From 9b0ab9d84cdf9e4ba31e6266066c4c5d10dc6c96 Mon Sep 17 00:00:00 2001
From: kennytm <kennytm@gmail.com>
Date: Wed, 14 Nov 2018 23:09:09 +0800
Subject: [PATCH] executor: properly escape backquotes in identifiers in SHOW
 CREATE TABLE (#8302)

---
 executor/show.go      | 32 +++++++++++++++++++++++++-------
 executor/show_test.go | 29 +++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/executor/show.go b/executor/show.go
index b00ac27d74957..c680ba7a2012c 100644
--- a/executor/show.go
+++ b/executor/show.go
@@ -462,19 +462,35 @@ func getDefaultCollate(charsetName string) string {
 	return ""
 }
 
+// escape the identifier for pretty-printing.
+// For instance, the identifier "foo `bar`" will become "`foo ``bar```".
+// The sqlMode controls whether to escape with backquotes (`) or double quotes
+// (`"`) depending on whether mysql.ModeANSIQuotes is enabled.
+func escape(cis model.CIStr, sqlMode mysql.SQLMode) string {
+	var quote string
+	if sqlMode&mysql.ModeANSIQuotes != 0 {
+		quote = `"`
+	} else {
+		quote = "`"
+	}
+	return quote + strings.Replace(cis.O, quote, quote+quote, -1) + quote
+}
+
 func (e *ShowExec) fetchShowCreateTable() error {
 	tb, err := e.getTable()
 	if err != nil {
 		return errors.Trace(err)
 	}
 
+	sqlMode := e.ctx.GetSessionVars().SQLMode
+
 	// TODO: let the result more like MySQL.
 	var buf bytes.Buffer
-	buf.WriteString(fmt.Sprintf("CREATE TABLE `%s` (\n", tb.Meta().Name.O))
+	buf.WriteString(fmt.Sprintf("CREATE TABLE %s (\n", escape(tb.Meta().Name, sqlMode)))
 	var pkCol *table.Column
 	var hasAutoIncID bool
 	for i, col := range tb.Cols() {
-		buf.WriteString(fmt.Sprintf("  `%s` %s", col.Name.O, col.GetTypeDesc()))
+		buf.WriteString(fmt.Sprintf("  %s %s", escape(col.Name, sqlMode), col.GetTypeDesc()))
 		if col.IsGenerated() {
 			// It's a generated column.
 			buf.WriteString(fmt.Sprintf(" GENERATED ALWAYS AS (%s)", col.GeneratedExprString))
@@ -530,7 +546,7 @@ func (e *ShowExec) fetchShowCreateTable() error {
 	if pkCol != nil {
 		// If PKIsHanle, pk info is not in tb.Indices(). We should handle it here.
 		buf.WriteString(",\n")
-		buf.WriteString(fmt.Sprintf("  PRIMARY KEY (`%s`)", pkCol.Name.O))
+		buf.WriteString(fmt.Sprintf("  PRIMARY KEY (%s)", escape(pkCol.Name, sqlMode)))
 	}
 
 	if len(tb.Indices()) > 0 {
@@ -548,14 +564,14 @@ func (e *ShowExec) fetchShowCreateTable() error {
 		if idxInfo.Primary {
 			buf.WriteString("  PRIMARY KEY ")
 		} else if idxInfo.Unique {
-			buf.WriteString(fmt.Sprintf("  UNIQUE KEY `%s` ", idxInfo.Name.O))
+			buf.WriteString(fmt.Sprintf("  UNIQUE KEY %s ", escape(idxInfo.Name, sqlMode)))
 		} else {
-			buf.WriteString(fmt.Sprintf("  KEY `%s` ", idxInfo.Name.O))
+			buf.WriteString(fmt.Sprintf("  KEY %s ", escape(idxInfo.Name, sqlMode)))
 		}
 
 		cols := make([]string, 0, len(idxInfo.Columns))
 		for _, c := range idxInfo.Columns {
-			colInfo := fmt.Sprintf("`%s`", c.Name.String())
+			colInfo := escape(c.Name, sqlMode)
 			if c.Length != types.UnspecifiedLength {
 				colInfo = fmt.Sprintf("%s(%s)", colInfo, strconv.Itoa(c.Length))
 			}
@@ -623,8 +639,10 @@ func (e *ShowExec) fetchShowCreateDatabase() error {
 		return infoschema.ErrDatabaseNotExists.GenByArgs(e.DBName.O)
 	}
 
+	sqlMode := e.ctx.GetSessionVars().SQLMode
+
 	var buf bytes.Buffer
-	fmt.Fprintf(&buf, "CREATE DATABASE `%s`", db.Name.O)
+	fmt.Fprintf(&buf, "CREATE DATABASE %s", escape(db.Name, sqlMode))
 	if s := db.Charset; len(s) > 0 {
 		fmt.Fprintf(&buf, " /* !40100 DEFAULT CHARACTER SET %s */", s)
 	}
diff --git a/executor/show_test.go b/executor/show_test.go
index ef105db383c19..6e77a157b8602 100644
--- a/executor/show_test.go
+++ b/executor/show_test.go
@@ -525,3 +525,32 @@ func (s *testSuite) TestShowTableStatus(c *C) {
 		c.Assert(row.GetString(3), Equals, "Compact")
 	}
 }
+
+func (s *testSuite) TestShowEscape(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists `t``abl\"e`")
+	tk.MustExec("create table `t``abl\"e`(`c``olum\"n` int(11) primary key)")
+	tk.MustQuery("show create table `t``abl\"e`").Check(testutil.RowsWithSep("|",
+		""+
+			"t`abl\"e CREATE TABLE `t``abl\"e` (\n"+
+			"  `c``olum\"n` int(11) NOT NULL,\n"+
+			"  PRIMARY KEY (`c``olum\"n`)\n"+
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin",
+	))
+
+	// ANSI_QUOTES will change the SHOW output
+	tk.MustExec("set @old_sql_mode=@@sql_mode")
+	tk.MustExec("set sql_mode=ansi_quotes")
+	tk.MustQuery("show create table \"t`abl\"\"e\"").Check(testutil.RowsWithSep("|",
+		""+
+			"t`abl\"e CREATE TABLE \"t`abl\"\"e\" (\n"+
+			"  \"c`olum\"\"n\" int(11) NOT NULL,\n"+
+			"  PRIMARY KEY (\"c`olum\"\"n\")\n"+
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin",
+	))
+
+	tk.MustExec("rename table \"t`abl\"\"e\" to t")
+	tk.MustExec("set sql_mode=@old_sql_mode")
+}