Re: [hackers] [libgrapheme] Use SIZE_MAX instead of (size_t)-1 || Laslo Hunhold

From: Ethan Sommer <e5ten.arch_AT_gmail.com>
Date: Sat, 18 Dec 2021 15:07:30 -0500

On Sat, Dec 18, 2021 at 3:02 PM Mattias Andrée <maandree_AT_kth.se> wrote:

> (size_t)-1 is also undefined behaviour.


It isn't, wrap-around with unsigned types is defined, it's only signed
overflow that isn't.


> On Sat, 18 Dec 2021 20:21:42 +0100
> <git_AT_suckless.org> wrote:
>
> > commit cb7e9c00899ae0ed57a84991308b7f880f4ddef6
> > Author: Laslo Hunhold <dev_AT_frign.de>
> > AuthorDate: Sat Dec 18 20:21:04 2021 +0100
> > Commit: Laslo Hunhold <dev_AT_frign.de>
> > CommitDate: Sat Dec 18 20:21:04 2021 +0100
> >
> > Use SIZE_MAX instead of (size_t)-1
> >
> > This makes a bit clearer what we mean, and given the library is C99
> > we can rely on this constant to exist.
> >
> > Signed-off-by: Laslo Hunhold <dev_AT_frign.de>
> >
> > diff --git a/man/grapheme_decode_utf8.3 b/man/grapheme_decode_utf8.3
> > index 26e3afb..d5c7c9d 100644
> > --- a/man/grapheme_decode_utf8.3
> > +++ b/man/grapheme_decode_utf8.3
> > _AT__AT_ -31,8 +31,8 @@ Given NUL has a unique 1 byte representation, it is
> safe to operate on
> > NUL-terminated strings by setting
> > .Va len
> > to
> > -.Dv (size_t)-1
> > -and terminating when
> > +.Dv SIZE_MAX
> > +(stdint.h is already included by grapheme.h) and terminating when
> > .Va cp
> > is 0 (see
> > .Sx EXAMPLES
> > _AT__AT_ -87,7 +87,7 @@ print_cps_nul_terminated(const char *str)
> > uint_least32_t cp;
> >
> > for (off = 0; (ret = grapheme_decode_utf8(str + off,
> > - (size_t)-1, &cp)) > 0 &&
> > + SIZE_MAX, &cp)) > 0 &&
> > cp != 0; off += ret) {
> > printf("%"PRIxLEAST32"\\n", cp);
> > }
> > diff --git a/src/character.c b/src/character.c
> > index 015b4e0..8f1143f 100644
> > --- a/src/character.c
> > +++ b/src/character.c
> > _AT__AT_ -197,19 +197,19 @@ grapheme_next_character_break(const char *str)
> > * miss it, even if the previous UTF-8 sequence terminates
> > * unexpectedly, as it would either act as an unexpected byte,
> > * saved for later, or as a null byte itself, that we can catch.
> > - * We pass (size_t)-1 to the length, as we will never read beyond
> > + * We pass SIZE_MAX to the length, as we will never read beyond
> > * the null byte for the reasons given above.
> > */
> >
> > /* get first codepoint */
> > - len += grapheme_decode_utf8(str, (size_t)-1, &cp0);
> > + len += grapheme_decode_utf8(str, SIZE_MAX, &cp0);
> > if (cp0 == GRAPHEME_INVALID_CODEPOINT) {
> > return len;
> > }
> >
> > while (cp0 != 0) {
> > /* get next codepoint */
> > - ret = grapheme_decode_utf8(str + len, (size_t)-1, &cp1);
> > + ret = grapheme_decode_utf8(str + len, SIZE_MAX, &cp1);
> >
> > if (cp1 == GRAPHEME_INVALID_CODEPOINT ||
> > grapheme_is_character_break(cp0, cp1, &state)) {
> >
>
>
>
Received on Sat Dec 18 2021 - 21:07:30 CET