mcs/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 + 1;
  62                         for (int i = 0; i < paths.Length; ++i) {
  63                                 if (paths [i] == null)
  64                                         throw new ArgumentNullException ("paths");
  65                                 len += paths [i].Length + 1;
  66                         }
  67
  68                         StringBuilder sb = new StringBuilder (len);
  69                         sb.Append (path1);
  70                         for (int i = 0; i < paths.Length; ++i)
  71                                 Combine (sb, paths [i]);
  72                         return sb.ToString ();
  73                 }
  74
  75                 private static void Combine (StringBuilder path, string part)
  76                 {
  77                         if (part.IndexOfAny (_InvalidPathChars) != -1)
  78                                 throw new ArgumentException ("Illegal characters in path", "path1");
  79                         char end = path [path.Length-1];
  80                         if (end != DirectorySeparatorChar &&
  81                                         end != AltDirectorySeparatorChar &&
  82                                         end != VolumeSeparatorChar)
  83                                 path.Append (DirectorySeparatorChar);
  84                         path.Append (part);
  85                 }
  86
  87                 public static string GetDirectoryName (string path)
  88                 {
  89                         CheckPath (path);
  90
  91                         int lastDir = path.LastIndexOf (DirectorySeparatorChar);
  92                         if (lastDir > 0)
  93                                 return path.Substring (0, lastDir);
  94                         return "";
  95                 }
  96
  97                 public static string GetFileName (string path)
  98                 {
  99                         if (path == null || path.Length == 0)
 100                                 return path;
 101
 102                         int lastDir = path.LastIndexOf (DirectorySeparatorChar);
 103                         if (lastDir >= 0)
 104                                 return path.Substring (lastDir+1);
 105
 106                         return path;
 107                 }
 108
 109                 public static string GetFullPath (string path)
 110                 {
 111                         path = _GetFullPath (path);
 112                         return GetCanonicalPath (path);
 113                 }
 114
 115                 private static string _GetFullPath (string path)
 116                 {
 117                         if (path == null)
 118                                 throw new ArgumentNullException ("path");
 119                         if (!IsPathRooted (path))
 120                                 path = UnixDirectoryInfo.GetCurrentDirectory() + DirectorySeparatorChar + path;
 121
 122                         return path;
 123                 }
 124
 125                 public static string GetCanonicalPath (string path)
 126                 {
 127                         string [] dirs;
 128                         int lastIndex;
 129                         GetPathComponents (path, out dirs, out lastIndex);
 130                         string end = string.Join ("/", dirs, 0, lastIndex);
 131                         return IsPathRooted (path) ? "/" + end : end;
 132                 }
 133
 134                 private static void GetPathComponents (string path,
 135                         out string[] components, out int lastIndex)
 136                 {
 137                         string [] dirs = path.Split (DirectorySeparatorChar);
 138                         int target = 0;
 139                         for (int i = 0; i < dirs.Length; ++i) {
 140                                 if (dirs [i] == "." || dirs [i] == string.Empty) continue;
 141                                 else if (dirs [i] == "..") {
 142                                         if (target != 0) --target;
 143                                         else ++target;
 144                                 }
 145                                 else
 146                                         dirs [target++] = dirs [i];
 147                         }
 148                         components = dirs;
 149                         lastIndex = target;
 150                 }
 151
 152                 public static string GetPathRoot (string path)
 153                 {
 154                         if (path == null)
 155                                 return null;
 156                         if (!IsPathRooted (path))
 157                                 return "";
 158                         return "/";
 159                 }
 160
 161                 public static string GetCompleteRealPath (string path)
 162                 {
 163                         if (path == null)
 164                                 throw new ArgumentNullException ("path");
 165                         string [] dirs;
 166                         int lastIndex;
 167                         GetPathComponents (path, out dirs, out lastIndex);
 168                         StringBuilder realPath = new StringBuilder ();
 169                         if (dirs.Length > 0) {
 170                                 string dir = IsPathRooted (path) ? "/" : "";
 171                                 dir += dirs [0];
 172                                 realPath.Append (GetRealPath (dir));
 173                         }
 174                         for (int i = 1; i < lastIndex; ++i) {
 175                                 realPath.Append ("/").Append (dirs [i]);
 176                                 string p = GetRealPath (realPath.ToString());
 177                                 realPath.Remove (0, realPath.Length);
 178                                 realPath.Append (p);
 179                         }
 180                         return realPath.ToString ();
 181                 }
 182
 183                 public static string GetRealPath (string path)
 184                 {
 185                         do {
 186                                 string name = ReadSymbolicLink (path);
 187                                 if (name == null)
 188                                         return path;
 189                                 if (IsPathRooted (name))
 190                                         path = name;
 191                                 else {
 192                                         path = GetDirectoryName (path) + DirectorySeparatorChar + name;
 193                                         path = GetCanonicalPath (path);
 194                                 }
 195                         } while (true);
 196                 }
 197
 198                 // Read the specified symbolic link.  If the file isn't a symbolic link,
 199                 // return null; otherwise, return the contents of the symbolic link.
 200                 //
 201                 // readlink(2) is horribly evil, as there is no way to query how big the
 202                 // symlink contents are.  Consequently, it's trial and error...
 203                 internal static string ReadSymbolicLink (string path)
 204                 {
 205                         StringBuilder buf = new StringBuilder (256);
 206                         do {
 207                                 int r = Native.Syscall.readlink (path, buf);
 208                                 if (r < 0) {
 209                                         Native.Errno e;
 210                                         switch (e = Native.Stdlib.GetLastError()) {
 211                                         case Native.Errno.EINVAL:
 212                                                 // path isn't a symbolic link
 213                                                 return null;
 214                                         default:
 215                                                 UnixMarshal.ThrowExceptionForError (e);
 216                                                 break;
 217                                         }
 218                                 }
 219                                 else if (r == buf.Capacity) {
 220                                         buf.Capacity *= 2;
 221                                 }
 222                                 else
 223                                         return buf.ToString (0, r);
 224                         } while (true);
 225                 }
 226
 227                 // Read the specified symbolic link.  If the file isn't a symbolic link,
 228                 // return null; otherwise, return the contents of the symbolic link.
 229                 //
 230                 // readlink(2) is horribly evil, as there is no way to query how big the
 231                 // symlink contents are.  Consequently, it's trial and error...
 232                 private static string ReadSymbolicLink (string path, out Native.Errno errno)
 233                 {
 234                         errno = (Native.Errno) 0;
 235                         StringBuilder buf = new StringBuilder (256);
 236                         do {
 237                                 int r = Native.Syscall.readlink (path, buf);
 238                                 if (r < 0) {
 239                                         errno = Native.Stdlib.GetLastError ();
 240                                         return null;
 241                                 }
 242                                 else if (r == buf.Capacity) {
 243                                         buf.Capacity *= 2;
 244                                 }
 245                                 else
 246                                         return buf.ToString (0, r);
 247                         } while (true);
 248                 }
 249
 250                 public static string TryReadLink (string path)
 251                 {
 252                         Native.Errno errno;
 253                         return ReadSymbolicLink (path, out errno);
 254                 }
 255
 256                 public static string ReadLink (string path)
 257                 {
 258                         Native.Errno errno;
 259                         path = ReadSymbolicLink (path, out errno);
 260                         if (errno != 0)
 261                                 UnixMarshal.ThrowExceptionForError (errno);
 262                         return path;
 263                 }
 264
 265                 public static bool IsPathRooted (string path)
 266                 {
 267                         if (path == null || path.Length == 0)
 268                                 return false;
 269                         return path [0] == DirectorySeparatorChar;
 270                 }
 271
 272                 internal static void CheckPath (string path)
 273                 {
 274                         if (path == null)
 275                                 throw new ArgumentNullException ();
 276                         if (path.Length == 0)
 277                                 throw new ArgumentException ("Path cannot contain a zero-length string", "path");
 278                         if (path.IndexOfAny (_InvalidPathChars) != -1)
 279                                 throw new ArgumentException ("Invalid characters in path.", "path");
 280                 }
 281         }
 282 }
 283
 284 // vim: noexpandtab