Linux Application Development

Michael K. Johnson Erik W. Troan

sockutil.c

/* sockutil.c - simple utility functions */

#include <stdio.h>
#include <unistd.h>

#include "sockutil.h"

/* issue an error message via perror() and terminate the program */
void die(char * message) {
    perror(message);
    exit(1);
}

/* Copies data from file descriptor 'from' to file descriptor 'to'
   until nothing is left to be copied. Exits if an error occurs.   */
void copyData(int from, int to) {
    char buf[1024];
    int amount;
    
    while ((amount = read(from, buf, sizeof(buf))) > 0) {
        if (write(to, buf, amount) != amount) {
            die("write");
            return;
        }
    }
    if (amount < 0)
        die("read");
}