On Sun, Nov 16, 2014 at 1:18 AM, Norihiro Tanaka <nori...@kcn.ne.jp> wrote: > On Sat, 15 Nov 2014 22:27:50 -0800 > Jim Meyering <j...@meyering.net> wrote: >> Thanks for confirming. >> In that case, since I see no harm in calling xnmalloc with N = 0, I >> will use a more conservative change: guard only the undefined use of >> memcpy. >> I've left your name on this amended patch. > > Thanks for the ajustment. You are right, but the purpose of the code > is to make a clone of original DFA. If we do not guard xnmalloc, when > calloc is 0, charclasses is NULL in original DFA, and it is *NOT* NULL > in the superset. I think that it is not right logically.
Does some code assume that V->charclasses != NULL implies 0 < V->calloc? I would argue that such code is incorrect. I.e., in the degenerate case (calloc == 0), the code should not distinguish between a NULL charclasses member and one that points to a malloc'd buffer of length 0.
