/* dirname.c -- return all but the last element in a path
   Copyright (C) 1990, 1998, 2000 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#ifdef STDC_HEADERS
# include <stdlib.h>
#else
char *malloc ();
#endif
#if defined STDC_HEADERS || defined HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
# ifndef strrchr
#  define strrchr rindex
# endif
#endif
#include <assert.h>

#ifndef HAVE_DECL_MEMRCHR
"this configure-time declaration test was not run"
#endif
#if !HAVE_DECL_MEMRCHR
void *memrchr ();
#endif

#include "dirname.h"

/* Richard Dawe <rich@phekda.freeserve.co.uk>: Cope with MS-DOSisms. */
#ifdef MSDOS
# undef FILESYSTEM_PREFIX_LEN
# define FILESYSTEM_PREFIX_LEN(Filename) \
  ((Filename)[0] && (Filename)[1] == ':' ? 2 : 0)
# undef ISSLASH
# define ISSLASH(c) (((c) == '/') || ((c) == '\\'))
#endif /* MSDOS */

#ifndef FILESYSTEM_PREFIX_LEN
# define FILESYSTEM_PREFIX_LEN(Filename) 0
#endif

#ifndef ISSLASH
# define ISSLASH(C) ((C) == '/')
#endif

#define BACKSLASH_IS_PATH_SEPARATOR ISSLASH ('\\')

/* Return the length of `dirname (PATH)' and set *RESULT to point
   to PATH or to `"."', as appropriate.  Works properly even if
   there are trailing slashes (by effectively ignoring them).
   WARNING: This function doesn't work for cwd-relative names like
   `a:foo' that are specified with a drive-letter prefix.  That case
   is handled in the caller.  */
static size_t
dir_name_r (char const *path, char const **result)
{
  char const *slash;
  size_t length;		/* Length of result, not including NUL.  */

  slash = strrchr (path, '/');
  if (BACKSLASH_IS_PATH_SEPARATOR)
    {
      char const *b = strrchr (path, '\\');
      if (b && slash < b)
	slash = b;
    }

  /* If the last byte of PATH is a slash, decrement SLASH until it's
     pointing at the leftmost in a sequence of trailing slashes.  */
  if (slash && slash[1] == 0)
    {
      while (path < slash && ISSLASH (slash[-1]))
	{
	  --slash;
	}

      if (path < slash)
	{
	  size_t len = slash - path;
	  slash = memrchr (path, '/', len);
	  if (BACKSLASH_IS_PATH_SEPARATOR)
	    {
	      char const *b = memrchr (path, '\\', len);
	      if (b && slash < b)
		slash = b;
	    }
	}
    }

  if (slash == 0)
    {
      /* File is in the current directory.  */

      length = FILESYSTEM_PREFIX_LEN (path);

      if (length == 0)
	{
	  path = ".";
	  length = 1;
	}
    }
  else
    {
      /* Remove any trailing slashes from the result.  If we have a
	 canonicalized "d:/path", leave alone the root case "d:/".  */
      char const *lim = path + FILESYSTEM_PREFIX_LEN (path);

      while (lim < slash && ISSLASH (*slash))
	--slash;

      length = slash - path + 1;
    }

  *result = path;
  return length;
}

/* Return the leading directories part of PATH,
   allocated with malloc.  If out of memory, return 0.
   Works properly even if there are trailing slashes
   (by effectively ignoring them).  */

char *
dir_name (char const *path)
{
  char const *result;
  size_t length = dir_name_r (path, &result);
  int append_dot;
  char *newpath;

  /* Richard Dawe <rich@phekda.freeserve.co.uk>: Always allocate space
   * for appending a dot, so that we avoid append_dot's initialisation
   * depending on newpath and vice-versa. */
  newpath = (char *) malloc (length + 1 /*append_dot*/ + 1);
  if (newpath == 0)
    return 0;
  strncpy (newpath, result, length);
  append_dot = (length && length == FILESYSTEM_PREFIX_LEN (newpath));
  /* If PATH is "d:foo", return "d:.", the CWD on drive d:  */
  if (append_dot)
    newpath[length++] = '.';
  newpath[length] = 0;
  return newpath;
}

#ifdef TEST_DIRNAME
/*

Run the test like this (expect no output):
  gcc -DHAVE_CONFIG_H -DTEST_DIRNAME -I.. -O -Wall memrchr.c dirname.c
  sed -n '/^BEGIN-DATA$/,/^END-DATA$/p' dirname.c|grep -v DATA|./a.out

BEGIN-DATA
foo//// .
bar/foo//// bar
foo/ .
/ /
. .
a .
END-DATA

*/

# define MAX_BUFF_LEN 1024
# include <stdio.h>
# include <stdlib.h>

int
main ()
{
  char buff[MAX_BUFF_LEN + 1];

  buff[MAX_BUFF_LEN] = 0;
  while (fgets (buff, MAX_BUFF_LEN, stdin) && buff[0])
    {
      char path[MAX_BUFF_LEN];
      char expected_result[MAX_BUFF_LEN];
      char const *result;
      sscanf (buff, "%s %s", path, expected_result);
      result = dir_name (path);
      if (strcmp (result, expected_result))
	printf ("%s: got %s, expected %s\n", path, result, expected_result);
    }
  exit (0);

}
#endif
