From: Andreas Schwab <schwab@linux-m68k.org>
To: Jeff King <peff@peff.net>
Cc: "Miriam R." <mirucam@gmail.com>, git <git@vger.kernel.org>
Subject: Re: [Outreachy] Return value before or after free()?
Date: Tue, 07 Jan 2020 00:34:52 +0100 [thread overview]
Message-ID: <87imlo6twj.fsf@igel.home> (raw)
In-Reply-To: <20200106213051.GD980197@coredump.intra.peff.net> (Jeff King's message of "Mon, 6 Jan 2020 16:30:51 -0500")
On Jan 06 2020, Jeff King wrote:
> On Mon, Jan 06, 2020 at 10:15:53PM +0100, Miriam R. wrote:
>
>> in run-command.c file `exists_in_PATH()` function does this:
>>
>> static int exists_in_PATH(const char *file)
>> {
>> char *r = locate_in_PATH(file);
>> free(r);
>> return r != NULL;
>> }
>>
>> I wonder if it is correct to do return r != NULL; after free(r);
>
> It is technically undefined behavior according to the C standard, but I
> think it would be hard to find an implementation where it was not
> perfectly fine in practice.
Compilers get constantly better at exploiting undefined behaviour, so I
would not count on it.
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
next prev parent reply other threads:[~2020-01-06 23:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-06 21:15 [Outreachy] Return value before or after free()? Miriam R.
2020-01-06 21:30 ` Jeff King
2020-01-06 22:47 ` Jonathan Nieder
2020-01-06 23:34 ` Andreas Schwab [this message]
2020-01-07 1:08 ` brian m. carlson
2020-01-07 1:58 ` brian m. carlson
2020-01-07 20:40 ` Miriam R.
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