testing2.c

//run with sudo
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
 
#define BUFFER_LENGTH 5000               ///< The buffer length (crude but fine)
static char receive[BUFFER_LENGTH];     ///< The receive buffer from the LKM
static char* str = "ABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVxyzABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSabrestjunkBCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKwilliamSynomaVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRStonkaTruckXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZABCDEFGHIJKLMNOPQRSTUVXYZ";
int i = 0; 

int main(){
   int ret, fd;
   char stringToSend[BUFFER_LENGTH];
   printf("Starting device test code example...\n");
   fd = open("/dev/char_driver", O_RDWR);             // Open the device with read/write access
   if (fd < 0){
      perror("Failed to open the device...");
      return errno;
   }

   printf("write 2050...\n");
   ret = write(fd, str, i = 2050); // Send the string to the LKM
   if (ret < 0){
      perror("Failed to write the message to the device.");
      return errno;
   }
 
   printf("Reading from the device 100...\n");
   ret = read(fd, receive, 100);        // Read the response from the LKM
   if (ret < 0){
      perror("Failed to read the message from the device.");
      return errno;
   }
   printf("The received message is: [%s]\n", receive);

   printf("write 200...\n");
   ret = write(fd, &str[i], 200); // Send the string to the LKM
   if (ret < 0){
      perror("Failed to write the message to the device.");
      return errno;
   }

   printf("Reading from the device...\n");
   ret = read(fd, receive, BUFFER_LENGTH);        // Read the response from the LKM
   if (ret < 0){
      perror("Failed to read the message from the device.");
      return errno;
   }
   printf("The received message is: [%s]\n", receive);
   printf("End of the program\n");
   return 0;
}