/* cleanname -- print the shortest pathname equivalent to each specified NAME
   Copyright (C) 1990-1999 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.  */

#include <config.h>
#include <stdlib.h>
#include <stdio.h>
#include <getopt.h>

#include "error.h"
#include "system.h"
#include "xalloc.h"

#define AUTHORS		"Leonard Stiles"
#define PROGRAM_NAME	"cleanname"

#define DIRSEP	'/'

char *program_name;

static struct option const longopts[] = {
  {"directory", 1, NULL, 'd'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

void
usage (int status)
{
  if (status)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_name);
  else
    {
      printf (_("Usage: %s [ -d PREFIX ] NAME...\n"), program_name);
      printf (_("\
Print the shortest pathname equivalent to each specified NAME.\n\
\n\
  -d, --directory=PREFIX   prefix relative pathnames with `PREFIX/'\n\
      --help               print this help and exit\n\
      --version            output version information and exit\n"));
      puts (_("\nReport bugs to <address@hidden>."));
    }
  exit (status);
}

/* return shortest pathname equivalent to s, rewriting it in place.
 * s must be at least two bytes long, to hold "." */
static char *
cleanname (char *s)
{
  int *stk = malloc (sizeof *s / 2); /* stack of dir. name indices */
  int iin = 0, iout = 0; /* input/output read/write indices */
  int firstchar, top = 0;

  /* return input unchanged if we can't allocate memory for stack */
  if (stk == NULL)
    return s;

  for (firstchar = 1; s[iin] != '\0'; firstchar = 0)
    {
      /* slash */
      if (s[iin] == DIRSEP)
	{
	  if (firstchar || (iout > 0 && s[iout - 1] != DIRSEP))
	    {
	      s[iout++] = s[iin++];
	    }
	  else
	    iin++;
	  continue;
	}

      /* dots */
      if (s[iin] == '.' && (iout == 0 || s[iin - 1] == DIRSEP))
	{
	  /* single dot */
	  if (s[iin + 1] == DIRSEP || s[iin + 1] == '\0')
	    {
	      iin++;
	      continue;
	    }

	  /* double dot */
	  if (s[iin + 1] == '.'
	      && (s[iin + 2] == DIRSEP || s[iin + 2] == '\0'))
	    {
	      if (top > 0)
		{
		  /* parent dir indices in stack */
		  iout = stk[--top];
		  iin += 2;
		}
	      else		/* copy literally */
		while (s[iin] == '.')
		  s[iout++] = s[iin++];
	      continue;
	    }
	}

      /* non-special */
      if (iout == 0 || s[iout - 1] == DIRSEP)
	stk[top++] = iout;
      while (s[iin] && s[iin] != DIRSEP)
	s[iout++] = s[iin++];
    }

  if (iout == 0)
    s[iout++] = '.';
  s[iout] = '\0';
  /* delete trailing slashes */
  if (iout > 1 && s[iout - 1] == DIRSEP)
    s[iout - 1] = '\0';

  free (stk);
  return s;
}

int
main (int argc, char **argv)
{
  int i, optc;
  char *prefix = NULL;

  program_name = *argv;
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  while ((optc = getopt_long (argc, argv, "d:", longopts, NULL)) != -1)
    switch (optc)
      {
      case 'd':
	prefix = optarg;
	break;
      case_GETOPT_HELP_CHAR;
      case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
      default:
	usage (1);
      }

  if (optind == argc)
    {
      error (0, 0, _("too few arguments"));
      usage (1);
    }

  for (i = optind; i < argc; i++)
    {
      char *instr;
      if (prefix != NULL && argv[i][0] != '/')
	{
	  instr = xmalloc (strlen (prefix) + strlen (argv[i]) + 2);
	  strcat (strcat (strcpy (instr, prefix), "/"), argv[i]);
	}
      else if (argv[i][0] == '\0')
	{
	  instr = xmalloc (sizeof ".");
	  *instr = '\0';
	}
      else
	instr = argv[i];

      puts (cleanname (instr));

      if (instr != argv[i]) free (instr);
    }
  return 0;
}