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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Use different mblen_table for different SJIS variants

In legacy text conversion filters, reset filter state in 'flush' function

Up until now, I believed that mbstring had been designed such
that (legacy) text conversion filter objects shoul

In legacy text conversion filters, reset filter state in 'flush' function

Up until now, I believed that mbstring had been designed such
that (legacy) text conversion filter objects should not be
re-used after the 'flush' function is called to complete a
text conversion operation.

However, it turns out that the implementation of
_php_mb_encoding_handler_ex DID re-use filter objects
after flush. That means that functions which were based on
_php_mb_encoding_handler_ex, including mb_parse_str and
php_mb_post_handler, would break in some cases; state left
over from converting one substring (perhaps a variable name)
would affect the results of converting another substring
(perhaps the value of the same variable), and could cause
extraneous characters to get inserted into the output.

All this code should be deleted soon, but fixing it helps me
to avoid spurious failures when fuzzing the new/old code to
look for differences in behavior.

(This bug fix commit was originally applied to PHP-8.2 when fuzzing
the new mbstring text conversion code to check for differences with
the old code. Later, Kentaro Ohkouchi kindly reported a problem with
mb_encode_mimeheader under PHP 8.1 which was caused by the same issue.
Hence, this commit was backported to PHP-8.1.)

Fixes GH-9683.

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Restore backwards-compatible mappings of U+005C and U+007E to SJIS-2004

In 0d0029d729 and 315d48b434, I changed the mappings used for Unicode
to Shift-JIS-2004, in an attempt to follow t

Restore backwards-compatible mappings of U+005C and U+007E to SJIS-2004

In 0d0029d729 and 315d48b434, I changed the mappings used for Unicode
to Shift-JIS-2004, in an attempt to follow the JISC specification
more closely. However, feedback from Japanese PHP users indicates
that most users of SJIS-2004 expect 0x5C and 0x7E to be treated as
equivalent to the same ASCII bytes. This is due to a long history of
non-complying implementations which then became a de-facto standard.

Therefore, restore the earlier mappings for U+005C and U+007E.

Thanks to the GitHub user 'youkidearitai' for reporting this issue.

Fixes GH-9528.

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mbstring no longer provides 'long' substitutions for erroneous input bytes

Previously, mbstring had a special mode whereby it would convert
erroneous input byte sequences to output like

mbstring no longer provides 'long' substitutions for erroneous input bytes

Previously, mbstring had a special mode whereby it would convert
erroneous input byte sequences to output like "BAD+XXXX", where "XXXX"
would be the erroneous bytes expressed in hexadecimal. This mode could
be enabled by calling `mb_substitute_character("long")`.

However, accurately reproducing input byte sequences from the cached
state of a conversion filter is often tricky, and this significantly
complicates the implementation. Further, the means used for passing
the erroneous bytes through to where the "BAD+XXXX" text is generated
only allows for up to 3 bytes to be passed, meaning that some erroneous
byte sequences are truncated anyways.

More to the point, a search of publically available PHP code indicates
that nobody is really using this feature anyways.

Incidentally, this feature also provided error output like "JIS+XXXX"
if the input 'should have' represented a JISX 0208 codepoint, but it
decodes to a codepoint which does not exist in the JISX 0208 charset.
Similarly, specific error output was provided for non-existent
JISX 0212 codepoints, and likewise for JISX 0213, CP932, and a few
other charsets. All of that is now consigned to the flames.

However, "long" error markers also include a somewhat more useful
"U+XXXX" marker for Unicode codepoints which were successfully
decoded from the input text, but cannot be represented in the output
encoding. Those are still supported.

With this change, there is no need to use a variety of special values
in the high bits of a wchar to represent different types of error
values. We can (and will) just use a single error value. This will be
equal to -1.

One complicating factor: Text conversion functions return an integer to
indicate whether the conversion operation should be immediately
aborted, and the magic 'abort' marker is -1. Also, almost all of these
functions would return the received byte/codepoint to indicate success.
That doesn't work with the new error value; if an input filter detects
an error and passes -1 to the output filter, and the output filter
returns it back, that would be taken to mean 'abort'.

Therefore, amend all these functions to return 0 for success.

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Test behavior of 'long' illegal character markers

After mb_substitute_character("long"), mbstring will respond to
erroneous input by inserting 'long' error markers into the output.
D

Test behavior of 'long' illegal character markers

After mb_substitute_character("long"), mbstring will respond to
erroneous input by inserting 'long' error markers into the output.
Depending on the situation, these error markers will either look like
BAD+XXXX (for general bad input), U+XXXX (when the input is OK, but it
converts to Unicode codepoints which cannot be represented in the
output encoding), or an encoding-specific marker like JISX+XXXX or
W932+XXXX.

We have almost no tests for this feature. Add a bunch of tests to
ensure that all our legacy encoding handlers work in a reasonable
way when 'long' error markers are enabled.

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Fix conversion of EUC-JP-2004 text (and add test suite)

- Truncated multi-byte characters are treated as an error now
- Invalid multi-byte characters are treated as an error rather than

Fix conversion of EUC-JP-2004 text (and add test suite)

- Truncated multi-byte characters are treated as an error now
- Invalid multi-byte characters are treated as an error rather than
being quietly swallowed
- ASCII control characters are not allowed to appear in the middle
of a multi-byte character

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Remove useless constant MBFL_ENCTYPE_MBCS

This flag indicated that an encoding was 'multi-byte'; it can use a variable
number of bytes to encode each character. As it turns out, we don't

Remove useless constant MBFL_ENCTYPE_MBCS

This flag indicated that an encoding was 'multi-byte'; it can use a variable
number of bytes to encode each character. As it turns out, we don't actually
need to check this flag anywhere, so it's better to remove it.

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Add comment explaining why ISO-2022-JP-2004, etc strings end with ESC ( B

These encodings have multiple modes which can be selected via escape sequences.
The default starting mode is ASC

Add comment explaining why ISO-2022-JP-2004, etc strings end with ESC ( B

These encodings have multiple modes which can be selected via escape sequences.
The default starting mode is ASCII. If a string _ends_ in a different mode, we
emit a 'redundant' escape sequence to switch back to ASCII.

If the resulting string is never concatenated with other strings, that extra
escape sequence serves no purpose. But if the resulting string is concatenated
with other strings of the same encoding, it ensures that the resulting string
will be valid.

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ISO-2022-JP-2004 conversion: handle invalid characters correctly

ISO-2022-JP-2004 conversion: treat unrecognized escapes as error

ISO-2022-JP-2004 conversion: represent backslash and tilde as ASCII

This issue dates back to some commits I merged recently, which made encodings
like Shift-JIS-2004 use appropriate JIS

ISO-2022-JP-2004 conversion: represent backslash and tilde as ASCII

This issue dates back to some commits I merged recently, which made encodings
like Shift-JIS-2004 use appropriate JIS X 0208 characters to represent
backslashes and tildes, rather than single-byte characters which are used in
those encodings with a different meaning (for example, in these encodings,
0x5C is used for a halfwidth Yen sign, rather than a backslash).

There was an unintended side effect: ISO-2022-JP-2004 was also made to
represent backslashes and tildes using JIS X 0208 characters. However,
ISO-2022-JP explicitly includes ASCII as one of its selectable character sets,
and ISO-2022-JP-2004 is just an extension of ISO-2022-JP. So when converting
text to ISO-2022-JP-2004, we can convert Unicode backslashes and tildes to ASCII
rather than using the corresponding JIS X 0208 characters.

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Don't pass invalid JIS X 0212, JIS X 0213, and Windows-CP932 characters through

Similarly to JIS X 0208, mbstring would pass kuten codes which are not mapped
in the JIS X 0212, JIS X 021

Don't pass invalid JIS X 0212, JIS X 0213, and Windows-CP932 characters through

Similarly to JIS X 0208, mbstring would pass kuten codes which are not mapped
in the JIS X 0212, JIS X 0213, or CP932 character sets through silently when
converting to another Japanese encoding.

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Don't mangle non-Japanese chars which appear after a 'combining' kana in SJIS-2004

Unicode has 'combining' characters which join with another following character.
Japanese hiragana and k

Don't mangle non-Japanese chars which appear after a 'combining' kana in SJIS-2004

Unicode has 'combining' characters which join with another following character.
Japanese hiragana and katakana with the 'two dots' voice mark can be represented
in this way, with one Unicode character for the 'base' kana and another one which
adds the voice mark.

In SJIS-2004, however, there are dedicated characters for voiced and unvoiced
kana. So some special checks are done to identify sequences of Unicode characters
which need to be 'collapsed' into a single SJIS-2004 character.

If a kana is immediately followed by some other unrelated character, like a
Cyrillic letter, then the cached kana should be output 'as is' and we
proceed with encoding the unrelated character. When doing this, though,
we need to re-initialize local variables, or else the unrelated character
will be mangled in some cases.

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SJIS-2004 encoding conversion: handle invalid (or truncated) 2nd byte for Kanji correctly

If the 2nd byte of a 2-byte character is invalid, then mb_substitute_character()
should be respe

SJIS-2004 encoding conversion: handle invalid (or truncated) 2nd byte for Kanji correctly

If the 2nd byte of a 2-byte character is invalid, then mb_substitute_character()
should be respected. Instead, what mbstring was doing was 'swallowing' the
first byte, then emitting the 2nd byte as if it was an ASCII character.

Likewise, if the 2nd byte is missing, instead of just keeping quiet, report an
illegal character as specified by mb_substitute_character().

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Remove mbstring identify filters

mbstring had an 'identify filter' for almost every supported text encoding
which was used when auto-detecting the most likely encoding for a string.

Remove mbstring identify filters

mbstring had an 'identify filter' for almost every supported text encoding
which was used when auto-detecting the most likely encoding for a string.
It would run over the string and set a 'flag' if it saw anything which
did not appear likely to be the encoding in question.

One problem with this scheme was that encodings which merely appeared
less likely to be the correct one were completely rejected, even if there
was no better candidate. Another problem was that the 'identify filters'
had a huge amount of code duplication with the 'conversion filters'.

Eliminate the identify filters. Instead, when auto-detecting text
encoding, use conversion filters to see whether the input string is valid
in candidate encodings or not. At the same type, watch the type of
codepoints which the string decodes to and mark it as less likely if
non-printable characters (ESC, form feed, bell, etc.) or 'private use
area' codepoints are seen.

Interestingly, one old test case in which JIS text was misidentified
as UTF-8 (and this wrong behavior was enshrined in the test) was 'fixed'
and the JIS string is now auto-detected as JIS.

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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 unneeded function mbfl_filt_ident_common_dtor

This was the default destructor for mbfl_identify_filter structs, but there's nothing
we actually need to do to those structs before

Remove unneeded function mbfl_filt_ident_common_dtor

This was the default destructor for mbfl_identify_filter structs, but there's nothing
we actually need to do to those structs before freeing them.

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Remove unneeded function mbfl_filt_conv_common_dtor

This is a default destructor for mbfl_convert_filter structs. The thing is: there
isn't really anything that needs to be done to those

Remove unneeded function mbfl_filt_conv_common_dtor

This is a default destructor for mbfl_convert_filter structs. The thing is: there
isn't really anything that needs to be done to those structs before freeing them.
The default destructor just zeroed out some fields, but there's no reason why
we should actually do that.

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Remove redundant includes from mbstring (and make sure correct config.h is used)

Very interesting... it turns out that when Valgrind support was enabled,
`#include "config.h"` from withi

Remove redundant includes from mbstring (and make sure correct config.h is used)

Very interesting... it turns out that when Valgrind support was enabled,
`#include "config.h"` from within mbstring was actually including the file "config.h"
from Valgrind, and not the one from mbstring!!

This is because -I/usr/include/valgrind was added to the compiler invocation _before_
-Iext/mbstring/libmbfl.

Make sure we actually include the file which was intended.

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Fix #68690: Hypothetical off-by-one condition

We fix this, even though `filter->cache == jisx0213_u2_tbl_len` can
never be true here.

Fix [-Wmissing-field-initializers] compiler warning in mbstring

Add missing NULL pointer for mbfl_convert_vtbl struct.

Don't short-circuit MBFL_OUTPUTFILTER_ILLEGAL_MODE_NONE

Make sure we always go through mbfl_filt_conv_illegal_output(), so
that the number of illegal characters gets counted.

Remove unused function prototype

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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