demokext.c Example File

#include <sys/types.h>
#include <sys/malloc.h>
#include <sys/uio.h>
#include <sys/dump.h>
#include <sys/errno.h>
#include <sys/uprintf.h>
#include <fcntl.h>
#include "demo.h"


/* Log routine prototypes */
int open_log(char *path, struct file **fpp);
int write_log(struct file *fpp, char *buf, int *bytes_written);
int close_log(struct file *fpp);

/* Unexported symbol */
int demokext_i = 9;
/* Exported symbol */
int demokext_j = 99;

/*
 * Kernel extension entry point, called at config. time.
 *
 * input:
 *	cmd - unused (typically 1=config, 2=unconfig)
 *	uiop - points to the uio structure.
 */
int
demokext(int cmd, struct uio *uiop)
	{
	int rc;
	char *bufp;
	struct file *fpp;
	int fstat;
	char buf[100];
	int bytes_written;
	static int j = 0;

	/*
	 * Open the log file.
	 */
	strcpy(buf, "./demokext.log");
	fstat = open_log(buf, &fpp);
	if (fstat != 0) return(fstat);

	/*
	 * Put a message out to the log file.
	 */
	strcpy(buf, "demokext was called for configuration\n");
	fstat = write_log(fpp, buf, &bytes_written);
	if (fstat != 0) return(fstat);

	/*
	 * Increment or decrement j and demokext_j based on 
	 * the input value for cmd.
	 */
	{
	switch (cmd)
		{
		case 1:  /* Increment */	
			sprintf(buf, "Before increment: j=%d demokext_j=%d\n",
			        j, demokext_j);
			write_log(fpp, buf, &bytes_written);
			demokext_j++;
			j++;
			sprintf(buf, "After increment: j=%d demokext_j=%d\n",
			        j, demokext_j);
			write_log(fpp, buf, &bytes_written);
			break;

		case 2:  /* Decrement */
			sprintf(buf, "Before decrement: j=%d demokext_j=%d\n",
			        j, demokext_j);
			write_log(fpp, buf, &bytes_written);
			demokext_j--;
			j--;
			sprintf(buf, "After decrement: j=%d demokext_j=%d\n",
			        j, demokext_j);
			write_log(fpp, buf, &bytes_written);
			break;

		default:  /* Unknown command value */
			sprintf(buf, "Received unknown command of %d\n", cmd);
			write_log(fpp, buf, &bytes_written);
			break;
		}
	}

	/*
	 * Close the log file.
	 */
	fstat = close_log(fpp);
	if (fstat !=0 ) return(fstat);
	return(0);
}

/***************************************************
 * Routines for logging debug information:         *
 * open_log - Opens a log file                     *
 * write_log - Output a string to a log file       *
 * close_log - Close a log file                    *
 ***************************************************/
int open_log (char *path, struct file **fpp)
	{
	int rc;
	rc = fp_open(path, O_CREAT | O_APPEND | O_WRONLY, 
	             S_IRUSR | S_IWUSR, 0, SYS_ADSPACE, fpp);
	return(rc);
	}

int write_log(struct file *fpp, char *buf, int *bytes_written)
	{
	int rc;
	rc = fp_write(fpp, buf, strlen(buf), 0, SYS_ADSPACE, bytes_written);
	return(rc);
	}
 
int close_log(struct file *fpp)
	{
	int rc;
	rc = fp_close(fpp);
	return(rc);
	}