PropertyReader.java

/*
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    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,
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    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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 */
package org.apache.wiki.util;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import javax.servlet.ServletContext;
import java.io.*;
import java.nio.file.Paths;
import java.util.*;
import java.util.stream.Collectors;
import java.nio.file.Files;


/**
 * Property Reader for the WikiEngine. Reads the properties for the WikiEngine
 * and implements the feature of cascading properties and variable substitution,
 * which come in handy in a multi wiki installation environment: It reduces the
 * need for (shell) scripting in order to generate different jspwiki.properties
 * to a minimum.
 *
 * @since 2.5.x
 */
public final class PropertyReader {

    private static final Logger LOG = LogManager.getLogger( PropertyReader.class );

    /**
     * Path to the base property file, {@value}, usually overridden by values provided in
     * a jspwiki-custom.properties file.
     */
    public static final String DEFAULT_JSPWIKI_CONFIG = "/ini/jspwiki.properties";

    /**
     * The servlet context parameter (from web.xml)  that defines where the config file is to be found. If it is not defined, checks
     * the Java System Property, if that is not defined either, uses the default as defined by DEFAULT_PROPERTYFILE.
     * {@value #DEFAULT_JSPWIKI_CONFIG}
     */
    public static final String PARAM_CUSTOMCONFIG = "jspwiki.custom.config";

    /**
     *  The prefix when you are cascading properties.
     *
     *  @see #loadWebAppProps(ServletContext)
     */
    public static final String PARAM_CUSTOMCONFIG_CASCADEPREFIX = "jspwiki.custom.cascade.";

    public static final String  CUSTOM_JSPWIKI_CONFIG = "/jspwiki-custom.properties";

    private static final String PARAM_VAR_DECLARATION = "var.";
    private static final String PARAM_VAR_IDENTIFIER  = "$";

    /**
     *  Private constructor to prevent instantiation.
     */
    private PropertyReader()
    {}

    /**
     *  Loads the webapp properties based on servlet context information, or
     *  (if absent) based on the Java System Property {@value #PARAM_CUSTOMCONFIG}.
     *  Returns a Properties object containing the settings, or null if unable
     *  to load it. (The default file is ini/jspwiki.properties, and can be
     *  customized by setting {@value #PARAM_CUSTOMCONFIG} in the server or webapp
     *  configuration.)
     *
     *  <h3>Properties sources</h3>
     *  The following properties sources are taken into account:
     *  <ol>
     *      <li>JSPWiki default properties</li>
     *      <li>System environment</li>
     *      <li>JSPWiki custom property files</li>
     *      <li>JSPWiki cascading properties</li>
     *      <li>System properties</li>
     *  </ol>
     *  With later sources taking precedence over the previous ones. To avoid leaking system information,
     *  only System environment and properties beginning with {@code jspwiki} (case unsensitive) are taken into account.
     *  Also, to ease docker integration, System env properties containing "_" are turned into ".". Thus,
     *  {@code ENV jspwiki_fileSystemProvider_pageDir} is loaded as {@code jspwiki.fileSystemProvider.pageDir}.
     *
     *  <h3>Cascading Properties</h3>
     *  <p>
     *  You can define additional property files and merge them into the default
     *  properties file in a similar process to how you define cascading style
     *  sheets; hence we call this <i>cascading property files</i>. This way you
     *  can overwrite the default values and only specify the properties you
     *  need to change in a multiple wiki environment.
     *  <p>
     *  You define a cascade in the context mapping of your servlet container.
     *  <pre>
     *  jspwiki.custom.cascade.1
     *  jspwiki.custom.cascade.2
     *  jspwiki.custom.cascade.3
     *  </pre>
     *  and so on. You have to number your cascade in a descending way starting
     *  with "1". This means you cannot leave out numbers in your cascade. This
     *  method is based on an idea by Olaf Kaus, see [JSPWiki:MultipleWikis].
     *
     *  @param context A Servlet Context which is used to find the properties
     *  @return A filled Properties object with all the cascaded properties in place
     */
    public static Properties loadWebAppProps( final ServletContext context ) {
        final String propertyFile = getInitParameter( context, PARAM_CUSTOMCONFIG );
        try( final InputStream propertyStream = loadCustomPropertiesFile(context, propertyFile) ) {
            final Properties props = getDefaultProperties();

            // add system env properties beginning with jspwiki...
            final Map< String, String > env = collectPropertiesFrom( System.getenv() );
            props.putAll( env );

            if( propertyStream == null ) {
                LOG.debug( "No custom property file found, relying on JSPWiki defaults." );
            } else {
                props.load( propertyStream );
            }

            // this will add additional properties to the default ones:
            LOG.debug( "Loading cascading properties..." );

            // now load the cascade (new in 2.5)
            loadWebAppPropsCascade( context, props );

            // property expansion so we can resolve things like ${TOMCAT_HOME}
            propertyExpansion( props );

            // sets the JSPWiki working directory (jspwiki.workDir)
            setWorkDir( context, props );

            // add system properties beginning with jspwiki...
            final Map< String, String > sysprops = collectPropertiesFrom( System.getProperties().entrySet().stream()
                                                                                .collect( Collectors.toMap( Object::toString, Object::toString ) ) );
            props.putAll( sysprops );

            // finally, expand the variables (new in 2.5)
            expandVars( props );

            return props;
        } catch( final Exception e ) {
            LOG.error( "JSPWiki: Unable to load and setup properties from jspwiki.properties. " + e.getMessage(), e );
        }

        return null;
    }

    static Map< String, String > collectPropertiesFrom( final Map< String, String > map ) {
        return map.entrySet().stream()
                  .filter( entry -> entry.getKey().toLowerCase().startsWith( "jspwiki" ) )
                  .map( entry -> new AbstractMap.SimpleEntry<>( entry.getKey().replace( "_", "." ), entry.getValue() ) )
                  .collect( Collectors.toMap( Map.Entry::getKey, Map.Entry::getValue ) );
    }

    /**
     * Figure out where our properties lie.
     *
     * @param context servlet context
     * @param propertyFile property file
     * @return InputStream holding the properties file
     * @throws FileNotFoundException properties file not found
     */
    static InputStream loadCustomPropertiesFile( final ServletContext context, final String propertyFile ) throws IOException {
        final InputStream propertyStream;
        if( propertyFile == null ) {
            LOG.debug( "No " + PARAM_CUSTOMCONFIG + " defined for this context, looking for custom properties file with default name of: " + CUSTOM_JSPWIKI_CONFIG );
            //  Use the custom property file at the default location
            propertyStream =  locateClassPathResource(context, CUSTOM_JSPWIKI_CONFIG);
        } else {
            LOG.debug( PARAM_CUSTOMCONFIG + " defined, using " + propertyFile + " as the custom properties file." );
            propertyStream = Files.newInputStream( new File(propertyFile).toPath() );
        }
        return propertyStream;
    }


    /**
     *  Returns the property set as a Properties object.
     *
     *  @return A property set.
     */
    public static Properties getDefaultProperties() {
        final Properties props = new Properties();
        try( final InputStream in = PropertyReader.class.getResourceAsStream( DEFAULT_JSPWIKI_CONFIG ) ) {
            if( in != null ) {
                props.load( in );
            }
        } catch( final IOException e ) {
            LOG.error( "Unable to load default propertyfile '{}' {}", DEFAULT_JSPWIKI_CONFIG, e.getMessage(), e );
        }

        return props;
    }

    /**
     *  Returns a property set consisting of the default Property Set overlaid with a custom property set
     *
     *  @param fileName Reference to the custom override file
     *  @return A property set consisting of the default property set and custom property set, with
     *          the latter's properties replacing the former for any common values
     */
    public static Properties getCombinedProperties( final String fileName ) {
        final Properties newPropertySet = getDefaultProperties();
        try( final InputStream in = PropertyReader.class.getResourceAsStream( fileName ) ) {
            if( in != null ) {
                newPropertySet.load( in );
            } else {
                LOG.error( "*** Custom property file \"" + fileName + "\" not found, relying on default file alone." );
            }
        } catch( final IOException e ) {
            LOG.error( "Unable to load propertyfile '" + fileName + "'" + e.getMessage(), e );
        }

        return newPropertySet;
    }

    /**
     * Returns the ServletContext Init parameter if has been set, otherwise checks for a System property of the same name. If neither are
     * defined, returns null. This permits both Servlet- and System-defined cascading properties.
     */
    private static String getInitParameter( final ServletContext context, final String name ) {
        final String value = context.getInitParameter( name );
        return value != null ? value : System.getProperty( name ) ;
    }


    /**
     *  Implement the cascade functionality.
     *
     * @param context             where to read the cascade from
     * @param defaultProperties   properties to merge the cascading properties to
     * @since 2.5.x
     */
    private static void loadWebAppPropsCascade( final ServletContext context, final Properties defaultProperties ) {
        if( getInitParameter( context, PARAM_CUSTOMCONFIG_CASCADEPREFIX + "1" ) == null ) {
            LOG.debug( " No cascading properties defined for this context" );
            return;
        }

        // get into cascade...
        int depth = 0;
        while( true ) {
            depth++;
            final String propertyFile = getInitParameter( context, PARAM_CUSTOMCONFIG_CASCADEPREFIX + depth );
            if( propertyFile == null ) {
                break;
            }

            try( final InputStream propertyStream = Files.newInputStream(Paths.get(( propertyFile ) ))) {
                LOG.info( " Reading additional properties from {} and merge to cascade.", propertyFile );
                final Properties additionalProps = new Properties();
                additionalProps.load( propertyStream );
                defaultProperties.putAll( additionalProps );
            } catch( final Exception e ) {
                LOG.error( "JSPWiki: Unable to load and setup properties from {}. {}", propertyFile, e.getMessage() );
            }
        }
    }

    /**
     * <p>Try to resolve properties whose value is something like {@code ${SOME_VALUE}} from a system property first and,
     * if not found, from a system environment variable. If not found on neither, the property value will remain as
     * {@code ${SOME_VALUE}}, and no more expansions will be processed.</p>
     *
     * <p>Several expansions per property is OK, but no we're not supporting fancy things like recursion. Reference to
     * other properties is achieved through {@link #expandVars(Properties)}. More than one property expansion per entry
     * is allowed.</p>
     *
     * @param properties properties to expand;
     */
    public static void propertyExpansion( final Properties properties ) {
        final Enumeration< ? > propertyList = properties.propertyNames();
        while( propertyList.hasMoreElements() ) {
            final String propertyName = ( String )propertyList.nextElement();
            String propertyValue = properties.getProperty( propertyName );
            while( propertyValue.contains( "${" ) && propertyValue.contains( "}" ) ) {
                final int start = propertyValue.indexOf( "${" );
                final int end = propertyValue.indexOf( "}", start );
                if( start >= 0 && end >= 0 && end > start ) {
                    final String substring = propertyValue.substring( start, end ).replace( "${", "" ).replace( "}", "" );
                    final String expansion = Objects.toString( System.getProperty( substring ), System.getenv( substring ) );
                    if( expansion != null ) {
                        propertyValue =  propertyValue.replace( "${" + substring + "}", expansion );
                        properties.setProperty( propertyName, propertyValue );
                    } else {
                        LOG.warn( "{} referenced on {} ({}) but not found on System props or env", substring, propertyName, propertyValue );
                        break;
                    }
                } else {
                    // no more matches or value like foo}${bar
                    break;
                }
            }
        }
    }

    /**
     *  <p>You define a property variable by using the prefix {@code var.x} as a property. In property values you can then use the "$x" identifier
     *  to use this variable.</p>
     *
     *  <p>For example, you could declare a base directory for all your files like this and use it in all your other property definitions with
     *  a {@code $basedir}. Note that it does not matter if you define the variable before its usage.
     *  <pre>
     *  var.basedir = /p/mywiki; # var.basedir = ${TOMCAT_HOME} would also be fine
     *  jspwiki.fileSystemProvider.pageDir =         $basedir/www/
     *  jspwiki.basicAttachmentProvider.storageDir = $basedir/www/
     *  jspwiki.workDir =                            $basedir/wrk/
     *  </pre></p>
     *
     * @param properties - properties to expand;
     */
    public static void expandVars( final Properties properties ) {
        //get variable name/values from properties...
        final Map< String, String > vars = new HashMap<>();
        Enumeration< ? > propertyList = properties.propertyNames();
        while( propertyList.hasMoreElements() ) {
            final String propertyName = ( String )propertyList.nextElement();
            final String propertyValue = properties.getProperty( propertyName );

            if ( propertyName.startsWith( PARAM_VAR_DECLARATION ) ) {
                final String varName = propertyName.substring( 4 ).trim();
                final String varValue = propertyValue.trim();
                vars.put( varName, varValue );
            }
        }

        //now, substitute $ values in property values with vars...
        propertyList = properties.propertyNames();
        while( propertyList.hasMoreElements() ) {
            final String propertyName = ( String )propertyList.nextElement();
            String propertyValue = properties.getProperty( propertyName );

            //skip var properties itself...
            if( propertyName.startsWith( PARAM_VAR_DECLARATION ) ) {
                continue;
            }

            for( final Map.Entry< String, String > entry : vars.entrySet() ) {
                final String varName = entry.getKey();
                final String varValue = entry.getValue();

                //replace old property value, using the same variabe. If we don't overwrite
                //the same one the next loop works with the original one again and
                //multiple var expansion won't work...
                propertyValue = TextUtil.replaceString( propertyValue, PARAM_VAR_IDENTIFIER + varName, varValue );

                //add the new PropertyValue to the properties
                properties.put( propertyName, propertyValue );
            }
        }
    }

    /**
     * Locate a resource stored in the class path. Try first with "WEB-INF/classes"
     * from the web app and fallback to "resourceName".
     *
     * @param context the servlet context
     * @param resourceName the name of the resource
     * @return the input stream of the resource or <b>null</b> if the resource was not found
     */
    public static InputStream locateClassPathResource( final ServletContext context, final String resourceName ) {
        InputStream result;
        String currResourceLocation;

        // garbage in - garbage out
        if( StringUtils.isEmpty( resourceName ) ) {
            return null;
        }

        // try with web app class loader searching in "WEB-INF/classes"
        currResourceLocation = createResourceLocation( "/WEB-INF/classes", resourceName );
        result = context.getResourceAsStream( currResourceLocation );
        if( result != null ) {
            LOG.debug( " Successfully located the following classpath resource : " + currResourceLocation );
            return result;
        }

        // if not found - try with the current class loader and the given name
        currResourceLocation = createResourceLocation( "", resourceName );
        result = PropertyReader.class.getResourceAsStream( currResourceLocation );
        if( result != null ) {
            LOG.debug( " Successfully located the following classpath resource : " + currResourceLocation );
            return result;
        }

        LOG.debug( " Unable to resolve the following classpath resource : " + resourceName );

        return result;
    }

    /**
     * Create a resource location with proper usage of "/".
     *
     * @param path a path
     * @param name a resource name
     * @return a resource location
     */
    static String createResourceLocation( final String path, final String name ) {
        Validate.notEmpty( name, "name is empty" );
        final StringBuilder result = new StringBuilder();

        // strip an ending "/"
        final String sanitizedPath = ( path != null && !path.isEmpty() && path.endsWith( "/" ) ? path.substring( 0, path.length() - 1 ) : path );

        // strip leading "/"
        final String sanitizedName = ( name.startsWith( "/" ) ? name.substring( 1 ) : name );

        // append the optional path
        if( sanitizedPath != null && !sanitizedPath.isEmpty() ) {
            if( !sanitizedPath.startsWith( "/" ) ) {
                result.append( "/" );
            }
            result.append( sanitizedPath );
        }
        result.append( "/" );

        // append the name
        result.append( sanitizedName );
        return result.toString();
    }

    /**
     * This method sets the JSPWiki working directory (jspwiki.workDir). It first checks if this property
     * is already set. If it isn't, it attempts to use the servlet container's temporary directory
     * (javax.servlet.context.tempdir). If that is also unavailable, it defaults to the system's temporary
     * directory (java.io.tmpdir).
     * <p>
     * This method is package-private to allow for unit testing.
     *
     * @param properties     the JSPWiki properties
     * @param servletContext the Servlet context from which to fetch the tempdir if needed
     * @since JSPWiki 2.11.1
     */
    static void setWorkDir( final ServletContext servletContext, final Properties properties ) {
        final String workDir = TextUtil.getStringProperty(properties, "jspwiki.workDir", null);
        if (workDir == null) {
            final File tempDir = (File) servletContext.getAttribute("javax.servlet.context.tempdir");
            if (tempDir != null) {
                properties.setProperty("jspwiki.workDir", tempDir.getAbsolutePath());
                LOG.info("Setting jspwiki.workDir to ServletContext's temporary directory: {}", tempDir.getAbsolutePath());
            } else {
                final String defaultTmpDir = System.getProperty("java.io.tmpdir");
                properties.setProperty("jspwiki.workDir", defaultTmpDir);
                LOG.info("ServletContext's temporary directory not found. Setting jspwiki.workDir to system's temporary directory: {}", defaultTmpDir);
            }
        } else {
            LOG.info("jspwiki.workDir is already set to: {}", workDir);
        }
    }

}