EPSIAE » eneraptor

/*

* ioctl.c − the process to use ioctl's to control the kernel module

*

* Until now we could have used cat for input and output. But now

* we need to do ioctl's, which require writing our own process.

*/

/*

* device specifics, such as ioctl numbers and the

* major device file.

*/

#include "drv_comm.h"

#include "generator.h"

#include <stdio.h>

#include <stdlib.h>

#include <fcntl.h>            /* open */

#include <unistd.h>            /* exit */

//#include <sys/ioctl.h>  /* ioctl */

/*

* Functions for the ioctl calls

*/

ioctl_set_msg(int file_desc, char *message)

{

        int ret_val;

        ret_val = ioctl(file_desc, IOCTL_SET_MSG, message);

        if (ret_val < 0) {

                printf("ioctl_set_msg failed:%d\n", ret_val);

                exit(-1);

        }

}

ioctl_get_msg(int file_desc)

{

        int ret_val;

        char message[100];

        /*

        * Warning − this is dangerous because we don't tell

        * the kernel how far it's allowed to write, so it

        * might overflow the buffer. In a real production

        * program, we would have used two ioctls − one to tell

        * the kernel the buffer length and another to give

        * it the buffer to fill

        */

        ret_val = ioctl(file_desc, IOCTL_GET_MSG, message);

        if (ret_val < 0) {

                printf("ioctl_get_msg failed:%d\n", ret_val);

                exit(-1);

        }

        //printf("get_msg message:%s\n", message);

}

int ioctl_get_nth_byte(int file_desc)

{

        int i, val;

        char c;

        val=0;

        i = 0;

        do {

                c = ioctl(file_desc, IOCTL_GET_NTH_BYTE, i++);

                if (c < 0) {

                        printf("ioctl_get_nth_byte failed at the %d'th byte:\n",i);

                        exit(-1);

                }

        val=val*10+atoi(&c);

        } while (c != 0);

        return (int)val/10; //because string termination character also gets read in loop we have to divide by 10

}

int get_device_value(const char *dev)

{

    //TODO use mutex?

    int file_desc, ret_val;

        char *msg = int_to_str(generate_value());

        file_desc = open(dev, 0);

        if (file_desc < 0) {

                printf("Can't open device file: %s\n", dev);

                ret_val = generate_value(); // TODO fake value in case driver doesnt work

        }

        else{

                //printf("Open device file: %s\n", dev);

        //ioctl_set_msg(file_desc, msg);

        ret_val = ioctl_get_nth_byte(file_desc);

        }

        close(file_desc);

        ret_val = ret_val+((random()%3-1)*5); //+- 5 (conversion to fload needed later)

        printf("Returning val %d\n", ret_val);

    return ret_val;

}