spin.c

/*
    Include headers
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>
#include "definitions.h"

/*
    get_seconds():
    Calculates the present time in seconds.
*/
double get_seconds() {
    struct timeval t;
    int rc = gettimeofday(&t, NULL);
    assert(rc == 0);
    return (double) ((double)t.tv_sec + (double)t.tv_usec / 1e6);
}

/*
    Main function calls the get_seconds() function to
    spin for the specified amount of time on the server.
*/
int main(int argc, char *argv[]) {
    // Extract arguments
    double spin_for = 0.0;
    char *buf;
    if ((buf = getenv("QUERY_STRING")) != NULL) {
	// just expecting a single number
	spin_for = (double) atoi(buf);
    }

    double t1 = get_seconds();
    while ((get_seconds() - t1) < spin_for)
	sleep(1);
    double t2 = get_seconds();
    
    /* Make the response body */
    char content[MAXBUF + 1];
    char spunfor[MAXBUF];
    snprintf(content, MAXBUF, "<p>Welcome to the CGI program (%s)</p>\r\n", buf);
    strncat(content, "%s<p>My only purpose is to waste time on the server!</p>\r\n", MAXBUF);
    snprintf(spunfor, MAXBUF, "<p>I spun for %.2f seconds</p>\r\n", t2 - t1);
    strncat(content, spunfor, MAXBUF);
    
    /* Generate the HTTP response */
    printf("Content-length: %lu\r\n", strlen(content));
    printf("Content-type: text/html\r\n\r\n");
    printf("%s", content);
    fflush(stdout);
    
    exit(0);
}