Re: [PATCH v3 1/2] pkt-line: add stdio packet write functions

From: Jeff King <peff@peff.net>
Date: Aug 31, 2021, 10:37 UTC
Message-ID: <YS4GVWdsnRqpM+4y@coredump.intra.peff.net>
In-Reply-To: <20210831093444.28199-2-jacob@gitlab.com>

On Tue, Aug 31, 2021 at 11:34:43AM +0200, Jacob Vosmaer wrote:

Show 5 quoted lines

> +void fwrite_or_die(FILE *f, const void *buf, size_t count)
> +{
> +	if (fwrite(buf, count, 1, f) != 1)
> +		die_errno("fwrite error");
> +}

One small oddity I noticed. The definition of fwrite is fwrite(ptr, size, nmemb, strea), where we write "nmemb" items of "size" bytes each. I'd argue we're writing "count" single bytes, so it should be:

  if (fwrite(buf, 1, count, f) != count)

This matters a lot for fread(), where any read shorter than "count" (e.g., due to EOF) would return "0" rather than a partial result. But I have a hard time imagining an implementation of fwrite() where the distinction would matter. And grepping around, we seem to have both forms in our code base already. So it's probably fine.

-Peff