From: Denys Vlasenko
> Sent: 17 December 2021 20:10
>
> On Thu, Dec 16, 2021 at 12:26 PM Ron Yorston <[email protected]> wrote:
> > The '%' character in a format specification may be followed by
> > one or more flags from the list "+- #0". BusyBox printf didn't
> > support the '0' flag or allow multiple flags to be provided.
> > As a result the formats '%0*d' and '%0 d' were considered to be
> > invalid.
> >
> > The lack of support for '0' was pointed out by Andrew Snyder on the
> > musl mailing list:
> >
> > https://www.openwall.com/lists/musl/2021/12/14/2
> >
> > function old new delta
> > printf_main 860 891 +31
> > .rodata 99281 99282 +1
> > ------------------------------------------------------------------------------
> > (add/remove: 0/0 grow/shrink: 2/0 up/down: 32/0) Total: 32
> > bytes
> >
> > Signed-off-by: Ron Yorston <[email protected]>
> > ---
> > coreutils/printf.c | 8 +++++---
> > testsuite/printf.tests | 10 ++++++++++
> > 2 files changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/coreutils/printf.c b/coreutils/printf.c
> > index dd94c8ade..e5cf5f942 100644
> > --- a/coreutils/printf.c
> > +++ b/coreutils/printf.c
> > @@ -313,9 +313,11 @@ static char **print_formatted(char *f, char **argv,
> > int *conv_err)
> > }
> > break;
> > }
> > - if (*f && strchr("-+ #", *f)) {
> > - ++f;
> > - ++direc_length;
> > + if (*f) {
> > + while (strchr("-+ #0", *f)) {
> > + ++f;
> > + ++direc_length;
> > + }
>
> This can walk off the end of "f", doesn't it?
> [strchr("anything", '\0') is not NULL]
> I propose
>
> while (*f && strchr("-+ #0", *f)) {
> ++f;
> ++direc_length;
> }
Or:
tmp = strspn(f, "-+ #0");
direc_length += tmp - f;
f = tmp;
Except that I'd have thought it would need to remember which flags are set.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT,
UK
Registration No: 1397386 (Wales)
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