class/Mono.Posix/Mono.Unix/UnixPath.cs

   1 //
   2 // Mono.Unix/UnixPath.cs
   3 //
   4 // Authors:
   5 //   Jonathan Pryor (jonpryor@vt.edu)
   6 //
   7 // (C) 2004-2006 Jonathan Pryor
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System;
  30 using System.Collections;
  31 using System.Text;
  32 using Mono.Unix;
  33
  34 namespace Mono.Unix {
  35
  36         public sealed class UnixPath
  37         {
  38                 private UnixPath () {}
  39
  40                 public static readonly char DirectorySeparatorChar = '/';
  41                 public static readonly char AltDirectorySeparatorChar = '/';
  42                 public static readonly char PathSeparator = ':';
  43                 public static readonly char VolumeSeparatorChar = '/';
  44
  45                 private static readonly char[] _InvalidPathChars = new char[]{};
  46
  47                 public static char[] GetInvalidPathChars ()
  48                 {
  49                         return (char[]) _InvalidPathChars.Clone ();
  50                 }
  51
  52                 public static string Combine (string path1, params string[] paths)
  53                 {
  54                         if (path1 == null)
  55                                 throw new ArgumentNullException ("path1");
  56                         if (paths == null)
  57                                 throw new ArgumentNullException ("paths");
  58                         if (path1.IndexOfAny (_InvalidPathChars) != -1)
  59                                 throw new ArgumentException ("Illegal characters in path", "path1");
  60
  61                         int len = path1.Length;
  62                         int start = -1;
  63                         for (int i = 0; i < paths.Length; ++i) {
  64                                 if (paths [i] == null)
  65                                         throw new ArgumentNullException ("paths[" + i + "]");
  66                                 if (paths [i].IndexOfAny (_InvalidPathChars) != -1)
  67                                         throw new ArgumentException ("Illegal characters in path", "paths[" + i + "]");
  68                                 if (IsPathRooted (paths [i])) {
  69                                         len = 0;
  70                                         start = i;
  71                                 }
  72                                 len += paths [i].Length + 1;
  73                         }
  74
  75                         StringBuilder sb = new StringBuilder (len);
  76                         if (start == -1) {
  77                                 sb.Append (path1);
  78                                 start = 0;
  79                         }
  80                         for (int i = start; i < paths.Length; ++i)
  81                                 Combine (sb, paths [i]);
  82                         return sb.ToString ();
  83                 }
  84
  85                 private static void Combine (StringBuilder path, string part)
  86                 {
  87                         if (path.Length > 0 && part.Length > 0) {
  88                                 char end = path [path.Length-1];
  89                                 if (end != DirectorySeparatorChar &&
  90                                                 end != AltDirectorySeparatorChar &&
  91                                                 end != VolumeSeparatorChar)
  92                                         path.Append (DirectorySeparatorChar);
  93                         }
  94                         path.Append (part);
  95                 }
  96
  97                 public static string GetDirectoryName (string path)
  98                 {
  99                         CheckPath (path);
 100
 101                         int lastDir = path.LastIndexOf (DirectorySeparatorChar);
 102                         if (lastDir > 0)
 103                                 return path.Substring (0, lastDir);
 104                         if (lastDir == 0)
 105                                 return "/";
 106                         return "";
 107                 }
 108
 109                 public static string GetFileName (string path)
 110                 {
 111                         if (path == null || path.Length == 0)
 112                                 return path;
 113
 114                         int lastDir = path.LastIndexOf (DirectorySeparatorChar);
 115                         if (lastDir >= 0)
 116                                 return path.Substring (lastDir+1);
 117
 118                         return path;
 119                 }
 120
 121                 public static string GetFullPath (string path)
 122                 {
 123                         path = _GetFullPath (path);
 124                         return GetCanonicalPath (path);
 125                 }
 126
 127                 private static string _GetFullPath (string path)
 128                 {
 129                         if (path == null)
 130                                 throw new ArgumentNullException ("path");
 131                         if (!IsPathRooted (path))
 132                                 path = UnixDirectoryInfo.GetCurrentDirectory() + DirectorySeparatorChar + path;
 133
 134                         return path;
 135                 }
 136
 137                 public static string GetCanonicalPath (string path)
 138                 {
 139                         string [] dirs;
 140                         int lastIndex;
 141                         GetPathComponents (path, out dirs, out lastIndex);
 142                         string end = string.Join ("/", dirs, 0, lastIndex);
 143                         return IsPathRooted (path) ? "/" + end : end;
 144                 }
 145
 146                 private static void GetPathComponents (string path,
 147                         out string[] components, out int lastIndex)
 148                 {
 149                         string [] dirs = path.Split (DirectorySeparatorChar);
 150                         int target = 0;
 151                         for (int i = 0; i < dirs.Length; ++i) {
 152                                 if (dirs [i] == "." || dirs [i] == string.Empty) continue;
 153                                 else if (dirs [i] == "..") {
 154                                         if (target != 0) --target;
 155                                         else ++target;
 156                                 }
 157                                 else
 158                                         dirs [target++] = dirs [i];
 159                         }
 160                         components = dirs;
 161                         lastIndex = target;
 162                 }
 163
 164                 public static string GetPathRoot (string path)
 165                 {
 166                         if (path == null)
 167                                 return null;
 168                         if (!IsPathRooted (path))
 169                                 return "";
 170                         return "/";
 171                 }
 172
 173                 public static string GetCompleteRealPath (string path)
 174                 {
 175                         if (path == null)
 176                                 throw new ArgumentNullException ("path");
 177                         string [] dirs;
 178                         int lastIndex;
 179                         GetPathComponents (path, out dirs, out lastIndex);
 180                         StringBuilder realPath = new StringBuilder ();
 181                         if (dirs.Length > 0) {
 182                                 string dir = IsPathRooted (path) ? "/" : "";
 183                                 dir += dirs [0];
 184                                 realPath.Append (GetRealPath (dir));
 185                         }
 186                         for (int i = 1; i < lastIndex; ++i) {
 187                                 realPath.Append ("/").Append (dirs [i]);
 188                                 string p = GetRealPath (realPath.ToString());
 189                                 realPath.Remove (0, realPath.Length);
 190                                 realPath.Append (p);
 191                         }
 192                         return realPath.ToString ();
 193                 }
 194
 195                 public static string GetRealPath (string path)
 196                 {
 197                         do {
 198                                 string name = ReadSymbolicLink (path);
 199                                 if (name == null)
 200                                         return path;
 201                                 if (IsPathRooted (name))
 202                                         path = name;
 203                                 else {
 204                                         path = GetDirectoryName (path) + DirectorySeparatorChar + name;
 205                                         path = GetCanonicalPath (path);
 206                                 }
 207                         } while (true);
 208                 }
 209
 210                 // Read the specified symbolic link.  If the file isn't a symbolic link,
 211                 // return null; otherwise, return the contents of the symbolic link.
 212                 //
 213                 // readlink(2) is horribly evil, as there is no way to query how big the
 214                 // symlink contents are.  Consequently, it's trial and error...
 215                 internal static string ReadSymbolicLink (string path)
 216                 {
 217                         StringBuilder buf = new StringBuilder (256);
 218                         do {
 219                                 int r = Native.Syscall.readlink (path, buf);
 220                                 if (r < 0) {
 221                                         Native.Errno e;
 222                                         switch (e = Native.Stdlib.GetLastError()) {
 223                                         case Native.Errno.EINVAL:
 224                                                 // path isn't a symbolic link
 225                                                 return null;
 226                                         default:
 227                                                 UnixMarshal.ThrowExceptionForError (e);
 228                                                 break;
 229                                         }
 230                                 }
 231                                 else if (r == buf.Capacity) {
 232                                         buf.Capacity *= 2;
 233                                 }
 234                                 else
 235                                         return buf.ToString (0, r);
 236                         } while (true);
 237                 }
 238
 239                 // Read the specified symbolic link.  If the file isn't a symbolic link,
 240                 // return null; otherwise, return the contents of the symbolic link.
 241                 //
 242                 // readlink(2) is horribly evil, as there is no way to query how big the
 243                 // symlink contents are.  Consequently, it's trial and error...
 244                 private static string ReadSymbolicLink (string path, out Native.Errno errno)
 245                 {
 246                         errno = (Native.Errno) 0;
 247                         StringBuilder buf = new StringBuilder (256);
 248                         do {
 249                                 int r = Native.Syscall.readlink (path, buf);
 250                                 if (r < 0) {
 251                                         errno = Native.Stdlib.GetLastError ();
 252                                         return null;
 253                                 }
 254                                 else if (r == buf.Capacity) {
 255                                         buf.Capacity *= 2;
 256                                 }
 257                                 else
 258                                         return buf.ToString (0, r);
 259                         } while (true);
 260                 }
 261
 262                 public static string TryReadLink (string path)
 263                 {
 264                         Native.Errno errno;
 265                         return ReadSymbolicLink (path, out errno);
 266                 }
 267
 268                 public static string ReadLink (string path)
 269                 {
 270                         Native.Errno errno;
 271                         path = ReadSymbolicLink (path, out errno);
 272                         if (errno != 0)
 273                                 UnixMarshal.ThrowExceptionForError (errno);
 274                         return path;
 275                 }
 276
 277                 public static bool IsPathRooted (string path)
 278                 {
 279                         if (path == null || path.Length == 0)
 280                                 return false;
 281                         return path [0] == DirectorySeparatorChar;
 282                 }
 283
 284                 internal static void CheckPath (string path)
 285                 {
 286                         if (path == null)
 287                                 throw new ArgumentNullException ();
 288                         if (path.Length == 0)
 289                                 throw new ArgumentException ("Path cannot contain a zero-length string", "path");
 290                         if (path.IndexOfAny (_InvalidPathChars) != -1)
 291                                 throw new ArgumentException ("Invalid characters in path.", "path");
 292                 }
 293         }
 294 }
 295
 296 // vim: noexpandtab