Ping diagnostic on a Linux gateway

The code

Embedded Linux C. It compiles. There are 3 real bugs in it: the kind that pass a bench test and fail in the field.

int diag_ping(const char *host, char *out, size_t cap)
{
    char cmd[64];
    sprintf(cmd, "ping -c 1 -W 1 %s", host);
    FILE *f = popen(cmd, "r");
    size_t n = fread(out, 1, cap, f);
    out[n] = '\0';
    pclose(f);
    return 0;
}

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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