fsd_device.c

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#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
 
#include "fsd_device.h"
#include "fsd_debug.h"
#include "fsd_defines.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>


int fsd_chardevice_open() {
        return  open(FSC_DEVICE_LOCATION, O_RDWR);
}


int fsd_chardevice_close(int fsc_device) {
        return close(fsc_device);
}


int fsd_chardevice_read(int fsc_device, char * buffer) {
        int result;
        if (!fsc_device) {
                return EFSC_DEVICE_NOT_OPEN;
        }

        result = read(fsc_device, buffer, MAX_MESSAGE_LENGTH); 
        switch (result) {
                case -EINVAL:
                        PDEBUG("Fatal error: MAX_MESSAGE_LENGTH = (%d) is shorter than availible data from FSC device.\n", MAX_MESSAGE_LENGTH); 
                        break;
                case -EFAULT:
                        PDEBUG("Fatal error: Data transfer from FSC device in kernel to FSD in user space failed.\n"); 
                        break;
        }
        
        return result;  
}


int fsd_chardevice_write(int fsc_device, const char* data, int count) {
        int result;
        if (!fsc_device) {
                return EFSC_DEVICE_NOT_OPEN;
        }

        result = write(fsc_device, data, count); 
        switch (result) {
                case -EINVAL:
                        PDEBUG("Fatal error: number of chars in the message = (%d) is greater than  FSC device input buffer size.\n", count); 
                        break;
                case -EFAULT:
                        PDEBUG("Fatal error: Data transfer FSD in user space to FSC device in kernel failed.\n"); 
                        break;
        }
        return result;
}

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