source: examples/tutorial/timedemo.c @ c909fad

/* Trivial libtrace program that prints a count of the number of packets
 * observed every 10 seconds in a trace.
 * Designed to demonstrate the use of trace_get_timeval()
 */
#include "libtrace.h"
#include <stdio.h>
#include <inttypes.h>
#include <assert.h>
#include <getopt.h>

uint64_t count = 0;
uint32_t next_report = 0;

static void per_packet(libtrace_packet_t *packet)
{
        struct timeval ts;
        
        /* Get the timestamp for the current packet */
        ts = trace_get_timeval(packet);

        /* If next_report is zero, then this is the first packet from the
         * trace so we need to determine the time at which the first report
         * must occur, i.e. 10 seconds from now. */
        if (next_report == 0) {
                next_report = ts.tv_sec + 10;

                /* This is also a good opportunity to print column headings */
                printf("Time\t\tPackets\n");
        }

        /* Check whether we need to report a packet count or not.
         *
         * If the timestamp for the current packet is beyond the time when the
         * next report was due then we have to output our current count and
         * reset it to zero.
         *
         * Note that I use a while loop here to ensure that we correctly deal
         * with periods in which no packets are observed.
         */
        while ((uint32_t)ts.tv_sec > next_report) {
                /* Print a timestamp for the report and the packet count */
                printf("%u \t%" PRIu64 "\n", next_report, count);
                /* Reset the counter */
                count = 0;
                /* Determine when the next report is due */
                next_report += 10;
        }

        /* No matter what else happens during this function call, we still
         * need to increment our counter */     
        count += 1;
}

/* Due to the amount of error checking required in our main function, it
 * is a lot simpler and tidier to place all the calls to various libtrace
 * destroy functions into a separate function.
 */
static void libtrace_cleanup(libtrace_t *trace, libtrace_packet_t *packet) {
        
        /* It's very important to ensure that we aren't trying to destroy
         * a NULL structure, so each of the destroy calls will only occur
         * if the structure exists */
        if (trace)
                trace_destroy(trace);

        if (packet)
                trace_destroy_packet(packet);

}

int main(int argc, char *argv[])
{
        /* This is essentially the same main function from readdemo.c */
        
        libtrace_t *trace = NULL;
        libtrace_packet_t *packet = NULL;
        
        /* Ensure we have at least one argument after the program name */
        if (argc < 2) {
                fprintf(stderr, "Usage: %s inputURI\n", argv[0]);
                return 1;
        }       

        packet = trace_create_packet();

        if (packet == NULL) {
                perror("Creating libtrace packet");
                libtrace_cleanup(trace, packet);
                return 1;
        }

        trace = trace_create(argv[1]);

        if (trace_is_err(trace)) {
                trace_perror(trace,"Opening trace file");
                libtrace_cleanup(trace, packet);
                return 1;
        }

        if (trace_start(trace) == -1) {
                trace_perror(trace,"Starting trace");
                libtrace_cleanup(trace, packet);
                return 1;
        }


        while (trace_read_packet(trace,packet)>0) {
                per_packet(packet);
        }


        if (trace_is_err(trace)) {
                trace_perror(trace,"Reading packets");
                libtrace_cleanup(trace, packet);
                return 1;
        }

        printf("%u \t%" PRIu64 "\n", next_report, count);

        libtrace_cleanup(trace, packet);
        return 0;
}