Re: printf bug(s?)

[Oliver Kiddle <okiddle@xxxxxxxxxxx>]

Harald van D?k wrote:
> When I run the command printf '%', zsh 4.2.5 gives me a segfault. It

I can't reproduce the segfault on any system I have access to so perhaps
it is platform specific. Your fix looks right so I'll commit it to
CVS. Thanks.

> 2:
> 
> That segfault I noticed when I tried to run printf '\045'. I expected
> this to print a single character '%', the same as printf '%%' would. zsh
> instead treats it exactly as an ordinary % character. Is this a bug, or

It's not a bug as such. Note that it is entirely consistent with how
printf works from C. I think there was a brief discussion about it when
printf was first added.

The current implementation makes it easier to share the \ handling code
with echo. It just calls getkeystring() on the whole format
specification first. I seem to remember that, at the time, a survey of
how other printf implementations worked showed a complete mix so it
seemed justifiable to take the lazy option. However, I would agree that
your expected behaviour would probably be better.

> " "\ddd", where ddd is a one, two, or three-digit octal number, shall
>   be written as a byte with the numeric value specified by the octal
>   number. "

It's difficult to know whether it was intended by the wording or not.

However, that wording also means that \7 should output a bell character
(you need \07 at the moment). Annoyingly, the specification for how \
escapes work is subtly different for echo and printf. I think \c has a
different definition too.

So what we probably need to do is have the printf code handle \ escapes
itself at the same time as it scans through the specification looking
for format specifiers.

Oliver


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