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From: NRK <nrk@disroot.org>
To: musl@lists.openwall.com
Cc: Tamir Duberstein <tamird@google.com>
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Subject: Re: [musl] undefined behavior in fread.c

On Fri, Feb 24, 2023 at 08:34:14AM -0500, Rich Felker wrote:
> Is there any indication that passing NULL as the first argument to
> fread is not itself undefined?

C99 says the following:

| If size or nmemb is zero, fread returns zero and the contents of the
| array and the state of the stream remain unchanged.

It doesn't explicitly mention weather stream can be NULL or not in case
of 0 size/nmemb - but regardless, is there any actual reason for not
returning early?

The following should be OK as far as I see:

-	if (!size) nmemb = 0;
+	if (!size || !nmemb) return 0;

or `if (!len) return 0;` could also work if multiplication overflow is
not a concern.

- NRK