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Use interpolation when loading properties, fixes #676 (#677)
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gnodet committed Aug 29, 2022
1 parent a8a7021 commit dc69f25
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import org.codehaus.plexus.util.StringUtils;
import org.codehaus.plexus.util.xml.pull.XmlPullParserException;
import org.mvndaemon.mvnd.common.Environment;
import org.mvndaemon.mvnd.common.InterpolationHelper;
import org.mvndaemon.mvnd.common.Os;
import org.mvndaemon.mvnd.common.SocketFamily;
import org.mvndaemon.mvnd.common.TimeUtils;
Expand Down Expand Up @@ -451,6 +452,8 @@ private static Properties loadProperties(Path path) {
if (Files.exists(path)) {
try (InputStream in = Files.newInputStream(path)) {
result.load(in);
InterpolationHelper.performSubstitution( ( Map<String, String> ) (Map) result,
new InterpolationHelper.SystemPropertiesSubstitutionCallback() );
} catch (IOException e) {
throw new RuntimeException("Could not read " + path);
}
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/*
* 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.mvndaemon.mvnd.common;

import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

/**
* <p>
* Enhancement of the standard <code>Properties</code>
* managing the maintain of comments, etc.
* </p>
*
* @author gnodet, jbonofre
*/
public class InterpolationHelper {

private InterpolationHelper() {
}

private static final char ESCAPE_CHAR = '\\';
private static final String DELIM_START = "${";
private static final String DELIM_STOP = "}";
private static final String MARKER = "$__";
private static final String ENV_PREFIX = "env:";

/**
* Callback for substitution
*/
public interface SubstitutionCallback {

String getValue(String key);

}

/**
* Perform substitution on a property set
*
* @param properties the property set to perform substitution on
*/
public static void performSubstitution(Map<String, String> properties) {
performSubstitution(properties, new SystemPropertiesSubstitutionCallback());
}

/**
* Perform substitution on a property set
*
* @param properties the property set to perform substitution on
* @param callback Callback for substituion
*/
public static void performSubstitution(Map<String, String> properties, SubstitutionCallback callback) {
performSubstitution(properties, callback, true, true, true);
}

/**
* Perform substitution on a property set
*
* @param properties the property set to perform substitution on
* @param callback the callback to obtain substitution values
* @param substituteFromConfig If substitute from configuration
* @param substituteFromSystemProperties If substitute from system properties
* @param defaultsToEmptyString sets an empty string if a replacement value is not found, leaves intact
* otherwise
*/
public static void performSubstitution(Map<String, String> properties,
SubstitutionCallback callback,
boolean substituteFromConfig,
boolean substituteFromSystemProperties,
boolean defaultsToEmptyString) {
Map<String, String> org = new HashMap<String, String>(properties);
for (String name : properties.keySet()) {
String value = properties.get(name);
properties.put(name,
substVars(value, name, null, org, callback, substituteFromConfig, substituteFromSystemProperties,
defaultsToEmptyString));
}
}

/**
* <p>
* This method performs property variable substitution on the
* specified value. If the specified value contains the syntax
* <tt>${&lt;prop-name&gt;}</tt>, where <tt>&lt;prop-name&gt;</tt>
* refers to either a configuration property or a system property,
* then the corresponding property value is substituted for the variable
* placeholder. Multiple variable placeholders may exist in the
* specified value as well as nested variable placeholders, which
* are substituted from inner most to outer most. Configuration
* properties override system properties.
* </p>
*
* @param val The string on which to perform property substitution.
* @param currentKey The key of the property being evaluated used to
* detect cycles.
* @param cycleMap Map of variable references used to detect nested cycles.
* @param configProps Set of configuration properties.
* @return The value of the specified string after system property substitution.
* @throws IllegalArgumentException If there was a syntax error in the
* property placeholder syntax or a recursive variable reference.
**/
public static String substVars(String val,
String currentKey,
Map<String, String> cycleMap,
Map<String, String> configProps)
throws IllegalArgumentException {
return substVars(val, currentKey, cycleMap, configProps, new SystemPropertiesSubstitutionCallback());
}

/**
* <p>
* This method performs property variable substitution on the
* specified value. If the specified value contains the syntax
* <tt>${&lt;prop-name&gt;}</tt>, where <tt>&lt;prop-name&gt;</tt>
* refers to either a configuration property or a system property,
* then the corresponding property value is substituted for the variable
* placeholder. Multiple variable placeholders may exist in the
* specified value as well as nested variable placeholders, which
* are substituted from inner most to outer most. Configuration
* properties override system properties.
* </p>
*
* @param val The string on which to perform property substitution.
* @param currentKey The key of the property being evaluated used to
* detect cycles.
* @param cycleMap Map of variable references used to detect nested cycles.
* @param configProps Set of configuration properties.
* @param callback the callback to obtain substitution values
* @return The value of the specified string after system property substitution.
* @throws IllegalArgumentException If there was a syntax error in the
* property placeholder syntax or a recursive variable reference.
**/
public static String substVars(String val,
String currentKey,
Map<String, String> cycleMap,
Map<String, String> configProps,
SubstitutionCallback callback)
throws IllegalArgumentException {
return substVars(val, currentKey, cycleMap, configProps, callback, true, true, true);
}

/**
* <p>
* This method performs property variable substitution on the
* specified value. If the specified value contains the syntax
* <tt>${&lt;prop-name&gt;}</tt>, where <tt>&lt;prop-name&gt;</tt>
* refers to either a configuration property or a system property,
* then the corresponding property value is substituted for the variable
* placeholder. Multiple variable placeholders may exist in the
* specified value as well as nested variable placeholders, which
* are substituted from inner most to outer most. Configuration
* properties override system properties.
* </p>
*
* @param val The string on which to perform property substitution.
* @param currentKey The key of the property being evaluated used to
* detect cycles.
* @param cycleMap Map of variable references used to detect nested cycles.
* @param configProps Set of configuration properties.
* @param callback the callback to obtain substitution values
* @param substituteFromConfig If substitute from configuration
* @param substituteFromSystemProperties If substitute from system properties
* @param defaultsToEmptyString sets an empty string if a replacement value is not found, leaves intact
* otherwise
* @return The value of the specified string after system property substitution.
* @throws IllegalArgumentException If there was a syntax error in the
* property placeholder syntax or a recursive variable reference.
**/
public static String substVars(String val,
String currentKey,
Map<String, String> cycleMap,
Map<String, String> configProps,
SubstitutionCallback callback,
boolean substituteFromConfig,
boolean substituteFromSystemProperties,
boolean defaultsToEmptyString)
throws IllegalArgumentException {
return unescape(doSubstVars(val, currentKey, cycleMap, configProps, callback, substituteFromConfig,
substituteFromSystemProperties, defaultsToEmptyString));
}

private static String doSubstVars(String val,
String currentKey,
Map<String, String> cycleMap,
Map<String, String> configProps,
SubstitutionCallback callback,
boolean substituteFromConfig,
boolean substituteFromSystemProperties,
boolean defaultsToEmptyString)
throws IllegalArgumentException {
if (cycleMap == null) {
cycleMap = new HashMap<String, String>();
}

// Put the current key in the cycle map.
cycleMap.put(currentKey, currentKey);

// Assume we have a value that is something like:
// "leading ${foo.${bar}} middle ${baz} trailing"

// Find the first ending '}' variable delimiter, which
// will correspond to the first deepest nested variable
// placeholder.
int startDelim;
int stopDelim = -1;
do {
stopDelim = val.indexOf(DELIM_STOP, stopDelim + 1);
while (stopDelim > 0 && val.charAt(stopDelim - 1) == ESCAPE_CHAR) {
stopDelim = val.indexOf(DELIM_STOP, stopDelim + 1);
}

// Find the matching starting "${" variable delimiter
// by looping until we find a start delimiter that is
// greater than the stop delimiter we have found.
startDelim = val.indexOf(DELIM_START);
while (stopDelim >= 0) {
int idx = val.indexOf(DELIM_START, startDelim + DELIM_START.length());
if ((idx < 0) || (idx > stopDelim)) {
break;
} else if (idx < stopDelim) {
startDelim = idx;
}
}
} while (startDelim >= 0 && stopDelim >= 0 && stopDelim < startDelim + DELIM_START.length());

// If we do not have a start or stop delimiter, then just
// return the existing value.
if ((startDelim < 0) || (stopDelim < 0)) {
cycleMap.remove(currentKey);
return val;
}

// At this point, we have found a variable placeholder so
// we must perform a variable substitution on it.
// Using the start and stop delimiter indices, extract
// the first, deepest nested variable placeholder.
String variable = val.substring(startDelim + DELIM_START.length(), stopDelim);
String org = variable;

// Strip expansion modifiers
int idx1 = variable.lastIndexOf(":-");
int idx2 = variable.lastIndexOf(":+");
int idx = idx1 >= 0 && idx2 >= 0 ? Math.min(idx1, idx2) : idx1 >= 0 ? idx1 : idx2;
String op = null;
if (idx >= 0 && idx < variable.length()) {
op = variable.substring(idx);
variable = variable.substring(0, idx);
}

// Verify that this is not a recursive variable reference.
if (cycleMap.get(variable) != null) {
throw new IllegalArgumentException("recursive variable reference: " + variable);
}

String substValue = null;
// Get the value of the deepest nested variable placeholder.
// Try to configuration properties first.
if (substituteFromConfig && configProps != null) {
substValue = configProps.get(variable);
}
if (substValue == null) {
if (variable.length() > 0) {
if (callback != null) {
substValue = callback.getValue(variable);
}
if (substValue == null && substituteFromSystemProperties) {
substValue = System.getProperty(variable);
}
}
}

if (op != null) {
if (op.startsWith(":-")) {
if (substValue == null || substValue.length() == 0) {
substValue = op.substring(":-".length());
}
} else if (op.startsWith(":+")) {
if (substValue != null && substValue.length() != 0) {
substValue = op.substring(":+".length());
}
} else {
throw new IllegalArgumentException("Bad substitution: ${" + org + "}");
}
}

if (substValue == null) {
if (defaultsToEmptyString) {
substValue = "";
} else {
// alters the original token to avoid infinite recursion
// altered tokens are reverted in substVarsPreserveUnresolved()
substValue = MARKER + "{" + variable + "}";
}
}

// Remove the found variable from the cycle map, since
// it may appear more than once in the value and we don't
// want such situations to appear as a recursive reference.
cycleMap.remove(variable);

// Append the leading characters, the substituted value of
// the variable, and the trailing characters to get the new
// value.
val = val.substring(0, startDelim) + substValue + val.substring(stopDelim + DELIM_STOP.length(),
val.length());

// Now perform substitution again, since there could still
// be substitutions to make.
val = doSubstVars(val, currentKey, cycleMap, configProps, callback, substituteFromConfig,
substituteFromSystemProperties, defaultsToEmptyString);

cycleMap.remove(currentKey);

// Return the value.
return val;
}

private static String unescape(String val) {
val = val.replaceAll("\\" + MARKER, "\\$");
int escape = val.indexOf(ESCAPE_CHAR);
while (escape >= 0 && escape < val.length() - 1) {
char c = val.charAt(escape + 1);
if (c == '{' || c == '}' || c == ESCAPE_CHAR) {
val = val.substring(0, escape) + val.substring(escape + 1);
}
escape = val.indexOf(ESCAPE_CHAR, escape + 1);
}
return val;
}

public static class SystemPropertiesSubstitutionCallback implements SubstitutionCallback {
private final Properties systemProperties;

public SystemPropertiesSubstitutionCallback() {
this(null);
}

public SystemPropertiesSubstitutionCallback(Properties systemProperties) {
this.systemProperties = systemProperties == null ? System.getProperties() : systemProperties;
}

public String getValue(String key) {
String value = null;
if (key.startsWith(ENV_PREFIX)) {
value = System.getenv(key.substring(ENV_PREFIX.length()));
} else {
value = systemProperties.getProperty(key);
}
return value;
}
}

}

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