UCS-2 aligning 0xAA -> 0x00AA

3 files changed, 49 insertions, 2 deletions

diff --git a/sql/item.h b/sql/item.h
index 5def1e2b710..e6ed8109534 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -477,7 +477,7 @@ public:
   	      CHARSET_INFO *cs, Derivation dv= DERIVATION_COERCIBLE)
   {
     collation.set(cs, dv);
-    str_value.set(str,length,cs);
+    str_value.set_or_copy_aligned(str,length,cs);
     /*
       We have to have a different max_length than 'length' here to
       ensure that we get the right length if we do use the item
@@ -493,7 +493,7 @@ public:
 	      CHARSET_INFO *cs, Derivation dv= DERIVATION_COERCIBLE)
   {
     collation.set(cs, dv);
-    str_value.set(str,length,cs);
+    str_value.set_or_copy_aligned(str,length,cs);
     max_length= str_value.numchars()*cs->mbmaxlen;
     set_name(name_par,0,cs);
     decimals=NOT_FIXED_DEC;
diff --git a/sql/sql_string.cc b/sql/sql_string.cc
index 89f48607969..9534c5605fe 100644
--- a/sql/sql_string.cc
+++ b/sql/sql_string.cc
@@ -228,6 +228,52 @@ bool String::copy(const char *str,uint32 arg_length, CHARSET_INFO *cs)
   return FALSE;
 }
 
+/*
+** For real multi-byte, ascii incompatible charactser sets,
+** like UCS-2, add leading zeros if we have an incomplete character.
+** Thus, 
+**   SELECT _ucs2 0xAA 
+** will automatically be converted into
+**   SELECT _ucs2 0x00AA
+*/
+
+bool String::set_or_copy_aligned(const char *str,uint32 arg_length,
+				 CHARSET_INFO *cs)
+{
+  /* How many bytes are in incomplete character */
+  uint32 offs= (arg_length % cs->mbminlen); 
+
+  if (!offs) /* All characters are complete, just copy */
+  {
+    set(str, arg_length, cs);
+    return FALSE;
+  }
+  
+  offs= cs->mbmaxlen - offs; /* How many zeros we should prepend */
+  uint32 aligned_length= arg_length + offs;
+  if (alloc(aligned_length))
+    return TRUE;
+  
+  /*
+    Probably this condition is not really necessary
+    because if aligned_length is 0 then offs is 0 too
+    and we'll return after calling set().
+  */
+  if ((str_length= aligned_length))
+  {
+    /*
+      Note, this is only safe for little-endian UCS-2.
+      If we add big-endian UCS-2 sometimes, this code
+      will be more complicated. But it's OK for now.
+    */
+    bzero((char*)Ptr, offs);
+    memcpy(Ptr + offs, str, arg_length);
+  }
+  Ptr[aligned_length]=0;
+  str_charset=cs;
+  return FALSE;
+}
+
 	/* Copy with charset convertion */
 
 bool String::copy(const char *str, uint32 arg_length,
diff --git a/sql/sql_string.h b/sql/sql_string.h
index 325611737ca..8817aa8eab8 100644
--- a/sql/sql_string.h
+++ b/sql/sql_string.h
@@ -183,6 +183,7 @@ public:
   bool copy();					// Alloc string if not alloced
   bool copy(const String &s);			// Allocate new string
   bool copy(const char *s,uint32 arg_length, CHARSET_INFO *cs);	// Allocate new string
+  bool set_or_copy_aligned(const char *s, uint32 arg_length, CHARSET_INFO *cs);
   bool copy(const char*s,uint32 arg_length, CHARSET_INFO *csfrom,
 	    CHARSET_INFO *csto);
   bool append(const String &s);