/*
 * nanowasm, a tiny WebAssembly/Wasm interpreter
 * Copyright (C) 2023-2025  Xavier Del Campo Romero
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include <nanowasm/nw.h>
#include <nw/io.h>
#include <nw/log.h>
#include <nw/routines.h>
#include <string.h>

static enum nw_state run(struct nw_mod *const m)
{
    static const unsigned char magic[] = {'\0', 'a', 's', 'm'};
    struct nw_sm_cm *const cm = &m->sm.check_magic;
    const struct nw_io_cfg *const cfg = &m->cfg.io;
    const enum nw_state n = nwp_io_read(cfg, &cm->io, cfg->user);

    if (n)
        return n;

    if (memcmp(cm->buf, magic, sizeof cm->buf))
    {
#ifdef NW_LOG
        nwp_log("wrong magic bytes\n");
#endif
        return NW_FATAL;
    }

    nwp_check_version(m);
    return NW_AGAIN;
}

void nwp_check_magic(struct nw_mod *const m)
{
    const struct nw_sm_cm cm = {0};
    struct nw_sm_cm *const pcm = &m->sm.check_magic;
    struct nw_sm_io *const io = &pcm->io;

    *pcm = cm;
    io->buf = &pcm->buf;
    io->n = sizeof pcm->buf;
    m->next = run;
}