Count unpaired carriage returns in adjustForLineEnding

src/main/java/org/apache/commons/validator/GenericValidator.java

@@ -53,7 +53,10 @@ private static int adjustForLineEnding(final String value, final int lineEndLeng
             }
         }
         final int rnCount = rCount + nCount;
-        return nCount * lineEndLength - rnCount;
+        // A carriage return that is not paired with a line feed is still a line ending, so the number of line
+        // endings is at least the number of carriage returns as well as the number of line feeds. Counting only
+        // the line feeds discounts every character of a CR-only value, leaving its adjusted length at zero.
+        return Math.max(nCount, rCount) * lineEndLength - rnCount;
     }
 
     /**

src/test/java/org/apache/commons/validator/GenericValidatorTest.java

@@ -34,6 +34,29 @@ void testIsDate() {
         assertFalse(GenericValidator.isDate("2/12/1999", "MM/dd/yyyy", true), "abbreviated month");
     }
 
+    /**
+     * A carriage return with no line feed next to it is a line ending in its own right, so it must not be
+     * discounted to zero characters.
+     */
+    @Test
+    void testLengthUnpairedCarriageReturn() {
+        // Use 0 for line end length
+        assertTrue(GenericValidator.maxLength("12345\r", 5, 0), "Max=5 End=0");
+        // Use 1 for line end length
+        assertFalse(GenericValidator.maxLength("12345\r", 5, 1), "Max=5 End=1");
+        assertTrue(GenericValidator.maxLength("12345\r", 6, 1), "Max=6 End=1");
+        // Use 2 for line end length
+        assertFalse(GenericValidator.maxLength("12345\r", 6, 2), "Max=6 End=2");
+        assertTrue(GenericValidator.maxLength("12345\r", 7, 2), "Max=7 End=2");
+        assertTrue(GenericValidator.minLength("12345\r", 7, 2), "Min=7 End=2");
+        assertFalse(GenericValidator.minLength("12345\r", 8, 2), "Min=8 End=2");
+        // Carriage returns alone used to leave the adjusted length at zero whatever the value's length
+        assertFalse(GenericValidator.maxLength("\r\r\r\r\r", 1, 2), "Max=1 End=2");
+        // The paired form is unchanged
+        assertFalse(GenericValidator.maxLength("12345\r\n", 6, 2), "Max=6 End=2 paired");
+        assertTrue(GenericValidator.maxLength("12345\r\n", 7, 2), "Max=7 End=2 paired");
+    }
+
     @Test
     void testMaxLength() {