BUG#30790 : Suspicious code in rpl_utility.cc

This patch clarifies some of the coding choices with documentationa and
removes a limitation in the code for future expansion of the CHAR and
BINARY fields to length > 255.
parent 1835b162
......@@ -6732,6 +6732,7 @@ const uint Field_varstring::MAX_SIZE= UINT_MAX16;
int Field_varstring::do_save_field_metadata(uchar *metadata_ptr)
{
char *ptr= (char *)metadata_ptr;
DBUG_ASSERT(field_length <= 65535);
int2store(ptr, field_length);
return 2;
}
......
......@@ -6469,6 +6469,16 @@ void Rows_log_event::print_helper(FILE *file,
data) in the table map are initialized as zero (0). The array size is the
same as the columns for the table on the slave.
Additionally, values saved for field metadata on the master are saved as a
string of bytes (uchar) in the binlog. A field may require 1 or more bytes
to store the information. In cases where values require multiple bytes
(e.g. values > 255), the endian-safe methods are used to properly encode
the values on the master and decode them on the slave. When the field
metadata values are captured on the slave, they are stored in an array of
type uint16. This allows the least number of casts to prevent casting bugs
when the field metadata is used in comparisons of field attributes. When
the field metadata is used for calculating addresses in pointer math, the
type used is uint32.
*/
/**
......
......@@ -31,31 +31,34 @@ uint32 table_def::calc_field_size(uint col, uchar *master_data) const
switch (type(col)) {
case MYSQL_TYPE_NEWDECIMAL:
length= my_decimal_get_binary_size(m_field_metadata[col] >> 8,
m_field_metadata[col] - ((m_field_metadata[col] >> 8) << 8));
m_field_metadata[col] & 0xff);
break;
case MYSQL_TYPE_DECIMAL:
case MYSQL_TYPE_FLOAT:
case MYSQL_TYPE_DOUBLE:
length= m_field_metadata[col];
break;
/*
The cases for SET and ENUM are include for completeness, however
both are mapped to type MYSQL_TYPE_STRING and their real types
are encoded in the field metadata.
*/
case MYSQL_TYPE_SET:
case MYSQL_TYPE_ENUM:
case MYSQL_TYPE_STRING:
{
if (((m_field_metadata[col] & 0xff00) == (MYSQL_TYPE_SET << 8)) ||
((m_field_metadata[col] & 0xff00) == (MYSQL_TYPE_ENUM << 8)))
uchar type= m_field_metadata[col] >> 8U;
if ((type == MYSQL_TYPE_SET) || (type == MYSQL_TYPE_ENUM))
length= m_field_metadata[col] & 0x00ff;
else
{
length= m_field_metadata[col] & 0x00ff;
DBUG_ASSERT(length > 0);
if (length > 255)
{
DBUG_ASSERT(uint2korr(master_data) > 0);
length= uint2korr(master_data) + 2;
}
else
length= (uint) *master_data + 1;
/*
We are reading the actual size from the master_data record
because this field has the actual lengh stored in the first
byte.
*/
length= (uint) *master_data + 1;
DBUG_ASSERT(length != 0);
}
break;
}
......@@ -95,6 +98,13 @@ uint32 table_def::calc_field_size(uint col, uchar *master_data) const
break;
case MYSQL_TYPE_BIT:
{
/*
Decode the size of the bit field from the master.
from_len is the length in bytes from the master
from_bit_len is the number of extra bits stored in the master record
If from_bit_len is not 0, add 1 to the length to account for accurate
number of bytes needed.
*/
uint from_len= (m_field_metadata[col] >> 8U) & 0x00ff;
uint from_bit_len= m_field_metadata[col] & 0x00ff;
DBUG_ASSERT(from_bit_len <= 7);
......@@ -136,7 +146,7 @@ uint32 table_def::calc_field_size(uint col, uchar *master_data) const
length= *master_data;
break;
case 2:
length= sint2korr(master_data);
length= uint2korr(master_data);
break;
case 3:
length= uint3korr(master_data);
......
......@@ -99,7 +99,7 @@ public:
/*
These types store a single byte.
*/
m_field_metadata[i]= (uchar)field_metadata[index];
m_field_metadata[i]= field_metadata[index];
index++;
break;
}
......@@ -107,14 +107,14 @@ public:
case MYSQL_TYPE_ENUM:
case MYSQL_TYPE_STRING:
{
short int x= field_metadata[index++] << 8U; // real_type
x = x + field_metadata[index++]; // pack or field length
uint16 x= field_metadata[index++] << 8U; // real_type
x+= field_metadata[index++]; // pack or field length
m_field_metadata[i]= x;
break;
}
case MYSQL_TYPE_BIT:
{
short int x= field_metadata[index++];
uint16 x= field_metadata[index++];
x = x + (field_metadata[index++] << 8U);
m_field_metadata[i]= x;
break;
......@@ -125,14 +125,14 @@ public:
These types store two bytes.
*/
char *ptr= (char *)&field_metadata[index];
m_field_metadata[i]= sint2korr(ptr);
m_field_metadata[i]= uint2korr(ptr);
index= index + 2;
break;
}
case MYSQL_TYPE_NEWDECIMAL:
{
short int x= field_metadata[index++] << 8U; // precision
x = x + field_metadata[index++]; // decimals
uint16 x= field_metadata[index++] << 8U; // precision
x+= field_metadata[index++]; // decimals
m_field_metadata[i]= x;
break;
}
......
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