GODRIVER-3240 Replace bit-shifting; apply size check for integer conv…

…ersions.

bson/bsoncodec/default_value_decoders.go

@@ -330,7 +330,7 @@ func (DefaultValueDecoders) intDecodeType(dc DecodeContext, vr bsonrw.ValueReade
 	case reflect.Int64:
 		return reflect.ValueOf(i64), nil
 	case reflect.Int:
-		if int64(int(i64)) != i64 { // Can we fit this inside of an int
+		if i64 > math.MaxInt { // Can we fit this inside of an int
 			return emptyValue, fmt.Errorf("%d overflows int", i64)
 		}
 
@@ -434,7 +434,7 @@ func (dvd DefaultValueDecoders) UintDecodeValue(dc DecodeContext, vr bsonrw.Valu
 			return fmt.Errorf("%d overflows uint64", i64)
 		}
 	case reflect.Uint:
-		if i64 < 0 || int64(uint(i64)) != i64 { // Can we fit this inside of an uint
+		if i64 < 0 || uint64(i64) > uint64(math.MaxUint) { // Can we fit this inside of an uint
 			return fmt.Errorf("%d overflows uint", i64)
 		}
 	default:

bson/bsoncodec/uint_codec.go

@@ -164,7 +164,7 @@ func (uic *UIntCodec) decodeType(dc DecodeContext, vr bsonrw.ValueReader, t refl
 
 		return reflect.ValueOf(uint64(i64)), nil
 	case reflect.Uint:
-		if i64 < 0 || int64(uint(i64)) != i64 { // Can we fit this inside of an uint
+		if i64 < 0 || uint64(i64) > uint64(math.MaxUint) { // Can we fit this inside of an uint
 			return emptyValue, fmt.Errorf("%d overflows uint", i64)
 		}
 

bson/bsonrw/extjson_wrappers.go

@@ -8,6 +8,7 @@ package bsonrw
 
 import (
 	"encoding/base64"
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"math"
@@ -95,12 +96,14 @@ func (ejv *extJSONValue) parseBinary() (b []byte, subType byte, err error) {
 				return nil, 0, fmt.Errorf("$binary subType value should be string, but instead is %s", val.t)
 			}
 
-			i, err := strconv.ParseInt(val.v.(string), 16, 64)
+			i, err := strconv.ParseUint(val.v.(string), 16, 64)
 			if err != nil {
 				return nil, 0, fmt.Errorf("invalid $binary subType string: %s", val.v.(string))
 			}
 
-			subType = byte(i)
+			b := []byte{0, 0, 0, 0, 0, 0, 0, 0}
+			binary.LittleEndian.PutUint64(b, i)
+			subType = b[0]
 			stFound = true
 		default:
 			return nil, 0, fmt.Errorf("invalid key in $binary object: %s", key)

bson/bsonrw/value_reader.go

@@ -842,7 +842,7 @@ func (vr *valueReader) peekLength() (int32, error) {
 	}
 
 	idx := vr.offset
-	return (int32(vr.d[idx]) | int32(vr.d[idx+1])<<8 | int32(vr.d[idx+2])<<16 | int32(vr.d[idx+3])<<24), nil
+	return int32(binary.LittleEndian.Uint32(vr.d[idx:])), nil
 }
 
 func (vr *valueReader) readLength() (int32, error) { return vr.readi32() }
@@ -854,7 +854,7 @@ func (vr *valueReader) readi32() (int32, error) {
 
 	idx := vr.offset
 	vr.offset += 4
-	return (int32(vr.d[idx]) | int32(vr.d[idx+1])<<8 | int32(vr.d[idx+2])<<16 | int32(vr.d[idx+3])<<24), nil
+	return int32(binary.LittleEndian.Uint32(vr.d[idx:])), nil
 }
 
 func (vr *valueReader) readu32() (uint32, error) {
@@ -864,7 +864,7 @@ func (vr *valueReader) readu32() (uint32, error) {
 
 	idx := vr.offset
 	vr.offset += 4
-	return (uint32(vr.d[idx]) | uint32(vr.d[idx+1])<<8 | uint32(vr.d[idx+2])<<16 | uint32(vr.d[idx+3])<<24), nil
+	return binary.LittleEndian.Uint32(vr.d[idx:]), nil
 }
 
 func (vr *valueReader) readi64() (int64, error) {
@@ -874,8 +874,7 @@ func (vr *valueReader) readi64() (int64, error) {
 
 	idx := vr.offset
 	vr.offset += 8
-	return int64(vr.d[idx]) | int64(vr.d[idx+1])<<8 | int64(vr.d[idx+2])<<16 | int64(vr.d[idx+3])<<24 |
-		int64(vr.d[idx+4])<<32 | int64(vr.d[idx+5])<<40 | int64(vr.d[idx+6])<<48 | int64(vr.d[idx+7])<<56, nil
+	return int64(binary.LittleEndian.Uint64(vr.d[idx:])), nil
 }
 
 func (vr *valueReader) readu64() (uint64, error) {
@@ -885,6 +884,5 @@ func (vr *valueReader) readu64() (uint64, error) {
 
 	idx := vr.offset
 	vr.offset += 8
-	return uint64(vr.d[idx]) | uint64(vr.d[idx+1])<<8 | uint64(vr.d[idx+2])<<16 | uint64(vr.d[idx+3])<<24 |
-		uint64(vr.d[idx+4])<<32 | uint64(vr.d[idx+5])<<40 | uint64(vr.d[idx+6])<<48 | uint64(vr.d[idx+7])<<56, nil
+	return binary.LittleEndian.Uint64(vr.d[idx:]), nil
 }

x/bsonx/bsoncore/bsoncore.go

@@ -8,6 +8,7 @@ package bsoncore // import "go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
 
 import (
 	"bytes"
+	"encoding/binary"
 	"fmt"
 	"math"
 	"strconv"
@@ -734,51 +735,47 @@ func readi32(src []byte) (int32, []byte, bool) {
 	if len(src) < 4 {
 		return 0, src, false
 	}
-	return (int32(src[0]) | int32(src[1])<<8 | int32(src[2])<<16 | int32(src[3])<<24), src[4:], true
+	return int32(binary.LittleEndian.Uint32(src)), src[4:], true
 }
 
 func appendi64(dst []byte, i64 int64) []byte {
-	return append(dst,
-		byte(i64), byte(i64>>8), byte(i64>>16), byte(i64>>24),
-		byte(i64>>32), byte(i64>>40), byte(i64>>48), byte(i64>>56),
-	)
+	b := []byte{0, 0, 0, 0, 0, 0, 0, 0}
+	binary.LittleEndian.PutUint64(b, uint64(i64))
+	return append(dst, b...)
 }
 
 func readi64(src []byte) (int64, []byte, bool) {
 	if len(src) < 8 {
 		return 0, src, false
 	}
-	i64 := (int64(src[0]) | int64(src[1])<<8 | int64(src[2])<<16 | int64(src[3])<<24 |
-		int64(src[4])<<32 | int64(src[5])<<40 | int64(src[6])<<48 | int64(src[7])<<56)
-	return i64, src[8:], true
+	return int64(binary.LittleEndian.Uint64(src)), src[8:], true
 }
 
 func appendu32(dst []byte, u32 uint32) []byte {
-	return append(dst, byte(u32), byte(u32>>8), byte(u32>>16), byte(u32>>24))
+	b := []byte{0, 0, 0, 0}
+	binary.LittleEndian.PutUint32(b, u32)
+	return append(dst, b...)
 }
 
 func readu32(src []byte) (uint32, []byte, bool) {
 	if len(src) < 4 {
 		return 0, src, false
 	}
 
-	return (uint32(src[0]) | uint32(src[1])<<8 | uint32(src[2])<<16 | uint32(src[3])<<24), src[4:], true
+	return binary.LittleEndian.Uint32(src), src[4:], true
 }
 
 func appendu64(dst []byte, u64 uint64) []byte {
-	return append(dst,
-		byte(u64), byte(u64>>8), byte(u64>>16), byte(u64>>24),
-		byte(u64>>32), byte(u64>>40), byte(u64>>48), byte(u64>>56),
-	)
+	b := []byte{0, 0, 0, 0, 0, 0, 0, 0}
+	binary.LittleEndian.PutUint64(b, u64)
+	return append(dst, b...)
 }
 
 func readu64(src []byte) (uint64, []byte, bool) {
 	if len(src) < 8 {
 		return 0, src, false
 	}
-	u64 := (uint64(src[0]) | uint64(src[1])<<8 | uint64(src[2])<<16 | uint64(src[3])<<24 |
-		uint64(src[4])<<32 | uint64(src[5])<<40 | uint64(src[6])<<48 | uint64(src[7])<<56)
-	return u64, src[8:], true
+	return binary.LittleEndian.Uint64(src), src[8:], true
 }
 
 // keep in sync with readcstringbytes