BUG#29549 (Endians: test failures on Solaris):

Refactoring code to add parameter to pack() and unpack() functions with
purpose of indicating if data should be packed in little-endian or
native order. Using new functions to always pack data for binary log
in little-endian order. The purpose of this refactoring is to allow
proper implementation of endian-agnostic pack() and unpack() functions.

Eliminating several versions of virtual pack() and unpack() functions
in favor for one single virtual function which is overridden in
subclasses.

Implementing pack() and unpack() functions for some field types that
packed data in native format regardless of the value of the
st_table_share::db_low_byte_first flag.

The field types that were packed in native format regardless are:
Field_real, Field_decimal, Field_tiny, Field_short, Field_medium,
Field_long, Field_longlong, and Field_blob.

Before the patch, row-based logging wrote the rows incorrectly on
big-endian machines where the storage engine defined its own
low_byte_first() to be FALSE on big-endian machines (the default
is TRUE), while little-endian machines wrote the fields in correct
order. The only known storage engine that does this is NDB. In effect,
this means that row-based replication from or to a big-endian
machine where the table was using NDB as storage engine failed if the
other engine was either non-NDB or on a little-endian machine.

With this patch, row-based logging is now always done in little-endian
order, while ORDER BY uses the native order if the storage engine
defines low_byte_first() to return FALSE for big-endian machines.

In addition, the max_data_length() function available in Field_blob
was generalized to the entire Field hierarchy to give the maximum
number of bytes that Field::pack() will write.


mysql-test/extra/rpl_tests/rpl_extraMaster_Col.test:
  Sorting by columns that produces deterministic order.
mysql-test/suite/rpl/r/rpl_extraColmaster_innodb.result:
  Result change.
mysql-test/suite/rpl/r/rpl_extraColmaster_myisam.result:
  Result change.
mysql-test/suite/rpl/r/rpl_row_extraColmaster_ndb.result:
  Result change.
mysql-test/suite/rpl/t/disabled.def:
  Enabling tests.
mysql-test/suite/rpl/t/rpl_row_mysqlbinlog.test:
  Adding missing sync_slave_with_master causing slave to keep tables
  after shutdown.
mysql-test/suite/rpl_ndb/t/disabled.def:
  Enabling tests.
mysql-test/suite/rpl_ndb/t/rpl_ndb_innodb2ndb-slave.opt:
  Adding --new option
mysql-test/suite/rpl_ndb/t/rpl_ndb_innodb2ndb.test:
  Adding have_log_bin.
mysql-test/suite/rpl_ndb/t/rpl_ndb_myisam2ndb-slave.opt:
  Adding --new option
mysql-test/suite/rpl_ndb/t/rpl_ndb_myisam2ndb.test:
  Adding have_log_bin
mysql-test/t/partition.test:
  Adding have_archive, since that is used in the test.
sql/field.cc:
  Eliminating all two-argument pack() and unpack() functions and moving
  functionality into the four-argument version. The four argument version
  is introduced so that it is possible to avoid using the storage engine
  default when writing and reading the packed format (the unpacked format
  still uses the storage engine's default). This is used by row-based
  replication to write the fields in a storage engine- and endian-agnostic
  format.
  
  Packing integral and floating-point numbers in little-endian format
  (if requested).
  
  Using pad_char for the field instead of spaces (0x20) when unpacking.
  
  Adding some Doxygen documentation.
  ---
  Adding max_data_length() to denote the maximum number of bytes that
  pack() will write.
  
  Adding casts to remove warnings for debug printouts.
sql/field.h:
  Eliminating all virtual pack() and unpack() functions except the four-
  argument version, which now is the function that shall be overridden.
  The two-argument versions are convenience functions, to prevent changes
  to code that uses these.
  
  Adding code to pack integer numbers and floating-point numbers in
  little-endian format, if requested.
  ---
  Adding max_data_length() to denote the maximum number of bytes that
  pack() will write.
sql/log.cc:
  Removing debug printout causing crash when starting NDB on Solaris.
sql/log_event.cc:
  Adding missing #ifndef causing compile failure. Adding debug printouts.
sql/rpl_record.cc:
  Debriding code. Using new pack() and unpack() functions to always pack
  fields little-endian. Adding debug printouts.
  ---
  Using max_data_length() when packing field into row.
  
  Adding casts to debug printouts.
sql/sql_show.cc:
  Adding code that causes crash on Solaris machines since printf() cannot
  handle NULL values for strings properly.
mysql-test/suite/rpl_ndb/r/rpl_ndb_innodb2ndb.result:
  New BitKeeper file ``mysql-test/suite/rpl_ndb/r/rpl_ndb_innodb2ndb.result''
mysql-test/suite/rpl_ndb/r/rpl_ndb_myisam2ndb.result:
  New BitKeeper file ``mysql-test/suite/rpl_ndb/r/rpl_ndb_myisam2ndb.result''

1 files changed, 265 insertions, 146 deletions

diff --git a/sql/field.cc b/sql/field.cc
index 49ffc6a252e..4a428eea6b4 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -1373,20 +1373,85 @@ int Field::store(const char *to, uint length, CHARSET_INFO *cs,
 
 
 /**
+   Pack the field into a format suitable for storage and transfer.
+
+   To implement packing functionality, only the virtual function
+   should be overridden. The other functions are just convenience
+   functions and hence should not be overridden.
+
+   The value of <code>low_byte_first</code> is dependent on how the
+   packed data is going to be used: for local use, e.g., temporary
+   store on disk or in memory, use the native format since that is
+   faster. For data that is going to be transfered to other machines
+   (e.g., when writing data to the binary log), data should always be
+   stored in little-endian format.
+
+   @note The default method for packing fields just copy the raw bytes
+   of the record into the destination, but never more than
+   <code>max_length</code> characters.
+
+   @param to
+   Pointer to memory area where representation of field should be put.
+
+   @param from
+   Pointer to memory area where record representation of field is
+   stored.
+
+   @param max_length
+   Maximum length of the field, as given in the column definition. For
+   example, for <code>CHAR(1000)</code>, the <code>max_length</code>
+   is 1000. This information is sometimes needed to decide how to pack
+   the data.
+
+   @param low_byte_first
+   @c TRUE if integers should be stored little-endian, @c FALSE if
+   native format should be used. Note that for little-endian machines,
+   the value of this flag is a moot point since the native format is
+   little-endian.
+*/
+uchar *
+Field::pack(uchar *to, const uchar *from, uint max_length,
+            bool low_byte_first __attribute__((unused)))
+{
+  uint32 length= pack_length();
+  set_if_smaller(length, max_length);
+  memcpy(to, from, length);
+  return to+length;
+}
+
+/**
    Unpack a field from row data.
 
-   This method is used to unpack a field from a master whose size 
-   of the field is less than that of the slave.
-  
+   This method is used to unpack a field from a master whose size of
+   the field is less than that of the slave.
+
+   The <code>param_data</code> parameter is a two-byte integer (stored
+   in the least significant 16 bits of the unsigned integer) usually
+   consisting of two parts: the real type in the most significant byte
+   and a original pack length in the least significant byte.
+
+   The exact layout of the <code>param_data</code> field is given by
+   the <code>Table_map_log_event::save_field_metadata()</code>.
+
+   This is the default method for unpacking a field. It just copies
+   the memory block in byte order (of original pack length bytes or
+   length of field, whichever is smaller).
+
    @param   to         Destination of the data
    @param   from       Source of the data
-   @param   param_data Pack length of the field data
+   @param   param_data Real type and original pack length of the field
+                       data
+
+   @param low_byte_first
+   If this flag is @c true, all composite entities (e.g., lengths)
+   should be unpacked in little-endian format; otherwise, the entities
+   are unpacked in native order.
 
    @return  New pointer into memory based on from + length of the data
 */
-const uchar *Field::unpack(uchar* to,
-                           const uchar *from, 
-                           uint param_data)
+const uchar *
+Field::unpack(uchar* to, const uchar *from, uint param_data,
+              bool low_byte_first __attribute__((unused)))
 {
   uint length=pack_length();
   int from_type= 0;
@@ -1399,19 +1464,18 @@ const uchar *Field::unpack(uchar* to,
     from_type= (param_data & 0xff00) >> 8U;  // real_type.
     param_data= param_data & 0x00ff;        // length.
   }
+
+  if ((param_data == 0) ||
+      (length == param_data) ||
+      (from_type != real_type()))
+  {
+    memcpy(to, from, length);
+    return from+length;
+  }
+
   uint len= (param_data && (param_data < length)) ?
             param_data : length;
-  /*
-    If the length is the same, use old unpack method.
-    If the param_data is 0, use the old unpack method.
-      This is possible if the table map was generated from a down-level
-      master or if the data was not available on the master.
-    If the real_types are not the same, use the old unpack method.
-  */
-  if ((length == param_data) ||
-      (param_data == 0) ||
-      (from_type != real_type()))
-    return(unpack(to, from));
+
   memcpy(to, from, param_data > length ? length : len);
   return from+len;
 }
@@ -2714,10 +2778,15 @@ uint Field_new_decimal::is_equal(Create_field *new_field)
 
    @return  New pointer into memory based on from + length of the data
 */
-const uchar *Field_new_decimal::unpack(uchar* to, 
-                                       const uchar *from, 
-                                       uint param_data)
+const uchar *
+Field_new_decimal::unpack(uchar* to,
+                          const uchar *from,
+                          uint param_data,
+                          bool low_byte_first)
 {
+  if (param_data == 0)
+    return Field::unpack(to, from, param_data, low_byte_first);
+
   uint from_precision= (param_data & 0xff00) >> 8U;
   uint from_decimal= param_data & 0x00ff;
   uint length=pack_length();
@@ -3857,6 +3926,49 @@ void Field_longlong::sql_type(String &res) const
 }
 
 
+/*
+  Floating-point numbers
+ */
+
+uchar *
+Field_real::pack(uchar *to, const uchar *from,
+                 uint max_length, bool low_byte_first)
+{
+  DBUG_ENTER("Field_real::pack");
+  DBUG_ASSERT(max_length >= pack_length());
+  DBUG_PRINT("debug", ("pack_length(): %u", pack_length()));
+#ifdef WORDS_BIGENDIAN
+  if (low_byte_first != table->s->db_low_byte_first)
+  {
+    const uchar *dptr= from + pack_length();
+    while (dptr-- > from)
+      *to++ = *dptr;
+    DBUG_RETURN(to);
+  }
+  else
+#endif
+    DBUG_RETURN(Field::pack(to, from, max_length, low_byte_first));
+}
+
+const uchar *
+Field_real::unpack(uchar *to, const uchar *from,
+                   uint param_data, bool low_byte_first)
+{
+  DBUG_ENTER("Field_real::unpack");
+  DBUG_PRINT("debug", ("pack_length(): %u", pack_length()));
+#ifdef WORDS_BIGENDIAN
+  if (low_byte_first != table->s->db_low_byte_first)
+  {
+    const uchar *dptr= from + pack_length();
+    while (dptr-- > from)
+      *to++ = *dptr;
+    DBUG_RETURN(from + pack_length());
+  }
+  else
+#endif
+    DBUG_RETURN(Field::unpack(to, from, param_data, low_byte_first));
+}
+
 /****************************************************************************
   single precision float
 ****************************************************************************/
@@ -6211,6 +6323,11 @@ int Field_longstr::store_decimal(const my_decimal *d)
   return store(str.ptr(), str.length(), str.charset());
 }
 
+uint32 Field_longstr::max_data_length() const
+{
+  return field_length + (field_length > 255 ? 2 : 1);
+}
+
 
 double Field_string::val_real(void)
 {
@@ -6355,7 +6472,9 @@ void Field_string::sql_type(String &res) const
 }
 
 
-uchar *Field_string::pack(uchar *to, const uchar *from, uint max_length)
+uchar *Field_string::pack(uchar *to, const uchar *from,
+                          uint max_length,
+                          bool low_byte_first __attribute__((unused)))
 {
   uint length=      min(field_length,max_length);
   uint local_char_length= max_length/field_charset->mbmaxlen;
@@ -6363,11 +6482,15 @@ uchar *Field_string::pack(uchar *to, const uchar *from, uint max_length)
     local_char_length= my_charpos(field_charset, from, from+length,
                                   local_char_length);
   set_if_smaller(length, local_char_length);
-  while (length && from[length-1] == ' ')
+  while (length && from[length-1] == field_charset->pad_char)
     length--;
+
+  // Length always stored little-endian
   *to++= (uchar) length;
   if (field_length > 255)
     *to++= (uchar) (length >> 8);
+
+  // Store the actual bytes of the string
   memcpy(to, from, length);
   return to+length;
 }
@@ -6389,34 +6512,27 @@ uchar *Field_string::pack(uchar *to, const uchar *from, uint max_length)
 
    @return  New pointer into memory based on from + length of the data
 */
-const uchar *Field_string::unpack(uchar *to,
-                                  const uchar *from,
-                                  uint param_data)
-{
-  uint from_len= param_data & 0x00ff;                 // length.
-  uint length= 0;
-  uint f_length;
-  f_length= (from_len < field_length) ? from_len : field_length;
-  DBUG_ASSERT(f_length <= 255);
-  length= (uint) *from++;
-  bitmap_set_bit(table->write_set,field_index);
-  store((const char *)from, length, system_charset_info);
-  return from+length;
-}
-
-
-const uchar *Field_string::unpack(uchar *to, const uchar *from)
-{
+const uchar *
+Field_string::unpack(uchar *to,
+                     const uchar *from,
+                     uint param_data,
+                     bool low_byte_first __attribute__((unused)))
+{
+  uint from_length=
+    param_data ? min(param_data & 0x00ff, field_length) : field_length;
   uint length;
-  if (field_length > 255)
+
+  if (from_length > 255)
   {
     length= uint2korr(from);
     from+= 2;
   }
   else
     length= (uint) *from++;
-  memcpy(to, from, (int) length);
-  bfill(to+length, field_length - length, ' ');
+
+  memcpy(to, from, length);
+  // Pad the string with the pad character of the fields charset
+  bfill(to + length, field_length - length, field_charset->pad_char);
   return from+length;
 }
 
@@ -6796,22 +6912,30 @@ uint32 Field_varstring::data_length()
   Here the number of length bytes are depending on the given max_length
 */
 
-uchar *Field_varstring::pack(uchar *to, const uchar *from, uint max_length)
+uchar *Field_varstring::pack(uchar *to, const uchar *from,
+                             uint max_length,
+                             bool low_byte_first __attribute__((unused)))
 {
   uint length= length_bytes == 1 ? (uint) *from : uint2korr(from);
   set_if_smaller(max_length, field_length);
   if (length > max_length)
     length=max_length;
-  *to++= (char) (length & 255);
+
+  /* Length always stored little-endian */
+  *to++= length & 0xFF;
   if (max_length > 255)
-    *to++= (char) (length >> 8);
-  if (length)
+    *to++= (length >> 8) & 0xFF;
+
+  /* Store bytes of string */
+  if (length > 0)
     memcpy(to, from+length_bytes, length);
   return to+length;
 }
 
 
-uchar *Field_varstring::pack_key(uchar *to, const uchar *key, uint max_length)
+uchar *
+Field_varstring::pack_key(uchar *to, const uchar *key, uint max_length,
+                          bool low_byte_first __attribute__((unused)))
 {
   uint length=  length_bytes == 1 ? (uint) *key : uint2korr(key);
   uint local_char_length= ((field_charset->mbmaxlen > 1) ?
@@ -6850,8 +6974,9 @@ uchar *Field_varstring::pack_key(uchar *to, const uchar *key, uint max_length)
     Pointer to end of 'key' (To the next key part if multi-segment key)
 */
 
-const uchar *Field_varstring::unpack_key(uchar *to, const uchar *key,
-                                         uint max_length)
+const uchar *
+Field_varstring::unpack_key(uchar *to, const uchar *key, uint max_length,
+                            bool low_byte_first __attribute__((unused)))
 {
   /* get length of the blob key */
   uint32 length= *key++;
@@ -6880,8 +7005,9 @@ const uchar *Field_varstring::unpack_key(uchar *to, const uchar *key,
     end of key storage
 */
 
-uchar *Field_varstring::pack_key_from_key_image(uchar *to, const uchar *from,
-                                                uint max_length)
+uchar *
+Field_varstring::pack_key_from_key_image(uchar *to, const uchar *from, uint max_length,
+                                         bool low_byte_first __attribute__((unused)))
 {
   /* Key length is always stored as 2 bytes */
   uint length= uint2korr(from);
@@ -6901,6 +7027,9 @@ uchar *Field_varstring::pack_key_from_key_image(uchar *to, const uchar *from,
 
    This method is used to unpack a varstring field from a master
    whose size of the field is less than that of the slave.
+
+   @note
+   The string length is always packed little-endian.
   
    @param   to         Destination of the data
    @param   from       Source of the data
@@ -6908,9 +7037,10 @@ uchar *Field_varstring::pack_key_from_key_image(uchar *to, const uchar *from,
 
    @return  New pointer into memory based on from + length of the data
 */
-const uchar *Field_varstring::unpack(uchar *to, 
-                                     const uchar *from,
-                                     uint param_data)
+const uchar *
+Field_varstring::unpack(uchar *to, const uchar *from,
+                        uint param_data,
+                        bool low_byte_first __attribute__((unused)))
 {
   uint length;
   uint l_bytes= (param_data && (param_data < field_length)) ? 
@@ -6922,28 +7052,7 @@ const uchar *Field_varstring::unpack(uchar *to,
     if (length_bytes == 2)
       to[1]= 0;
   }
-  else
-  {
-    length= uint2korr(from);
-    to[0]= *from++;
-    to[1]= *from++;
-  }
-  if (length)
-    memcpy(to+ length_bytes, from, length);
-  return from+length;
-}
-
-
-/*
-  unpack field packed with Field_varstring::pack()
-*/
-
-const uchar *Field_varstring::unpack(uchar *to, const uchar *from)
-{
-  uint length;
-  if (length_bytes == 1)
-    length= (uint) (*to= *from++);
-  else
+  else /* l_bytes == 2 */
   {
     length= uint2korr(from);
     to[0]= *from++;
@@ -7192,9 +7301,9 @@ void Field_blob::store_length(uchar *i_ptr,
 }
 
 
-uint32 Field_blob::get_length(const uchar *pos, bool low_byte_first)
+uint32 Field_blob::get_length(const uchar *pos, uint packlength_arg, bool low_byte_first)
 {
-  switch (packlength) {
+  switch (packlength_arg) {
   case 1:
     return (uint32) pos[0];
   case 2:
@@ -7608,28 +7717,37 @@ void Field_blob::sql_type(String &res) const
   }
 }
 
-
-uchar *Field_blob::pack(uchar *to, const uchar *from, uint max_length)
+uchar *Field_blob::pack(uchar *to, const uchar *from,
+                        uint max_length, bool low_byte_first)
 {
+  DBUG_ENTER("Field_blob::pack");
+  DBUG_PRINT("enter", ("to: 0x%lx; from: 0x%lx;"
+                       " max_length: %u; low_byte_first: %d",
+                       (ulong) to, (ulong) from,
+                       max_length, low_byte_first));
+  DBUG_DUMP("record", from, table->s->reclength);
   uchar *save= ptr;
   ptr= (uchar*) from;
   uint32 length=get_length();			// Length of from string
-  if (length > max_length)
-  {
-    ptr=to;
-    length=max_length;
-    store_length(length);			// Store max length
-    ptr= (uchar*) from;
-  }
-  else
-    memcpy(to,from,packlength);			// Copy length
-  if (length)
+
+  /*
+    Store max length, which will occupy packlength bytes. If the max
+    length given is smaller than the actual length of the blob, we
+    just store the initial bytes of the blob.
+  */
+  store_length(to, packlength, min(length, max_length), low_byte_first);
+
+  /*
+    Store the actual blob data, which will occupy 'length' bytes.
+   */
+  if (length > 0)
   {
     get_ptr((uchar**) &from);
     memcpy(to+packlength, from,length);
   }
   ptr=save;					// Restore org row pointer
-  return to+packlength+length;
+  DBUG_DUMP("packed", to, packlength + length);
+  DBUG_RETURN(to+packlength+length);
 }
 
 
@@ -7644,28 +7762,26 @@ uchar *Field_blob::pack(uchar *to, const uchar *from, uint max_length)
 
    @param   to         Destination of the data
    @param   from       Source of the data
-   @param   param_data <not used>
 
    @return  New pointer into memory based on from + length of the data
 */
 const uchar *Field_blob::unpack(uchar *to, 
                                 const uchar *from,
-                                uint param_data)
-{
-  return unpack(to, from);
-}
-
-
-const uchar *Field_blob::unpack(uchar *to, const uchar *from)
-{
-  memcpy(to,from,packlength);
-  uint32 length=get_length(from);
-  from+=packlength;
-  if (length)
-    memcpy_fixed(to+packlength, &from, sizeof(from));
-  else
-    bzero(to+packlength,sizeof(from));
-  return from+length;
+                                uint param_data,
+                                bool low_byte_first)
+{
+  DBUG_ENTER("Field_blob::unpack");
+  DBUG_PRINT("enter", ("to: 0x%lx; from: 0x%lx;"
+                       " param_data: %u; low_byte_first: %d",
+                       (ulong) to, (ulong) from, param_data, low_byte_first));
+  uint const master_packlength=
+    param_data > 0 ? param_data & 0xFF : packlength;
+  uint32 const length= get_length(from, master_packlength, low_byte_first);
+  DBUG_DUMP("packed", from, length + master_packlength);
+  store(reinterpret_cast<const char*>(from) + master_packlength,
+        length, field_charset);
+  DBUG_DUMP("record", to, table->s->reclength);
+  DBUG_RETURN(from + master_packlength + length);
 }
 
 /* Keys for blobs are like keys on varchars */
@@ -7715,7 +7831,9 @@ int Field_blob::pack_cmp(const uchar *b, uint key_length_arg,
 
 /* Create a packed key that will be used for storage from a MySQL row */
 
-uchar *Field_blob::pack_key(uchar *to, const uchar *from, uint max_length)
+uchar *
+Field_blob::pack_key(uchar *to, const uchar *from, uint max_length,
+                     bool low_byte_first __attribute__((unused)))
 {
   uchar *save= ptr;
   ptr= (uchar*) from;
@@ -7760,8 +7878,9 @@ uchar *Field_blob::pack_key(uchar *to, const uchar *from, uint max_length)
     Pointer into 'from' past the last byte copied from packed key.
 */
 
-const uchar *Field_blob::unpack_key(uchar *to, const uchar *from,
-                                    uint max_length)
+const uchar *
+Field_blob::unpack_key(uchar *to, const uchar *from, uint max_length,
+                       bool low_byte_first __attribute__((unused)))
 {
   /* get length of the blob key */
   uint32 length= *from++;
@@ -7784,8 +7903,9 @@ const uchar *Field_blob::unpack_key(uchar *to, const uchar *from,
 
 /* Create a packed key that will be used for storage from a MySQL key */
 
-uchar *Field_blob::pack_key_from_key_image(uchar *to, const uchar *from,
-                                           uint max_length)
+uchar *
+Field_blob::pack_key_from_key_image(uchar *to, const uchar *from, uint max_length,
+                                    bool low_byte_first __attribute__((unused)))
 {
   uint length=uint2korr(from);
   if (length > max_length)
@@ -8672,9 +8792,11 @@ void Field_bit::sql_type(String &res) const
 }
 
 
-uchar *Field_bit::pack(uchar *to, const uchar *from, uint max_length)
+uchar *
+Field_bit::pack(uchar *to, const uchar *from, uint max_length,
+                bool low_byte_first __attribute__((unused)))
 {
-  DBUG_ASSERT(max_length);
+  DBUG_ASSERT(max_length > 0);
   uint length;
   if (bit_len > 0)
   {
@@ -8709,28 +8831,44 @@ uchar *Field_bit::pack(uchar *to, const uchar *from, uint max_length)
 /**
    Unpack a bit field from row data.
 
-   This method is used to unpack a bit field from a master whose size 
+   This method is used to unpack a bit field from a master whose size
    of the field is less than that of the slave.
-  
+
    @param   to         Destination of the data
    @param   from       Source of the data
    @param   param_data Bit length (upper) and length (lower) values
 
    @return  New pointer into memory based on from + length of the data
 */
-const uchar *Field_bit::unpack(uchar *to,
-                               const uchar *from,
-                               uint param_data)
+const uchar *
+Field_bit::unpack(uchar *to, const uchar *from, uint param_data,
+                  bool low_byte_first __attribute__((unused)))
 {
   uint const from_len= (param_data >> 8U) & 0x00ff;
   uint const from_bit_len= param_data & 0x00ff;
   /*
-    If the master and slave have the same sizes, then use the old
-    unpack() method.
+    If the parameter data is zero (i.e., undefined), or if the master
+    and slave have the same sizes, then use the old unpack() method.
   */
-  if ((from_bit_len == bit_len) &&
-      (from_len == bytes_in_rec)) 
-    return(unpack(to, from));
+  if (param_data == 0 ||
+      (from_bit_len == bit_len) && (from_len == bytes_in_rec))
+  {
+    if (bit_len > 0)
+    {
+      /*
+        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);
+    return from + bytes_in_rec;
+  }
+
   /*
     We are converting a smaller bit field to a larger one here.
     To do that, we first need to construct a raw value for the original
@@ -8758,25 +8896,6 @@ const uchar *Field_bit::unpack(uchar *to,
 }
 
 
-const uchar *Field_bit::unpack(uchar *to, const uchar *from)
-{
-  if (bit_len > 0)
-  {
-    /*
-      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);
-  return from + bytes_in_rec;
-}
-
-
 void Field_bit::set_default()
 {
   if (bit_len > 0)