Exercise 8.1. Rewrite the program cat from Chapter 7 using read, write, open, and close instead of their standard library equivalents

Exercise 8.1. Rewrite the program cat from Chapter 7 using read, write, open, and close instead of their standard library equivalents. Perform experiments to determine the relative speeds of the two versions.


#include <stdio.h>
#include <fcntl.h>
#include "syscalls.h"


/* cat */
int main(int argc, char *argv[])
{
    int fp;
    void filecopy(int ifp, int ofp);
   
    if(argc == 1) //no arguments, default stdin
        filecopy(0, 1);
    else
        while(--argc > 0)
            if((fp = open(*++argv, 0_RDONLY)) == -1)
                error("cat: can`t open the file %s\n", *argv);
            else
            {
                filecopy(fp, 1);
                close(fp);
            }
    return 0;
}

/* filecopy: copy file ifp into file ofp */
void filecopy(int ifp, int ofp)
{
    int n;
    char buf[BUFSIZ];
   
    while((n = read(ifp, buf, BUFSIZ)) > 0)
        if(write(ofp, buf, n) != n)
            error("cat:write error");
}