src/io/read.c


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/*
 * 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 <stddef.h>

enum nw_state nwp_io_read(const struct nw_io_cfg *const cfg,
    struct nw_sm_io *const io, void *const user)
{
    void *const buf = (unsigned char *)io->buf + io->read;
    const size_t rem = io->n - io->read;
    const int n = cfg->read(buf, rem, user);

    if (n < 0 || (!n && cfg->eof(user)))
        return NW_FATAL;

    if ((io->read += n) >= io->n)
    {
        io->read = 0;
        return NW_OK;
    }

    return NW_AGAIN;
}