// SPDX-License-Identifier: GPL-2.0
/*
 * rv tool, the interface for the Linux kernel RV subsystem and home of
 * user-space controlled monitors.
 *
 * Copyright (C) 2022 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org>
 */

#include <stdlib.h>
#include <signal.h>
#include <unistd.h>

#include <trace.h>
#include <utils.h>
#include <in_kernel.h>

static int stop_session;

/*
 * stop_rv - tell monitors to stop
 */
static void stop_rv(int sig)
{
        stop_session = 1;
}

/**
 * should_stop - check if the monitor should stop.
 *
 * Returns 1 if the monitor should stop, 0 otherwise.
 */
int should_stop(void)
{
        return stop_session;
}

/*
 * rv_list - list all available monitors
 */
static void rv_list(int argc, char **argv)
{
        static const char *const usage[] = {
                "",
                "  usage: rv list [-h] [container]",
                "",
                "       list all available monitors",
                "",
                "       -h/--help: print this menu",
                "",
                "       [container]: list only monitors in this container",
                NULL,
        };
        int i, print_help = 0, retval = 0;
        char *container = NULL;

        if (argc == 2) {
                if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
                        print_help = 1;
                        retval = 0;
                } else if (argv[1][0] == '-') {
                        /* assume invalid option */
                        print_help = 1;
                        retval = 1;
                } else
                        container = argv[1];
        } else if (argc > 2) {
                /* more than 2 is always usage */
                print_help = 1;
                retval = 1;
        }
        if (print_help) {
                fprintf(stderr, "rv version %s\n", VERSION);
                for (i = 0; usage[i]; i++)
                        fprintf(stderr, "%s\n", usage[i]);
                exit(retval);
        }

        ikm_list_monitors(container);

        exit(0);
}

/*
 * rv_mon - try to run a monitor passed as argument
 */
static void rv_mon(int argc, char **argv)
{
        char *monitor_name;
        int i, run = 0;

        static const char *const usage[] = {
                "",
                "  usage: rv mon [-h] monitor [monitor options]",
                "",
                "       run a monitor",
                "",
                "       -h/--help: print this menu",
                "",
                "       monitor [monitor options]: the monitor, passing",
                "       the arguments to the [monitor options]",
                NULL,
        };

        /* requires at least one argument */
        if (argc == 1) {

                fprintf(stderr, "rv version %s\n", VERSION);

                for (i = 0; usage[i]; i++)
                        fprintf(stderr, "%s\n", usage[i]);
                exit(1);
        } else if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {

                fprintf(stderr, "rv version %s\n", VERSION);

                for (i = 0; usage[i]; i++)
                        fprintf(stderr, "%s\n", usage[i]);
                exit(0);
        }

        monitor_name = argv[1];
        /*
         * Call all possible monitor implementations, looking
         * for the [monitor].
         */
        run += ikm_run_monitor(monitor_name, argc-1, &argv[1]);

        if (!run)
                err_msg("rv: monitor %s does not exist\n", monitor_name);
        exit(!run);
}

static void usage(int exit_val, const char *fmt, ...)
{
        char message[1024];
        va_list ap;
        int i;

        static const char *const usage[] = {
                "",
                "  usage: rv command [-h] [command_options]",
                "",
                "       -h/--help: print this menu",
                "",
                "       command: run one of the following command:",
                "         list: list all available monitors",
                "         mon:  run a monitor",
                "",
                "       [command options]: each command has its own set of options",
                "                          run rv command -h for further information",
                NULL,
        };

        va_start(ap, fmt);
        vsnprintf(message, sizeof(message), fmt, ap);
        va_end(ap);

        fprintf(stderr, "rv version %s: %s\n", VERSION, message);

        for (i = 0; usage[i]; i++)
                fprintf(stderr, "%s\n", usage[i]);

        exit(exit_val);
}

/*
 * main - select which main sending the command
 *
 * main itself redirects the arguments to the sub-commands
 * to handle the options.
 *
 * subcommands should exit.
 */
int main(int argc, char **argv)
{
        if (geteuid())
                usage(1, "%s needs root permission", argv[0]);

        if (argc <= 1)
                usage(1, "%s requires a command", argv[0]);

        if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help"))
                usage(0, "help");

        if (!strcmp(argv[1], "list"))
                rv_list(--argc, &argv[1]);

        if (!strcmp(argv[1], "mon")) {
                /*
                 * monitor's main should monitor should_stop() function.
                 * and exit.
                 */
                signal(SIGINT, stop_rv);
                signal(SIGTERM, stop_rv);

                rv_mon(argc - 1, &argv[1]);
        }

        /* invalid sub-command */
        usage(1, "%s does not know the %s command, old version?", argv[0], argv[1]);
}