From: Daniel Borkmann <daniel@iogearbox•net>
To: Phil Sutter <phil@nwl•cc>,
Stephen Hemminger <stephen@networkplumber•org>
Cc: netdev@vger•kernel.org
Subject: Re: [iproute PATCH] lib/bpf: Fix bytecode-file parsing
Date: Wed, 30 Aug 2017 15:53:59 +0200 [thread overview]
Message-ID: <59A6C377.90705@iogearbox.net> (raw)
In-Reply-To: <20170829150945.7077-1-phil@nwl.cc>
On 08/29/2017 05:09 PM, Phil Sutter wrote:
> The signedness of char type is implementation dependent, and there are
> architectures on which it is unsigned by default. In that case, the
> check whether fgetc() returned EOF failed because the return value was
> assigned an (unsigned) char variable prior to comparison with EOF (which
> is defined to -1). Fix this by using int as type for 'c' variable, which
> also matches the declaration of fgetc().
>
> While being at it, fix the parser logic to correctly handle multiple
> empty lines and consecutive whitespace and tab characters to further
> improve the parser's robustness. Note that this will still detect double
> separator characters, so doesn't soften up the parser too much.
>
> Fixes: 3da3ebfca85b8 ("bpf: Make bytecode-file reading a little more robust")
> Cc: Daniel Borkmann <daniel@iogearbox•net>
> Signed-off-by: Phil Sutter <phil@nwl•cc>
Definitely ack on the EOF bug:
Acked-by: Daniel Borkmann <daniel@iogearbox•net>
[...]
> @@ -228,18 +229,20 @@ static int bpf_parse_string(char *arg, bool from_file, __u16 *bpf_len,
> case '\n':
> if (c_prev != ',')
> *(pos++) = ',';
> + c_prev = ',';
> break;
> case ' ':
> case '\t':
> if (c_prev != ' ')
> *(pos++) = c;
> + c_prev = ' ';
> break;
> default:
> *(pos++) = c;
> + c_prev = c;
> }
> if (pos - tmp_string == tmp_len)
> break;
> - c_prev = c;
I don't really have a strong opinion on this, but the logic for
normalizing here is getting a bit convoluted. Is your use case
for making the parser more robust mainly so you can just use the
-ddd output from tcpdump for cBPF w/o piping through tr? But even
that shouldn't give multiple empty lines afaik, no?
next prev parent reply other threads:[~2017-08-30 13:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-29 15:09 [iproute PATCH] lib/bpf: Fix bytecode-file parsing Phil Sutter
2017-08-30 13:53 ` Daniel Borkmann [this message]
2017-08-30 14:11 ` Phil Sutter
2017-09-01 19:13 ` Daniel Borkmann
2017-09-04 19:09 ` Stephen Hemminger
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