sendfiletest.c

#include <sys/types.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/sendfile.h>

int main() {
        int input, output;
        ssize_t count, written;

        count = 4294967296;

        input = open("/tmp/bigfile", O_RDONLY);
        output = open("/tmp/output", O_WRONLY | O_CREAT);

        written = sendfile(output, input, NULL, count);

        if (written == -1) {
                perror("Sendfile error");
        }
        else {
                printf("Success, asked for: %zu, written: %zu\n", count, written);
        }

        return 0;
}