[Xastir-dev] Switching string length discussion to here

[Jason Godfrey]

There is also strlcat.

- Jason

On Sun, Dec 19, 2021 at 11:58 AM Tom Russo <russo at bogodyn.org> wrote:

> Oh, and certainly you *could* use "xastir_snprintf" to do a sort of strncat
> operation:
>
>    xastir_snprintf(dest,dest_size,"%s%s",dest,src);
>
> instead of
>    strncat(dest,src,dest_size-1-strnlen(dest));
>
> but that would be less efficient (because of all the format processing and
> such in xastir_snprintf) and even more typing.  I advocate just undoing the
> mistake of how strncat was used.
>
> On Sun, Dec 19, 2021 at 09:30:37AM -0800, we recorded a bogon-computron
> collision of the <curt.we7u at gmail.com> flavor, containing:
> > Tom,
> >
> > Thanks for your recent explanation in the issue discussion (Issue
> > #188). This is good general "string" talk and applicable to a wide
> > range of code. For that reason I'm moving the discussion here so it's
> > more easily found later, instead of hidden in Github issue comments.
> >
> > Pardon me while I summarize my limited knowledge of "strings" at this
> point:
> >
> > There aren't actually strings in C, only null-terminated character
> > buffers. We can't run past the end or else we read/write from other
> > stuff in memory.
> >
> > In Xastir we often use character buffers of size MAX_DEVICE_BUFFER,
> > which is the case for the Opentrac code.
> >
> > At one point we got rid of almost all of the strnXX() type of calls,
> > switching to xastir_snprintf() instead... Perhaps the Opentrac
> > routines were coded up later or weren't converted at the time.
> >
> > >From Tom:
> > -----
> > "There was a lot if incorrect use of strncat in Xastir, mostly using
> > incorrect values of "n" --- it's supposed to be the maximum number of
> > characters that can fit into the destination string, and in many cases
> > the code had been written to specify that number as the number of
> > characters to copy out of the source string instead. We fixed a lot of
> > that, but the opentrac code had a lot of it.
> >
> > The "right" fix is to fix the strncat calls so that one keeps track of
> > how much room is left in the destination string, and use that as
> > the"n" in strncat."
> > -----
> >
> > I can certainly do that last but it seems like a lot of busy work in
> > C. Other languages have string functions which handle all of this. Are
> > there any C libraries that make it easier these days? I know I
> > couldn't find a good one before and that's why xastir_snprintf() came
> > about.
> >
> > --
> > Curt, WE7U        http://xastir.org        http://www.sarguydigital.com
> > _______________________________________________
> > Xastir-dev mailing list
> > Xastir-dev at lists.xastir.org
> > http://xastir.org/mailman/listinfo/xastir-dev
>
> --
> Tom Russo    KM5VY
> Tijeras, NM
>
>  echo "prpv_a'rfg_cnf_har_cvcr" | sed -e 's/_/ /g' | tr [a-m][n-z]
> [n-z][a-m]
>
> _______________________________________________
> Xastir-dev mailing list
> Xastir-dev at lists.xastir.org
> http://xastir.org/mailman/listinfo/xastir-dev
>
-- 
"The problem with quotes on the Internet is that it is often difficult to
verify their authenticity." - *Abraham Lincoln*