/* dirname - return directory part of PATH.

   Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <libgen.h>

#include <string.h>

char *

dirname (char *path)

{

  static const char dot[] = ".";

  char *last_slash;

  /* Find last '/'.  */

  last_slash = path != NULL ? strrchr (path, '/') : NULL;

  if (last_slash != NULL && last_slash != path && last_slash[1] == '\0')

    {

      /* Determine whether all remaining characters are slashes.  */

      char *runp;

      for (runp = last_slash; runp != path; --runp)

	if (runp[-1] != '/')

	  break;

      /* The '/' is the last character, we have to look further.  */

      if (runp != path)

	last_slash = __memrchr (path, '/', runp - path);

    }

  if (last_slash != NULL)

    {

      /* Determine whether all remaining characters are slashes.  */

      char *runp;

      for (runp = last_slash; runp != path; --runp)

	if (runp[-1] != '/')

	  break;

      /* Terminate the path.  */

      if (runp == path)

	{

	  /* The last slash is the first character in the string.  We have to

	     return "/".  As a special case we have to return "//" if there

	     are exactly two slashes at the beginning of the string.  See

	     XBD 4.10 Path Name Resolution for more information.  */

	  if (last_slash == path + 1)

	    ++last_slash;

	  else

	    last_slash = path + 1;

	}

      else

	last_slash = runp;

      last_slash[0] = '\0';

    }

  else

    /* This assignment is ill-designed but the XPG specs require to

       return a string containing "." in any case no directory part is

       found and so a static and constant string is required.  */

    path = (char *) dot;

  return path;

}