mbstring has a bad habit of passing invalid characters through silently
when converting to the same (or a "compatible") encoding.
For example, if you give it an invalid JIS X 0208 kuten code encoded with SJIS,
and try to convert that to EUC-JP, mbstring will just quietly re-encode the
invalid code in the EUC-JP representation.
At the same, some parts of the code (like `mb_check_encoding`) assume that
invalid characters will be treated as... well, invalid. Let's unbreak things
by actually catching errors and reporting them, instead of swallowing them.
Note that some text encoding conversion libraries, such as Solaris iconv
and FreeBSD iconv, map 0x30-0x39 to the Arabic script numerals rather than
the 'regular' Roman numerals. (That is, to Unicode codepoints 0x660-0x669.)
Further, Windows CP28596 adds more mappings to use the unused bytes in
ISO-8859-6.
There are some bytes in this encoding which are not mapped to any character.
Notably, MicroSoft added their own mappings for these 'unused' bits in their
version of Latin-3, called CP28593.
Interestingly, it looks like the original author intended to add an identify filter
for this encoding, but never did so. The needed struct is there, but was never added
to the list of identify filters in mbfl_ident.c.
There was one faulty test in the suite which only passed before because UTF-16 had no
identify filter. After this was fixed, it exposed the problem with the test.
- 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.
The check ensures that the decoded codepoint is between 0x10000-0x10FFFF,
which is the valid range which can be encoded in a UTF-16 surrogate pair.
However, just looking at the code, it's obvious that this will be true.
First of all, 0x10000 is added to the decoded codepoint on the previous
line, so how could it be less than 0x10000?
Further, even if the 20 data bits already decoded were 0xFFFFF (all ones),
when you add 0x10000, it comes to 0x10FFFF, which is the very top of the
valid range. So how could the decoded codepoint be more than 0x10FFFF?
It can't.
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.
These were unused, and almost certainly will never be used:
- MBFL_ENCTYPE_MWC4BE
- MBFL_ENCTYPE_MWC4LE
- MBFL_ENCTYPE_SHFTCODE
- MBFL_ENCTYPE_ENC_STRM
For the latter two, there were some encodings which were marked with these flags;
but nothing ever _checked_ these particular flags.
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.
All memory allocation and deallocation for mbstring bounces through a table of
function pointers before going to emalloc/efree/etc. But this is unnecessary.
The allocators are never swapped out. Better to just call them directly.
"pass" is not a real encoding, it just means "don't perform any
conversion". Using it as an internal encoding or passing it to
any of the mbstring() function will not work (and on master commonly
assert).
I replaced it with a multiplication overflow check in
18599f9c52. However, we need both,
because the code for restoring the number can't handle numbers
with many leading zeros right now and I don't feel like teaching it.
Alex Dowad