fix(mysql): escape backslash char in strings

dialect/append.go

@@ -1,10 +1,8 @@
 package dialect
 
 import (
-	"encoding/hex"
 	"math"
 	"strconv"
-	"unicode/utf8"
 
 	"github.com/uptrace/bun/internal"
 )
@@ -48,50 +46,6 @@ func appendFloat(b []byte, v float64, bitSize int) []byte {
 	}
 }
 
-func AppendString(b []byte, s string) []byte {
-	b = append(b, '\'')
-	for _, r := range s {
-		if r == '\000' {
-			continue
-		}
-
-		if r == '\'' {
-			b = append(b, '\'', '\'')
-			continue
-		}
-
-		if r < utf8.RuneSelf {
-			b = append(b, byte(r))
-			continue
-		}
-
-		l := len(b)
-		if cap(b)-l < utf8.UTFMax {
-			b = append(b, make([]byte, utf8.UTFMax)...)
-		}
-		n := utf8.EncodeRune(b[l:l+utf8.UTFMax], r)
-		b = b[:l+n]
-	}
-	b = append(b, '\'')
-	return b
-}
-
-func AppendBytes(b, bs []byte) []byte {
-	if bs == nil {
-		return AppendNull(b)
-	}
-
-	b = append(b, `'\x`...)
-
-	s := len(b)
-	b = append(b, make([]byte, hex.EncodedLen(len(bs)))...)
-	hex.Encode(b[s:], bs)
-
-	b = append(b, '\'')
-
-	return b
-}
-
 //------------------------------------------------------------------------------
 
 func AppendIdent(b []byte, field string, quote byte) []byte {

dialect/mysqldialect/dialect.go

@@ -6,6 +6,7 @@ import (
 	"log"
 	"strings"
 	"time"
+	"unicode/utf8"
 
 	"golang.org/x/mod/semver"
 
@@ -82,14 +83,45 @@ func (d *Dialect) IdentQuote() byte {
 	return '`'
 }
 
-func (d *Dialect) AppendTime(b []byte, tm time.Time) []byte {
+func (*Dialect) AppendTime(b []byte, tm time.Time) []byte {
 	b = append(b, '\'')
 	b = tm.AppendFormat(b, "2006-01-02 15:04:05.999999")
 	b = append(b, '\'')
 	return b
 }
 
-func (d *Dialect) AppendBytes(b []byte, bs []byte) []byte {
+func (*Dialect) AppendString(b []byte, s string) []byte {
+	b = append(b, '\'')
+loop:
+	for _, r := range s {
+		switch r {
+		case '\000':
+			continue loop
+		case '\'':
+			b = append(b, "''"...)
+			continue loop
+		case '\\':
+			b = append(b, '\\', '\\')
+			continue loop
+		}
+
+		if r < utf8.RuneSelf {
+			b = append(b, byte(r))
+			continue
+		}
+
+		l := len(b)
+		if cap(b)-l < utf8.UTFMax {
+			b = append(b, make([]byte, utf8.UTFMax)...)
+		}
+		n := utf8.EncodeRune(b[l:l+utf8.UTFMax], r)
+		b = b[:l+n]
+	}
+	b = append(b, '\'')
+	return b
+}
+
+func (*Dialect) AppendBytes(b []byte, bs []byte) []byte {
 	if bs == nil {
 		return dialect.AppendNull(b)
 	}
@@ -105,7 +137,7 @@ func (d *Dialect) AppendBytes(b []byte, bs []byte) []byte {
 	return b
 }
 
-func (d *Dialect) AppendJSON(b, jsonb []byte) []byte {
+func (*Dialect) AppendJSON(b, jsonb []byte) []byte {
 	b = append(b, '\'')
 
 	for _, c := range jsonb {

internal/dbtest/db_test.go

@@ -265,6 +265,11 @@ func testSelectScan(t *testing.T, db *bun.DB) {
 	err = db.NewSelect().TableExpr("(SELECT 10) AS t").Where("FALSE").Scan(ctx, &num)
 	require.Equal(t, sql.ErrNoRows, err)
 
+	var str string
+	err = db.NewSelect().ColumnExpr("?", "\\\"'hello\n%_").Scan(ctx, &str)
+	require.NoError(t, err)
+	require.Equal(t, "\\\"'hello\n%_", str)
+
 	var flag bool
 	err = db.NewSelect().
 		ColumnExpr("EXISTS (?)", db.NewSelect().ColumnExpr("1")).

query_select.go

@@ -10,7 +10,6 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/uptrace/bun/dialect"
 	"github.com/uptrace/bun/internal"
 	"github.com/uptrace/bun/schema"
 )
@@ -542,7 +541,7 @@ func (q *SelectQuery) appendColumns(fmter schema.Formatter, b []byte) (_ []byte,
 		if len(q.table.Fields) > 10 && fmter.IsNop() {
 			b = append(b, q.table.SQLAlias...)
 			b = append(b, '.')
-			b = dialect.AppendString(b, fmt.Sprintf("%d columns", len(q.table.Fields)))
+			b = fmter.Dialect().AppendString(b, fmt.Sprintf("%d columns", len(q.table.Fields)))
 		} else {
 			b = appendColumns(b, q.table.SQLAlias, q.table.Fields)
 		}

schema/append.go

@@ -31,7 +31,7 @@ func Append(fmter Formatter, b []byte, v interface{}) []byte {
 	case float64:
 		return dialect.AppendFloat64(b, v)
 	case string:
-		return dialect.AppendString(b, v)
+		return fmter.Dialect().AppendString(b, v)
 	case time.Time:
 		return fmter.Dialect().AppendTime(b, v)
 	case []byte:

schema/append_value.go

@@ -194,7 +194,7 @@ func appendArrayBytesValue(fmter Formatter, b []byte, v reflect.Value) []byte {
 }
 
 func AppendStringValue(fmter Formatter, b []byte, v reflect.Value) []byte {
-	return dialect.AppendString(b, v.String())
+	return fmter.Dialect().AppendString(b, v.String())
 }
 
 func AppendJSONValue(fmter Formatter, b []byte, v reflect.Value) []byte {
@@ -217,20 +217,20 @@ func appendTimeValue(fmter Formatter, b []byte, v reflect.Value) []byte {
 
 func appendIPValue(fmter Formatter, b []byte, v reflect.Value) []byte {
 	ip := v.Interface().(net.IP)
-	return dialect.AppendString(b, ip.String())
+	return fmter.Dialect().AppendString(b, ip.String())
 }
 
 func appendIPNetValue(fmter Formatter, b []byte, v reflect.Value) []byte {
 	ipnet := v.Interface().(net.IPNet)
-	return dialect.AppendString(b, ipnet.String())
+	return fmter.Dialect().AppendString(b, ipnet.String())
 }
 
 func appendJSONRawMessageValue(fmter Formatter, b []byte, v reflect.Value) []byte {
 	bytes := v.Bytes()
 	if bytes == nil {
 		return dialect.AppendNull(b)
 	}
-	return dialect.AppendString(b, internal.String(bytes))
+	return fmter.Dialect().AppendString(b, internal.String(bytes))
 }
 
 func appendQueryAppenderValue(fmter Formatter, b []byte, v reflect.Value) []byte {

schema/dialect.go

@@ -2,8 +2,10 @@ package schema
 
 import (
 	"database/sql"
+	"encoding/hex"
 	"strconv"
 	"time"
+	"unicode/utf8"
 
 	"github.com/uptrace/bun/dialect"
 	"github.com/uptrace/bun/dialect/feature"
@@ -24,6 +26,7 @@ type Dialect interface {
 	AppendUint32(b []byte, n uint32) []byte
 	AppendUint64(b []byte, n uint64) []byte
 	AppendTime(b []byte, tm time.Time) []byte
+	AppendString(b []byte, s string) []byte
 	AppendBytes(b []byte, bs []byte) []byte
 	AppendJSON(b, jsonb []byte) []byte
 }
@@ -47,8 +50,48 @@ func (BaseDialect) AppendTime(b []byte, tm time.Time) []byte {
 	return b
 }
 
+func (BaseDialect) AppendString(b []byte, s string) []byte {
+	b = append(b, '\'')
+	for _, r := range s {
+		if r == '\000' {
+			continue
+		}
+
+		if r == '\'' {
+			b = append(b, '\'', '\'')
+			continue
+		}
+
+		if r < utf8.RuneSelf {
+			b = append(b, byte(r))
+			continue
+		}
+
+		l := len(b)
+		if cap(b)-l < utf8.UTFMax {
+			b = append(b, make([]byte, utf8.UTFMax)...)
+		}
+		n := utf8.EncodeRune(b[l:l+utf8.UTFMax], r)
+		b = b[:l+n]
+	}
+	b = append(b, '\'')
+	return b
+}
+
 func (BaseDialect) AppendBytes(b, bs []byte) []byte {
-	return dialect.AppendBytes(b, bs)
+	if bs == nil {
+		return dialect.AppendNull(b)
+	}
+
+	b = append(b, `'\x`...)
+
+	s := len(b)
+	b = append(b, make([]byte, hex.EncodedLen(len(bs)))...)
+	hex.Encode(b[s:], bs)
+
+	b = append(b, '\'')
+
+	return b
 }
 
 func (BaseDialect) AppendJSON(b, jsonb []byte) []byte {