Source for gnu.classpath.SystemProperties

   1: /* SystemProperties.java -- Manage the System properties.
   2:    Copyright (C) 2004, 2005, 2006 Free Software Foundation
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package gnu.classpath;
  40: 
  41: import java.util.Properties;
  42: 
  43: /**
  44:  * The class manages the System properties. This class is only available to
  45:  * privileged code (i.e. code loaded by the bootstrap class loader) and
  46:  * therefore doesn't do any security checks.
  47:  * This class is separated out from java.lang.System to simplify bootstrap
  48:  * dependencies and to allow trusted code a simple and efficient mechanism
  49:  * to access the system properties.
  50:  */
  51: public class SystemProperties
  52: {
  53:   /**
  54:    * Stores the current system properties. This can be modified by
  55:    * {@link #setProperties(Properties)}, but will never be null, because
  56:    * setProperties(null) sucks in the default properties.
  57:    */
  58:   private static Properties properties;
  59: 
  60:   /**
  61:    * The default properties. Once the default is stabilized,
  62:    * it should not be modified;
  63:    * instead it is cloned when calling <code>setProperties(null)</code>.
  64:    */
  65:   private static final Properties defaultProperties = new Properties();
  66: 
  67:   private static native void insertSystemProperties(Properties properties);
  68: 
  69:   static
  70:   {
  71:     insertSystemProperties(defaultProperties);
  72: 
  73:     defaultProperties.put("gnu.classpath.version",
  74:                           Configuration.CLASSPATH_VERSION);
  75: 
  76:     // Set base URL if not already set.
  77:     if (defaultProperties.get("gnu.classpath.home.url") == null)
  78:       defaultProperties.put("gnu.classpath.home.url",
  79:                 "file://"
  80:                 + defaultProperties.get("gnu.classpath.home")
  81:                         + "/lib");
  82: 
  83:     // Set short name if not already set.
  84:     if (defaultProperties.get("gnu.classpath.vm.shortname") == null)
  85:       {
  86:     String value = defaultProperties.getProperty("java.vm.name");
  87:     int index = value.lastIndexOf(' ');
  88:     if (index != -1)
  89:       value = value.substring(index + 1);
  90:     defaultProperties.put("gnu.classpath.vm.shortname", value);
  91:       }
  92: 
  93:     // Network properties
  94:     if (defaultProperties.get("http.agent") == null)
  95:       {
  96:     String userAgent = ("gnu-classpath/"
  97:                         + defaultProperties.getProperty("gnu.classpath.version")
  98:                         + " ("
  99:                         + defaultProperties.getProperty("gnu.classpath.vm.shortname")
 100:                         + "/"
 101:                         + defaultProperties.getProperty("java.vm.version")
 102:                         + ")");
 103:      defaultProperties.put("http.agent", userAgent);
 104:       }
 105: 
 106:     defaultProperties.put("gnu.cpu.endian",
 107:               isWordsBigEndian() ? "big" : "little");
 108: 
 109:     // XXX FIXME - Temp hack for old systems that set the wrong property
 110:     if (defaultProperties.get("java.io.tmpdir") == null)
 111:       defaultProperties.put("java.io.tmpdir",
 112:                             defaultProperties.get("java.tmpdir"));
 113: 
 114:     // Note that we use clone here and not new.  Some programs assume
 115:     // that the system properties do not have a parent.
 116:     properties = (Properties) defaultProperties.clone();
 117:   }
 118: 
 119:   public static String getProperty(String name)
 120:   {
 121:     return properties.getProperty(name);
 122:   }
 123: 
 124:   public static String getProperty(String name, String defaultValue)
 125:   {
 126:     return properties.getProperty(name, defaultValue);
 127:   }
 128: 
 129:   public static String setProperty(String name, String value)
 130:   {
 131:     return (String) properties.setProperty(name, value);
 132:   }
 133: 
 134:   public static Properties getProperties()
 135:   {
 136:     return properties;
 137:   }
 138: 
 139:   public static void setProperties(Properties properties)
 140:   {
 141:     if (properties == null)
 142:       {
 143:         // Note that we use clone here and not new.  Some programs
 144:         // assume that the system properties do not have a parent.
 145:         properties = (Properties)defaultProperties.clone();
 146:       }
 147: 
 148:     SystemProperties.properties = properties;
 149:   }
 150: 
 151:   /**
 152:    * Detect big-endian systems.
 153:    *
 154:    * @return true if the system is big-endian.
 155:    */
 156:   private static native boolean isWordsBigEndian();
 157: 
 158:   /**
 159:    * Removes the supplied system property and its current value.
 160:    * If the specified property does not exist, nothing happens.
 161:    * 
 162:    * @throws NullPointerException if the property name is null.
 163:    * @return the value of the removed property, or null if no
 164:    *         such property exists.
 165:    */
 166:   public static String remove(String name)
 167:   {
 168:     return (String) properties.remove(name);
 169:   }
 170: 
 171: }