src/sandbox-dev/canonicalize.c

/* Return the canonical absolute name of a given file.
   Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/*
 * $Id: /var/cvsroot/gentoo-src/portage/src/sandbox-dev/Attic/canonicalize.c,v 1.2 2002/08/26 03:28:30 azarah Exp $
 */

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stddef.h>
                     
#ifndef __set_errno
# define __set_errno(val) errno = (val)
#endif

/* Return the canonical absolute name of file NAME.  A canonical name
   does not contain any `.', `..' components nor any repeated path
   separators ('/') or symlinks.  All path components must exist.  If
   RESOLVED is null, the result is malloc'd; otherwise, if the
   canonical name is PATH_MAX chars or more, returns null with `errno'
   set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
   returns the name in RESOLVED.  If the name cannot be resolved and
   RESOLVED is non-NULL, it contains the path of the first component
   that cannot be resolved.  If the path can be resolved, RESOLVED
   holds the same value as the value returned.  */

/* Modified: 19 Aug 2002; Martin Schlemmer <azarah@gentoo.org>
 * 
 *  Cleaned up unneeded stuff, and change so that it will not
 *  resolve symlinks.  Also prepended a 'e' to functions that
 *  I did not rip out.
 *  
 */

static char *
ecanonicalize (const char *name, char *resolved)
{
  char *rpath, *dest;
  const char *start, *end, *rpath_limit;
  long int path_max;

  if (name == NULL)
    {
      /* As per Single Unix Specification V2 we must return an error if
         either parameter is a null pointer.  We extend this to allow
         the RESOLVED parameter to be NULL in case the we are expected to
         allocate the room for the return value.  */
      __set_errno (EINVAL);
      return NULL;
    }

  if (name[0] == '\0')
    {
      /* As per Single Unix Specification V2 we must return an error if
         the name argument points to an empty string.  */
      __set_errno (ENOENT);
      return NULL;
    }

#ifdef PATH_MAX
  path_max = PATH_MAX;
#else
  path_max = pathconf (name, _PC_PATH_MAX);
  if (path_max <= 0)
    path_max = 1024;
#endif

  rpath = resolved ? alloca (path_max) : malloc (path_max);
  rpath_limit = rpath + path_max;

  if (name[0] != '/')
    {
      if (!getcwd (rpath, path_max))
        {
          rpath[0] = '\0';
          goto error;
        }
      dest = strchr (rpath, '\0');
    }
  else
    {
      rpath[0] = '/';
      dest = rpath + 1;
    }

  for (start = end = name; *start; start = end)
    {
      /* Skip sequence of multiple path-separators.  */
      while (*start == '/')
        ++start;

      /* Find end of path component.  */
      for (end = start; *end && *end != '/'; ++end)
        /* Nothing.  */;

      if (end - start == 0)
        break;
      else if (end - start == 1 && start[0] == '.')
        /* nothing */;
      else if (end - start == 2 && start[0] == '.' && start[1] == '.')
        {
          /* Back up to previous component, ignore if at root already.  */
          if (dest > rpath + 1)
            while ((--dest)[-1] != '/');
        }
      else
        {
          size_t new_size;

          if (dest[-1] != '/')
            *dest++ = '/';

          if (dest + (end - start) >= rpath_limit)
            {
              ptrdiff_t dest_offset = dest - rpath;

              if (resolved)
                {
                  __set_errno (ENAMETOOLONG);
                  if (dest > rpath + 1)
                    dest--;
                  *dest = '\0';
                  goto error;
                }
              new_size = rpath_limit - rpath;
              if (end - start + 1 > path_max)
                new_size += end - start + 1;
              else
                new_size += path_max;
              rpath = realloc (rpath, new_size);
              rpath_limit = rpath + new_size;
              if (rpath == NULL)
                return NULL;

              dest = rpath + dest_offset;
            }

          dest = __mempcpy (dest, start, end - start);
          *dest = '\0';

          }
    }
#if 0
  if (dest > rpath + 1 && dest[-1] == '/')
    --dest;
#endif
  *dest = '\0';

  return resolved ? memcpy (resolved, rpath, dest - rpath + 1) : rpath;

error:
  if (resolved)
    strcpy (resolved, rpath);
  else
    free (rpath);
  return NULL;
}


char *
erealpath (const char *name, char *resolved)
{
  if (resolved == NULL)
    {
      __set_errno (EINVAL);
      return NULL;
    }

  return ecanonicalize (name, resolved);
}


// vim:expandtab noai:cindent ai