problem in reading from usb mass storage device

[mahnaz0098]

Hello

when i use below program to write and read data from USB mass storage device(flash memory) i am getting following error. I've succeeded with usb_bulk_write() but can't utilize
usb_bulk_read(). It returns an error.

Set configuration
usb_bulk_write: 12 bytes written
33 5b 2 1 0 5 1 3 7 f 7f 1f
read failed: libusb0-dll:err [_usb_reap_async] reaping request failed, win error
: A device attached to the system is not functioning.

usb_bulk_read: -5 bytes read:

what is the problem in this code?

 #include "lusb0_usb.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>


  #define VENDOR_ID    0x13FE
  #define PRODUCT_ID   0x3600 
  #define CONFIGURATION 0x01
  #define TIMEOUT 5000



  struct usb_device *current_device;
  usb_dev_handle *current_handle;

  struct usb_device *locate_usb_dev(void)   
  {
    struct usb_bus *bus_search; 
    struct usb_device *device_search;   
    struct usb_device *device_found;

    device_found = NULL;    

    bus_search = usb_busses;    
    while (bus_search != NULL)
    {   
        device_search = bus_search->devices;    
        while (device_search != NULL)
        {   
            if ((device_search->descriptor.idVendor ==VENDOR_ID)
                && (device_search->descriptor.idProduct ==PRODUCT_ID)
                && (device_found == NULL))
            {
                 device_found = device_search;
            }
            device_search = device_search->next;    
        }
        bus_search = bus_search->next;  
    }
    if(device_found == NULL)
    {
        printf("USB Device not found!\n");
        exit(1);
    }
    return device_found;    
  }



  void f_claim(void)
  {
    if (usb_claim_interface(current_handle, 0) < 0)
    {
        fprintf(stderr, "Could not claim interface 0: %s\n", usb_strerror());
        return;
    }
    usb_set_altinterface(current_handle, 0);
  }


int f_read(void)
{
    int size = 512;
    char *data = (char *) malloc(size*sizeof(char));
int r = usb_bulk_read(current_handle,0x81,data, size,TIMEOUT);
     if (r < 0){
        printf("read failed: %s\n", usb_strerror());
      }
    printf("usb_bulk_read: %d bytes read: ", r);
   for (int i = 0; i < r; ++i) {
        printf("%3x ", data[i]);
  }
  printf("\n");
  free(data);
  return r;
 }


  int f_write(void)
 {
    int size = 12;
    char *data = (char *) malloc(size*sizeof(char));
    data[0] = 0x33;
    data[1] = 0x5B;
    data[2] = 0x02;
    data[3] = 0x01;
    data[4] = 0x00;
    data[5] = 0x05;
    data[6] = 0x01;
    data[7] = 0x03;
    data[8] = 0x07;
    data[9] = 0x0F;
    data[10] = 0x7F;
    data[11] = 0x1F;
   int w=usb_bulk_write(current_handle,0x02,data,size,TIMEOUT);
   if (w < 0){
       printf("usb_bulk_write failed: %s\n", usb_strerror());
       return -1;
   }

       printf("usb_bulk_write: %d bytes written\n", w);
       for (int i = 0; i < size; ++i) {
            printf("%3x ", data[i]);
        }
     printf("\n");
     free(data);
     return w;
  }



  void f_release(void)
  {
    usb_release_interface(current_handle, 0);

  }


  int f_init(void)
  {
    usb_init();         
    usb_find_busses();      
    usb_find_devices();     
    current_device = locate_usb_dev();  
    if (current_device == NULL)
    {
        fprintf(stderr, "Cannot find FLASH Device on any Bus\n");
        return -1;
    }
    current_handle = usb_open(current_device);


    printf("Set configuration\n");
if (usb_set_configuration(current_handle, CONFIGURATION) < 0) {
printf("error on usb_set_configuration: %s\n", usb_strerror());
system("PAUSE");
return -1;
}


    return 0;
  }


  void f_exit(void)
  { 
    usb_close(current_handle);  
  }

  int main(void)
  {
    f_init();
    f_claim();
    f_write();
    f_release();
    f_claim();
    f_read();
    f_release();
    f_exit();
  }