netdev - Re: [PATCH bpf-next 1/2] selftests/bpf: test

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Message-ID: <549829f5-6c93-6417-0582-ed10c7269c1f@iogearbox.net>
Date:   Tue, 3 Sep 2019 15:40:59 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Stanislav Fomichev <sdf@...gle.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     davem@...emloft.net, ast@...nel.org
Subject: Re: [PATCH bpf-next 1/2] selftests/bpf: test_progs: fix verbose mode
 garbage

On 8/31/19 4:34 AM, Stanislav Fomichev wrote:
> fseeko(.., 0, SEEK_SET) on a memstream just puts the buffer pointer
> to the beginning so when we call fflush on it we get some garbage
> log data from the previous test. Let's manually set terminating
> byte to zero at the reported buffer size.
> 
> To show the issue consider the following snippet:
> 
> 	stream = open_memstream (&buf, &len);
> 
> 	fprintf(stream, "aaa");
> 	fflush(stream);
> 	printf("buf=%s, len=%zu\n", buf, len);
> 	fseeko(stream, 0, SEEK_SET);
> 
> 	fprintf(stream, "b");
> 	fflush(stream);
> 	printf("buf=%s, len=%zu\n", buf, len);
> 
> Output:
> 
> 	buf=aaa, len=3
> 	buf=baa, len=1
> 
> Fixes: 946152b3c5d6 ("selftests/bpf: test_progs: switch to open_memstream")
> Signed-off-by: Stanislav Fomichev <sdf@...gle.com>

Both applied, thanks!