pipe.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string.h>
#include <unistd.h>
#include <time.h>

/* WARNING. No error handling */
char *read_entire_file(char *name)
	{
	FILE *fh = fopen(name, "rb");
	fseek(fh, 0, SEEK_END);
	long fsize = ftell(fh);
	fseek(fh, 0, SEEK_SET);

	char *buffer = malloc(fsize + 1);
	fread(buffer, fsize, 1, fh);
	fclose(fh);
	buffer[fsize] = 0;

	return buffer;
	}

int main(void)
	{
    int pfds[2];

	char *license = read_entire_file("LICENSE");
	long fsize = strlen(license); /* Yes. I know */
	fprintf(stderr, "Using file %d bytes long\n", fsize);
	char *buffer = malloc(fsize + 1);
	long runs = 1000000; /* 1 million dollars */

	clock_t start, end;

	start = clock();

    pipe(pfds);

    if (!fork())
		{
        printf(" CHILD: writing to the pipe\n");
		for (long i = 0; i < runs; i++)
        	write(pfds[1], license, fsize + 1);
        printf(" CHILD: exiting\n");
        exit(0);
		}
	else
		{
        printf("PARENT: reading from pipe\n");
		for (long i = 0; i < runs; i++)
        	read(pfds[0], buffer, fsize + 1);
        printf("PARENT: read\n");
        wait(NULL);
    	}

	end = clock();
	fprintf(stderr, "Runs     | Time taken\n");
	fprintf(stderr, "%8d   %f\n", runs, (end - start) / (double)CLOCKS_PER_SEC);
	fprintf(stderr, "per run: %f\n", (end - start) / (double)CLOCKS_PER_SEC / runs);

    return 0;
	}