[Dropping debian-h...@lists.debian.org as the Hurd defines all of them] On 8 Oct 2017, at 12:18, Kang-Che Sung <explore...@gmail.com> wrote: > 2017年10月8日 18:50，"James Clarke" <jrt...@jrtc27.com>寫道： >> On 8 Oct 2017, at 02:34, Kang-Che Sung <explore...@gmail.com> wrote: >> > On Sun, Oct 8, 2017 at 1:53 AM, James Clarke <jrt...@jrtc27.com> wrote: >> >> diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c >> >> index 9cbfb2836..95dac656a 100644 >> >> --- a/libbb/xfuncs.c >> >> +++ b/libbb/xfuncs.c >> >> @@ -22,6 +22,16 @@ >> >> */ >> >> #include "libbb.h" >> >> >> >> +#ifndef IMAXBEL >> >> +# define IMAXBEL 0 >> >> +#endif >> >> +#ifndef IUCLC >> >> +# define IUCLC 0 >> >> +#endif >> >> +#ifndef IXANY >> >> +# define IXANY 0 >> >> +#endif >> >> + >> > >> > I wonder, how do these break, and why does defining them as 0 solve the >> > problem? >> >> FreeBSD (well, GNU/kFreeBSD at least) does not define IUCLC. They are only >> used >> in the line: >> >> > newterm.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL); >> >> Thus, by defining them as 0 when not present, it is as if they were omitted >> from that list, without needing a bunch of confusing #ifdef's in the >> expression >> itself. While IMAXBEL and IXANY are defined everywhere Debian cares about, >> they >> are still non-standard, so I did the same for them in case there is a >> platform >> out there without them. >> >> Regards, >> James > > > Why not just fix that usage line so that the bitwise OR's are all enclosed in > #ifdef lines? I think it's better than defining the macros to a value that > may cause further problems when reused. > > Analogy: You probably won't define an unsupported signal, say SIGUSR3, to a > zero value anyway. They are undefined for a reason. Hope you understand.
I can understand your reasoning; the only reason I did it that way was because coreutils/stty.c has a whole load of instances of this, including for IMAXBEL, IUCLC and IXANY, but looking at it more closely I now see that all uses of them are in fact guarded by whether they are non-zero, so I'm not sure whether there's really much point even for that file. I shall therefore change it to use #ifdef's for the OR just like you said to avoid potential confusion. Regards, James
