TLV provisioning parser

The code

Embedded C for Cortex-M. It compiles. There are 4 real bugs in it: the kind that pass a bench test and fail in the field.

void parse_tlv(const uint8_t *buf, size_t len)
{
    size_t i = 0;
    while (i < len) {
        uint8_t type = buf[i];
        uint8_t l    = buf[i + 1];
        const uint8_t *val = &buf[i + 2];

        switch (type) {
        case T_SSID:
            memcpy(g_ssid, val, l);
            break;
        case T_CHANNEL:
            g_channel = val[0];
            break;
        }
        i += 2 + l;
    }
}

What an interviewer expects

• Point to each line you'd stop in a code review.
• Say what actually breaks: the failure mode, not just the rule it violates.
• Fix it, then defend the fix when asked the follow-up.

The bugs, reference fixes and the follow-up question are in the practice app, after you've tried it.

Companies that test this

Matched on the skills each company's embedded roles emphasise.

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