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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: }