How do I read data from a pendrive through USB using libusb on Windows using the C programming language

Question

I am trying to read data from a pendrive connected through USB on Windows using libusb and C-programming. I am able to list out my USB connections, but I couldn't connect to one and transfer data from the USB in to my computer.

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

#include "libusb.h"

#define BULK_EP_OUT     0x63
#define BULK_EP_IN      0x08

int interface_ref = 0;
int alt_interface, interface_number;

int print_configuration(struct libusb_device_handle *hDevice, struct libusb_config_descriptor *config)
{
    char *data;
    int index;

    data = (char *)malloc(512);
    memset(data, 0, 512);

    index = config->iConfiguration;

    libusb_get_string_descriptor_ascii(hDevice, index, data, 512);

    printf("\nInterface Descriptors: ");
    printf("\n\tNumber of Interfaces: %d", config->bNumInterfaces);
    printf("\n\tLength: %d", config->bLength);
    printf("\n\tDesc_Type: %d", config->bDescriptorType);
    printf("\n\tConfig_index: %d", config->iConfiguration);
    printf("\n\tTotal length: %lu", config->wTotalLength);
    printf("\n\tConfiguration Value: %d", config->bConfigurationValue);
    printf("\n\tConfiguration Attributes: %d", config->bmAttributes);
    printf("\n\tMaxPower(mA): %d\n", config->MaxPower);

    free(data);
    data = NULL;
    return 0;
}

struct libusb_endpoint_descriptor* active_config(struct libusb_device *dev, struct libusb_device_handle *handle)
{
    struct libusb_device_handle *hDevice_req;
    struct libusb_config_descriptor *config;
    struct libusb_endpoint_descriptor *endpoint;
    int altsetting_index, interface_index=0, ret_active;
    int i, ret_print;

    hDevice_req = handle;

    ret_active = libusb_get_active_config_descriptor(dev, &config);
    ret_print = print_configuration(hDevice_req, config);

    for (interface_index=0;interface_index<config->bNumInterfaces;interface_index++)
    {
        const struct libusb_interface *iface = &config->interface[interface_index];
        for (altsetting_index=0; altsetting_index<iface->num_altsetting; altsetting_index++)
        {
            const struct libusb_interface_descriptor *altsetting = &iface->altsetting[altsetting_index];

            int endpoint_index;
            for(endpoint_index=0; endpoint_index<altsetting->bNumEndpoints; endpoint_index++)
            {
                const struct libusb_endpoint_desriptor *ep = &altsetting->endpoint[endpoint_index];
                endpoint = ep;
                alt_interface = altsetting->bAlternateSetting;
                interface_number = altsetting->bInterfaceNumber;
            }

            printf("\nEndPoint Descriptors: ");
            printf("\n\tSize of EndPoint Descriptor: %d", endpoint->bLength);
            printf("\n\tType of Descriptor: %d", endpoint->bDescriptorType);
            printf("\n\tEndpoint Address: 0x0%x", endpoint->bEndpointAddress);
            printf("\n\tMaximum Packet Size: %x", endpoint->wMaxPacketSize);
            printf("\n\tAttributes applied to Endpoint: %d", endpoint->bmAttributes);
            printf("\n\tInterval for Polling for data Tranfer: %d\n", endpoint->bInterval);
        }
    }
    libusb_free_config_descriptor(NULL);
    return endpoint;
}

int main(void)
{
    int r = 1, found1;
    struct libusb_device **devs;
    struct libusb_device_handle *handle = NULL, *hDevice_expected = NULL;
    struct libusb_device *dev, *dev_expected;

    struct libusb_device_descriptor desc;
    struct libusb_endpoint_descriptor *epdesc;
    struct libusb_interface_descriptor *intdesc;
    libusb_context *context = NULL;

    ssize_t cnt;
    int e = 0, config2;
    int i = 0, index;
    char str1[64], str2[64];
    char found = 0;

    // Init libusb
    r = libusb_init(NULL);
    if(r < 0)
    {
        printf("\nFailed to initialise libusb\n");
        return 1;
    }
    else
        printf("\nInit successful!\n");

    // Get a list of USB devices
    cnt = libusb_get_device_list(NULL, &devs);
    if (cnt < 0)
    {
        printf("\nThere are no USB devices on the bus\n");
        return -1;
    }
    printf("\nDevice count: %d\n-------------------------------\n", cnt);

    while ((dev = devs[i++]) > 0)
    {
        r = libusb_get_device_descriptor(dev, &desc);
        if (r < 0)
            {
            printf("Failed to get device descriptor\n");
            libusb_free_device_list(devs, 1);
            libusb_close(handle);
            break;
        }

        e = libusb_open(dev, &handle);

        if (e < 0)
        {
            printf("Error opening device\n");
            printf(e);
            libusb_free_device_list(devs, 1);
            libusb_close(handle);
            break;
        }

        printf("\nDevice Descriptors: ");
        printf("\n\tVendor ID: %x", desc.idVendor);
        printf("\n\tProduct ID: %x", desc.idProduct);
        printf("\n\tSerial Number: %x", desc.iSerialNumber);
        printf("\n\tSize of Device Descriptor: %d", desc.bLength);
        printf("\n\tType of Descriptor: %d", desc.bDescriptorType);
        printf("\n\tUSB Specification Release Number: %d", desc.bcdUSB);
        printf("\n\tDevice Release Number: %d", desc.bcdDevice);
        printf("\n\tDevice Class: %d", desc.bDeviceClass);
        printf("\n\tDevice Sub-Class: %d", desc.bDeviceSubClass);
        printf("\n\tDevice Protocol: %d", desc.bDeviceProtocol);
        printf("\n\tMax. Packet Size: %d", desc.bMaxPacketSize0);
        printf("\n\tNumber of Configurations: %d\n", desc.bNumConfigurations);

        e = libusb_get_string_descriptor_ascii(handle, desc.iManufacturer, (unsigned char*) str1, sizeof(str1));
        if (e < 0)
        {
            libusb_free_device_list(devs, 1);
            libusb_close(handle);
            break;
        }
        printf("\nManufactured: %s", str1);

        e = libusb_get_string_descriptor_ascii(handle, desc.iProduct, (unsigned char*) str2, sizeof(str2));
        if(e < 0)
        {
            libusb_free_device_list(devs, 1);
            libusb_close(handle);
            break;
        }
        printf("\nProduct: %s", str2);
        printf("\n----------------------------------------");

        if(desc.idVendor == 0x0781 && desc.idProduct == 0x5567)
        {
           found1 = 1;
            break;
        }
    }//end of while

    if (found1 == 0)
    {
        printf("\nDevice NOT found\n");
        libusb_free_device_list(devs, 1);
        libusb_close(handle);
        return 1;
    }
    else
    {
        printf("\nDevice found");
        dev_expected = dev;
        hDevice_expected = handle;
    }

    e = libusb_get_configuration(handle, &config2);
    if (e!=0)
    {
        printf("\n***Error in libusb_get_configuration\n");
        libusb_free_device_list(devs, 1);
        libusb_close(handle);
        return -1;
    }
    printf("\nConfigured value: %d", config2);

    if (config2 != 1)
    {
        libusb_set_configuration(handle, 1);
        if(e!=0)
        {
            printf("Error in libusb_set_configuration\n");
            libusb_free_device_list(devs, 1);
            libusb_close(handle);
            return -1;
        }
        else
            printf("\nDevice is in configured state!");
    }

    libusb_free_device_list(devs, 1);

    if(libusb_kernel_driver_active(handle, 0) == 1)
    {
        printf("\nKernel Driver Active");
        if(libusb_detach_kernel_driver(handle, 0) == 0)
            printf("\nKernel Driver Detached!");
        else
        {
            printf("\nCouldn't detach kernel driver!\n");
            libusb_free_device_list(devs, 1);
            libusb_close(handle);
            return -1;
        }
    }

    e = libusb_claim_interface(handle, 0);
    if (e < 0)
    {
        printf("\nCannot Claim Interface");
        libusb_free_device_list(devs, 1);
        libusb_close(handle);
        return -1;
    }
    else
        printf("\nClaimed Interface\n");

    active_config(dev_expected, hDevice_expected);


    char *my_string, *my_string1;
    int transferred = 0;
    int received = 0;
    int length = 0;
    int nbytes = 256;

    my_string = (char *)malloc(nbytes + 1);
    my_string1 = (char *)malloc(nbytes + 1);

    memset(my_string, '\0', 64);
    memset(my_string1, '\0', 64);

    strcpy(my_string, "Prasad Divesd");
    length = strlen(my_string);

    printf("\nTo be sent: %s", my_string);


    for(i = 0; i < length; i++)
    {
        e = libusb_bulk_transfer(handle, BULK_EP_OUT, my_string1, 64, &received, 0); //64: Max Packet Length
        if(e == 0)
        {
            printf("\nReceived: ");
            printf("%c", my_string1[i]);
            _sleep(1);
        }
        else
        {
            printf("\nError in read! e = %d and received = %d\n", e, received);
            return -1;
        }
    }

    e = libusb_release_interface(handle, 0);

    libusb_close(handle);
    libusb_exit(NULL);

    printf("\n");
    return 0;
}

score 0 · Answer 1 · edited May 23 '17 at 12:33

The code from Read/write on a pen drive using libusb: libusb_bulk_transfer() is for Linux. The sequence below is to detach the kernel driver in Linux.

This is done to be able write a bulk transfer to the USB mass storage device (pendrive). In Linux this is necessary, in Windows not because in Windows libusb has its own driver:

if(libusb_kernel_driver_active(handle, 0) == 1)
{
    printf("\nKernel Driver Active");
    if(libusb_detach_kernel_driver(handle, 0) == 0)
        printf("\nKernel Driver Detached!");
    else
    {
        printf("\nCouldn't detach kernel driver!\n");
        libusb_free_device_list(devs, 1);
        libusb_close(handle);
        return -1;
    }
}

So you have to delete at least this code.

Then notice that libusb on Windows has some limitations, see https://github.com/libusb/libusb/wiki/Windows.

If you want to debug programs use a debugger like WinDbg (Viewing the Call Stack in WinDbg) and get a stack trace (Windows Debuggers: Part 1: A WinDbg Tutorial and Viewing the Call Stack in WinDbg)

For more information on USB, see USB in a NutShell.

Beside this the code you posted should work (when removing the Linux-specific lines, etc.).

How do I read data from a pendrive through USB using libusb on Windows using the C programming language

1 Answers1