testebbchar.c File Reference

A Linux user space program that communicates with the ebbchar.c LKM. It passes a string to the LKM and reads the response from the LKM. For this example to work the device must be called /dev/ebbchar. More...

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

Include dependency graph for testebbchar.c:

Macros
#define	BUFFER_LENGTH   256
	The buffer length (crude but fine) More...

Functions
int	main ()

Variables
static char	receive [BUFFER_LENGTH]
	The receive buffer from the LKM. More...

Detailed Description

A Linux user space program that communicates with the ebbchar.c LKM. It passes a string to the LKM and reads the response from the LKM. For this example to work the device must be called /dev/ebbchar.

Author

Derek Molloy

Date

7 April 2015

Version

0.1

See also

http://www.derekmolloy.ie/ for a full description and follow-up descriptions.

Macro Definition Documentation

#define BUFFER_LENGTH   256

The buffer length (crude but fine)

Function Documentation

int main

(

)

          {
   int ret, fd;
   char stringToSend[BUFFER_LENGTH];
   printf("Starting device test code example...\n");
   fd = open("/dev/ebbchar", O_RDWR);             // Open the device with read/write access
   if (fd < 0){
      perror("Failed to open the device...");
      return errno;
   }
   printf("Type in a short string to send to the kernel module:\n");
   scanf("%[^\n]%*c", stringToSend);                // Read in a string (with spaces)
   printf("Writing message to the device [%s].\n", stringToSend);
   ret = write(fd, stringToSend, strlen(stringToSend)); // Send the string to the LKM
   if (ret < 0){
      perror("Failed to write the message to the device.");
      return errno;
   }

   printf("Press ENTER to read back from the device...\n");
   getchar();

   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;
}

Variable Documentation

char receive[BUFFER_LENGTH]

static

The receive buffer from the LKM.