Import SQLite 3.7.6.3.

third_party/sqlite/src/ext/icu/README.txt

 
 This directory contains source code for the SQLite "ICU" extension, an
 integration of the "International Components for Unicode" library with
 SQLite. Documentation follows.
 
     1. Features
     
         1.1  SQL Scalars upper() and lower()
         1.2  Unicode Aware LIKE Operator
         1.3  ICU Collation Sequences
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     pragma. If this pragma is used before the ICU extension is loaded,
     then the pragma has no effect. If the pragma is used after the ICU
     extension is loaded, then SQLite ignores the ICU implementation and
     always uses the built-in LIKE operator.
 
     The ICU extension LIKE operator is always case insensitive.
 
   3.2 The SQLITE_MAX_LIKE_PATTERN_LENGTH Macro
 
     Passing very long patterns to the built-in SQLite LIKE operator can
-    cause a stack overflow. To curb this problem, SQLite defines the
+    cause excessive CPU usage. To curb this problem, SQLite defines the
     SQLITE_MAX_LIKE_PATTERN_LENGTH macro as the maximum length of a
     pattern in bytes (irrespective of encoding). The default value is
     defined in internal header file "limits.h".
     
     The ICU extension LIKE implementation suffers from the same 
     problem and uses the same solution. However, since the ICU extension
     code does not include the SQLite file "limits.h", modifying
     the default value therein does not affect the ICU extension.
     The default value of SQLITE_MAX_LIKE_PATTERN_LENGTH used by
     the ICU extension LIKE operator is 50000, defined in source 
     file "icu.c".
 
   3.3 Collation Sequence Security Issue
 
     Internally, SQLite assumes that indices stored in database files
     are sorted according to the collation sequence indicated by the
     SQL schema. Changing the definition of a collation sequence after
     an index has been built is therefore equivalent to database
     corruption. The SQLite library is not very well tested under
     these conditions, and may contain potential buffer overruns
     or other programming errors that could be exploited by a malicious
     programmer.
 
     If the ICU extension is used in an environment where potentially
     malicious users may execute arbitrary SQL (i.e. gears), they
     should be prevented from invoking the icu_load_collation() function,
     possibly using the authorisation callback.
-