Add standard options to readlink

#include <stdlib.h>

#include <unistd.h>

static int skip_newline, quiet_errors, canonicalize;

static void usage(char* name) {

    fprintf(stderr, "Usage: %s FILE\n", name);

    fprintf(stderr, "Usage: %s [OPTION]... FILE\n", name);

}

int readlink_main(int argc, char* argv[]) {

    if (argc != 2) {

    int c;

    while ((c = getopt(argc, argv, "nfqs")) != -1) {

        switch (c) {

        case 'n':

            skip_newline = 1;

            break;

        case 'f':

            canonicalize = 1;

            break;

        case 'q':

        case 's':

            quiet_errors = 1;

            break;

        case '?':

        default:

            usage(argv[0]);

            return EXIT_FAILURE;

        }

    }

    int index = optind;

    if (argc - index != 1) {

        usage(argv[0]);

        return EXIT_FAILURE;

    }

    char name[PATH_MAX+1];

    if (canonicalize) {

        if(!realpath(argv[optind], name)) {

            if (!quiet_errors) {

                perror("readlink");

            }

            return EXIT_FAILURE;

        }

    } else {

        ssize_t len = readlink(argv[1], name, PATH_MAX);

        if (len < 0) {

            if (!quiet_errors) {

                perror("readlink");

            }

            return EXIT_FAILURE;

        }

        name[len] = '\0';

    printf("%s\n", name);

    }

    fputs(name, stdout);

    if (!skip_newline) {

        fputs("\n", stdout);

    }

    return EXIT_SUCCESS;

}