Fix italic and underline ANSI escape codes

log4j-core-test/src/test/java/org/apache/logging/log4j/core/pattern/AnsiEscapeTest.java

@@ -0,0 +1,63 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.logging.log4j.core.pattern;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+/**
+ * Regression tests for ANSI SGR attribute codes (GitHub issue #4105).
+ * <p>
+ * Expected values are hard-coded SGR sequences so a wrong mapping cannot
+ * compare equal to itself.
+ * </p>
+ */
+class AnsiEscapeTest {
+
+    @ParameterizedTest
+    @CsvSource({
+        // Log4j style names
+        "normal, 0",
+        "bold, 1",
+        "dim, 2",
+        "italic, 3",
+        "underline, 4",
+        "blink, 5",
+        "reverse, 7",
+        "hidden, 8",
+        // Jansi AnsiRenderer.Code names / aliases (post-#3070 parity)
+        "reset, 0",
+        "intensity_bold, 1",
+        "faint, 2",
+        "intensity_faint, 2",
+        "blink_slow, 5",
+        "blink_fast, 6",
+        "blink_off, 25",
+        "negative_on, 7",
+        "negative_off, 27",
+        "conceal_on, 8",
+        "conceal_off, 28",
+        "underline_double, 21",
+        "underline_off, 24",
+        "bg_default, 49",
+    })
+    void styleMapsToSgr(final String name, final String sgrCode) {
+        assertEquals("\u001B[" + sgrCode + "m", AnsiEscape.createSequence(name));
+    }
+}

log4j-core-test/src/test/java/org/apache/logging/log4j/core/pattern/JAnsiTextRendererTest.java

@@ -39,6 +39,14 @@ public static Stream<Arguments> testRendering() {
                         "",
                         "@|white key|@ = @|cyan,bold some value|@",
                         "\u001b[37mkey\u001b[m = \u001b[36;1msome value\u001b[m"),
+                Arguments.of(
+                        "",
+                        "@|italic italic text|@ and @|underline underlined text|@",
+                        "\u001b[3mitalic text\u001b[m and \u001b[4munderlined text\u001b[m"),
+                Arguments.of(
+                        "",
+                        "@|faint faint text|@ and @|blink_slow blinking text|@",
+                        "\u001b[2mfaint text\u001b[m and \u001b[5mblinking text\u001b[m"),
                 // Return broken escapes as is
                 Arguments.of("", "Hello @|crazy|@ world!", "Hello @|crazy|@ world!"),
                 Arguments.of("", "Hello @|world!", "Hello @|world!"));

log4j-core/src/main/java/org/apache/logging/log4j/core/pattern/AnsiEscape.java

@@ -58,6 +58,11 @@ public enum AnsiEscape {
      */
     NORMAL("0"),
 
+    /**
+     * Reset general attribute (Jansi {@code AnsiRenderer.Code} name).
+     */
+    RESET("0"),
+
     /**
      * Bright general attribute.
      *
@@ -72,31 +77,96 @@ public enum AnsiEscape {
      */
     BOLD("1"),
 
+    /**
+     * Bold intensity attribute (Jansi {@code AnsiRenderer.Code} name).
+     */
+    INTENSITY_BOLD("1"),
+
     /**
      * Dim general attribute.
      */
     DIM("2"),
 
+    /**
+     * Faint / dim general attribute (Jansi {@code AnsiRenderer.Code} name).
+     */
+    FAINT("2"),
+
+    /**
+     * Faint intensity attribute (Jansi {@code AnsiRenderer.Code} name).
+     */
+    INTENSITY_FAINT("2"),
+
+    /**
+     * Italic general attribute.
+     */
+    ITALIC("3"),
+
     /**
      * Underline general attribute.
      */
-    UNDERLINE("3"),
+    UNDERLINE("4"),
 
     /**
      * Blink general attribute.
      */
     BLINK("5"),
 
+    /**
+     * Slow blink general attribute (Jansi {@code AnsiRenderer.Code} name).
+     */
+    BLINK_SLOW("5"),
+
+    /**
+     * Fast blink general attribute.
+     */
+    BLINK_FAST("6"),
+
     /**
      * Reverse general attribute.
      */
     REVERSE("7"),
 
     /**
-     * Normal general attribute.
+     * Reverse / negative general attribute (Jansi {@code AnsiRenderer.Code} name).
+     */
+    NEGATIVE_ON("7"),
+
+    /**
+     * Conceal / hidden general attribute.
      */
     HIDDEN("8"),
 
+    /**
+     * Conceal general attribute (Jansi {@code AnsiRenderer.Code} name).
+     */
+    CONCEAL_ON("8"),
+
+    /**
+     * Double underline general attribute.
+     */
+    UNDERLINE_DOUBLE("21"),
+
+    /**
+     * Turns underline off.
+     */
+    UNDERLINE_OFF("24"),
+
+    /**
+     * Turns blink off.
+     */
+    BLINK_OFF("25"),
+
+    /**
+     * Turns reverse / negative video off.
+     */
+    NEGATIVE_OFF("27"),
+
+    /**
+     * Turns conceal off.
+     */
+    CONCEAL_OFF("28"),
+
     /**
      * Black foreground color.
      */
@@ -227,6 +297,11 @@ public enum AnsiEscape {
      */
     BG_WHITE("47"),
 
+    /**
+     * Default background color.
+     */
+    BG_DEFAULT("49"),
+
     /**
      * Bright black foreground color.
      */

src/changelog/.2.x.x/4105_fix_AnsiEscape_italic_underline.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns="https://logging.apache.org/xml/ns"
+       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xsi:schemaLocation="
+           https://logging.apache.org/xml/ns
+           https://logging.apache.org/xml/ns/log4j-changelog-0.xsd"
+       type="fixed">
+  <issue id="4105" link="https://github.com/apache/logging-log4j2/issues/4105"/>
+  <description format="asciidoc">
+    Fix `AnsiEscape` italic/underline SGR codes and restore missing Jansi `AnsiRenderer.Code` style names (for example `faint`, `blink_slow`)
+  </description>
+</entry>

src/site/antora/modules/ROOT/pages/manual/pattern-layout.adoc

@@ -1465,8 +1465,8 @@ In EBNF form the syntax of a style expression is:
                    | <keyword>
 <hex> ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7"
         | "8" | "9" | "a" | "b" | "c" | "d" | "e" | "f"
-<keyword> ::= "normal" | "bold" | "dim" | "underline"
-            | "blink" | "reverse" | "hidden"
+<keyword> ::= "normal" | "reset" | "bold" | "dim" | "faint" | "italic" | "underline"
+            | "underline_double" | "blink" | "blink_slow" | "blink_fast" | "reverse" | "hidden"
             | "black" | "bg_black" | "bright_black" | "bg_bright_black"
             | "red" | "bg_red" | "bright_red" | "bg_bright_red"
             | "green" | "bg_green" | "bright_green" | "bg_bright_green"
@@ -1481,11 +1481,14 @@ For example, you can use `underline blue bg_bright_yellow` to specify a blue und
 
 The style specifiers have the following effects (see https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters[Select Graphic Rendition] for details):
 
-`normal`:: Reverts all parameters to their default value
+`normal` / `reset`:: Reverts all parameters to their default value
 `bold`:: Increases the font weight or the color intensity
-`dim`:: Decreases the fond weight or the color intensity
+`dim` / `faint`:: Decreases the font weight or the color intensity
+`italic`:: Renders the text in italic on terminals that support it
 `underline`:: Underlines the text on some terminals
-`blink`:: Causes the text to blink
+`underline_double`:: Double-underlines the text on terminals that support it
+`blink` / `blink_slow`:: Causes the text to blink
+`blink_fast`:: Causes the text to blink rapidly on terminals that support it
 `reverse`:: Swaps foreground and background colors
 `hidden`:: Hides the text