mysql-haskell-1.4.0: src/Database/MySQL/Protocol/MySQLValue.hs
{-# OPTIONS_GHC -funbox-strict-fields #-}
{-# LANGUAGE UnboxedSums #-}
{-# LANGUAGE UnboxedTuples #-}
{-|
Module : Database.MySQL.Protocol.MySQLValue
Description : Text and binary protocol
Copyright : (c) Winterland, 2016
License : BSD
Maintainer : drkoster@qq.com
Stability : experimental
Portability : PORTABLE
Core text and binary row decoder/encoder machinery.
-}
module Database.MySQL.Protocol.MySQLValue
( -- * MySQLValue decoder and encoder
MySQLValue(..)
, RawDate(..)
, putParamMySQLType
, getTextField
, putTextField
, getTextRow
, getTextRowVector
-- * Text rows with the column types resolved once per result set
, ColumnKind(..)
, ValueKind(..)
, columnKind
, decodeTextRow
, decodeTextRowVector
, ColumnNumber(..)
, nextColumn
, RowError(..)
, RowErrorKind(..)
, TextFieldError(..)
, describeRowError
, getBinaryField
, putBinaryField
, getBinaryRow
, getBinaryRowVector
, decodeMySQLLatin1
-- * Internal utilities
, decodeTextValue
, decodeTextBit
, lengthEncodedInt
, lexSignedIntegral
, lexSignedFraction
, textDateParts
, lexDateTimeParts
, calendarDate
, dateValue
, dateTimeValue
, timeStampValue
, lexSignedTime
, getBits
, BitMap(..)
, isColumnSet
, isColumnNull
, makeNullMap
) where
import qualified Blaze.Text as Textual
import Control.Monad
import Data.Binary.Put
import Data.Binary.Parser
import Data.Bits
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
import qualified Data.ByteString.Builder as BB
import Data.ByteString.Builder.Scientific (FPFormat (..),
formatScientificBuilder)
import qualified Data.ByteString.Char8 as BC
import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString.Lex.Fractional as LexFrac
import qualified Data.ByteString.Lex.Integral as LexInt
import qualified Data.ByteString.Unsafe as B
import Data.Fixed (Pico)
import Data.Int
import Data.Scientific (Scientific)
import Data.Text (Text)
import qualified Data.Text.Encoding as T
import Data.Time.Calendar (Day, fromGregorianValid,
toGregorian)
import Data.Time.Format (defaultTimeLocale,
formatTime)
import Data.Time.LocalTime (LocalTime (..),
TimeOfDay (..))
import Data.Word
import Database.MySQL.Protocol.ColumnDef
import Database.MySQL.Protocol.Escape
import Database.MySQL.Protocol.FloatingPoint (readDouble, readFloat)
import Database.MySQL.Protocol.Packet
import GHC.Generics (Generic)
import Text.Printf (printf)
import qualified Data.Text as T
import qualified Data.Vector as V
import qualified Unwitch.Convert.Int as Int
import qualified Unwitch.Convert.Word16 as Word16
import qualified Unwitch.Convert.Word64 as Word64
import qualified Unwitch.Convert.Word8 as Word8
--------------------------------------------------------------------------------
-- | Data type mapping between MySQL values and haskell values.
--
-- There're some subtle differences between MySQL values and haskell values:
--
-- MySQL's @DATETIME@ and @TIMESTAMP@ are different on timezone handling:
--
-- * DATETIME and DATE is just a represent of a calendar date, it has no timezone information involved,
-- you always get the same value as you put no matter what timezone you're using with MySQL.
--
-- * MySQL converts TIMESTAMP values from the current time zone to UTC for storage,
-- and back from UTC to the current time zone for retrieval. If you put a TIMESTAMP with timezone A,
-- then read it with timezone B, you may get different result because of this conversion, so always
-- be careful about setting up the right timezone with MySQL, you can do it with a simple @SET time_zone = timezone;@
-- for more info on timezone support, please read <http://dev.mysql.com/doc/refman/5.7/en/time-zone-support.html>
--
-- So we use 'LocalTime' to present both @DATETIME@ and @TIMESTAMP@, but the local here is different.
--
-- A @DATE@, @DATETIME@ or @TIMESTAMP@ whose date a 'Day' cannot hold, such as the zero
-- date @0000-00-00@, arrives as 'MySQLDateRaw', 'MySQLDateTimeRaw' or 'MySQLTimeStampRaw'
-- and is sent back unchanged, see 'RawDate'.
--
-- MySQL's @TIME@ type can present time of day, but also elapsed time or a time interval between two events.
-- @TIME@ values may range from @-838:59:59@ to @838:59:59@, so 'MySQLTime' values consist of a sign and a
-- 'TimeOfDay' whose hour part may exceeded 24. you can use @timeOfDayToTime@ to get the absolute time interval.
--
-- Under MySQL >= 5.7, @DATETIME@, @TIMESTAMP@ and @TIME@ may contain fractional part, which matches haskell's
-- precision.
--
data MySQLValue
= MySQLDecimal !Scientific -- ^ DECIMAL, NEWDECIMAL
| MySQLInt8U !Word8 -- ^ Unsigned TINY
| MySQLInt8 !Int8 -- ^ TINY
| MySQLInt16U !Word16 -- ^ Unsigned SHORT
| MySQLInt16 !Int16 -- ^ SHORT
| MySQLInt32U !Word32 -- ^ Unsigned LONG, INT24
| MySQLInt32 !Int32 -- ^ LONG, INT24
| MySQLInt64U !Word64 -- ^ Unsigned LONGLONG
| MySQLInt64 !Int64 -- ^ LONGLONG
| MySQLFloat !Float -- ^ IEEE 754 single precision format
| MySQLDouble !Double -- ^ IEEE 754 double precision format
| MySQLYear !Word16 -- ^ YEAR
| MySQLDateTime !LocalTime -- ^ DATETIME
| MySQLTimeStamp !LocalTime -- ^ TIMESTAMP
| MySQLDate !Day -- ^ DATE
| MySQLDateRaw !RawDate -- ^ DATE that a 'Day' cannot hold
| MySQLDateTimeRaw !RawDate !TimeOfDay -- ^ DATETIME whose date a 'Day' cannot hold
| MySQLTimeStampRaw !RawDate !TimeOfDay -- ^ TIMESTAMP whose date a 'Day' cannot hold
| MySQLTime !Word8 !TimeOfDay -- ^ sign(0 = non-negative, 1 = negative) hh mm ss microsecond
-- The sign is OPPOSITE to binlog one !!!
| MySQLGeometry !ByteString -- ^ todo: parsing to something meanful
| MySQLBytes !ByteString
| MySQLBit !Word64
| MySQLText !Text
| MySQLNull
deriving (Show, Eq, Generic)
-- | A date as the server stores it, when a 'Day' cannot hold it: the zero date
-- @0000-00-00@, a date with a zero month or day such as @2024-05-00@ (unless
-- @NO_ZERO_DATE@ and @NO_ZERO_IN_DATE@ are set), or under @ALLOW_INVALID_DATES@
-- a day past the end of its month such as @2024-02-30@.
data RawDate = RawDate
{ rawDateYear :: !Word16
, rawDateMonth :: !Word8
, rawDateDay :: !Word8
} deriving (Show, Eq, Generic)
-- | 'Right' when a 'Day' can hold the date.
calendarDate :: RawDate -> Either RawDate Day
calendarDate raw@(RawDate year month day) =
maybe (Left raw) Right
(fromGregorianValid (Word16.toInteger year) (Word8.toInt month) (Word8.toInt day))
dateValue :: RawDate -> MySQLValue
dateValue = either MySQLDateRaw MySQLDate . calendarDate
dateTimeValue :: RawDate -> TimeOfDay -> MySQLValue
dateTimeValue raw time =
either (`MySQLDateTimeRaw` time) (\day -> MySQLDateTime (LocalTime day time)) (calendarDate raw)
timeStampValue :: RawDate -> TimeOfDay -> MySQLValue
timeStampValue raw time =
either (`MySQLTimeStampRaw` time) (\day -> MySQLTimeStamp (LocalTime day time)) (calendarDate raw)
-- | Put 'FieldType' and usigned bit(0x80/0x00) for 'MySQLValue's.
--
putParamMySQLType :: MySQLValue -> Put
putParamMySQLType (MySQLDecimal _) = putFieldType mySQLTypeDecimal >> putWord8 0x00
putParamMySQLType (MySQLInt8U _) = putFieldType mySQLTypeTiny >> putWord8 0x80
putParamMySQLType (MySQLInt8 _) = putFieldType mySQLTypeTiny >> putWord8 0x00
putParamMySQLType (MySQLInt16U _) = putFieldType mySQLTypeShort >> putWord8 0x80
putParamMySQLType (MySQLInt16 _) = putFieldType mySQLTypeShort >> putWord8 0x00
putParamMySQLType (MySQLInt32U _) = putFieldType mySQLTypeLong >> putWord8 0x80
putParamMySQLType (MySQLInt32 _) = putFieldType mySQLTypeLong >> putWord8 0x00
putParamMySQLType (MySQLInt64U _) = putFieldType mySQLTypeLongLong >> putWord8 0x80
putParamMySQLType (MySQLInt64 _) = putFieldType mySQLTypeLongLong >> putWord8 0x00
putParamMySQLType (MySQLFloat _) = putFieldType mySQLTypeFloat >> putWord8 0x00
putParamMySQLType (MySQLDouble _) = putFieldType mySQLTypeDouble >> putWord8 0x00
putParamMySQLType (MySQLYear _) = putFieldType mySQLTypeShort >> putWord8 0x80
putParamMySQLType (MySQLDateTime _) = putFieldType mySQLTypeDateTime >> putWord8 0x00
putParamMySQLType (MySQLTimeStamp _) = putFieldType mySQLTypeTimestamp>> putWord8 0x00
putParamMySQLType (MySQLDate _) = putFieldType mySQLTypeDate >> putWord8 0x00
putParamMySQLType (MySQLDateRaw _) = putFieldType mySQLTypeDate >> putWord8 0x00
putParamMySQLType (MySQLDateTimeRaw _ _) = putFieldType mySQLTypeDateTime >> putWord8 0x00
putParamMySQLType (MySQLTimeStampRaw _ _) = putFieldType mySQLTypeTimestamp >> putWord8 0x00
putParamMySQLType (MySQLTime _ _) = putFieldType mySQLTypeTime >> putWord8 0x00
putParamMySQLType (MySQLBytes _) = putFieldType mySQLTypeBlob >> putWord8 0x00
putParamMySQLType (MySQLGeometry _) = putFieldType mySQLTypeGeometry >> putWord8 0x00
putParamMySQLType (MySQLBit _) = putFieldType mySQLTypeLongLong >> putWord8 0x80
putParamMySQLType (MySQLText _) = putFieldType mySQLTypeString >> putWord8 0x00
putParamMySQLType MySQLNull = putFieldType mySQLTypeNull >> putWord8 0x00
--------------------------------------------------------------------------------
-- | Text protocol decoder
getTextField :: ColumnDef -> Get MySQLValue
getTextField f = case columnKind f of
NullColumn -> pure MySQLNull
ValueColumn fieldType value -> do
bytes <- getLenEncBytes
case decodeTextValue fieldType value bytes of
Left fieldError -> fail (describeTextFieldError fieldError)
Right decoded -> pure decoded
{- Note [Text rows decoded once per result set]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'getTextRow' runs 'getTextField' for every field of every row, which compares
the column type against two dozen constants before it reads a byte, inside
binary's continuation-based 'Get' over a lazy packet body. Decoding text rows
was 47.5% of select CPU (benchmark/cpu-profile-1.3.3.md).
The query functions in "Database.MySQL.Base" instead resolve each column to a
'ColumnKind' once, when the column definitions arrive, and decode every row
with 'decodeTextRow': a walk over the row as one strict 'ByteString' that
returns unboxed sums, so no 'Either' or tuple is allocated per field.
Decision: values stay as lazy as 'getTextField' leaves them. Evaluating every
value while decoding saved 3% of the instructions when a caller uses every
value, and cost 2.75 times the instructions when it uses none
(docs/direct-row-decoding.md). Only a string's bytes are checked at once, as
UTF-8, so bytes that are not fail the row with a 'TextFieldInvalidUtf8' rather
than raise an exception from pure code when the value is used.
'getTextField' and 'getTextRow' keep their 'Get' interface and share
'columnKind' and 'decodeTextValue', so both paths turn the same bytes into the
same values. They differ only on rows a server does not send: an 8-byte length
above 'maxBound' of 'Int', which 'decodeTextRow' rejects, and a zero-length
BIT field, which is now 0 instead of the byte after it.
-}
-- | How a column's fields decode, in either protocol, resolved once per result
-- set by 'columnKind'. See Note [Text rows decoded once per result set].
--
-- @since 1.4.0
data ColumnKind
= NullColumn
-- ^ a column of type NULL: every field of it is NULL, so no bytes of a
-- text-protocol row belong to it beyond the NULL marker
| ValueColumn !FieldType !ValueKind
-- ^ a column with values; the column type is kept for error messages
deriving (Show, Eq)
-- | The 'MySQLValue' constructor a column's non-NULL fields become.
--
-- @since 1.4.0
data ValueKind
= KindDecimal
| KindInt8U
| KindInt8
| KindInt16U
| KindInt16
| KindInt32U
| KindInt32
| KindInt64U
| KindInt64
| KindFloat
| KindDouble
| KindYear
| KindTimeStamp
| KindDateTime
| KindDate
| KindTime
| KindGeometry
| KindText !Word16
-- ^ a string column in a character set other than binary or latin1, read
-- as UTF-8; the character set id is kept for error messages
| KindLatin1Text -- ^ a string column in latin1, which MySQL means as Windows-1252
| KindBytes -- ^ a string column in the binary character set
| KindBit
| KindUnsupported -- ^ a column type without a decoder
deriving (Show, Eq)
-- | How a column's fields decode.
--
-- @since 1.4.0
columnKind :: ColumnDef -> ColumnKind
columnKind f =
if | t == mySQLTypeNull -> NullColumn
| t == mySQLTypeDecimal || t == mySQLTypeNewDecimal -> ValueColumn t KindDecimal
| t == mySQLTypeTiny ->
ValueColumn t (if isUnsigned then KindInt8U else KindInt8)
| t == mySQLTypeShort ->
ValueColumn t (if isUnsigned then KindInt16U else KindInt16)
| t == mySQLTypeLong || t == mySQLTypeInt24 ->
ValueColumn t (if isUnsigned then KindInt32U else KindInt32)
| t == mySQLTypeLongLong ->
ValueColumn t (if isUnsigned then KindInt64U else KindInt64)
| t == mySQLTypeFloat -> ValueColumn t KindFloat
| t == mySQLTypeDouble -> ValueColumn t KindDouble
| t == mySQLTypeYear -> ValueColumn t KindYear
| t == mySQLTypeTimestamp || t == mySQLTypeTimestamp2 -> ValueColumn t KindTimeStamp
| t == mySQLTypeDateTime || t == mySQLTypeDateTime2 -> ValueColumn t KindDateTime
| t == mySQLTypeDate || t == mySQLTypeNewDate -> ValueColumn t KindDate
| t == mySQLTypeTime || t == mySQLTypeTime2 -> ValueColumn t KindTime
| t == mySQLTypeGeometry -> ValueColumn t KindGeometry
| t == mySQLTypeVarChar
|| t == mySQLTypeEnum
|| t == mySQLTypeSet
|| t == mySQLTypeTinyBlob
|| t == mySQLTypeMediumBlob
|| t == mySQLTypeLongBlob
|| t == mySQLTypeBlob
|| t == mySQLTypeVarString
|| t == mySQLTypeString ->
ValueColumn t (stringKind (columnCharSet f))
| t == mySQLTypeBit -> ValueColumn t KindBit
| otherwise -> ValueColumn t KindUnsupported
where
t = columnType f
isUnsigned = flagUnsigned (columnFlags f)
-- | Why the bytes of a text-protocol field did not decode.
--
-- @since 1.4.0
data TextFieldError
= TextFieldUnparsable !FieldType !ByteString
-- ^ the bytes are not a value of the column's type
| TextFieldBitTooWide !Int
-- ^ a BIT field longer than the 8 bytes of a 'Word64'
| TextFieldUnsupportedType !FieldType
-- ^ a column type without a text decoder
| TextFieldInvalidUtf8 !Word16 !ByteString
-- ^ a string in this character set id whose bytes are not UTF-8
deriving (Show, Eq)
-- | The message 'getTextField' fails with.
describeTextFieldError :: TextFieldError -> String
describeTextFieldError fieldError = case fieldError of
TextFieldUnparsable fieldType bytes ->
"Database.MySQL.Protocol.MySQLValue: parsing " ++ show fieldType
++ " failed, input: " ++ BC.unpack bytes
TextFieldBitTooWide width ->
"Database.MySQL.Protocol.MySQLValue: wrong bit length size: " ++ show width
TextFieldUnsupportedType fieldType ->
"Database.MySQL.Protocol.MySQLValue: missing text decoder for " ++ show fieldType
TextFieldInvalidUtf8 charsetId _ ->
"Database.MySQL.Protocol.MySQLValue: a string column arrived in character set id "
++ show charsetId ++ ", which mysql-haskell can only decode as UTF-8 or latin1,"
++ " and its bytes are not valid UTF-8. Use a UTF-8 connection charset such as"
++ " defaultConnectInfoMB4's, or select the column as BINARY to get its bytes."
-- | The value of a field's bytes. The lexer runs at once, so a malformed field
-- fails while the row is read; a lexed value and the 'Text' of a string are left lazy,
-- while a constructor around bytes already in hand is built at once, as that
-- is cheaper than a thunk. See Note [Text rows decoded once per result set].
-- Inlined so that 'decodeTextFieldAt' matches the 'Right' away instead of
-- allocating it.
decodeTextValue :: FieldType -> ValueKind -> ByteString -> Either TextFieldError MySQLValue
decodeTextValue fieldType value bytes = case value of
KindDecimal -> lexedValue fieldType MySQLDecimal lexSignedFraction bytes
KindInt8U -> lexedValue fieldType MySQLInt8U lexSignedIntegral bytes
KindInt8 -> lexedValue fieldType MySQLInt8 lexSignedIntegral bytes
KindInt16U -> lexedValue fieldType MySQLInt16U lexSignedIntegral bytes
KindInt16 -> lexedValue fieldType MySQLInt16 lexSignedIntegral bytes
KindInt32U -> lexedValue fieldType MySQLInt32U lexSignedIntegral bytes
KindInt32 -> lexedValue fieldType MySQLInt32 lexSignedIntegral bytes
KindInt64U -> lexedValue fieldType MySQLInt64U lexSignedIntegral bytes
KindInt64 -> lexedValue fieldType MySQLInt64 lexSignedIntegral bytes
KindFloat -> lexedValue fieldType MySQLFloat readFloat bytes
KindDouble -> lexedValue fieldType MySQLDouble readDouble bytes
KindYear -> lexedValue fieldType MySQLYear lexSignedIntegral bytes
KindTimeStamp -> lexedValue fieldType (uncurry timeStampValue) lexDateTimeParts bytes
KindDateTime -> lexedValue fieldType (uncurry dateTimeValue) lexDateTimeParts bytes
KindDate -> lexedValue fieldType dateValue textDateParts bytes
KindTime -> lexedValue fieldType id lexTime bytes
KindGeometry -> Right $! MySQLGeometry bytes
KindText charsetId -> utf8Value charsetId bytes
KindLatin1Text -> Right (MySQLText (decodeMySQLLatin1 bytes))
KindBytes -> Right $! MySQLBytes bytes
KindBit -> decodeTextBit bytes
KindUnsupported -> Left (TextFieldUnsupportedType fieldType)
{-# INLINE decodeTextValue #-}
-- | Checked by 'B.isValidUtf8' at once, so the lazy 'T.decodeUtf8' cannot fail
-- when the value is used. See Note [Text rows decoded once per result set].
utf8Value :: Word16 -> ByteString -> Either TextFieldError MySQLValue
utf8Value charsetId bytes =
if B.isValidUtf8 bytes
then Right (MySQLText (T.decodeUtf8 bytes))
else Left (TextFieldInvalidUtf8 charsetId bytes)
{-# INLINE utf8Value #-}
lexedValue :: FieldType -> (a -> MySQLValue) -> (ByteString -> Maybe a) -> ByteString
-> Either TextFieldError MySQLValue
lexedValue fieldType construct lexer bytes = case lexer bytes of
Just lexed -> Right (construct lexed)
Nothing -> Left (TextFieldUnparsable fieldType bytes)
{-# INLINE lexedValue #-}
-- | A BIT field's bytes, most significant first.
decodeTextBit :: ByteString -> Either TextFieldError MySQLValue
decodeTextBit bytes =
if B.length bytes > 8
then Left (TextFieldBitTooWide (B.length bytes))
else Right $! MySQLBit (B.foldl' appendBitByte 0 bytes)
appendBitByte :: Word64 -> Word8 -> Word64
appendBitByte bits byte = unsafeShiftL bits 8 .|. Word8.toWord64 byte
lexSignedIntegral :: Integral a => ByteString -> Maybe a
lexSignedIntegral bytes = fst <$> LexInt.readSigned LexInt.readDecimal bytes
-- Specialised here so that "Database.MySQL.Decoder", which reaches these
-- lexers through higher-order arguments, gets the same specialised digit loops
-- as 'decodeTextValue' instead of the dictionary-passing ones.
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Int8 #-}
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Word8 #-}
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Int16 #-}
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Word16 #-}
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Int32 #-}
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Word32 #-}
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Int64 #-}
{-# SPECIALIZE lexSignedIntegral :: ByteString -> Maybe Word64 #-}
lexSignedFraction :: Fractional a => ByteString -> Maybe a
lexSignedFraction bytes = fst <$> LexFrac.readSigned LexFrac.readDecimal bytes
{-# SPECIALIZE lexSignedFraction :: ByteString -> Maybe Scientific #-}
-- | @YYYY-MM-DD hh:mm:ss[.fraction]@, as DATETIME and TIMESTAMP fields come;
-- the date may be one a 'Day' cannot hold.
lexDateTimeParts :: ByteString -> Maybe (RawDate, TimeOfDay)
lexDateTimeParts bytes = do
guard (B.length bytes >= 12)
(,) <$> textDateParts bytes <*> lexTimeOfDay (B.drop 11 bytes)
lexTime :: ByteString -> Maybe MySQLValue
lexTime bytes = uncurry MySQLTime <$> lexSignedTime bytes
-- | A TIME field: an optional minus sign before @hh:mm:ss[.fraction]@, where the
-- hours may exceed 24. The sign is 1 for negative, as in 'MySQLTime'.
lexSignedTime :: ByteString -> Maybe (Word8, TimeOfDay)
lexSignedTime bytes = do
guard (not (B.null bytes))
if B.index bytes 0 == 45 -- '-'
then (,) 1 <$> lexTimeOfDay (B.drop 1 bytes)
else (,) 0 <$> lexTimeOfDay bytes
-- | @hh:mm:ss[.fraction]@.
lexTimeOfDay :: ByteString -> Maybe TimeOfDay
lexTimeOfDay bytes = do
(hh, rest) <- LexInt.readDecimal bytes
guard (not (B.null rest))
(mm, rest') <- LexInt.readDecimal (B.tail rest)
guard (not (B.null rest'))
(ss, _) <- LexFrac.readDecimal (B.tail rest')
return (TimeOfDay hh mm ss)
-- | A column's position in a result set, counting from 0.
--
-- @since 1.4.0
newtype ColumnNumber = ColumnNumber Int
deriving (Show, Eq, Ord)
-- | @since 1.4.0
nextColumn :: ColumnNumber -> ColumnNumber
nextColumn (ColumnNumber column) = ColumnNumber (column + 1)
-- | Where and why a text-protocol row did not decode.
--
-- @since 1.4.0
data RowError = RowError
{ rowErrorColumn :: !ColumnNumber
, rowErrorOffset :: !Int -- ^ byte offset of that column's field in the row
, rowErrorKind :: !RowErrorKind
} deriving (Show, Eq)
-- | @since 1.4.0
data RowErrorKind
= RowEndsEarly
-- ^ the row ends before this column's field does
| RowInvalidLengthPrefix !Word8
-- ^ a field starting with a byte that is neither a length nor the NULL marker
| RowLengthOverflow
-- ^ an 8-byte length above 'maxBound' of 'Int'
| RowFieldError !TextFieldError
-- ^ the field's bytes did not decode
deriving (Show, Eq)
-- | @since 1.4.0
describeRowError :: RowError -> String
describeRowError (RowError (ColumnNumber column) offset kind) =
"Database.MySQL.Protocol.MySQLValue: column " ++ show column ++ " at byte "
++ show offset ++ ": " ++ kindDescription
where
kindDescription = case kind of
RowEndsEarly -> "the row ends inside this field"
RowInvalidLengthPrefix prefix -> "invalid length prefix " ++ show prefix
RowLengthOverflow -> "length does not fit an Int"
RowFieldError fieldError -> describeTextFieldError fieldError
-- | The values of a text-protocol row, one per 'ColumnKind'. Bytes after the
-- last column are ignored, as 'getTextRow' ignores them.
-- See Note [Text rows decoded once per result set].
--
-- @since 1.4.0
decodeTextRow :: [ColumnKind] -> ByteString -> Either RowError [MySQLValue]
decodeTextRow columns row = case decodeTextFields row (ColumnNumber 0) 0 columns of
(# rowError | #) -> Left rowError
(# | values #) -> Right values
-- | 'V.Vector' version of 'decodeTextRow'.
--
-- @since 1.4.0
decodeTextRowVector :: V.Vector ColumnKind -> ByteString -> Either RowError (V.Vector MySQLValue)
decodeTextRowVector columns row =
V.fromListN (V.length columns) <$> decodeTextRow (V.toList columns) row
-- | The fields of @columns@, the first of which is @column@ and starts at byte
-- @offset@ of the row.
decodeTextFields :: ByteString -> ColumnNumber -> Int -> [ColumnKind] -> (# RowError | [MySQLValue] #)
decodeTextFields row columnNumber offset columns = case columns of
[] -> (# | [] #)
column : laterColumns -> case decodeTextFieldAt row columnNumber offset column of
(# rowError | #) -> (# rowError | #)
(# | (# value, nextOffset #) #) ->
case decodeTextFields row (nextColumn columnNumber) nextOffset laterColumns of
(# rowError | #) -> (# rowError | #)
(# | values #) -> (# | value : values #)
-- | The field at byte @offset@ and the offset after it. The NULL marker is
-- checked before the column, as 'getTextRow' does.
decodeTextFieldAt :: ByteString -> ColumnNumber -> Int -> ColumnKind
-> (# RowError | (# MySQLValue, Int #) #)
decodeTextFieldAt row columnNumber offset column =
if | offset >= B.length row ->
(# RowError columnNumber offset RowEndsEarly | #)
| B.unsafeIndex row offset == 0xFB -> (# | (# MySQLNull, offset + 1 #) #)
| otherwise -> case column of
NullColumn -> (# | (# MySQLNull, offset #) #)
ValueColumn fieldType value -> case lengthEncodedInt row offset of
(# kind | #) -> (# RowError columnNumber offset kind | #)
(# | (# fieldLength, fieldStart #) #) ->
if fieldLength > B.length row - fieldStart
then (# RowError columnNumber offset RowEndsEarly | #)
else case decodeTextValue fieldType value
(B.unsafeTake fieldLength (B.unsafeDrop fieldStart row)) of
Left fieldError ->
(# RowError columnNumber offset (RowFieldError fieldError) | #)
Right decoded -> (# | (# decoded, fieldStart + fieldLength #) #)
-- | The length-encoded integer at byte @offset@, which must be inside the row,
-- and the offset after it.
lengthEncodedInt :: ByteString -> Int -> (# RowErrorKind | (# Int, Int #) #)
lengthEncodedInt row offset =
let prefix = B.unsafeIndex row offset
in if | prefix < 0xFB -> (# | (# Word8.toInt prefix, offset + 1 #) #)
| prefix == 0xFC -> littleEndianLength row (offset + 1) 2
| prefix == 0xFD -> littleEndianLength row (offset + 1) 3
| prefix == 0xFE -> littleEndianLength row (offset + 1) 8
| otherwise -> (# RowInvalidLengthPrefix prefix | #)
-- | The little-endian length of @width@ bytes at byte @start@, and the offset after it.
littleEndianLength :: ByteString -> Int -> Int -> (# RowErrorKind | (# Int, Int #) #)
littleEndianLength row start width =
if width > B.length row - start
then (# RowEndsEarly | #)
else case Word64.toInt (B.foldr' prependLittleEndianByte 0
(B.unsafeTake width (B.unsafeDrop start row))) of
Nothing -> (# RowLengthOverflow | #)
Just fieldLength -> (# | (# fieldLength, start + width #) #)
prependLittleEndianByte :: Word8 -> Word64 -> Word64
prependLittleEndianByte byte higherBytes = unsafeShiftL higherBytes 8 .|. Word8.toWord64 byte
-- | The @YYYY-MM-DD@ that starts a text-protocol date, which may be zero.
textDateParts :: ByteString -> Maybe RawDate
textDateParts bs = do
(yyyy, rest) <- LexInt.readDecimal bs :: Maybe (Int, ByteString)
guard (not (B.null rest))
(mm, rest') <- LexInt.readDecimal (B.tail rest) :: Maybe (Int, ByteString)
guard (not (B.null rest'))
(dd, _) <- LexInt.readDecimal (B.tail rest') :: Maybe (Int, ByteString)
RawDate <$> Int.toWord16 yyyy <*> Int.toWord8 mm <*> Int.toWord8 dd
-- | How the bytes of a string column decode, by the character set id the
-- server sent them in. See Note [Result character sets].
stringKind :: Word16 -> ValueKind
stringKind charsetId =
if | charsetId == 63 -> KindBytes
| charsetId `elem` latin1Collations -> KindLatin1Text
| otherwise -> KindText charsetId
-- | The ids of @information_schema.collations@ whose character set is latin1,
-- in MySQL 8.0 and MariaDB 11.4 (which adds the two nopad ones).
latin1Collations :: [Word16]
latin1Collations = [5, 8, 15, 31, 47, 48, 49, 94, 1032, 1071]
-- Note [Result character sets]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- The server converts string columns to character_set_results, so with a
-- UTF-8 connection charset every text column arrives as UTF-8. A connection
-- set to another charset, as after @SET NAMES latin1@, gets that charset's
-- bytes. latin1 is decoded here; any other charset is read as UTF-8, which
-- keeps ASCII-only values working as they always did, and fails with a
-- 'TextFieldInvalidUtf8' naming the charset on bytes that are not UTF-8,
-- rather than return mangled text.
stringColumnValue :: ColumnDef -> ByteString -> Get MySQLValue
stringColumnValue column bytes =
case decodeTextValue (columnType column) (stringKind (columnCharSet column)) bytes of
Right value -> pure value
Left fieldError ->
fail (describeTextFieldError fieldError ++ " Column: " ++ show (columnName column))
-- | MySQL's latin1, which is Windows-1252 with its five unassigned bytes
-- (0x81, 0x8D, 0x8F, 0x90, 0x9D) mapped to the C1 controls of the same number.
-- 'T.decodeLatin1' alone is ISO-8859-1, which reads all of 0x80 to 0x9F as
-- C1 controls, so the 27 bytes Windows-1252 assigns are remapped after it.
decodeMySQLLatin1 :: ByteString -> Text
decodeMySQLLatin1 = T.map windows1252Char . T.decodeLatin1
windows1252Char :: Char -> Char
windows1252Char char = case char of
'\x80' -> '\x20AC'
'\x82' -> '\x201A'
'\x83' -> '\x0192'
'\x84' -> '\x201E'
'\x85' -> '\x2026'
'\x86' -> '\x2020'
'\x87' -> '\x2021'
'\x88' -> '\x02C6'
'\x89' -> '\x2030'
'\x8A' -> '\x0160'
'\x8B' -> '\x2039'
'\x8C' -> '\x0152'
'\x8E' -> '\x017D'
'\x91' -> '\x2018'
'\x92' -> '\x2019'
'\x93' -> '\x201C'
'\x94' -> '\x201D'
'\x95' -> '\x2022'
'\x96' -> '\x2013'
'\x97' -> '\x2014'
'\x98' -> '\x02DC'
'\x99' -> '\x2122'
'\x9A' -> '\x0161'
'\x9B' -> '\x203A'
'\x9C' -> '\x0153'
'\x9E' -> '\x017E'
'\x9F' -> '\x0178'
sameCodePoint -> sameCodePoint
feedLenEncBytes :: FieldType -> (t -> b) -> (ByteString -> Maybe t) -> Get b
feedLenEncBytes typ con parser = do
bs <- getLenEncBytes
case parser bs of
Just v -> return (con v)
Nothing -> fail $ "Database.MySQL.Protocol.MySQLValue: parsing " ++ show typ ++ " failed, \
\input: " ++ BC.unpack bs
{-# INLINE feedLenEncBytes #-}
--------------------------------------------------------------------------------
-- | Text protocol encoder
putTextField :: MySQLValue -> Put
putTextField (MySQLDecimal n) = putBuilder (formatScientificBuilder Fixed Nothing n)
putTextField (MySQLInt8U n) = putBuilder (Textual.integral n)
putTextField (MySQLInt8 n) = putBuilder (Textual.integral n)
putTextField (MySQLInt16U n) = putBuilder (Textual.integral n)
putTextField (MySQLInt16 n) = putBuilder (Textual.integral n)
putTextField (MySQLInt32U n) = putBuilder (Textual.integral n)
putTextField (MySQLInt32 n) = putBuilder (Textual.integral n)
putTextField (MySQLInt64U n) = putBuilder (Textual.integral n)
putTextField (MySQLInt64 n) = putBuilder (Textual.integral n)
putTextField (MySQLFloat x) = putBuilder (Textual.float x)
putTextField (MySQLDouble x) = putBuilder (Textual.double x)
putTextField (MySQLYear n) = putBuilder (Textual.integral n)
putTextField (MySQLDateTime dt) = putInQuotes $
putByteString (BC.pack (formatTime defaultTimeLocale "%F %T%Q" dt))
putTextField (MySQLTimeStamp dt) = putInQuotes $
putByteString (BC.pack (formatTime defaultTimeLocale "%F %T%Q" dt))
putTextField (MySQLDate d) = putInQuotes $
putByteString (BC.pack (formatTime defaultTimeLocale "%F" d))
putTextField (MySQLDateRaw d) = putInQuotes $ putByteString (BC.pack (rawDateText d))
putTextField (MySQLDateTimeRaw d t) = putInQuotes $
putByteString (BC.pack (rawDateText d ++ formatTime defaultTimeLocale " %T%Q" t))
putTextField (MySQLTimeStampRaw d t) = putInQuotes $
putByteString (BC.pack (rawDateText d ++ formatTime defaultTimeLocale " %T%Q" t))
putTextField (MySQLTime sign t) = putInQuotes $ do
when (sign == 1) (putCharUtf8 '-')
putByteString (BC.pack (formatTime defaultTimeLocale "%T%Q" t))
-- this works even for hour > 24
putTextField (MySQLGeometry bs) = putInQuotes $ putByteString . escapeBytes $ bs
putTextField (MySQLBytes bs) = putInQuotes $ putByteString . escapeBytes $ bs
putTextField (MySQLText t) = putInQuotes $
putByteString . T.encodeUtf8 . escapeText $ t
putTextField (MySQLBit b) = do putBuilder "b\'"
putBuilder . execPut $ putTextBits b
putCharUtf8 '\''
where
putTextBits :: Word64 -> Put
putTextBits word = forM_ [63,62..0] $ \ pos ->
if word `testBit` pos then putCharUtf8 '1' else putCharUtf8 '0'
{-# INLINE putTextBits #-}
putTextField MySQLNull = putBuilder "NULL"
rawDateText :: RawDate -> String
rawDateText (RawDate year month day) = printf "%04d-%02d-%02d" year month day
putInQuotes :: Put -> Put
putInQuotes p = putCharUtf8 '\'' >> p >> putCharUtf8 '\''
{-# INLINE putInQuotes #-}
--------------------------------------------------------------------------------
-- | Text row decoder
getTextRow :: [ColumnDef] -> Get [MySQLValue]
getTextRow fs = forM fs $ \ f -> do
p <- peek
if p == 0xFB
then skipN 1 >> return MySQLNull
else getTextField f
{-# INLINE getTextRow #-}
getTextRowVector :: V.Vector ColumnDef -> Get (V.Vector MySQLValue)
getTextRowVector fs = V.forM fs $ \ f -> do
p <- peek
if p == 0xFB
then skipN 1 >> return MySQLNull
else getTextField f
{-# INLINE getTextRowVector #-}
--------------------------------------------------------------------------------
-- | Binary protocol decoder
getBinaryField :: ColumnDef -> Get MySQLValue
getBinaryField f
| t == mySQLTypeNull = pure MySQLNull
| t == mySQLTypeDecimal
|| t == mySQLTypeNewDecimal = feedLenEncBytes t MySQLDecimal fracLexer
| t == mySQLTypeTiny = if isUnsigned then MySQLInt8U <$> getWord8
else MySQLInt8 <$> getInt8
| t == mySQLTypeShort = if isUnsigned then MySQLInt16U <$> getWord16le
else MySQLInt16 <$> getInt16le
| t == mySQLTypeLong
|| t == mySQLTypeInt24 = if isUnsigned then MySQLInt32U <$> getWord32le
else MySQLInt32 <$> getInt32le
| t == mySQLTypeYear = MySQLYear <$> getWord16le
| t == mySQLTypeLongLong = if isUnsigned then MySQLInt64U <$> getWord64le
else MySQLInt64 <$> getInt64le
| t == mySQLTypeFloat = MySQLFloat <$> getFloatle
| t == mySQLTypeDouble = MySQLDouble <$> getDoublele
| t == mySQLTypeTimestamp
|| t == mySQLTypeTimestamp2 = do
n <- getLenEncInt
case n of
0 -> pure $ timeStampValue (RawDate 0 0 0) (TimeOfDay 0 0 0)
4 -> do
d <- getBinaryDateParts
pure $ timeStampValue d (TimeOfDay 0 0 0)
7 -> do
d <- getBinaryDateParts
td <- TimeOfDay <$> getInt8' <*> getInt8' <*> getSecond4
pure $ timeStampValue d td
11 -> do
d <- getBinaryDateParts
td <- TimeOfDay <$> getInt8' <*> getInt8' <*> getSecond8
pure $ timeStampValue d td
_ -> fail "Database.MySQL.Protocol.MySQLValue: wrong TIMESTAMP length"
| t == mySQLTypeDateTime
|| t == mySQLTypeDateTime2 = do
n <- getLenEncInt
case n of
0 -> pure $ dateTimeValue (RawDate 0 0 0) (TimeOfDay 0 0 0)
4 -> do
d <- getBinaryDateParts
pure $ dateTimeValue d (TimeOfDay 0 0 0)
7 -> do
d <- getBinaryDateParts
td <- TimeOfDay <$> getInt8' <*> getInt8' <*> getSecond4
pure $ dateTimeValue d td
11 -> do
d <- getBinaryDateParts
td <- TimeOfDay <$> getInt8' <*> getInt8' <*> getSecond8
pure $ dateTimeValue d td
_ -> fail "Database.MySQL.Protocol.MySQLValue: wrong DATETIME length"
| t == mySQLTypeDate
|| t == mySQLTypeNewDate = do
n <- getLenEncInt
case n of
0 -> pure $ dateValue (RawDate 0 0 0)
4 -> dateValue <$> getBinaryDateParts
_ -> fail "Database.MySQL.Protocol.MySQLValue: wrong DATE length"
| t == mySQLTypeTime
|| t == mySQLTypeTime2 = do
n <- getLenEncInt
case n of
0 -> pure $ MySQLTime 0 (TimeOfDay 0 0 0)
8 -> do
sign <- getWord8 -- is_negative(1 if minus, 0 for plus)
d <- fromIntegral <$> getWord32le
h <- getInt8'
MySQLTime sign <$> (TimeOfDay (d*24 + h) <$> getInt8' <*> getSecond4)
12 -> do
sign <- getWord8 -- is_negative(1 if minus, 0 for plus)
d <- fromIntegral <$> getWord32le
h <- getInt8'
MySQLTime sign <$> (TimeOfDay (d*24 + h) <$> getInt8' <*> getSecond8)
_ -> fail "Database.MySQL.Protocol.MySQLValue: wrong TIME length"
| t == mySQLTypeGeometry = MySQLGeometry <$> getLenEncBytes
| t == mySQLTypeVarChar
|| t == mySQLTypeEnum
|| t == mySQLTypeSet
|| t == mySQLTypeTinyBlob
|| t == mySQLTypeMediumBlob
|| t == mySQLTypeLongBlob
|| t == mySQLTypeBlob
|| t == mySQLTypeVarString
|| t == mySQLTypeString = getLenEncBytes >>= stringColumnValue f
| t == mySQLTypeBit = MySQLBit <$> (getBits =<< getLenEncInt)
| otherwise = fail $ "Database.MySQL.Protocol.MySQLValue:\
\ missing binary decoder for " ++ show t
where
t = columnType f
isUnsigned = flagUnsigned (columnFlags f)
fracLexer bs = fst <$> LexFrac.readSigned LexFrac.readDecimal bs
getInt8' :: Get Int
getInt8' = fromIntegral <$> getWord8
getSecond4 :: Get Pico
getSecond4 = realToFrac <$> getWord8
getSecond8 :: Get Pico
getSecond8 = do
s <- getInt8'
ms <- fromIntegral <$> getWord32le :: Get Int
pure $! (realToFrac s + realToFrac ms / 1000000 :: Pico)
getBinaryDateParts :: Get RawDate
getBinaryDateParts = RawDate <$> getWord16le <*> getWord8 <*> getWord8
-- | Get a bit sequence as a Word64
--
-- Since 'Word64' has a @Bits@ instance, it's easier to deal with in haskell.
--
getBits :: Int -> Get Word64
getBits bytes =
if | bytes == 0 || bytes == 1 -> fromIntegral <$> getWord8
| bytes == 2 -> fromIntegral <$> getWord16be
| bytes == 3 -> fromIntegral <$> getWord24be
| bytes == 4 -> fromIntegral <$> getWord32be
| bytes == 5 -> getWord40be
| bytes == 6 -> getWord48be
| bytes == 7 -> getWord56be
| bytes == 8 -> getWord64be
| otherwise -> fail $ "Database.MySQL.Protocol.MySQLValue: \
\wrong bit length size: " ++ show bytes
{-# INLINE getBits #-}
--------------------------------------------------------------------------------
-- | Binary protocol encoder
putBinaryField :: MySQLValue -> Put
putBinaryField (MySQLDecimal n) = putLenEncBytes . L.toStrict . BB.toLazyByteString $
formatScientificBuilder Fixed Nothing n
putBinaryField (MySQLInt8U n) = putWord8 n
putBinaryField (MySQLInt8 n) = putWord8 (fromIntegral n)
putBinaryField (MySQLInt16U n) = putWord16le n
putBinaryField (MySQLInt16 n) = putInt16le n
putBinaryField (MySQLInt32U n) = putWord32le n
putBinaryField (MySQLInt32 n) = putInt32le n
putBinaryField (MySQLInt64U n) = putWord64le n
putBinaryField (MySQLInt64 n) = putInt64le n
putBinaryField (MySQLFloat x) = putFloatle x
putBinaryField (MySQLDouble x) = putDoublele x
putBinaryField (MySQLYear n) = putWord16le n
putBinaryField (MySQLTimeStamp (LocalTime date time)) = do putWord8 11 -- always put full
putBinaryDay date
putBinaryTime' time
putBinaryField (MySQLDateTime (LocalTime date time)) = do putWord8 11 -- always put full
putBinaryDay date
putBinaryTime' time
putBinaryField (MySQLDate d) = do putWord8 4
putBinaryDay d
putBinaryField (MySQLDateRaw d) = do putWord8 4
putRawDate d
putBinaryField (MySQLDateTimeRaw d time) = do putWord8 11
putRawDate d
putBinaryTime' time
putBinaryField (MySQLTimeStampRaw d time) = do putWord8 11
putRawDate d
putBinaryTime' time
putBinaryField (MySQLTime sign t) = do putWord8 12 -- always put full
putWord8 sign
putBinaryTime t
putBinaryField (MySQLGeometry bs) = putLenEncBytes bs
putBinaryField (MySQLBytes bs) = putLenEncBytes bs
putBinaryField (MySQLBit word) = putWord64le word
putBinaryField (MySQLText t) = putLenEncBytes (T.encodeUtf8 t)
putBinaryField MySQLNull = return ()
putBinaryDay :: Day -> Put
putBinaryDay d = do let (yyyy, mm, dd) = toGregorian d
putWord16le (fromIntegral yyyy)
putWord8 (fromIntegral mm)
putWord8 (fromIntegral dd)
{-# INLINE putBinaryDay #-}
putRawDate :: RawDate -> Put
putRawDate (RawDate year month day) = putWord16le year >> putWord8 month >> putWord8 day
putBinaryTime' :: TimeOfDay -> Put
putBinaryTime' (TimeOfDay hh mm ss) = do let s = floor ss
ms = floor $ (ss - realToFrac s) * 1000000
putWord8 (fromIntegral hh)
putWord8 (fromIntegral mm)
putWord8 s
putWord32le ms
{-# INLINE putBinaryTime' #-}
putBinaryTime :: TimeOfDay -> Put
putBinaryTime (TimeOfDay hh mm ss) = do let s = floor ss
ms = floor $ (ss - realToFrac s) * 1000000
(d, h) = hh `quotRem` 24 -- hour may exceed 24 here
putWord32le (fromIntegral d)
putWord8 (fromIntegral h)
putWord8 (fromIntegral mm)
putWord8 s
putWord32le ms
{-# INLINE putBinaryTime #-}
--------------------------------------------------------------------------------
-- | Binary row decoder
--
-- MySQL use a special null bitmap without offset = 2 here.
--
getBinaryRow :: [ColumnDef] -> Int -> Get [MySQLValue]
getBinaryRow fields flen = do
skipN 1 -- 0x00
let maplen = (flen + 7 + 2) `shiftR` 3
nullmap <- BitMap <$> getByteString maplen
go fields nullmap 0
where
go :: [ColumnDef] -> BitMap -> Int -> Get [MySQLValue]
go [] _ _ = pure []
go (f:fs) nullmap pos = do
r <- if isColumnNull nullmap pos
then return MySQLNull
else getBinaryField f
let pos' = pos + 1
rest <- pos' `seq` go fs nullmap pos'
return (r `seq` (r : rest))
{-# INLINE getBinaryRow #-}
getBinaryRowVector :: V.Vector ColumnDef -> Int -> Get (V.Vector MySQLValue)
getBinaryRowVector fields flen = do
skipN 1 -- 0x00
let maplen = (flen + 7 + 2) `shiftR` 3
nullmap <- BitMap <$> getByteString maplen
(`V.imapM` fields) $ \ pos f ->
if isColumnNull nullmap pos then return MySQLNull else getBinaryField f
{-# INLINE getBinaryRowVector #-}
--------------------------------------------------------------------------------
-- | Use 'ByteString' to present a bitmap.
--
-- When used for represent bits values, the underlining 'ByteString' follows:
--
-- * byteString: head -> tail
-- * bit: high bit -> low bit
--
-- When used as a null-map/present-map, every bit inside a byte
-- is mapped to a column, the mapping order is following:
--
-- * byteString: head -> tail
-- * column: left -> right
--
-- We don't use 'Int64' here because there maybe more than 64 columns.
--
newtype BitMap = BitMap { fromBitMap :: ByteString } deriving (Eq, Show)
-- | Test if a column is set(binlog protocol).
--
-- The number counts from left to right.
--
isColumnSet :: BitMap -> Int -> Bool
isColumnSet (BitMap bitmap) pos =
let i = pos `unsafeShiftR` 3
j = pos .&. 7
in (bitmap `B.unsafeIndex` i) `testBit` j
{-# INLINE isColumnSet #-}
-- | Test if a column is null(binary protocol).
--
-- The number counts from left to right.
--
isColumnNull :: BitMap -> Int -> Bool
isColumnNull (BitMap nullmap) pos =
let
pos' = pos + 2
i = pos' `unsafeShiftR` 3
j = pos' .&. 7
in (nullmap `B.unsafeIndex` i) `testBit` j
{-# INLINE isColumnNull #-}
-- | Make a nullmap for params(binary protocol) without offset.
--
makeNullMap :: [MySQLValue] -> BitMap
makeNullMap values = BitMap . B.pack $ go values 0x00 0
where
go :: [MySQLValue] -> Word8 -> Int -> [Word8]
go [] byte 8 = [byte]
go vs byte 8 = byte : go vs 0x00 0
go [] byte _ = [byte]
go (MySQLNull:vs) byte pos = let pos' = pos + 1
byte' = byte .|. bit pos
in pos' `seq` byte' `seq` go vs byte' pos'
go (_ :vs) byte pos = let pos' = pos + 1 in pos' `seq` go vs byte pos'
--------------------------------------------------------------------------------
-- TODO: add helpers to parse mySQLTypeGEOMETRY
-- reference: https://github.com/felixge/node-mysql/blob/master/lib/protocol/Parser.js