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.w...@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@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@lists.xastir.org http://xastir.org/mailman/listinfo/xastir-dev
