bk commit into 5.1 tree (mats:1.2478) BUG#26969

[Mats Kindahl]

Below is the list of changes that have just been committed into a local
5.1 repository of mats. When mats does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html

ChangeSet@stripped, 2007-03-20 14:13:07+01:00, mats@romeo.(none) +2 -0
  BUG#26969:
    Field_bit::pack() and Field_bit::unpack() does not work correctly
  
  Fixing code for Field_bit packing and unpacking to work with arbitrary
  pointers instead of requiring Field::ptr

  sql/field.cc@stripped, 2007-03-20 14:13:02+01:00, mats@romeo.(none) +30 -4
    Fixing Field_bit::pack() and Field_bit::unpack() so that they accept
    an arbitrary pointer to pack/unpack to/from.

  sql/sql_class.cc@stripped, 2007-03-20 14:13:02+01:00, mats@romeo.(none) +1 -3
    Removing unneeded move_field_offset() nefore packing field.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	mats
# Host:	romeo.(none)
# Root:	/home/bk/b22583-mysql-5.1-new-rpl

--- 1.378/sql/field.cc	2007-03-20 14:13:18 +01:00
+++ 1.379/sql/field.cc	2007-03-20 14:13:18 +01:00
@@ -8505,9 +8505,28 @@
 {
   DBUG_ASSERT(max_length);
   uint length;
-  if (bit_len)
+  if (bit_len > 0)
   {
-    uchar bits= get_rec_bits(bit_ptr, bit_ofs, bit_len);
+    /*
+      We have the following:
+
+      ptr        Points into a field in record R1
+      from       Points to a field in a record R2
+      bit_ptr    Points to the byte (in the null bytes) that holds the
+                 odd bits of R1
+      from_bitp  Points to the byte that holds the odd bits of R2
+
+      We have the following:
+
+          ptr - bit_ptr = from - from_bitp
+
+      We want to isolate 'from_bitp', so this gives:
+
+          ptr - bit_ptr - from = - from_bitp
+          - ptr + bit_ptr + from = from_bitp
+          bit_ptr + from - ptr = from_bitp
+     */
+    uchar bits= get_rec_bits(bit_ptr + (from - ptr), bit_ofs, bit_len);
     *to++= bits;
   }
   length= min(bytes_in_rec, max_length - (bit_len > 0));
@@ -8518,9 +8537,16 @@
 
 const char *Field_bit::unpack(char *to, const char *from)
 {
-  if (bit_len)
+  if (bit_len > 0)
   {
-    set_rec_bits(*from, bit_ptr, bit_ofs, bit_len);
+    /*
+      set_rec_bits is a macro, don't put the post-increment in the
+      argument since that might cause strange side-effects.
+
+      For the choice of the second argument, see the explanation for
+      Field_bit::pack().
+    */
+    set_rec_bits(*from, bit_ptr + (to - ptr), bit_ofs, bit_len);
     from++;
   }
   memcpy(to, from, bytes_in_rec);

--- 1.320/sql/sql_class.cc	2007-03-20 14:13:18 +01:00
+++ 1.321/sql/sql_class.cc	2007-03-20 14:13:18 +01:00
@@ -2619,9 +2619,7 @@
         /*
           We only store the data of the field if it is non-null
          */
-        field->move_field_offset(offset);
-        pack_ptr= (byte*)field->pack((char *) pack_ptr, field->ptr);
-        field->move_field_offset(-offset);
+        pack_ptr= (byte*)field->pack((char *) pack_ptr, field->ptr + offset);
       }
 
       null_mask <<= 1;