old-autovect-branch/libjava/classpath/gnu/java/io/PlatformHelper.java

   1 /* PlatformHelper.java -- Isolate OS-specific IO helper methods and variables
   2    Copyright (C) 1998, 2002 Free Software Foundation, Inc.
   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 package gnu.java.io;
  39
  40 import java.util.StringTokenizer;
  41
  42 /**
  43  * We had many changes in File.java, URLStreamHandler.java etc. to handle
  44  * path representations on different platforms (Windows/Unix-family).
  45  * Finally we'd like to collect all these ad hoc codes into this utility class.
  46  *       --Gansha
  47  */
  48 public class PlatformHelper
  49 {
  50   public static final boolean isWindows = System.getProperty("os.name").indexOf("Windows") >= 0;
  51   public static final String separator = System.getProperty("file.separator");
  52   public static final char separatorChar = separator.charAt(0);
  53   public static final String pathSeparator = System.getProperty("path.separator");
  54   public static final char pathSeparatorChar = pathSeparator.charAt(0);
  55
  56   /**
  57    * On most platforms 260 is equal or greater than a max path value,
  58    * so we can set the initial buffer size of StringBuffer to half of this value
  59    * to improve performance.
  60    */
  61   public static final int INITIAL_MAX_PATH = 260/2;
  62
  63   /**
  64    * This routine checks the input param "path" whether it begins with root path
  65    * prefix.
  66    * if not, return 0;
  67    * if yes, return the len of root path prefix;
  68    *   --for Unix-family platform, root path begins with "/" and len is 1
  69    *   --for Windows platform, root path begins with "drive:\\" and len is 3
  70    */
  71   public static final int beginWithRootPathPrefix(String path)
  72   {
  73     if (path.startsWith("/") || path.startsWith("\\"))
  74       return 1;
  75
  76     if (!isWindows)
  77       return 0;
  78
  79     if (path.length() > 2
  80         && Character.isLetter(path.charAt(0))
  81         && path.charAt(1) == ':'
  82         && (path.charAt(2) == '/' || path.charAt(2) == '\\'))
  83       return 3;
  84
  85     return 0;
  86   }
  87
  88   /**
  89    * This routine checks the input param "path" whether it's root directory.
  90    *  --for Unix-family platform, root directory is "/"
  91    *  --for Windows platform, root directory is "\\" or "drive:\\".
  92    */
  93   public static final boolean isRootDirectory(String path)
  94   {
  95     int len = path.length();
  96     return len > 0 && beginWithRootPathPrefix(path) == len;
  97   }
  98
  99   /**
 100    * This routine canonicalizes input param "path" to formal path representation
 101    *  for current platform, including interpreting ".." and "." .
 102    */
 103   public static final String toCanonicalForm(String path)
 104   {
 105     /*??
 106     if(path.indexOf('.') < 0 && path.indexOf("..") < 0)
 107         return path;
 108     */
 109     String tmppath = path.replace('/', separatorChar);
 110     StringBuffer canonpath;
 111
 112     int i;
 113
 114     if ((i = beginWithRootPathPrefix(tmppath)) == 0 )
 115       return path;
 116
 117     /* The original
 118            "canonpath = new StringBuffer(tmppath.substring(0, i))"
 119        isn't very efficient because StringBuffer's
 120        ensureCapacity_unsynchronized will fail definitely each time
 121        and will enlarge buffer and copy contents.       .
 122     */
 123     canonpath = new StringBuffer(INITIAL_MAX_PATH);
 124     canonpath.append(tmppath.substring(0, i));
 125     tmppath = tmppath.substring(i);
 126     // pathdepth==0 indicates there're only root path in the buffer
 127     int pathdepth = 0;
 128
 129     StringTokenizer st = new StringTokenizer(tmppath, separator);
 130
 131     // Traverse each element of the path, handling "." and ".."
 132     // Should handle "~" too?
 133     if (st.hasMoreTokens())
 134       do
 135         {
 136           String s = st.nextToken();
 137
 138           // Handle "." or an empty element.
 139           if (s.equals(".") || s.equals(""))
 140             continue;
 141
 142           // Handle ".." by deleting the last element from the path
 143           if (s.equals(".."))
 144             {
 145               if (pathdepth == 0)
 146                 continue;
 147
 148               // Strip of trailing separator
 149               canonpath.setLength(canonpath.length() - 1/*separator.length()*/);
 150               String tmpstr = canonpath.toString();
 151               int idx = tmpstr.lastIndexOf(separator);
 152
 153               if ((idx == -1) || ((idx + 1/*separator.length()*/) > tmpstr.length()))
 154                 //throw new IOException("Can't happen error");
 155                 return path; // Shouldn't happen
 156
 157               canonpath.setLength(idx + 1/*separator.length()*/);
 158               pathdepth--;
 159               continue;
 160             }
 161
 162           canonpath.append(s);
 163           pathdepth++; //now it's more than root path
 164
 165           if (st.hasMoreTokens())
 166             canonpath.append(separator);
 167         }
 168       while (st.hasMoreTokens());
 169
 170     if (endWithSeparator(path))
 171       canonpath.append(separator);
 172
 173     String tmpstr = canonpath.toString();
 174     //if (pathdepth > 0 && endWithSeparator(tmpstr) )
 175     //    tmpstr = tmpstr.substring(0, tmpstr.length() - 1/*separator.length()*/);
 176
 177     return tmpstr;
 178   }
 179
 180   /**
 181    * This routine canonicalizes input param "path" to formal path representation
 182    *  for current platform, and normalize all separators to "sepchar".
 183    */
 184   public static final String toCanonicalForm(String path, char sepchar)
 185   {
 186     String tmpstr = toCanonicalForm(path);
 187     tmpstr = tmpstr.replace(separatorChar, sepchar);
 188     return tmpstr;
 189   }
 190
 191   /**
 192    * This routine checks whether input param "path" ends with separator
 193    */
 194   public static final boolean endWithSeparator(String path)
 195   {
 196     if (path.endsWith("\\") || path.endsWith("/"))
 197       return true;
 198
 199     return false;
 200   }
 201
 202   /**
 203    * This routine removes from input param "path" the tail separator if it exists,
 204    * and return the remain part.
 205    */
 206   public static final String removeTailSeparator(String path)
 207   {
 208     if (endWithSeparator(path) && !isRootDirectory(path))
 209       return path.substring(0, path.length() - 1);
 210
 211     return path;
 212   }
 213
 214   /**
 215    * This routine returns last index of separator in input param "path",
 216    * and return it.
 217    */
 218   public static final int lastIndexOfSeparator(String path)
 219   {
 220     return Math.max(path.lastIndexOf("/"), path.lastIndexOf("\\"));
 221   }
 222
 223 }