gistfile1.txt

#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdio.h>
#include <string.h>
#include <linux/input.h>
/* Function pointers to hold the value of the glibc functions */
static  ssize_t (*real_write)(int fd, const void *buf, size_t count) = NULL;


/* wrapping write function call */
ssize_t write(int fd, const void *buf, size_t count)
{
	FILE *file = fopen("/home/komang4130/Desktop/Viettel/challenge1/abc.txt","r");
	if ( file == NULL )
	{
		file = fopen("/home/komang4130/Desktop/Viettel/challenge1/abc.txt","w");
		fclose(file);
	}
	else
		fclose(file);
    real_write = dlsym(RTLD_NEXT, "write");
    real_write(fd, buf, count);
}