Programming

static int a;

 int a;

#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#include <string.h>

#define ck(x) if((x)==NULL)\
{perror("Error"); exit(EXIT_FAILURE);}
/* read nbyte from a file  - can read whole file */
ssize_t readall(int fd, void *buf, size_t nbyte){
     ssize_t nread = 0,
                   n=0;

     do {
         if ((n = read(fd, &((char *)buf)[nread], nbyte - nread)) == -1) {
             if (errno == EINTR)
                 continue;
             else
                 return (-1);
         }
         if (n == 0)
             return nread;
         nread += n;
     } while (nread < nbyte);
     return nread;
}

 /* get file size */
size_t file_size(FILE *in)
{
	 struct stat st;
	 if(fstat(fileno(in), &st) == (-1))
	 {
	 	perror("stat error");
	 	exit(EXIT_FAILURE);
	 }	
     return st.st_size;
}

int main(int argc, char *argv[1])
{
	char *buf=NULL;
	FILE *in=fopen(argv[1],"r");    /* open afile for read */
	size_t filebytes=0;

	ck(in);                       /* check file errors */
	filebytes=file_size(in);      /* get size of buf we need */
	if(filebytes)                 /* do we have a file with data in it? */
	{
		ck(buf=malloc(filebytes+1) );	/* create storage */
		memset(buf,0x0, filebytes+1);   /* init storage */
		if( readall(fileno(in),buf,filebytes)>0 ) /* read entire file */
		{
			ck(fprintf(stdout,"%s",buf)); /* print whole file */
		}
		else                         /* complain about errors reading file */
		{
			ck(fprintf(stderr,"file read error\n") );
			exit(EXIT_FAILURE);
	    }
	    free(buf);                 /* release the buffer */
	}
	if(! fclose(in)	)              /* close file with error check */
    {
    	return 0;                  /* normal return */
    }
	ck(fprintf(stderr, "filesystem error\n") );
	return EXIT_FAILURE;           /* file close error - return */
}