001/**
002 * Logback: the reliable, generic, fast and flexible logging framework.
003 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
004 *
005 * This program and the accompanying materials are dual-licensed under
006 * either the terms of the Eclipse Public License v1.0 as published by
007 * the Eclipse Foundation
008 *
009 *   or (per the licensee's choosing)
010 *
011 * under the terms of the GNU Lesser General Public License version 2.1
012 * as published by the Free Software Foundation.
013 */
014package ch.qos.logback.classic.spi;
015
016import ch.qos.logback.core.CoreConstants;
017
018import java.util.List;
019
020import static ch.qos.logback.core.CoreConstants.NA;
021
022/**
023 * This class computes caller data returning the result in the form of a
024 * StackTraceElement array.
025 *
026 * @author Ceki Gülcü
027 */
028public class CallerData {
029
030
031    // All logger call's in log4j-over-slf4j use the Category class
032    private static final String LOG4J_CATEGORY = "org.apache.log4j.Category";
033    private static final String SLF4J_BOUNDARY = "org.slf4j.Logger";
034
035    /**
036     * When caller information is not available this constant is used for the line
037     * number.
038     */
039    public static final int LINE_NA = -1;
040
041    public static final String CALLER_DATA_NA = "?#?:?" + CoreConstants.LINE_SEPARATOR;
042
043    /**
044     * This value is returned in case no caller data could be extracted.
045     */
046    public static final StackTraceElement[] EMPTY_CALLER_DATA_ARRAY = new StackTraceElement[0];
047
048    /**
049     * Extract caller data information as an array based on a Throwable passed as
050     * parameter
051     */
052    public static StackTraceElement[] extract(Throwable t, String fqnOfInvokingClass, final int maxDepth,
053            List<String> frameworkPackageList) {
054        if (t == null) {
055            return null;
056        }
057
058        StackTraceElement[] steArray = t.getStackTrace();
059        StackTraceElement[] callerDataArray;
060
061        int found = LINE_NA;
062        for (int i = 0; i < steArray.length; i++) {
063            if (isInFrameworkSpace(steArray[i].getClassName(), fqnOfInvokingClass, frameworkPackageList)) {
064                // the caller is assumed to be the next stack frame, hence the +1.
065                found = i + 1;
066            } else {
067                if (found != LINE_NA) {
068                    break;
069                }
070            }
071        }
072
073        // we failed to extract caller data
074        if (found == LINE_NA) {
075            return EMPTY_CALLER_DATA_ARRAY;
076        }
077
078        int availableDepth = steArray.length - found;
079        int desiredDepth = maxDepth < (availableDepth) ? maxDepth : availableDepth;
080
081        callerDataArray = new StackTraceElement[desiredDepth];
082        for (int i = 0; i < desiredDepth; i++) {
083            callerDataArray[i] = steArray[found + i];
084        }
085        return callerDataArray;
086    }
087
088    static boolean isInFrameworkSpace(String currentClass, String fqnOfInvokingClass,
089            List<String> frameworkPackageList) {
090        // the check for org.apache.log4j.Category class is intended to support
091        // log4j-over-slf4j. it solves http://bugzilla.slf4j.org/show_bug.cgi?id=66
092        if (currentClass.equals(fqnOfInvokingClass) || currentClass.equals(LOG4J_CATEGORY)
093                || currentClass.startsWith(SLF4J_BOUNDARY)
094                || isInFrameworkSpaceList(currentClass, frameworkPackageList)) {
095            return true;
096        } else {
097            return false;
098        }
099    }
100
101    /**
102     * Is currentClass present in the list of packages considered part of the
103     * logging framework?
104     */
105    private static boolean isInFrameworkSpaceList(String currentClass, List<String> frameworkPackageList) {
106        if (frameworkPackageList == null)
107            return false;
108
109        for (String s : frameworkPackageList) {
110            if (currentClass.startsWith(s))
111                return true;
112        }
113        return false;
114    }
115
116    /**
117     * Returns a StackTraceElement where all string fields are set to {@link CoreConstants#NA}
118     * and line number is set to {@link #LINE_NA}.
119     *
120     * @return StackTraceElement with values set to NA constants.
121     * @since 1.0.10
122     */
123    public static StackTraceElement naInstance() {
124        return new StackTraceElement(NA, NA, NA, LINE_NA);
125    }
126
127}