Bug#8321 - myisampack bug in compression algorithm

Added 64-bit extensions, comments, extended statistics 
and trace prints.

include/my_base.h

@@ -367,6 +367,7 @@ enum ha_base_keytype {
 #define HA_STATE_EXTEND_BLOCK	2048
 #define HA_STATE_RNEXT_SAME	4096	/* rnext_same was called */
 
+/* myisampack expects no more than 32 field types. */
 enum en_fieldtype {
   FIELD_LAST=-1,FIELD_NORMAL,FIELD_SKIP_ENDSPACE,FIELD_SKIP_PRESPACE,
   FIELD_SKIP_ZERO,FIELD_BLOB,FIELD_CONSTANT,FIELD_INTERVALL,FIELD_ZERO,

myisam/mi_packrec.c

@@ -416,8 +416,19 @@ static uint find_longest_bitstream(uint16 *table, uint16 *end)
 }
 
 
-	/* Read record from datafile */
-	/* Returns length of packed record, -1 if error */
+/*
+  Read record from datafile.
+
+  SYNOPSIS
+    _mi_read_pack_record()
+    info                        A pointer to MI_INFO.
+    filepos                     File offset of the record.
+    buf                 RETURN  The buffer to receive the record.
+
+  RETURN
+    0                                   on success
+    HA_ERR_WRONG_IN_RECORD or -1        on error
+*/
 
 int _mi_read_pack_record(MI_INFO *info, my_off_t filepos, byte *buf)
 {

mysys/tree.c

@@ -263,6 +263,9 @@ TREE_ELEMENT *tree_insert(TREE *tree, void *key, uint key_size,
     if (tree->flag & TREE_NO_DUPS)
       return(NULL);
     element->count++;
+    /* Avoid a wrap over of the count. */
+    if (! element->count)
+      element->count--;
   }
   DBUG_EXECUTE("check_tree", test_rb_tree(tree->root););
   return element;