Under terms of MDEV 27490 we'll add support for non-BMP identifiers
and upgrade casefolding information to Unicode version 14.0.0.
In Unicode-14.0.0 conversion to lower and upper cases can increase octet length
of the string, so conversion won't be possible in-place any more.
This patch removes virtual functions performing in-place casefolding:
- my_charset_handler_st::casedn_str()
- my_charset_handler_st::caseup_str()
and fixes the code to use the non-inplace functions instead:
- my_charset_handler_st::casedn()
- my_charset_handler_st::caseup()
- Moving get_canonical_filename() from a public function to a method in handler.
- Adding a helper method is_canonical_filename() to handler.
- Adding helper methods left(), substr(), starts_with() to Lex_cstring.
- Adding helper methods is_sane(), buffer_overlaps(),
max_data_size() to CharBuffer.
- Adding append_casedn() to CharBuffer. It implements the main functionality
that replaces the being removed my_casedn_str() call.
- Adding a class Table_path_buffer,
a descendant of CharBuffer with size FN_REFLEN.
- Changing get_canonical_filename() to get a pointer to Table_path_buffer
instead just a pointer to char.
- Changing the data type of the "path" parameter and the return type of
get_canonical_filename() from char* to Lex_cstring.
Replacing my_casedn_str() called on local char[] buffer variables
to CharBuffer::copy_casedn() calls.
This is a sub-task for MDEV-31531 Remove my_casedn_str()
Details:
- Adding a helper template class IdentBuffer (a CharBuffer descendant),
which assumes utf8 data. Like CharBuffer, it's initialized to an empty
string in the constructor, but can be populated with lower-cased data
later.
- Adding a helper template class IdentBufferCasedn, which initializes
to lower case right in the constructor.
- Removing char[] buffers, replacing them to IdentBuffer and IdentBufferCasedn.
- Changing the data type of "db" and "table" parameters from
"const char*" to LEX_CSTRING in the following functions:
find_field_in_table_ref()
insert_fields()
set_thd_db()
mysql_grant()
to reuse IdentBuffer easeir.
- Adding a class Lex_ident_fs, to store identifiers for on-disk
database objects, such as databases, tables, triggers.
- Moving the validation code from check_db_name()
to non-modifying methods in Lex_ident_fs:
Lex_ident_fs::check_body()
Lex_ident_fs::check_db_name()
Adding a new method Lex_ident_fs::check_db_name_with_error(),
which performs validation and raises an error on validation failure.
Unlike the old function check_db_name(), the new class Lex_ident_fs
does not lower-case the identifier during the validation.
Lower-casing must be done before calling Lex_ident_fs validation methods.
- Adding a low level helper template class CharBuffer which can:
* store exact or lower-cased strings with a short fixed maximum length
* return the value as a LEX_CSTRING efficiently
- Adding a helper template class DBNameBuffer (deriving from CharBuffer), to
allocate optionally lower-cased database identifiers on stack when relevant.
Useful for temporary values which don't need to be allocated on MEM_ROOT.
- Using DBNameBuffer in mysql_change_db()
- Using DBNameBuffer in show_create_db()
