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Re: PCAP_ERROR/PCAP_ERROR_BREAK or -1/-2?


From: Guy Harris <gharris () sonic net>
Date: Wed, 25 Jul 2018 01:11:23 -0700

On Jul 25, 2018, at 12:57 AM, Denis Ovsienko <denis () ovsienko info> wrote:

Roughly a half of the libpcap man pages text uses the values -1 and -2 to discuss the return value of particular 
libpcap functions, the other half uses PCAP_ERROR and PCAP_ERROR_BREAK.

Is there a good reason to keep it this way instead of using PCAP_ERROR/PCAP_ERROR_BREAK consistently in all man pages?

About the only reason for *code* not to use PCAP_ERROR and PCAP_ERROR_BREAK would be if it has to compile with versions 
of libpcap prior to 1.0.

The only reason not to use PCAP_ERROR and PCAP_ERROR_BREAK in man pages for APIs existing in pre-1.0 releases would be 
to discourage people from writing code that wouldn't compile with pre-1.0 releases.

However, they could *also* just do

        #ifndef PCAP_ERROR
        #define PCAP_ERROR      -1
        #endif
        #ifndef PCAP_ERROR_BREAK
        #define PCAP_ERROR_BREAK        -2
        #endif

in the files that use them with those APIs, or in a header file included by those files, so I'm not sure that's a 
strong enough reason not to just use them uniformly.

And if they're making calls to APIs *not* present in pre-1.0 releases, their code won't compile with a pre-1.0 release 
anyway, so....
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