BUG#27441 (There is no COLS bitmap for the after image of an update

rows event):

Adding a after image COLS bitmap to Update_rows_log_event (for telling
what columns that are present in the after image of each row update).

Also fixing case where Rows_log_event length was not correctly computed
(happened when the number of columns in a table was more than 251). 

mysql-test/r/rpl_row_inexist_tbl.result

@@ -39,7 +39,7 @@ Replicate_Wild_Ignore_Table
 Last_Errno	1146
 Last_Error	Error 'Table 'test.t1' doesn't exist' on opening table `test`.`t1`
 Skip_Counter	0
-Exec_Master_Log_Pos	522
+Exec_Master_Log_Pos	523
 Relay_Log_Space	#
 Until_Condition	None
 Until_Log_File	

sql/log_event.cc

@@ -5604,7 +5604,10 @@ Rows_log_event::Rows_log_event(THD *thd_arg, TABLE *tbl_arg, ulong tid,
       memcpy(m_cols.bitmap, cols->bitmap, no_bytes_in_map(cols));
   }
   else
-    m_cols.bitmap= 0; // to not free it
+  {
+    // Needed because bitmap_init() does not set it to null on failure
+    m_cols.bitmap= 0;
+  }
 }
 #endif
 
@@ -5641,14 +5644,57 @@ Rows_log_event::Rows_log_event(const char *buf, uint event_len,
 
   m_flags= uint2korr(post_start);
 
-  byte const *const var_start= (const byte *)buf + common_header_len + 
-    post_header_len;
+  byte const *const var_start=
+    (const byte *)buf + common_header_len + post_header_len;
   byte const *const ptr_width= var_start;
   uchar *ptr_after_width= (uchar*) ptr_width;
+  DBUG_PRINT("debug", ("Reading from %p", ptr_after_width));
   m_width = net_field_length(&ptr_after_width);
+  DBUG_PRINT("debug", ("m_width=%lu", m_width));
+  /* if bitmap_init fails, catched in is_valid() */
+  if (likely(!bitmap_init(&m_cols,
+                          m_width <= sizeof(m_bitbuf)*8 ? m_bitbuf : NULL,
+                          (m_width + 7) & ~7UL,
+                          false)))
+  {
+    DBUG_PRINT("debug", ("Reading from %p", ptr_after_width));
+    memcpy(m_cols.bitmap, ptr_after_width, (m_width + 7) / 8);
+    ptr_after_width+= (m_width + 7) / 8;
+    DBUG_DUMP("m_cols", (char*) m_cols.bitmap, no_bytes_in_map(&m_cols));
+  }
+  else
+  {
+    // Needed because bitmap_init() does not set it to null on failure
+    m_cols.bitmap= NULL;
+    DBUG_VOID_RETURN;
+  }
+
+  m_cols_ai.bitmap= m_cols.bitmap; /* See explanation in is_valid() */
+
+  if (event_type == UPDATE_ROWS_EVENT)
+  {
+    DBUG_PRINT("debug", ("Reading from %p", ptr_after_width));
+
+    /* if bitmap_init fails, catched in is_valid() */
+    if (likely(!bitmap_init(&m_cols_ai,
+                            m_width <= sizeof(m_bitbuf_ai)*8 ? m_bitbuf_ai : NULL,
+                            (m_width + 7) & ~7UL,
+                            false)))
+    {
+      DBUG_PRINT("debug", ("Reading from %p", ptr_after_width));
+      memcpy(m_cols_ai.bitmap, ptr_after_width, (m_width + 7) / 8);
+      ptr_after_width+= (m_width + 7) / 8;
+      DBUG_DUMP("m_cols_ai", (char*) m_cols_ai.bitmap, no_bytes_in_map(&m_cols_ai));
+    }
+    else
+    {
+      // Needed because bitmap_init() does not set it to null on failure
+      m_cols_ai.bitmap= 0;
+      DBUG_VOID_RETURN;
+    }
+  }
 
-  const uint byte_count= (m_width + 7) / 8;
-  const byte* const ptr_rows_data= var_start + byte_count + 1;
+  const byte* const ptr_rows_data= (const byte*) ptr_after_width;
 
   my_size_t const data_size= event_len - (ptr_rows_data - (const byte *) buf);
   DBUG_PRINT("info",("m_table_id: %lu  m_flags: %d  m_width: %lu  data_size: %lu",
@@ -5657,12 +5703,6 @@ Rows_log_event::Rows_log_event(const char *buf, uint event_len,
   m_rows_buf= (byte*)my_malloc(data_size, MYF(MY_WME));
   if (likely((bool)m_rows_buf))
   {
-    /* if bitmap_init fails, catched in is_valid() */
-    if (likely(!bitmap_init(&m_cols,
-                            m_width <= sizeof(m_bitbuf)*8 ? m_bitbuf : NULL,
-                            (m_width + 7) & ~7UL,
-                            false)))
-      memcpy(m_cols.bitmap, ptr_after_width, byte_count);
     m_rows_end= m_rows_buf + data_size;
     m_rows_cur= m_rows_end;
     memcpy(m_rows_buf, ptr_rows_data, data_size);
@@ -5681,6 +5721,29 @@ Rows_log_event::~Rows_log_event()
   my_free((gptr)m_rows_buf, MYF(MY_ALLOW_ZERO_PTR));
 }
 
+int Rows_log_event::get_data_size()
+{
+  int const type_code= get_type_code();
+
+  char buf[sizeof(m_width)+1];
+  char *end= net_store_length(buf, (m_width + 7) / 8);
+
+  DBUG_EXECUTE_IF("old_row_based_repl_4_byte_map_id_master",
+                  return 6 + no_bytes_in_map(&m_cols) + (end - buf) +
+                  (type_code == UPDATE_ROWS_EVENT ? no_bytes_in_map(&m_cols_ai) : 0) +
+                  (m_rows_cur - m_rows_buf););
+  int data_size= ROWS_HEADER_LEN;
+  data_size+= no_bytes_in_map(&m_cols);
+  data_size+= end - buf;
+
+  if (type_code == UPDATE_ROWS_EVENT)
+    data_size+= no_bytes_in_map(&m_cols_ai);
+
+  data_size+= (m_rows_cur - m_rows_buf);
+  return data_size; 
+}
+
+
 #ifndef MYSQL_CLIENT
 int Rows_log_event::do_add_row_data(byte *const row_data,
                                     my_size_t const length)
@@ -5911,7 +5974,7 @@ int Rows_log_event::do_apply_event(RELAY_LOG_INFO const *rli)
     If m_table_id == ~0UL, then we have a dummy event that does not
     contain any data.  In that case, we just remove all tables in the
     tables_to_lock list, close the thread tables, and return with
-    success.  The relay log position will be stepped in 
+    success.
    */
   if (m_table_id == ~0UL)
   {
@@ -6291,15 +6354,35 @@ bool Rows_log_event::write_data_body(IO_CACHE*file)
   */
   char sbuf[sizeof(m_width)];
   my_ptrdiff_t const data_size= m_rows_cur - m_rows_buf;
+  bool res= false;
 
   char *const sbuf_end= net_store_length((char*) sbuf, (uint) m_width);
   DBUG_ASSERT(static_cast<my_size_t>(sbuf_end - sbuf) <= sizeof(sbuf));
 
-  return (my_b_safe_write(file, reinterpret_cast<byte*>(sbuf),
-                          sbuf_end - sbuf) ||
-          my_b_safe_write(file, reinterpret_cast<byte*>(m_cols.bitmap),
-                          no_bytes_in_map(&m_cols)) ||
-          my_b_safe_write(file, m_rows_buf, (uint) data_size));
+  DBUG_DUMP("m_width", sbuf, sbuf_end - sbuf);
+  res= res || my_b_safe_write(file,
+                              reinterpret_cast<byte*>(sbuf),
+                              sbuf_end - sbuf);
+
+  DBUG_DUMP("m_cols", (char*) m_cols.bitmap, no_bytes_in_map(&m_cols));
+  res= res || my_b_safe_write(file,
+                              reinterpret_cast<byte*>(m_cols.bitmap),
+                              no_bytes_in_map(&m_cols));
+  /*
+    TODO[refactor write]: Remove the "down cast" here (and elsewhere).
+   */
+  if (get_type_code() == UPDATE_ROWS_EVENT)
+  {
+    DBUG_DUMP("m_cols_ai", (char*) m_cols_ai.bitmap, no_bytes_in_map(&m_cols_ai));
+    res= res || my_b_safe_write(file,
+                                reinterpret_cast<byte*>(m_cols_ai.bitmap),
+                                no_bytes_in_map(&m_cols_ai));
+  }
+  DBUG_DUMP("rows", m_rows_buf, data_size);
+  res= res || my_b_safe_write(file, m_rows_buf, (uint) data_size);
+
+  return res;
+
 }
 #endif
 
@@ -7584,16 +7667,55 @@ void Delete_rows_log_event::print(FILE *file,
  */
 #if !defined(MYSQL_CLIENT)
 Update_rows_log_event::Update_rows_log_event(THD *thd_arg, TABLE *tbl_arg,
-                                             ulong tid, MY_BITMAP const *cols,
+                                             ulong tid,
+                                             MY_BITMAP const *cols_bi,
+                                             MY_BITMAP const *cols_ai,
+                                             bool is_transactional)
+: Rows_log_event(thd_arg, tbl_arg, tid, cols_bi, is_transactional)
+#ifdef HAVE_REPLICATION
+  , m_memory(NULL), m_key(NULL)
+
+#endif
+{
+  init(cols_ai);
+}
+
+Update_rows_log_event::Update_rows_log_event(THD *thd_arg, TABLE *tbl_arg,
+                                             ulong tid,
+                                             MY_BITMAP const *cols,
                                              bool is_transactional)
 : Rows_log_event(thd_arg, tbl_arg, tid, cols, is_transactional)
 #ifdef HAVE_REPLICATION
   , m_memory(NULL), m_key(NULL)
 #endif
 {
+  init(cols);
+}
+
+void Update_rows_log_event::init(MY_BITMAP const *cols)
+{
+  /* if bitmap_init fails, catched in is_valid() */
+  if (likely(!bitmap_init(&m_cols_ai,
+                          m_width <= sizeof(m_bitbuf_ai)*8 ? m_bitbuf_ai : NULL,
+                          (m_width + 7) & ~7UL,
+                          false)))
+  {
+    /* Cols can be zero if this is a dummy binrows event */
+    if (likely(cols != NULL))
+      memcpy(m_cols_ai.bitmap, cols->bitmap, no_bytes_in_map(cols));
+  }
 }
 #endif /* !defined(MYSQL_CLIENT) */
 
+
+Update_rows_log_event::~Update_rows_log_event()
+{
+  if (m_cols_ai.bitmap == m_bitbuf_ai) // no my_malloc happened
+    m_cols_ai.bitmap= 0; // so no my_free in bitmap_free
+  bitmap_free(&m_cols_ai); // To pair with bitmap_init().
+}
+
+
 /*
   Constructor used by slave to read the event from the binary log.
  */
@@ -7678,7 +7800,7 @@ int Update_rows_log_event::do_prepare_row(THD *thd, RELAY_LOG_INFO const *rli,
   store_record(table, record[1]);
   char const *next_start = *row_end;
   /* m_after_image is the after image for the update */
-  error= unpack_row(rli, table, m_width, next_start, &m_cols, row_end,
+  error= unpack_row(rli, table, m_width, next_start, &m_cols_ai, row_end,
                     &m_master_reclength, table->write_set, UPDATE_ROWS_EVENT);
   bmove_align(m_after_image, table->record[0], table->s->reclength);
   restore_record(table, record[1]);

sql/log_event.h

@@ -2160,14 +2160,7 @@ class Rows_log_event : public Log_event
 #endif
 
   /* Member functions to implement superclass interface */
-  virtual int get_data_size()
-  { 
-    DBUG_EXECUTE_IF("old_row_based_repl_4_byte_map_id_master",
-                    return 6 + 1 + no_bytes_in_map(&m_cols) + 
-                    (m_rows_cur - m_rows_buf);); 
-    return ROWS_HEADER_LEN + 1 + no_bytes_in_map(&m_cols) + 
-      (m_rows_cur - m_rows_buf); 
-  }
+  virtual int get_data_size();
 
   MY_BITMAP const *get_cols() const { return &m_cols; }
   my_size_t get_width() const       { return m_width; }
@@ -2178,9 +2171,14 @@ class Rows_log_event : public Log_event
   virtual bool write_data_body(IO_CACHE *file);
   virtual const char *get_db() { return m_table->s->db.str; }
 #endif
+  /*
+    Check that malloc() succeeded in allocating memory for the rows
+    buffer and the COLS vector. Checking that an Update_rows_log_event
+    is valid is done in the Update_rows_log_event::is_valid()
+    function.
+  */
   virtual bool is_valid() const
   {
-    /* that's how we check malloc() succeeded */
     return m_rows_buf && m_cols.bitmap;
   }
 
@@ -2213,10 +2211,20 @@ class Rows_log_event : public Log_event
   ulong       m_table_id;	/* Table ID */
   MY_BITMAP   m_cols;		/* Bitmap denoting columns available */
   ulong       m_width;          /* The width of the columns bitmap */
+  /*
+    Bitmap for columns available in the after image, if present. These
+    fields are only available for Update_rows events. Observe that the
+    width of both the before image COLS vector and the after image
+    COLS vector is the same: the number of columns of the table on the
+    master.
+  */
+  MY_BITMAP   m_cols_ai;
+
   ulong       m_master_reclength; /* Length of record on master side */
 
-  /* Bit buffer in the same memory as the class */
+  /* Bit buffers in the same memory as the class */
   uint32    m_bitbuf[128/(sizeof(uint32)*8)];
+  uint32    m_bitbuf_ai[128/(sizeof(uint32)*8)];
 
   byte    *m_rows_buf;		/* The rows in packed format */
   byte    *m_rows_cur;		/* One-after the end of the data */
@@ -2377,9 +2385,19 @@ class Update_rows_log_event : public Rows_log_event
 
 #ifndef MYSQL_CLIENT
   Update_rows_log_event(THD*, TABLE*, ulong table_id,
-			MY_BITMAP const *cols, bool is_transactional);
+			MY_BITMAP const *cols_bi,
+			MY_BITMAP const *cols_ai,
+                        bool is_transactional);
+
+  Update_rows_log_event(THD*, TABLE*, ulong table_id,
+			MY_BITMAP const *cols,
+                        bool is_transactional);
+
+  void init(MY_BITMAP const *cols);
 #endif
 
+  virtual ~Update_rows_log_event();
+
 #ifdef HAVE_REPLICATION
   Update_rows_log_event(const char *buf, uint event_len, 
 			const Format_description_log_event *description_event);
@@ -2398,6 +2416,11 @@ class Update_rows_log_event : public Rows_log_event
   }
 #endif
 
+  virtual bool is_valid() const
+  {
+    return Rows_log_event::is_valid() && m_cols_ai.bitmap;
+  }
+
 private:
   virtual Log_event_type get_type_code() { return (Log_event_type)TYPE_CODE; }