Explain the following code. Then try to rewrite it to modern C++.static unsigned long get_auxiliary_vector_base(int at_key)
{
    unsigned long base = 0;

#ifdef GETAUXVAL_SUPPORTED
    base = getauxval(at_key);
    return base;
#else
    FILE *f = NULL;
    int err = 0;

    f = fopen("/proc/self/auxv", "r");
    if (!f) {
        err = -errno;
        ebpf_log("failed to open /proc/self/auxv: %d\n", err);
        return 0;
    }

    while (true) {
        unsigned long key   = 0;
        unsigned long value = 0;
        int ret             = -1;
        ret                 = fread(&key, sizeof(key), 1, f);
        if (ret != 1)
            break;
        ret = fread(&value, sizeof(value), 1, f);
        if (ret != 1)
            break;
        if (key == 0 && value == 0)
            break;
        if (key == at_key) {
            base = value;
            return base;
        }
    }
    return base;
#endif
} Make sure to only use capital letters in your entire response.
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