Date: Mon, 02 Jul 2018 17:17:43 +0200
From: Leonardo Taccari <l...@netbsd.org>
Message-ID: <20180702151748.7d45a84...@mail.netbsd.org>
| What should we do if we receive just a `printf '\''?
Pretty much whatever we please ... (including printing the environment, if
that was sane..., even dumping core)
| IIUC according POSIX this is unspecified behaviour
It is when the stray terminating \ is in the arg to a %b conversion,
when it is in the format it is just "forgotten". There are some in
posix who believe that being "forgotten" is the same as "unspecified"
(as they haven't specified anything...) - I consider it to simply be
a bug (in posix.)
| and for consistency I have treated it similarly to the `default' case
| for "unknown escape sequence"
I think that's best.
For comparison, bash's builtin printf simply prints the \ and doesn't
treat it as an error - I think that's sub-optimal (not in the spirit of posix)
which is fairly clear that error messages should be printed, and the
exit code not be 0, whenever something incorrect is detected.
I have committed a slightly different version of your patch (just to
make it more consistent with what was there before) ... and then I
also fixed the "print error messages twice when there's a bad \
conversion in a %b string" which I noticed while testing this.
While here, and discussing printf, it is also worth noting that we
treat
printf %b '\64'
as a valid way to print '4', whereas posix actually requires:
printf %b '\064'
(which also works, of course, including where there are 3
octal digits after the \0.) The earlier case is another
one which is unspecified.
Does anyone have any problem with that extension?
(nb: in the format string, the 0 after the \ is not required,
and if given counts as being one of the (max 3) digits
that are converted from octal to a char - that is, \0123
in a format string, and in a %b arg are treated differently.
That's just the way it is....)
kre
