Re: if anyone wanted to practice fixing compiler warnings in tcpdump...

[Denis Ovsienko <denis () ovsienko info>]

 ---- On Mon, 30 Jul 2018 02:08:51 +0100 Guy Harris <gharris () sonic net> wrote ---- 
> On Jul 29, 2018, at 5:48 AM, Denis Ovsienko <denis () ovsienko info> wrote: 
>  
> > Building (configure+gcc) tcpdump master branch with libpcap 0.6.1 yields the following compiler warnings, some of 
> > which are as easy as decorating a variable declaration with #ifdef: 
> >  
> > ./tcpdump.c: In function ‘open_interface’: 
> > ./tcpdump.c:1382:22: warning: passing argument 1 of ‘pcap_open_live’ discards ‘const’ qualifier from pointer 
> > target type [-Wdiscarded-qualifiers] 
> >  pc = pcap_open_live(device, ndo->ndo_snaplen, !pflag, 1000, ebuf); 
> >                      ^~~~~~ 
> > In file included from ./tcpdump.c:97:0: 
> > ../libpcap/pcap.h:136:9: note: expected ‘char *’ but argument is of type ‘const char *’ 
> > pcap_t *pcap_open_live(char *, int, int, int, char *); 
> >         ^~~~~~~~~~~~~~ 
>  
> Libpcap *should* have had it as const since the beginning, but const was new back when libpcap was introduced; we 
> later added const to a bunch of argument declarations. 
>  
> In this particular case, we could make the argument to open_interface() a "char *" rather than a "const char *" - 
> it's just a routine internal to tcpdump, so it's not as if we're claiming "hey, we might modify this" to code using 
> it. 

Well, that, and a comment, looks a little better than a compiler warning.

Thank you for fixing the other warnings. Though I initially hoped some bored hacker would pick the easy warnings first, 
then do more difficult ones and eventually warm up to the point where they would close a few bugs on the issue tracker. 
My imagination was too powerful this time...

-- 
    Denis Ovsienko


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