Re: Doubt on pid value in grammar.y

[Nuno Martins <nuno.martins () caixamagica pt>]

On 27 February 2012 18:38, Guy Harris <guy () alum mit edu> wrote:

> On Feb 27, 2012, at 9:40 AM, Nuno Martins wrote:
>
> > I'm having a trouble to find the purpose of pid identifier in grammar.y
> > file. #line 398
> >
> > This identifier is related to what protocol ?
> >
> > I'm supposing that this pid is not related in any way with processes
> (like
> > pid process identifier), right?
>
> Right.
>
> The grammar rules for pid are
>
> pid:      nid
>        | qid and id
>        | qid or id
>        ;
>
> so it's either a nid by itself:
>
> nid:      ID
>        | HID '/' NUM
>        | HID NETMASK HID
>        | HID
>        | HID6 '/' NUM
>        | HID6
>        | EID
>        | AID
>        | not id
>        ;
>
> which is a "network ID" (host name, IPv4 address+netmask, IPv6 address +
> CIDRish number, Ethernet ID, ATM ID, or a negated version of any of those),
> or it's a qid ANDed or ORed with an id:
>
> qid:      pnum
>        | pid
>        ;
>
> pnum:     NUM
>        | paren pnum ')'
>        ;
>
> id:       nid
>        | pnum
>        | paren pid ')'
>        ;
>
> The "p" in "pid" presumably refers to Parentheses, not to Protocols or
> Processes; the "pid" rule exists not to define a symbol that has some
> inherent semantics the user would care about, it just exists to allow the
> parenthesization rules of the libpcap expression syntax to be stated.-

Thanks, your explanation took all my doubts.

Nuno Martins


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