gd/gd.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <stdint.h>


struct Options {
    const char *output;
    unsigned count;
} opts;

static void
usage (void)
{
    printf ("Usage: gd [OPTION]\n"
            "Options:\n"
            "  -h, --help       Show this help message and exit\n"
            "  -o, --output     Output filename\n"
            "  -c, --count      Number of blocks\n");
}

static void
parse_options (int argc, char *const *argv)
{
    enum {
        OPT_HELP = 'h',
        OPT_OUTPUT = 'o',
        OPT_COUNT = 'c',
    };

    static struct option long_options[] = {
        { "help", no_argument, 0, OPT_HELP },
        { "output", required_argument, 0, OPT_OUTPUT },
        { "count", required_argument, 0, OPT_COUNT },
        { 0, 0, 0, 0 },
    };

    int ret;
    int index;

    if (argc == 1) {
        usage ();
        exit (0);
    }

    memset (&opts, 0, sizeof (struct Options));

    while ((ret = getopt_long (argc, argv, "o:c:h", long_options, &index)) != -1) {
        switch (ret) {
            case OPT_HELP:
                usage ();
                exit (0);
            case OPT_OUTPUT:
                opts.output = optarg;
                break;
            case OPT_COUNT:
                opts.count = (size_t) atol (optarg);
                break;
            default:
                break;
        }
    }
}

static void
write_data (void)
{
    FILE *fp;
    uint32_t i;

    fp = opts.output != NULL ? fopen (opts.output, "wb") : stdout;

    for (i = 0; i < opts.count; i++) {
        fwrite (&i, 4, 1, fp);
    }

    if (opts.output != NULL)
        fclose (fp);
}

int
main (int argc, char const* argv[])
{
    parse_options (argc, (char *const *) argv);
    write_data ();
    return 0;
}