propval.unistr);
    if (ret != PTP_RC_OK) {
      printf("LIBMTP_Update_Track_Metadata(): could not set track title\n");
      return -1;
    }
  }

  // Update album
  if (metadata->album != NULL) {
    propval.unistr = utf8_to_ucs2((const unsigned char *) metadata->album);
    ret = ptp_mtp_setobjectpropvalue(params, metadata->item_id, PTP_OPC_AlbumName, &propval, PTP_DTC_UNISTR);
    free(propval.unistr);
    if (ret != PTP_RC_OK) {
      printf("LIBMTP_Update_Track_Metadata(): could not set track album name\n");
      return -1;
    }
  }

  // Update artist
  if (metadata->artist != NULL) {
    propval.unistr = utf8_to_ucs2((const unsigned char *) metadata->artist);
    ret = ptp_mtp_setobjectpropvalue(params, metadata->item_id, PTP_OPC_Artist, &propval, PTP_DTC_UNISTR);
    free(propval.unistr);
    if (ret != PTP_RC_OK) {
      printf("LIBMTP_Update_Track_Metadata(): could not set track artist name\n");
      return -1;
    }
  }

  // Update genre
  if (metadata->genre != NULL) {
    propval.unistr = utf8_to_ucs2((const unsigned char *) metadata->genre);
    ret = ptp_mtp_setobjectpropvalue(params, metadata->item_id, PTP_OPC_Genre, &propval, PTP_DTC_UNISTR);
    free(propval.unistr);
    if (ret != PTP_RC_OK) {
      printf("LIBMTP_Update_Track_Metadata(): could not set track genre name\n");
      return -1;
    }
  }

  // Update duration
  if (metadata->duration != 0) {
    propval.u32 = metadata->duration;
    ret = ptp_mtp_setobjectpropvalue(params, metadata->item_id, PTP_OPC_Duration, &propval, PTP_DTC_UINT32);
    if (ret != PTP_RC_OK) {
      printf("LIBMTP_Update_Track_Metadata(): could not set track duration\n");
      return -1;
    }
  }

  // Update track number.
  if (metadata->tracknumber != 0) {
    propval.u16 = metadata->tracknumber;
    ret = ptp_mtp_setobjectpropvalue(params, metadata->item_id, PTP_OPC_Track, &propval, PTP_DTC_UINT16);
    if (ret != PTP_RC_OK) {
      printf("LIBMTP_Update_Track_Metadata(): could not set track tracknumber\n");
      return -1;
    }
  }

  // Update creation datetime
  if (metadata->date != NULL) {
    propval.str = metadata->date;
    ret = ptp_mtp_setobjectpropvalue(params, metadata->item_id, PTP_OPC_OriginalReleaseDate, &propval, PTP_DTC_STR);
    if (ret != PTP_RC_OK) {
      printf("LIBMTP_Update_Track_Metadata(): could not set track release date\n");
      return -1;
    }
  }
  
  // NOTE: File size is not updated, this should not change anyway.
  // neither will we change the filename.
  
  return 0;
}

/**
 * Internal function called to delete tracks and files alike.
 * @param device a pointer to the device to delete the item from.
 * @param item_id the item to delete.
 * @return 0 on success, any other value means failure.
 */
static int delete_item(LIBMTP_mtpdevice_t *device, 
			uint32_t item_id)
{
  int ret;
  PTPParams *params = (PTPParams *) device->params;

  ret = ptp_deleteobject(params, item_id, 0);
  if (ret != PTP_RC_OK) {
    ptp_perror(params, ret);
    printf("delete_item(): could not delete track object\n");    
    return -1;
  }
  return 0;
}

/**
 * This function deletes a single file or track off the MTP device,
 * identified by an object ID.
 * @param device a pointer to the device to delete the file or track from.
 * @param item_id the item to delete.
 * @return 0 on success, any other value means failure.
 */
int LIBMTP_Delete_File(LIBMTP_mtpdevice_t *device, 
			uint32_t item_id)
{
  return delete_item(device, item_id);
}

/**
 * Helper function. This indicates if a track exists on the device
 * @param device a pointer to the device to get the track from.
 * @param id the track ID of the track to retrieve.
 * @return TRUE (1) if the track exists, FALSE (0) if not
 */
int LIBMTP_Track_Exists(LIBMTP_mtpdevice_t *device,
           uint32_t const id)
{
  PTPObjectInfo oi;
  PTPParams *params = (PTPParams *) device->params;

  if (ptp_getobjectinfo(params, id, &oi) == PTP_RC_OK) {
    return 1;
  }
  return 0;
}

/**
 * This creates a new folder structure and allocates memory
 * for it. Notice that if you add strings to this structure they
 * will be freed by the corresponding <code>LIBMTP_folder_track_t</code>
 * operation later, so be careful of using strdup() when assigning
 * strings, e.g.:
 *
 * @return a pointer to the newly allocated folder structure.
 * @see LIBMTP_destroy_folder_t()
 */
LIBMTP_folder_t *LIBMTP_new_folder_t(void)
{
  LIBMTP_folder_t *new = (LIBMTP_folder_t *) malloc(sizeof(LIBMTP_folder_t));
  if (new == NULL) {
    return NULL;
  }
  new->folder_id = 0;
  new->parent_id = 0;
  new->name = NULL;
  new->sibling = NULL;
  new->child = NULL;
  return new;
}

/**
 * This recursively deletes the memory for a folder structure
 *
 * @param folder folder structure to destroy
 * @see LIBMTP_new_folder_t()
 */
void LIBMTP_destroy_folder_t(LIBMTP_folder_t *folder)
{

  if(folder == NULL) {
     return;
  }

  //Destroy from the bottom up
  if(folder->child != NULL) {
     LIBMTP_destroy_folder_t(folder->child);
  }

  if(folder->sibling != NULL) {
    LIBMTP_destroy_folder_t(folder->sibling);
  }

  if(folder->name != NULL) {
    free(folder->name);
  }

  free(folder);
}

/**
 * Helper function. Returns a folder structure for a
 * specified id.
 *
 * @param folderlist list of folders to search
 * @id id of folder to look for
 * @return a folder or NULL if not found
 */
LIBMTP_folder_t *LIBMTP_Find_Folder(LIBMTP_folder_t *folderlist, uint32_t id)
{
  LIBMTP_folder_t *ret = NULL;
  
  if(folderlist == NULL) {
    return NULL;
  }
  
  if(folderlist->folder_id == id) {
    return folderlist;
  }
  
  if(folderlist->sibling) {
    ret = LIBMTP_Find_Folder(folderlist->sibling, id);
  }
  
  if(folderlist->child && ret == NULL) {
    ret = LIBMTP_Find_Folder(folderlist->child, id);
  }
  
  return ret;
}

/**
 * This returns a list of all folders available
 * on the current MTP device.
 *
 * @param device a pointer to the device to get the track listing for.
 * @return a list of folders
 */
LIBMTP_folder_t *LIBMTP_Get_Folder_List(LIBMTP_mtpdevice_t *device)
{
  uint32_t i = 0;
  LIBMTP_folder_t *retfolders = NULL;
  PTPParams *params = (PTPParams *) device->params;
  uint32_t ret = 0;
  
  if (params->handles.Handler == NULL) {
    // Get all the handles if we haven't already done that
    if ((ret=ptp_getobjecthandles(params,
				  PTP_GOH_ALL_STORAGE, 
				  PTP_GOH_ALL_FORMATS,
				  PTP_GOH_ALL_ASSOCS, 
				  &params->handles)) != PTP_RC_OK) {
      printf("LIBMTP_Get_Folder_List: Could not get object handles...(0x%08X)\n", ret);
      return NULL;
    }
  }
  
  for (i = 0; i < params->handles.n; i++) {
    LIBMTP_folder_t *folder;
    PTPObjectInfo oi;
    
    if (ptp_getobjectinfo(params, params->handles.Handler[i], &oi) == PTP_RC_OK) {
      if (oi.ObjectFormat != PTP_OFC_Association) {
        continue;
      }
      folder = LIBMTP_new_folder_t();
      folder->folder_id = params->handles.Handler[i];
      folder->parent_id = oi.ParentObject;
      folder->name = (char *)strdup(oi.Filename);
      
      // Work out where to put this new item
      if(retfolders == NULL) {
	retfolders = folder;
	continue;
      } else {
	LIBMTP_folder_t *parent_folder;
	LIBMTP_folder_t *current_folder;
	
	parent_folder = LIBMTP_Find_Folder(retfolders, folder->parent_id);
	
	if(parent_folder == NULL) {
	  current_folder = retfolders;
	} else {
	  if(parent_folder->child == NULL) {
	    parent_folder->child = folder;
	    continue;
	  } else {
	    current_folder = parent_folder->child;
	  }
	}
	
	while(current_folder->sibling != NULL) {
	  current_folder=current_folder->sibling;
	}
	
	current_folder->sibling = folder;
      }
    }
  }
  return retfolders;
}

/**
 * This create a folder on the current MTP device.
 *
 * @param device a pointer to the device to get the track listing for.
 * @param name name of folder
 * @param parent_id id of parent folder to add to.
 * @return id to new folder or -1 if an error
 */
uint32_t LIBMTP_Create_Folder(LIBMTP_mtpdevice_t *device, char *name, uint32_t parent_id)
{
  PTPParams *params = (PTPParams *) device->params;
  uint32_t parenthandle = 0;
  uint32_t store = 0;
  PTPObjectInfo new_folder;
  uint32_t ret;
  uint32_t new_id = 0;

  memset(&new_folder, 0, sizeof(new_folder));
  new_folder.Filename = name;
  new_folder.ObjectCompressedSize = 1;
  new_folder.ObjectFormat = PTP_OFC_Association;
  new_folder.ParentObject = parent_id;

  parenthandle = parent_id;
  // Create the object
  ret = ptp_sendobjectinfo(params, &store, &parenthandle, &new_id, &new_folder);
  if (ret != PTP_RC_OK) {
    ptp_perror(params, ret);
    printf("LIBMTP_Create_Folder: Could not send object info\n");
    return -1;
  }
  return new_id;
}