Add mbstring support for GB18030-2022 text encoding

The previous version of the GB-18030 standard was published in 2005.
This commit adds support for the updated (2022) version of this t

Add mbstring support for GB18030-2022 text encoding

The previous version of the GB-18030 standard was published in 2005.
This commit adds support for the updated (2022) version of this text
encoding. The existing GB18030 implementation has been left unchanged
for backwards compatibility; users who want to use the new standard
must explicitly indicate the desired text encoding is 'GB18030-2022'.

The document which defines GB18030-2022, published by the government
of the People's Republic of China, defines three levels of standards
compliance. This implementation is intended to achieve Implementation
Level 3, which is the highest level of compliance.

Experts in the GB18030 standard are requested to assess this
implementation and report any deviation from the standard.

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Avoid temporary string allocations in php_mb_parse_encoding_list() (#12714)

This brings execution time down from 0.91s to 0.86s on the reference
benchmark [1].

[1] https://githu

Avoid temporary string allocations in php_mb_parse_encoding_list() (#12714)

This brings execution time down from 0.91s to 0.86s on the reference
benchmark [1].

[1] https://github.com/php/php-src/issues/12684#issuecomment-1813799924

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Add fast mb_strcut implementation for UTF-8

The old implementation runs through the entire string to pick out the
part which should be returned by mb_strcut. This creates significant

Add fast mb_strcut implementation for UTF-8

The old implementation runs through the entire string to pick out the
part which should be returned by mb_strcut. This creates significant
performance overhead. The new specialized implementation of mb_strcut
for UTF-8 usually only examines a few bytes around the starting and
ending cut points, meaning it generally runs in constant time.

For UTF-8 strings just a few bytes long, the new implementation is
around 10% faster (according to microbenchmarks which I ran locally).
For strings around 10,000 bytes in length, it is 50-300x faster.
(Yes, that is 300x and not 300%.)

The new implementation behaves identically to the old one on VALID
UTF-8 strings; a fuzzer was used to help ensure this is the case.
On invalid UTF-8 strings, there is a difference: in some cases, the
old implementation will pass invalid byte sequences through unchanged,
while in others it will remove them. The new implementation has
behavior which is perhaps slightly more predictable: it simply backs
up the starting and ending cut points to the preceding "starter
byte" (one which is not a UTF-8 continuation byte).

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Fix phpGH-10648: add check function pointer into mbfl_encoding

Previously, mbstring used the same logic for encoding validation as for
encoding conversion.

However, there are ca

Fix phpGH-10648: add check function pointer into mbfl_encoding

Previously, mbstring used the same logic for encoding validation as for
encoding conversion.

However, there are cases where we want to use different logic for validation
and conversion. For example, if a string ends up with missing input
required by the encoding, or if a character is input that is invalid
as an encoding but can be converted, the conversion should succeed and
the validation should fail.

To achieve this, a function pointer mb_check_fn has been added to
struct mbfl_encoding to implement the logic used for validation.
Also, added implementation of validation logic for UTF-7, UTF7-IMAP,
ISO-2022-JP and JIS.

(The same change has already been made to PHP 8.2 and 8.3; see
6fc8d014df. This commit is backporting the change to PHP 8.1.)

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Fix phpGH-10648: add check function pointer into mbfl_encoding

Previously, mbstring used the same logic for encoding validation as for
encoding conversion.

However, there are ca

Fix phpGH-10648: add check function pointer into mbfl_encoding

Previously, mbstring used the same logic for encoding validation as for
encoding conversion.

However, there are cases where we want to use different logic for validation
and conversion. For example, if a string ends up with missing input
required by the encoding, or if a character is input that is invalid
as an encoding but can be converted, the conversion should succeed and
the validation should fail.

To achieve this, a function pointer mb_check_fn has been added to
struct mbfl_encoding to implement the logic used for validation.
Also, added implementation of validation logic for UTF-7, UTF7-IMAP,
ISO-2022-JP and JIS.

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Implement mb_encode_mimeheader using fast text conversion filters

The behavior of the new mb_encode_mimeheader implementation closely
follows the old implementation, except for three poi

Implement mb_encode_mimeheader using fast text conversion filters

The behavior of the new mb_encode_mimeheader implementation closely
follows the old implementation, except for three points:

• The old implementation was missing a call to the mbfl_convert_filter
flush function. So it would sometimes truncate the input string just
before its end.

• The old implementation would drop zero bytes when QPrint-encoding.
So for example, if you tried to QPrint-encode the UTF-32BE string
"\x00\x00\x12\x34", its QPrint-encoding would be "=12=34", which
does not decode to a valid UTF-32BE string. This is now fixed.

• In some rare corner cases, the new implementation will choose to
Base64-encode or QPrint-encode the input string, where the old
implementation would have just added newlines to it. Specifically,
this can happen when there is a non-space ASCII character, followed
by a large number of ASCII spaces, followed by a non-ASCII character.

The new implementation is around 2.5-8x faster than the old one,
depending on the text encoding and transfer encoding used. Performance
gains are greater with Base64 transfer encoding than with QPrint
transfer encoding; this is not because QPrint-encoding bytes is slow,
but because QPrint-encoded output is much bigger than Base64-encoded
output and takes more lines, so we have to go through the process of
finding the right place to break a line many more times.

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Remove unneeded function mbfl_no2preferred_mime_name

Remove unneeded function mbfl_name2no_encoding

Mark UTF-8 strings emitted by mbstring functions as valid UTF-8

We now have a couple of mbstring functions which have fast paths for
strings marked as 'valid UTF-8'. Later, we may likely

Mark UTF-8 strings emitted by mbstring functions as valid UTF-8

We now have a couple of mbstring functions which have fast paths for
strings marked as 'valid UTF-8'. Later, we may likely have more. So
that these fast paths can be used more frequently, mark UTF-8 strings
emitted by mbstring as 'valid UTF-8'. This is always a correct thing
to do, because mbstring never returns invalid UTF-8 as the result of
a conversion (or similar) operation.

Internally, we do have a conversion mode which deliberately emits
invalid UTF-8 in some cases. (This is done to prevent unwanted matches
when we are converting strings to UTF-8 before performing matching
operations on them.) For such strings, don't set the 'valid UTF-8' flag.
It probably wouldn't hurt anything to set it, because strings generated
using that special conversion mode should *never* be returned to
userland, and I don't think we do anything with them which cares about
the IS_STR_VALID_UTF8 flag... but still, it would likely cause
confusion for developers.

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Merge branch 'PHP-8.1'

* PHP-8.1:
Reintroduce legacy 'SJIS-win' text encoding in mbstring

Reintroduce legacy 'SJIS-win' text encoding in mbstring

In e2459857af, I combined mbstring's "SJIS-win" text encoding
into CP932. This was done after doing some testing which appeared

Reintroduce legacy 'SJIS-win' text encoding in mbstring

In e2459857af, I combined mbstring's "SJIS-win" text encoding
into CP932. This was done after doing some testing which appeared
to show that the mappings for "SJIS-win" were the same as those
for "CP932".

Later, it was found that there was actually a small difference
prior to e2459857af when converting Unicode to CP932. The
mappings for the following two codepoints were different:

CP932 SJIS-win
U+203E 0x7E 0x81 0x50
U+00A5 0x5C 0x81 0x8F

As shown, mbstring's "CP932" mapped Unicode's 'OVERLINE' and
'YEN SIGN' to the ASCII bytes which have conflicting uses in
most legacy Japanese text encodings. "SJIS-win" mapped these
to equivalent JIS X 0208 fullwidth characters.

Since e2459867af was not intended to cause any user-visible
change in behavior, I am rolling back the merge of "CP932"
and "SJIS-win".

It seems doubtful whether these two text encodings should
be kept separate or merged in a future release. An extensive
discussion of the related historical background and
compatibility issues involved can be found in this
GitHub thread:

https://github.com/php/php-src/issues/8308

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Use fast conversion filters to implement php_mb_ord

Even for single-character strings, this is about 50% faster for
ASCII, UTF-8, and UTF-16. For long strings, the performance gain is

Use fast conversion filters to implement php_mb_ord

Even for single-character strings, this is about 50% faster for
ASCII, UTF-8, and UTF-16. For long strings, the performance gain is
enormous, since the old code would convert the ENTIRE string, just
to pick out the first codepoint.

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Add assertions to help catch buffer overflows in mbstring text conversion code

New internal interface for fast text conversion in mbstring

When converting text to/from wchars, mbstring makes one function call
for each and every byte or wchar to be converted. Typica

New internal interface for fast text conversion in mbstring

When converting text to/from wchars, mbstring makes one function call
for each and every byte or wchar to be converted. Typically, each of
these conversion functions contains a state machine, and its state has
to be restored and then saved for every single one of these calls.
It doesn't take much to see that this is grossly inefficient.

Instead of converting one byte or wchar on each call, the new
conversion functions will either fill up or drain a whole buffer of
wchars on each call. In benchmarks, this is about 3-10× faster.

Adding the new, faster conversion functions for all supported legacy
text encodings still needs some work. Also, all the code which uses
the old-style conversion functions needs to be converted to use the
new ones. After that, the old code can be dropped. (The mailparse
extension will also have to be fixed up so it will still compile.)

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Remove unused typedef 'mbfl_encoding_id'

Remove duplicate implementation of CP932 from mbstring

Sigh. Double sigh. After fruitlessly searching the Internet for information on
this mysterious text encoding called "SJIS-open", I

Remove duplicate implementation of CP932 from mbstring

Sigh. Double sigh. After fruitlessly searching the Internet for information on
this mysterious text encoding called "SJIS-open", I wrote a script to try
converting every Unicode codepoint from 0-0xFFFF and compare the results from
different variants of Shift-JIS, to see which one "SJIS-open" would be most
similar to.

The result? It's just CP932. There is no difference at all. So why do we have
two implementations of CP932 in mbstring?

In case somebody, somewhere is using "SJIS-open" (or its aliases "SJIS-win" or
"SJIS-ms"), add these as aliases to CP932 so existing code will continue to
work.

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Mark various functions with void arguments.

This fixes a bunch of [-Wstrict-prototypes] warning,
because in C func() and func(void) have different semantics.

Remove useless mbstring encoding 'JIS-ms'

MicroSoft invented three encodings very similar to ISO-2022-JP/JIS7/JIS8, called
CP50220, CP50221, and CP50222. All three are supported by mbstr

Remove useless mbstring encoding 'JIS-ms'

MicroSoft invented three encodings very similar to ISO-2022-JP/JIS7/JIS8, called
CP50220, CP50221, and CP50222. All three are supported by mbstring.

Since these encodings are very similar, some code can be shared. Actually,
conversion of CP50220/1/2 to Unicode is exactly the same operation; it's when
converting from Unicode to CP50220/1/2 that some small differences arise in how
certain katakana are handled.

The most important common code was a function called `mbfl_filt_wchar_jis_ms`.
The `jis_ms` part doubtless refers to the fact that these encodings are modified
versions of 'JIS' invented by 'MS'. mbstring also went a step further and exported
'JIS-ms' to userland as a separate encoding from CP50220/1/2. If users requested
'JIS-ms' conversion, they got something like CP50220/1/2, minus their special
ways of handling half-width katakana when converting from Unicode.

But... that 'encoding' is not something which actually exists in the world outside
of mbstring. CP50220/1/2 do exist in MicroSoft software, but not 'JIS-ms'.

For a text encoding conversion library, inventing new variant encodings and
implementing them is not very productive. Our interest is in handling text
encodings which real people actually use for... you know, storing actual text
and things like that.

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Remove useless mbstring encoding 'CP50220-raw'

CP50220 is a variant of ISO-2022-JP invented by MicroSoft, which handles some
Unicode characters which are not representable in ISO-2022-JP

Remove useless mbstring encoding 'CP50220-raw'

CP50220 is a variant of ISO-2022-JP invented by MicroSoft, which handles some
Unicode characters which are not representable in ISO-2022-JP by converting
them to similar characters which are representable.

What, then, is CP50220-raw? An Internet search turns up absolutely nothing.
Reference works which I consulted don't say anything about it. Other text
conversion libraries don't support it.

From looking at the code: It's just the same as CP50220, but it accepts
unmapped JIS X 0208 characters passed through from other Japanese encodings
and silently encodes them using the usual ISO-2022-JP escape sequence and
representation for JIS X 0208 characters.

It's hard to see how this could be useful. OK, let me come out and say it:
it's _not_ useful. We can confidently jettison this (mis)feature.

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Remove useless byte{2,4}{be,le} encodings from mbstring

There is no meaningful difference between these and UCS-{2,4}. They are
just a little bit more lax about passing errors silently.

Remove useless byte{2,4}{be,le} encodings from mbstring

There is no meaningful difference between these and UCS-{2,4}. They are
just a little bit more lax about passing errors silently. They also have
no known use.

Alias to UCS-{2,4} in case someone, somewhere is using them.

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Refactor mbfl_ident.c, mbfl_encoding.c, mbfl_memory_device.c, mbfl_string.c

- Make everything less gratuitously verbose
- Don't litter the code with lots of unneeded NULL checks (for thi

Refactor mbfl_ident.c, mbfl_encoding.c, mbfl_memory_device.c, mbfl_string.c

- Make everything less gratuitously verbose
- Don't litter the code with lots of unneeded NULL checks (for things which
will never be NULL)
- Don't return success/failure code from functions which can never fail
- For encoding structs, don't use pointers to pointers to pointers for the
list of alias strings. Pointers to pointers (2 levels of indirection)
is what actually makes sense. This gets rid of some extraneous
dereference operations.

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Remove unused functions from mbstring

- mbfl_buffer_converter_reset
- mbfl_buffer_converter_strncat
- mbfl_buffer_converter_getbuffer
- mbfl_oddlen
- mbfl_filter_output_pipe_

Remove unused functions from mbstring

- mbfl_buffer_converter_reset
- mbfl_buffer_converter_strncat
- mbfl_buffer_converter_getbuffer
- mbfl_oddlen
- mbfl_filter_output_pipe_flush
- mbfl_memory_device_output2
- mbfl_memory_device_output4
- mbfl_is_support_encoding
- mbfl_buffer_converter_feed2
- _php_mb_regex_globals_dtor
- mime_header_encoder_feed
- mime_header_decoder_feed
- mbfl_convert_filter_feed

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Remove the "auto" encoding

"auto" is only meaningful in functions which accept an encoding
*list* and support encoding detection. These functions have
explicit checks for "auto". It

Remove the "auto" encoding

"auto" is only meaningful in functions which accept an encoding
*list* and support encoding detection. These functions have
explicit checks for "auto". It cannot be used as a standalone
encoding in any meaningful capacity, so I'm dropping it entirely.

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Store input and output filters in mbfl encodings

For functions like mb_chr() and mb_ord() just looking up the
input/output filter for the encoding dominates the runtime. This
commit

Store input and output filters in mbfl encodings

For functions like mb_chr() and mb_ord() just looking up the
input/output filter for the encoding dominates the runtime. This
commit stores the input/output filter for an encoding in the
mbfl encoding structure, so it can be looked up directly, rather
than scanning through filter function lists.

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trailing whitespace removal