fix: LOG4J2-3627 and gh issue 1729

Author: alan0428a

log4j-core-test/src/test/java/org/apache/logging/log4j/core/impl/ThrowableProxyRendererTest.java

@@ -33,6 +33,7 @@ public void test_formatExtendedStackTraceTo() {
  new ArrayList<>(),
  new PlainTextRenderer(),
  "",
- System.lineSeparator());
+ System.lineSeparator(),
+ null);
  }
 }

log4j-core/src/main/java/org/apache/logging/log4j/core/impl/ThrowableProxy.java

@@ -255,7 +255,7 @@ public ThrowableProxy getCauseProxy() {
  * @param suffix Append this to the end of each stack frame.
  */
  public String getCauseStackTraceAsString(final String suffix) {
- return this.getCauseStackTraceAsString(null, PlainTextRenderer.getInstance(), suffix, EOL_STR);
+ return this.getCauseStackTraceAsString(null, PlainTextRenderer.getInstance(), suffix, EOL_STR, null);
  }
 
  /**
@@ -266,7 +266,7 @@ public String getCauseStackTraceAsString(final String suffix) {
  * @return The formatted Throwable that caused this Throwable.
  */
  public String getCauseStackTraceAsString(final List<String> packages, final String suffix) {
- return getCauseStackTraceAsString(packages, PlainTextRenderer.getInstance(), suffix, EOL_STR);
+ return getCauseStackTraceAsString(packages, PlainTextRenderer.getInstance(), suffix, EOL_STR, null);
  }
 
  /**
@@ -279,7 +279,7 @@ public String getCauseStackTraceAsString(final List<String> packages, final Stri
  */
  public String getCauseStackTraceAsString(
  final List<String> ignorePackages, final TextRenderer textRenderer, final String suffix) {
- return getCauseStackTraceAsString(ignorePackages, textRenderer, suffix, EOL_STR);
+ return getCauseStackTraceAsString(ignorePackages, textRenderer, suffix, EOL_STR, null);
  }
 
  /**
@@ -295,12 +295,35 @@ public String getCauseStackTraceAsString(
  final List<String> ignorePackages,
  final TextRenderer textRenderer,
  final String suffix,
- final String lineSeparator) {
+ final String lineSeparator,
+ final Integer linesToKeep) {
  final StringBuilder sb = new StringBuilder();
- ThrowableProxyRenderer.formatCauseStackTrace(this, sb, ignorePackages, textRenderer, suffix, lineSeparator);
+ ThrowableProxyRenderer.formatCauseStackTraceTo(
+ this, sb, ignorePackages, textRenderer, suffix, lineSeparator, linesToKeep);
  return sb.toString();
  }
 
+ /**
+ * Formats the stack trace with cause exception.
+ *
+ * @param sb Destination.
+ * @param ignorePackages List of packages to be ignored in the trace.
+ * @param textRenderer The message renderer.
+ * @param suffix Append this to the end of each stack frame.
+ * @param lineSeparator The end-of-line separator.
+ * @param linesToKeep The total line count of final result
+ */
+ public void formatCauseStackTraceTo(
+ final StringBuilder sb,
+ final List<String> ignorePackages,
+ final TextRenderer textRenderer,
+ final String suffix,
+ final String lineSeparator,
+ final Integer linesToKeep) {
+ ThrowableProxyRenderer.formatCauseStackTraceTo(
+ this, sb, ignorePackages, textRenderer, suffix, lineSeparator, linesToKeep);
+ }
+
  /**
  * Returns the number of elements that are being omitted because they are common with the parent Throwable's stack
  * trace.
@@ -389,7 +412,7 @@ public String getExtendedStackTraceAsString(
  final String suffix,
  final String lineSeparator) {
  final StringBuilder sb = new StringBuilder(1024);
- formatExtendedStackTraceTo(sb, ignorePackages, textRenderer, suffix, lineSeparator);
+ formatExtendedStackTraceTo(sb, ignorePackages, textRenderer, suffix, lineSeparator, null);
  return sb.toString();
  }
 
@@ -401,15 +424,17 @@ public String getExtendedStackTraceAsString(
  * @param textRenderer The message renderer.
  * @param suffix Append this to the end of each stack frame.
  * @param lineSeparator The end-of-line separator.
+ * @param linesToKeep The total line count of final result
  */
  public void formatExtendedStackTraceTo(
  final StringBuilder sb,
  final List<String> ignorePackages,
  final TextRenderer textRenderer,
  final String suffix,
- final String lineSeparator) {
+ final String lineSeparator,
+ final Integer linesToKeep) {
  ThrowableProxyRenderer.formatExtendedStackTraceTo(
- this, sb, ignorePackages, textRenderer, suffix, lineSeparator);
+ this, sb, ignorePackages, textRenderer, suffix, lineSeparator, linesToKeep);
  }
 
  public String getLocalizedMessage() {

log4j-core/src/main/java/org/apache/logging/log4j/core/impl/ThrowableProxyRenderer.java

@@ -240,10 +240,9 @@ static void formatExtendedStackTraceTo(
  final List<String> ignorePackages,
  final TextRenderer textRenderer,
  final String suffix,
- final String lineSeparator) {
- textRenderer.render(src.getName(), sb, "Name");
- textRenderer.render(": ", sb, "NameMessageSeparator");
- textRenderer.render(src.getMessage(), sb, "Message");
+ final String lineSeparator,
+ final Integer linesToKeep) {
+ renderOn(src, sb, textRenderer);
  renderSuffix(suffix, sb, textRenderer);
  textRenderer.render(lineSeparator, sb, "Text");
  final StackTraceElement[] causedTrace =
@@ -260,6 +259,7 @@ static void formatExtendedStackTraceTo(
  lineSeparator);
  formatSuppressed(sb, TAB, src.getSuppressedProxies(), ignorePackages, textRenderer, suffix, lineSeparator);
  formatCause(sb, Strings.EMPTY, src.getCauseProxy(), ignorePackages, textRenderer, suffix, lineSeparator);
+ truncateLines(sb, lineSeparator, linesToKeep, textRenderer);
  }
 
  /**
@@ -272,23 +272,24 @@ static void formatExtendedStackTraceTo(
  * @param suffix Append this to the end of each stack frame.
  * @param lineSeparator The end-of-line separator.
  */
- static void formatCauseStackTrace(
+ static void formatCauseStackTraceTo(
  final ThrowableProxy src,
  final StringBuilder sb,
  final List<String> ignorePackages,
  final TextRenderer textRenderer,
  final String suffix,
- final String lineSeparator) {
+ final String lineSeparator,
+ final Integer linesToKeep) {
  final ThrowableProxy causeProxy = src.getCauseProxy();
  if (causeProxy != null) {
  formatWrapper(sb, causeProxy, ignorePackages, textRenderer, suffix, lineSeparator);
  sb.append(WRAPPED_BY_LABEL);
- ThrowableProxyRenderer.renderSuffix(suffix, sb, textRenderer);
+ renderSuffix(suffix, sb, textRenderer);
  }
  renderOn(src, sb, textRenderer);
- ThrowableProxyRenderer.renderSuffix(suffix, sb, textRenderer);
+ renderSuffix(suffix, sb, textRenderer);
  textRenderer.render(lineSeparator, sb, "Text");
- ThrowableProxyRenderer.formatElements(
+ formatElements(
  sb,
  Strings.EMPTY,
  0,
@@ -298,6 +299,7 @@ static void formatCauseStackTrace(
  textRenderer,
  suffix,
  lineSeparator);
+ truncateLines(sb, lineSeparator, linesToKeep, textRenderer);
  }
 
  private static void renderOn(
@@ -309,4 +311,24 @@ private static void renderOn(
  textRenderer.render(msg, output, "Message");
  }
  }
+
+ private static void truncateLines(
+ StringBuilder sb, String lineSeparator, Integer linesToKeep, TextRenderer textRenderer) {
+ if (linesToKeep == null) {
+ return;
+ }
+
+ String content = sb.toString();
+ String[] lines = content.split(lineSeparator);
+
+ if (lines.length <= linesToKeep) {
+ return;
+ }
+
+ sb.setLength(0);
+ for (int i = 0; i < linesToKeep; i++) {
+ sb.append(lines[i]);
+ textRenderer.render(lineSeparator, sb, "Text");
+ }
+ }
 }

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

@@ -76,7 +76,8 @@ public void format(final LogEvent event, final StringBuilder toAppendTo) {
  options.getIgnorePackages(),
  options.getTextRenderer(),
  getSuffix(event),
- options.getSeparator());
+ options.getSeparator(),
+ options.allLines() ? null : options.getLines());
  }
  }
 }

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

@@ -20,7 +20,6 @@
 import org.apache.logging.log4j.core.config.Configuration;
 import org.apache.logging.log4j.core.config.plugins.Plugin;
 import org.apache.logging.log4j.core.impl.ThrowableProxy;
-import org.apache.logging.log4j.util.Strings;
 
 /**
  * Outputs the Throwable portion of the LoggingEvent as a full stack trace
@@ -68,27 +67,17 @@ public void format(final LogEvent event, final StringBuilder toAppendTo) {
  super.format(event, toAppendTo);
  return;
  }
- final String trace = proxy.getCauseStackTraceAsString(
- options.getIgnorePackages(), options.getTextRenderer(), getSuffix(event), options.getSeparator());
  final int len = toAppendTo.length();
  if (len > 0 && !Character.isWhitespace(toAppendTo.charAt(len - 1))) {
  toAppendTo.append(' ');
  }
- if (!options.allLines() || !Strings.LINE_SEPARATOR.equals(options.getSeparator())) {
- final StringBuilder sb = new StringBuilder();
- final String[] array = trace.split(Strings.LINE_SEPARATOR);
- final int limit = options.minLines(array.length) - 1;
- for (int i = 0; i <= limit; ++i) {
- sb.append(array[i]);
- if (i < limit) {
- sb.append(options.getSeparator());
- }
- }
- toAppendTo.append(sb.toString());
-
- } else {
- toAppendTo.append(trace);
- }
+ proxy.formatCauseStackTraceTo(
+ toAppendTo,
+ options.getIgnorePackages(),
+ options.getTextRenderer(),
+ getSuffix(event),
+ options.getSeparator(),
+ options.allLines() ? null : options.getLines());
  }
  }
 }

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

@@ -18,7 +18,6 @@
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.io.PrintWriter;
-import java.io.StringWriter;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -188,23 +187,24 @@ private void formatOption(final Throwable throwable, final String suffix, final
  if (len > 0 && !Character.isWhitespace(buffer.charAt(len - 1))) {
  buffer.append(' ');
  }
- if (!options.allLines() || nonStandardLineSeparator || Strings.isNotBlank(suffix)) {
- final StringWriter w = new StringWriter();
- throwable.printStackTrace(new PrintWriter(w));
-
- final String[] array = w.toString().split(Strings.LINE_SEPARATOR);
- final int limit = options.minLines(array.length) - 1;
- final boolean suffixNotBlank = Strings.isNotBlank(suffix);
- for (int i = 0; i <= limit; ++i) {
- buffer.append(array[i]);
- if (suffixNotBlank) {
- buffer.append(' ');
- buffer.append(suffix);
- }
- if (i < limit) {
- buffer.append(options.getSeparator());
+ if (requireAdditionalFormatting(suffix)) {
+ StackTraceElement[] stackTrace = throwable.getStackTrace();
+ int ignoredCount = 0;
+ for (StackTraceElement stackTraceElement : stackTrace) {
+ if (!ignoreElement(stackTraceElement, options.getIgnorePackages())) {
+ if (ignoredCount > 0) {
+ appendSuppressedCount(buffer, ignoredCount, suffix, options.getSeparator());
+ ignoredCount = 0;
+ }
+ appendEntry(stackTraceElement, buffer, suffix, options.getSeparator());
+ } else {
+ ++ignoredCount;
  }
  }
+ if (ignoredCount > 0) {
+ appendSuppressedCount(buffer, ignoredCount, suffix, options.getSeparator());
+ }
+ truncateLines(buffer, options.getSeparator(), options.allLines() ? null : options.getLines());
  } else {
  throwable.printStackTrace(new PrintWriter(new StringBuilderWriter(buffer)));
  }
@@ -235,4 +235,69 @@ protected String getSuffix(final LogEvent event) {
  public ThrowableFormatOptions getOptions() {
  return options;
  }
+
+ private boolean requireAdditionalFormatting(String suffix) {
+ return !options.allLines() || nonStandardLineSeparator || Strings.isNotBlank(suffix) || options.hasPackages();
+ }
+
+ private boolean ignoreElement(final StackTraceElement element, final List<String> ignorePackages) {
+ if (ignorePackages != null) {
+ final String className = element.getClassName();
+ for (final String pkg : ignorePackages) {
+ if (className.startsWith(pkg)) {
+ return true;
+ }
+ }
+ }
+ return false;
+ }
+
+ private void appendSuppressedCount(
+ final StringBuilder sb, final int count, final String suffix, final String lineSeparator) {
+ if (count == 1) {
+ sb.append("\t... ");
+ } else {
+ sb.append("\t... suppressed ");
+ sb.append(count);
+ sb.append(" lines");
+ }
+ appendSuffix(sb, suffix);
+ sb.append(lineSeparator);
+ }
+
+ private void appendEntry(
+ final StackTraceElement stackTraceElement,
+ final StringBuilder sb,
+ final String suffix,
+ final String lineSeparator) {
+ sb.append(stackTraceElement.toString());
+ appendSuffix(sb, suffix);
+ sb.append(lineSeparator);
+ }
+
+ private void appendSuffix(StringBuilder buffer, String suffix) {
+ if (Strings.isNotBlank(suffix)) {
+ buffer.append(' ');
+ buffer.append(suffix);
+ }
+ }
+
+ private void truncateLines(StringBuilder sb, String lineSeparator, Integer linesToKeep) {
+ if (linesToKeep == null) {
+ return;
+ }
+
+ String content = sb.toString();
+ String[] lines = content.split(lineSeparator);
+
+ if (lines.length <= linesToKeep) {
+ return;
+ }
+
+ sb.setLength(0);
+ for (int i = 0; i < linesToKeep; i++) {
+ sb.append(lines[i]);
+ sb.append(lineSeparator);
+ }
+ }
 }