[SPARK-17160] Properly escape field names in code-generated error messages

This patch addresses a corner-case escaping bug where field names which contain special characters were unsafely interpolated into error message string literals in generated Java code, leading to compilation errors.

This patch addresses these issues by using `addReferenceObj` to store the error messages as string fields rather than inline string constants.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #15156 from JoshRosen/SPARK-17160.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/misc.scala

@@ -477,10 +477,13 @@ case class PrintToStderr(child: Expression) extends UnaryExpression {
 
   protected override def nullSafeEval(input: Any): Any = input
 
+  private val outputPrefix = s"Result of ${child.simpleString} is "
+
   override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+    val outputPrefixField = ctx.addReferenceObj("outputPrefix", outputPrefix)
     nullSafeCodeGen(ctx, ev, c =>
       s"""
-         | System.err.println("Result of ${child.simpleString} is " + $c);
+         | System.err.println($outputPrefixField + $c);
          | ${ev.value} = $c;
        """.stripMargin)
   }
@@ -501,10 +504,12 @@ case class AssertTrue(child: Expression) extends UnaryExpression with ImplicitCa
 
   override def prettyName: String = "assert_true"
 
+  private val errMsg = s"'${child.simpleString}' is not true!"
+
   override def eval(input: InternalRow) : Any = {
     val v = child.eval(input)
     if (v == null || java.lang.Boolean.FALSE.equals(v)) {
-      throw new RuntimeException(s"'${child.simpleString}' is not true!")
+      throw new RuntimeException(errMsg)
     } else {
       null
     }
@@ -512,9 +517,10 @@ case class AssertTrue(child: Expression) extends UnaryExpression with ImplicitCa
 
   override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
     val eval = child.genCode(ctx)
+    val errMsgField = ctx.addReferenceObj("errMsg", errMsg)
     ExprCode(code = s"""${eval.code}
        |if (${eval.isNull} || !${eval.value}) {
-       |  throw new RuntimeException("'${child.simpleString}' is not true.");
+       |  throw new RuntimeException($errMsgField);
        |}""".stripMargin, isNull = "true", value = "null")
   }
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/objects/objects.scala

@@ -938,7 +938,10 @@ case class GetExternalRowField(
   override def eval(input: InternalRow): Any =
     throw new UnsupportedOperationException("Only code-generated evaluation is supported")
 
+  private val errMsg = s"The ${index}th field '$fieldName' of input row cannot be null."
+
   override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+    val errMsgField = ctx.addReferenceObj("errMsg", errMsg)
     val row = child.genCode(ctx)
     val code = s"""
       ${row.code}
@@ -948,8 +951,7 @@ case class GetExternalRowField(
       }
 
       if (${row.value}.isNullAt($index)) {
-        throw new RuntimeException("The ${index}th field '$fieldName' of input row " +
-          "cannot be null.");
+        throw new RuntimeException($errMsgField);
       }
 
       final Object ${ev.value} = ${row.value}.get($index);
@@ -974,7 +976,10 @@ case class ValidateExternalType(child: Expression, expected: DataType)
   override def eval(input: InternalRow): Any =
     throw new UnsupportedOperationException("Only code-generated evaluation is supported")
 
+  private val errMsg = s" is not a valid external type for schema of ${expected.simpleString}"
+
   override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+    val errMsgField = ctx.addReferenceObj("errMsg", errMsg)
     val input = child.genCode(ctx)
     val obj = input.value
 
@@ -995,8 +1000,7 @@ case class ValidateExternalType(child: Expression, expected: DataType)
         if ($typeCheck) {
           ${ev.value} = (${ctx.boxedType(dataType)}) $obj;
         } else {
-          throw new RuntimeException($obj.getClass().getName() + " is not a valid " +
-            "external type for schema of ${expected.simpleString}");
+          throw new RuntimeException($obj.getClass().getName() + $errMsgField);
         }
       }
 

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CodeGenerationSuite.scala

@@ -23,7 +23,7 @@ import org.apache.spark.sql.Row
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.dsl.expressions._
 import org.apache.spark.sql.catalyst.expressions.codegen._
-import org.apache.spark.sql.catalyst.expressions.objects.CreateExternalRow
+import org.apache.spark.sql.catalyst.expressions.objects.{CreateExternalRow, GetExternalRowField, ValidateExternalType}
 import org.apache.spark.sql.catalyst.util.{ArrayBasedMapData, GenericArrayData}
 import org.apache.spark.sql.types._
 import org.apache.spark.unsafe.types.UTF8String
@@ -265,4 +265,15 @@ class CodeGenerationSuite extends SparkFunSuite with ExpressionEvalHelper {
       Literal.create("\\\\u001/Compilation error occurs", StringType) :: Nil)
 
   }
+
+  test("SPARK-17160: field names are properly escaped by GetExternalRowField") {
+    val inputObject = BoundReference(0, ObjectType(classOf[Row]), nullable = true)
+    GenerateUnsafeProjection.generate(
+      ValidateExternalType(
+        GetExternalRowField(inputObject, index = 0, fieldName = "\"quote"), IntegerType) :: Nil)
+  }
+
+  test("SPARK-17160: field names are properly escaped by AssertTrue") {
+    GenerateUnsafeProjection.generate(AssertTrue(Cast(Literal("\""), BooleanType)) :: Nil)
+  }
 }