107 if sys.platform == 'darwin':

   108     def realpath(path):

   109         '''

   110         Returns the true, canonical file system path equivalent to the given

   111         path.

   112 

   113         Equivalent means, in this case, resulting in the same, unique

   114         file system link to the path. Every file system entry, whether a file,

   115         directory, hard link or symbolic link or special, will have a single

   116         path preferred by the system, but may allow multiple, differing path

   117         lookups to point to it.

   118 

   119         Most regular UNIX file systems only allow a file system entry to be

   120         looked up by its distinct path. Obviously, this does not apply to case

   121         insensitive file systems, whether case preserving or not. The most

   122         complex issue to deal with is file systems transparently reencoding the

   123         path, such as the non-standard Unicode normalisation required for HFS+

   124         and HFSX.

   125         '''

   126         # Constants copied from /usr/include/sys/fcntl.h

   127         F_GETPATH = 50

   128         O_SYMLINK = 0x200000

   129 

   130         try:

   131             fd = os.open(path, O_SYMLINK)

   132         except OSError, err:

   133             if err.errno is errno.ENOENT:

   134                 return path

   135             raise

   136 

   137         try:

   138             return fcntl.fcntl(fd, F_GETPATH, '\0' * 1024).rstrip('\0')

   139         finally:

   140             os.close(fd)

   141 else:

   142     # Fallback to the likely inadequate Python builtin function.

   143     realpath = os.path.realpath

   144