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/* Libiberty realpath.  Like realpath, but more consistent behavior.

   Based on gdb_realpath from GDB.

   Copyright 2003 Free Software Foundation, Inc.

   This file is part of the libiberty library.

   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 of the License, 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., 51 Franklin Street - Fifth Floor,

   Boston, MA 02110-1301, USA.  */

/*

@deftypefn Replacement {const char*} lrealpath (const char *@var{name})

Given a pointer to a string containing a pathname, returns a canonical

version of the filename.  Symlinks will be resolved, and ``.'' and ``..''

components will be simplified.  The returned value will be allocated using

@code{malloc}, or @code{NULL} will be returned on a memory allocation error.

@end deftypefn

*/

#include "config.h"

#include "ansidecl.h"

#include "libiberty.h"

#ifdef HAVE_LIMITS_H

#include 

#endif

#ifdef HAVE_STDLIB_H

#include 

#endif

#ifdef HAVE_UNISTD_H

#include 

#endif

#ifdef HAVE_STRING_H

#include 

#endif

/* On GNU libc systems the declaration is only visible with _GNU_SOURCE.  */

#if defined(HAVE_CANONICALIZE_FILE_NAME) \

    && defined(NEED_DECLARATION_CANONICALIZE_FILE_NAME)

extern char *canonicalize_file_name (const char *);

#endif

#if defined(HAVE_REALPATH)

# if defined (PATH_MAX)

#  define REALPATH_LIMIT PATH_MAX

# else

#  if defined (MAXPATHLEN)

#   define REALPATH_LIMIT MAXPATHLEN

#  endif

# endif

#else

  /* cygwin has realpath, so it won't get here.  */

# if defined (_WIN32)

#  define WIN32_LEAN_AND_MEAN

#  include  /* for GetFullPathName */

# endif

#endif

char *

lrealpath (const char *filename)

{

  /* Method 1: The system has a compile time upper bound on a filename

     path.  Use that and realpath() to canonicalize the name.  This is

     the most common case.  Note that, if there isn't a compile time

     upper bound, you want to avoid realpath() at all costs.  */

#if defined(REALPATH_LIMIT)

  {

    char buf[REALPATH_LIMIT];

    const char *rp = realpath (filename, buf);

    if (rp == NULL)

      rp = filename;

    return strdup (rp);

  }

#endif /* REALPATH_LIMIT */

  /* Method 2: The host system (i.e., GNU) has the function

     canonicalize_file_name() which malloc's a chunk of memory and

     returns that, use that.  */

#if defined(HAVE_CANONICALIZE_FILE_NAME)

  {

    char *rp = canonicalize_file_name (filename);

    if (rp == NULL)

      return strdup (filename);

    else

      return rp;

  }

#endif

  /* Method 3: Now we're getting desperate!  The system doesn't have a

     compile time buffer size and no alternative function.  Query the

     OS, using pathconf(), for the buffer limit.  Care is needed

     though, some systems do not limit PATH_MAX (return -1 for

     pathconf()) making it impossible to pass a correctly sized buffer

     to realpath() (it could always overflow).  On those systems, we

     skip this.  */

#if defined (HAVE_REALPATH) && defined (HAVE_UNISTD_H)

  {

    /* Find out the max path size.  */

    long path_max = pathconf ("/", _PC_PATH_MAX);

    if (path_max > 0)

      {

	/* PATH_MAX is bounded.  */

	char *buf, *rp, *ret;

	buf = (char *) malloc (path_max);

	if (buf == NULL)

	  return NULL;

	rp = realpath (filename, buf);

	ret = strdup (rp ? rp : filename);

	free (buf);

	return ret;

      }

  }

#endif

  /* The MS Windows method.  If we don't have realpath, we assume we

     don't have symlinks and just canonicalize to a Windows absolute

     path.  GetFullPath converts ../ and ./ in relative paths to

     absolute paths, filling in current drive if one is not given

     or using the current directory of a specified drive (eg, "E:foo").

     It also converts all forward slashes to back slashes.  */

#if defined (_WIN32)

  {

    char buf[MAX_PATH];

    char* basename;

    DWORD len = GetFullPathName (filename, MAX_PATH, buf, &basename);

    if (len == 0 || len > MAX_PATH - 1)

      return strdup (filename);

    else

      {

	/* The file system is case-preserving but case-insensitive,

	   Canonicalize to lowercase, using the codepage associated

	   with the process locale.  */

        CharLowerBuff (buf, len);

        return strdup (buf);

      }

  }

#endif

  /* This system is a lost cause, just duplicate the filename.  */

  return strdup (filename);

}