Throw error on invalid escape pattern

3 files changed, 31 insertions, 19 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
index 8ee987e5ba..3df6effb6f 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
@@ -71,16 +71,16 @@ trait StringRegexExpression extends ImplicitCastInputTypes {
   usage = "str _FUNC_ pattern - Returns true if str matches pattern, " +
     "null if any arguments are null, false otherwise.",
   extended =
-    "The pattern is a string which is matched literally, with exception to the " +
-    "following special symbols:\n\n" +
+    "The pattern is a string which is matched literally, with exception to the following " +
+    "special symbols:\n\n" +
     "    _ matches any one character in the input (similar to . in posix " +
     "regular expressions)\n\n" +
     "    % matches zero ore more characters in the input (similar to .* in " +
-    "posix regular expressions\n\n" +
-    "The default escape character is '\\'. If an escape character precedes a special symbol or " +
-    "another escape character, the following character is matched literally, otherwise the " +
-     "escape character is treated literally. I.e. '\\%' would match '%', whereas '\\a' matches " +
-     "'\\a'.\n\n" +
+    "posix regular expressions)\n\n" +
+    "The escape character is '\\'. If an escape character precedes a special symbol or " +
+    "another escape character, the following character is matched literally, For example, " +
+    "the expression `<path> like \\%SystemDrive\\%\\\\Users%` will match any `<path>` that " +
+    "starts with '%SystemDrive%\\Users'. It is invalid to escape any other character.\n\n" +
     "Use RLIKE to match with standard regular expressions.")
 case class Like(left: Expression, right: Expression)
   extends BinaryExpression with StringRegexExpression {
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala
index 79c61023b4..b760b994f2 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringUtils.scala
@@ -19,6 +19,7 @@ package org.apache.spark.sql.catalyst.util
 
 import java.util.regex.{Pattern, PatternSyntaxException}
 
+import org.apache.spark.sql.AnalysisException
 import org.apache.spark.unsafe.types.UTF8String
 
 object StringUtils {
@@ -28,16 +29,18 @@ object StringUtils {
     val in = str.toIterator
     val out = new StringBuilder()
 
+    def fail(message: String) = throw new AnalysisException(
+      s"the pattern '$str' is invalid, $message")
+
     while (in.hasNext) {
       in.next match {
         case '\\' if in.hasNext =>
-          in.next match {
-            case '\\' => out ++= Pattern.quote("\\")
-            case '_' => out ++= Pattern.quote("_")
-            case '%' => out ++= Pattern.quote("%")
-            // escape before non-escapable character treated literally
-            case c => out ++= Pattern.quote("\\" + c)
+          val c = in.next
+          c match {
+            case '_' | '%' | '\\' => out ++= Pattern.quote(Character.toString(c))
+            case _ => fail(s"the escape character is not allowed to precede '$c'")
           }
+        case '\\' => fail("it is not allowed to end with the escape character")
         case '_' => out ++= "."
         case '%' => out ++= ".*"
         case c => out ++= Pattern.quote(Character.toString(c))
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala
index 71292dd701..6de2ba2131 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.sql.catalyst.expressions
 
 import org.apache.spark.SparkFunSuite
+import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.dsl.expressions._
 import org.apache.spark.sql.types.{IntegerType, StringType}
 
@@ -77,9 +78,13 @@ class RegexpExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     checkEvaluation("a\u20ACa" like "_€_", true)
     // scalastyle:on nonascii
 
-    // escaping non-escapable should match literally
-    checkEvaluation("""\a""" like """\a""", true)
-    checkEvaluation("""a\""" like """a\""", true)
+    // invalid escaping
+    intercept[AnalysisException] {
+      evaluate("""a""" like """\a""")
+    }
+    intercept[AnalysisException] {
+      evaluate("""a""" like """a\""")
+    }
 
     // case
     checkEvaluation("A" like "a%", false)
@@ -125,9 +130,13 @@ class RegexpExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     checkEvaluation("a\u20ACa" like regEx, true, create_row("_€_"))
     // scalastyle:on nonascii
 
-    // escaping non-escapable should match literally
-    checkEvaluation("""\a""" like regEx, true, create_row("""\a"""))
-    checkEvaluation("""a\""" like regEx, true, create_row("""a\"""))
+    // invalid escaping
+    intercept[AnalysisException] {
+      evaluate("""a""" like regEx, create_row("""\a"""))
+    }
+    intercept[AnalysisException] {
+      evaluate("""a""" like regEx, create_row("""a\"""))
+    }
 
     checkEvaluation("A" like regEx, false, create_row("a%"))
     checkEvaluation("a" like regEx, false, create_row("A%"))