Function fs_read

host/sysenv/sys_fs.cpp:113–128

read(fd:i32, buf_ptr, buf_len) -> i32

// read(fd:i32, buf_ptr, buf_len) -> i32
static std::vector<Value> fs_read(Stack& stack) {
    Frame& frame = stack.frames.top();
    i32_t fd      = std::get<i32_t>(frame.locals[0]);
    i64_t buf_ptr = get_ptr(frame.locals[1]);
    i64_t buf_len = get_ptr(frame.locals[2]);
    FdEntry* e = fd_table.get(fd);
    if(!e || e->is_dir) return {Value(i32_t(-EBADF))};
    try {
        auto sp = mem_span(stack, buf_ptr, buf_len);
        auto n = sys_read(e->os_fd, sp.data(), sp.size());
        if(n < 0) return {Value(err_code())};
        return {Value(i32_t(n))};
    } catch(...) {
        return {Value(i32_t(-EFAULT))};
    }
}

// write(fd:i32, buf_ptr, buf_len) -> i32
static std::vector<Value> fs_write(Stack& stack) {