In 6fc8d014df, pakutoma added specialized validity checking functions
for some legacy text encodings like ISO-2022-JP and UTF-7. These
check functions perform a more strict validity check than the encoding
conversion functions for the same text encodings. For example, the
check function for ISO-2022-JP verifies that the string ends in the
correct state required by the specification for ISO-2022-JP.
These check functions are already being used to make detection of text
encoding more accurate when 'strict' detection mode is enabled.
However, since the default is 'non-strict' detection (a bad API design
but we're stuck with it now), most users will not benefit from
pakutoma's work. I was previously reluctant to enable this new logic
for non-strict detection mode. My intention was to reduce the scope of
behavior changes, since almost *any* behavior change may affect *some*
user in a way we don't expect.
However, we definitely have users whose (production) code was broken
by the changes I made in 28b346bc06, and enabling pakutoma's check
functions for non-strict detection mode would un-break it. (See
GH-10192 as an example.) The added checks do also make sense.
In non-strict detection mode, we will not immediately reject candidate
encodings whose validity check function returns false; but they will
be much less likely to be selected. However, failure of the validity
check function is weighted less heavily than an encoding error detected
by the encoding conversion function.
The documentation for mb_detect_encoding says that this function
"Detects the most likely character encoding for string `string` from an
ordered list of candidates".
Prior to 28b346bc06, mb_detect_encoding did not really attempt to
determine the "most likely" text encoding for the input string. It
would just return the first candidate encoding for which the string was
valid. In 28b346bc06, I amended this function so that it uses heuristics
to try to guess which candidate encoding is "most likely".
However, the caller did not have any way to indicate which candidate
text encoding(s) they consider to be more likely, in case the
heuristics applied are inconclusive. In the language of Bayesian
probability, there was no way for the caller to indicate their 'prior'
assignment of probabilities.
Further, the documentation for mb_detect_encoding also says that the
second parameter `encodings` is "a list of character encodings to try,
in order". The documentation clearly implies that the order of
the `encodings` argument should be significant.
Therefore, amend mb_detect_encoding so that while it still uses
heuristics to guess the most likely text encoding for the input string,
it favors those which are earlier in the list of candidate encodings.
One complication is that many callers of mb_detect_encoding use it
in this way:
mb_detect_encoding($string, mb_list_encodings());
In a majority of cases, this is bad code; mb_detect_encoding will both
be much slower and the results will be less reliable than if a smaller
list of candidates is used. However, since such code already exists and
people are using it in production, we should not unnecessarily break it.
The order of candidate encodings obviously does not express any prior
belief of which candidates are more likely in this case, and treating
it as if it did will degrade the accuracy of the result.
Since mb_list_encodings now returns a single, immutable array on each
call, we can avoid that problem by turning off the new behavior when
we receive the array of encodings returned by mb_list_encodings.
This implementation means that if the user does this:
$a = mb_list_encodings();
mb_detect_encoding($string, $a);
...then the order of candidate encodings will not be considered.
However, if the user explicitly initializes their own array of all
supported legacy text encodings, then the order *will* be considered.
The other functions which also follow this new behavior are:
• mb_convert_variables
• mb_convert_encoding (when multiple candidate input encodings are
listed)
Other places where "detection" (or really "guessing") of text encoding
may be performed include:
• mb_send_mail
• Zend engine, when determining the encoding of a PHP script
• mbstring processing of HTTP request contents, when http_input INI
parameter is set to a list
In these cases, the new logic based on order of candidate encodings
is *not* enabled. It *might* be logical to consider the order of
candidate encodings in some or all of these cases, but I'm not sure if
that is true, so it seems wiser to avoid more behavior changes than is
necessary. Further, ever since the new encoding detection heuristics
were implemented in 28b346bc06, we have not received any complaints of
user code being broken in these areas. So I am reluctant to "fix what
isn't broken".
Well, some might say that applying the new detection heuristics
to mb_send_mail, etc. in 28b346bc06 was "fixing what wasn't broken",
but (cough cough) I don't have any comment on that...
This will allow us to easily check in other mbstring functions if the
list of all supported encodings, returned by mb_list_encodings, is
passed in as input to another function.
Co-authored-by: Ilija Tovilo <ilija.tovilo@me.com>
We're setting the encoding from PHP_FUNCTION(mb_strpos), but mbfl_strpos would
discard it, setting it to mbfl_encoding_pass, making zend_memnrstr fail due to a
null-pointer exception.
Fixes GH-11217
Closes GH-11220
Compiling in release mode with UBSAN gives me the following compiler warning:
```
In function ‘mb_wchar_to_sjismac’:
mbfilter_sjis.c:1419:89: warning: ‘i’ may be used uninitialized [-Wmaybe-uninitialized]
1419 | buf->state = (i << 24) | (index << 16) | (w & 0xFFFF);
| ^~
mbfilter_sjis.c:1398:42: note: ‘i’ was declared here
1398 | for (int i = 0; i < code_tbl_m_len; i++) {
| ^
```
Since the if condition will always be taken after the goto, we can get
rid of the warning by moving the label inside the if.
Signed-off-by: Alex Dowad <alexinbeijing@gmail.com>
For mb_parse_str, when mbstring.http_input (INI parameter) is a list of
multiple possible text encodings (which is not the case by default),
this new implementation is about 25% faster.
When mbstring.http_input is a single value, then nothing is changed.
(No automatic encoding detection is done in that case.)
The documentation for mb_strcut states:
mb_strcut(
string $string,
int $start,
?int $length = null,
?string $encoding = null
): string
mb_strcut() extracts a substring from a string similarly to mb_substr(),
but operates on bytes instead of characters. If the cut position happens
to be between two bytes of a multi-byte character, the cut is performed
starting from the first byte of that character.
My understanding of the $length parameter for mb_strcut is that it
specified the range of bytes to extract from $string, and that all
characters encoded by those bytes should be included in the returned
string, even if that means the returned string would be longer than
$length bytes. This can happen either if 1) there is more than one way
to encode the same character in $encoding, and one way requires more
bytes than the other, or 2) $encoding uses escape sequences.
However, discussion with users of mb_strcut indicates that many of them
interpret $length as the maximum length of the *returned* string.
This is also the historical behavior of the function.
Hence, there is no need to modify the behavior of mb_strcut and then
remove XFAIL from these test cases afterwards. We can keep the current
behavior.
This (rare) situation was already handled correctly for the 1st and 2nd
of every 3 codepoints in a Base64-encoded section of a UTF-7 string.
However, it was not handled correctly if it happened on the 3rd,
6th, 9th, etc. codepoint of such a Base64-encoded section.
In 6fc8d014df, pakutoma added some additional validation logic to
mb_detect_encoding. Since the implementation of mb_detect_encoding
has changed significantly between PHP 8.2 and 8.3, when merging this
change down from PHP-8.2 into master, I had to port his code over to
the new implementation in master.
However, I did this in a wrong way. In merge commit 0779950768,
the ported code modifies a function argument (to mb_guess_encoding)
which is marked 'const'. In the Windows CI job, MS VC++ rightly
flags this as a compile error.
Adjust the code to accomplish the same thing, but without destructively
modifying 'const' arguments.
When I built and tested 0779950768 locally, the build was successful
and all tests passed. However, in CI, some CI jobs are failing due to
compile errors. Fix those.
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 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.
Thanks to Ilija Tovilo for noticing and reporting this problem. Thanks
also to Michael Voříšek for finding the StackOverflow post which
explained the reason for the failure.
* PHP-8.2:
Propagate error checks for mbfl_filt_conv_illegal_output()
Use CK() macro to check the output function in mbfilter_unicode2sjis_emoji_sb()
Make error checks on encoding methods for docomo, kddi, sb consistent
* PHP-8.1:
Propagate error checks for mbfl_filt_conv_illegal_output()
Use CK() macro to check the output function in mbfilter_unicode2sjis_emoji_sb()
Make error checks on encoding methods for docomo, kddi, sb consistent
Some places use an if check, which implicitly checks for a non-zero
value, and some places use > 0. The > 0 is the correct one because at
least some of those functions already use the CK() macro to return -1 on
error. Because -1 != 0 this is wrongly interpreted as a success instead
of a failure.
Multiple tests had to be changed to escape the arguments in shell
commands. Some tests are skipped because they behave differently with
spaces in the path versus without. One notable example of this is the
hashbang test which does not work because spaces in hashbangs paths are
not supported in Linux.
Co-authored-by: Michael Voříšek <mvorisek@mvorisek.cz>
The new implementation is 2.5x-3x faster.
If an invalid charset name was used, the old implementation would get
'stuck' trying to parse the charset name and would not interpret any
other MIME encoded words up to the end of the input string. The new
implementation fixes this bug.
If an (invalid) encoded word ends abruptly and a new (valid) encoded
word starts, the old implementation would not decode the valid encoded
word. The new implementation also fixes this.
Otherwise, the behavior of the new implementation has been designed to
closely match that of the old implementation.
In ed0c0df351, Niels Dossche fixed a bug in mbstring whereby
mb_convert_encoding could dereference a NULL pointer and crash if
it was called on an array, with multiple candidate encodings, and at
least one of the strings inside the array was invalid in all the
candidate encodings.
He kindly included a test case, but after being merged into master,
the test case was not actually testing what it was intended to test.
That is now fixed.
Fixes GH-10627
The php_mb_convert_encoding() function can return NULL on error, but
this case was not handled, which led to a NULL pointer dereference and
hence a crash.
Closes GH-10628
Signed-off-by: George Peter Banyard <girgias@php.net>
Commit 8bbd0952e5 added a check rejecting empty strings; in the
merge commiot 379d9a1cfc however it was changed to a NULL check,
one that did not make sense because ZSTR_VAL() is guaranteed to never
be NULL; the length check was accidently removed by that merge commit.
This bug was found by GCC's -Waddress warning:
ext/mbstring/mbstring.c:748:27: warning: the comparison will always evaluate as ‘true’ for the address of ‘val’ will never be NULL [-Waddress]
748 | if (!new_value || !ZSTR_VAL(new_value)) {
| ^
Closes GH-10532
Signed-off-by: George Peter Banyard <girgias@php.net>
As with other SIMD-accelerated functions in php-src, the new UTF-16
encoding and decoding routines can be compiled either with AVX2
acceleration "always on", "always off", or else with runtime detection
of AVX2 support.
With the new UTF-16 decoder/encoder, conversion of extremely short
strings (as in several bytes) has the same performance as before,
and conversion of medium-length (~100 character) strings is about 65%
faster, but conversion of long (~10,000 character) strings is around
6 times faster.
Many other mbstring functions will also be faster now when handling
UTF-16; for example, mb_strlen is almost 3 times faster on medium
strings, and almost 9 times faster on long strings. (Why does mb_strlen
benefit more from AVX2 acceleration than mb_convert_encoding? It's
because mb_strlen only needs to decode, but not re-encode, the input
string, and the UTF-16 decoder benefits much more from SIMD
acceleration than the UTF-16 encoder.)
In a GitHub thread, Michael Voříšek and Kamil Tekiela mentioned that
the PCRE2 function `pcre_match` can be used to validate UTF-8, and that
historically it was more efficient than mbstring's `mb_check_encoding`.
`mb_check_encoding` is now much faster on hosts with SSE2, and much
faster again on hosts with AVX2. However, while all x86-64 CPUs support
at least SSE2, not all PHP users run their code on x86-64 hardware.
For example, some use recent Macs with ARM CPUs.
Therefore, borrow PCRE2's UTF-8 validation function as a fallback for
hosts with no SSE2/AVX2 support. On long UTF-8 strings, this code is
50% faster than mbstring's existing fallback code.
From some local benchmarks which I ran, the AVX2-based version is about
2.8x faster than the SSE2-based version on long (~10,000 byte) strings,
1.6x faster on medium (~100 byte) strings, and just about the same
on very short strings.
I followed the example of the code in the 'standard' module, using
preprocessor directives so that the code can be compiled in any of
4 ways:
1) With no AVX2 support at all (for example, when PHP is compiled for
CPU architectures other than AMD64)
2) For CPUs with AVX2 only (for example, when PHP is built with
CCFLAGS='-march=native' on a host which implements AVX2)
3) With runtime detection of AVX2 performed by the dynamic linker;
this requires a dynamic linker which supports the STT_GNU_IFUNC
symbol type extension to the ELF binary standard. This is true of
glibc's dynamic linker, as of late 2009.
4) With runtime detection of AVX2 performed by the module init function.
The detection is done by checking the output of CPUID and then a
function pointer is set accordingly. In this case, all calls to the
UTF-8 validation routine are indirect calls through that
function pointer.
This code is a few percent faster for short UTF-8 strings. For long
(~10,000 byte) strings, it is also consistently faster on my local
microbenchmarks, but by less than 1%.
This moves them from ``.data`` to ``.rodata`` and allows more compiler optimizations.
* ext/opcache/zend_accelerator_hash: make prime_numbers const
* Zend/zend_signal: make zend_sigs const
* ext/dba: make dba_handler pointers const
* ext/exif: make php_tiff_bytes_per_format and other globals const
* ext/intl/grapheme: make grapheme_extract_iters const
* ext/mstring: make rare_codepoint_bitvec const
* ext/snmp: make objid_mib const
* ext/opcache: make all zend_shared_memory_handlers const
When this INI option is enabled, it reverts the line separator for
headers and message to LF which was a non conformant behavior in PHP 7.
It is done because some non conformant MTAs fail to parse CRLF line
separator for headers and body.
This is used for mail and mb_send_mail functions.
