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perlapi: Combine the UTF8SKIP entries into a single one

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Karl Williamson 2024-06-10 15:19:14 -06:00
parent 3f18121e99
commit dfad42ddbc
1 changed files with 29 additions and 46 deletions
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75
utf8.h
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@ -740,70 +740,53 @@ uppercase/lowercase/titlecase/fold into.
/*
=for apidoc Am|STRLEN|UTF8SKIP|char* s
returns the number of bytes a non-malformed UTF-8 encoded character whose first
(perhaps only) byte is pointed to by C<s>.
=for apidoc Am|STRLEN|UTF8SKIP|const char* s
=for apidoc_item |STRLEN|UTF8_SKIP|const char* s
=for apidoc_item |STRLEN|UTF8_CHK_SKIP|const char* s
=for apidoc_item |STRLEN|UTF8_SAFE_SKIP|const char* s|const char* e
Each of these returns the number of bytes in the UTF-8 encoded character
whose first (perhaps only) byte is pointed to by C<s>.
C<UTF8SKIP> and C<UTF8_SKIP> are synonyms. Use them when there is no
possibility that the character pointed to by C<s> is malformed.
If there is a possibility of malformed input, use instead:
=over
=item C<L</UTF8_SAFE_SKIP>> if you know the maximum ending pointer in the
buffer pointed to by C<s>; or
=item C<L</UTF8_SAFE_SKIP>> if you know the maximum ending pointer in the buffer pointed to by C<s>
=item C<L</UTF8_CHK_SKIP>> if you don't know it.
If the buffer has enough bytes to hold the character, it returns the
same value as C<UTF8SKIP> and C<UTF8_SKIP> would. If the buffer has
fewer bytes than can fit, it returns the number of bytes available in
the buffer, which could be 0 if S<C<s E<gt>= e>>. On DEBUGGING builds,
it asserts that S<C<s E<lt>= e>>.
=back
=item C<L</UTF8_CHK_SKIP>> if you don't know the maximum ending pointer
It is better to restructure your code so the end pointer is passed down so that
you know what it actually is at the point of this call, but if that isn't
possible, C<L</UTF8_CHK_SKIP>> can minimize the chance of accessing beyond the end
of the input buffer.
=cut
*/
#define UTF8SKIP(s) PL_utf8skip[*(const U8*)(ASSERT_IS_PTR(s))]
/*
=for apidoc Am|STRLEN|UTF8_SKIP|char* s
This is a synonym for C<L</UTF8SKIP>>
=cut
*/
#define UTF8_SKIP(s) UTF8SKIP(s)
/*
=for apidoc Am|STRLEN|UTF8_CHK_SKIP|char* s
This is a safer version of C<L</UTF8SKIP>>, but still not as safe as
C<L</UTF8_SAFE_SKIP>>. This version doesn't blindly assume that the input
string pointed to by C<s> is well-formed, but verifies that there isn't a NUL
terminating character before the expected end of the next character in C<s>.
The length C<UTF8_CHK_SKIP> returns stops just before any such NUL.
This version doesn't blindly assume that the input string pointed to by
C<s> is well-formed, but verifies that there isn't a NUL terminating
character before the expected end of the next character in C<s>. The
length C<UTF8_CHK_SKIP> returns stops just before any such NUL.
Perl tends to add NULs, as an insurance policy, after the end of strings in
SV's, so it is likely that using this macro will prevent inadvertent reading
beyond the end of the input buffer, even if it is malformed UTF-8.
SV's, so it is likely that using this macro on an SV string will prevent
inadvertent reading beyond the end of the input buffer, even if it is
malformed UTF-8.
This macro is intended to be used by XS modules where the inputs could be
malformed, and it isn't feasible to restructure to use the safer
C<L</UTF8_SAFE_SKIP>>, for example when interfacing with a C library.
=cut
*/
#define UTF8_CHK_SKIP(s) \
(UNLIKELY(s[0] == '\0') ? 1 : my_strnlen((const char *) (s), UTF8SKIP(s)))
/*
=for apidoc Am|STRLEN|UTF8_SAFE_SKIP|char* s|char* e
returns 0 if S<C<s E<gt>= e>>; otherwise returns the number of bytes in the
UTF-8 encoded character whose first byte is pointed to by C<s>. But it never
returns beyond C<e>. On DEBUGGING builds, it asserts that S<C<s E<lt>= e>>.
=back
=cut
*/
#define UTF8SKIP(s) PL_utf8skip[*(const U8*)(ASSERT_IS_PTR(s))]
#define UTF8_SKIP(s) UTF8SKIP(s)
#define UTF8_CHK_SKIP(s) \
(UNLIKELY(s[0] == '\0') ? 1 : my_strnlen((const char *) (s), UTF8SKIP(s)))
#define UTF8_SAFE_SKIP(s, e) (__ASSERT_((e) >= (s)) \
UNLIKELY(((e) - (s)) <= 0) \
? 0 \