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  1. /* Libiberty realpath.  Like realpath, but more consistent behavior.
  2.    Based on gdb_realpath from GDB.
  3.  
  4.    Copyright 2003 Free Software Foundation, Inc.
  5.  
  6.    This file is part of the libiberty library.
  7.  
  8.    This program is free software; you can redistribute it and/or modify
  9.    it under the terms of the GNU General Public License as published by
  10.    the Free Software Foundation; either version 2 of the License, or
  11.    (at your option) any later version.
  12.  
  13.    This program is distributed in the hope that it will be useful,
  14.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16.    GNU General Public License for more details.
  17.  
  18.    You should have received a copy of the GNU General Public License
  19.    along with this program; if not, write to the Free Software
  20.    Foundation, Inc., 51 Franklin Street - Fifth Floor,
  21.    Boston, MA 02110-1301, USA.  */
  22.  
  23. /*
  24.  
  25. @deftypefn Replacement {const char*} lrealpath (const char *@var{name})
  26.  
  27. Given a pointer to a string containing a pathname, returns a canonical
  28. version of the filename.  Symlinks will be resolved, and ``.'' and ``..''
  29. components will be simplified.  The returned value will be allocated using
  30. @code{malloc}, or @code{NULL} will be returned on a memory allocation error.
  31.  
  32. @end deftypefn
  33.  
  34. */
  35.  
  36. #include "config.h"
  37. #include "ansidecl.h"
  38. #include "libiberty.h"
  39.  
  40. #ifdef HAVE_LIMITS_H
  41. #include <limits.h>
  42. #endif
  43. #ifdef HAVE_STDLIB_H
  44. #include <stdlib.h>
  45. #endif
  46. #ifdef HAVE_UNISTD_H
  47. #include <unistd.h>
  48. #endif
  49. #ifdef HAVE_STRING_H
  50. #include <string.h>
  51. #endif
  52.  
  53. /* On GNU libc systems the declaration is only visible with _GNU_SOURCE.  */
  54. #if defined(HAVE_CANONICALIZE_FILE_NAME) \
  55.     && defined(NEED_DECLARATION_CANONICALIZE_FILE_NAME)
  56. extern char *canonicalize_file_name (const char *);
  57. #endif
  58.  
  59. #if defined(HAVE_REALPATH)
  60. # if defined (PATH_MAX)
  61. #  define REALPATH_LIMIT PATH_MAX
  62. # else
  63. #  if defined (MAXPATHLEN)
  64. #   define REALPATH_LIMIT MAXPATHLEN
  65. #  endif
  66. # endif
  67. #else
  68.   /* cygwin has realpath, so it won't get here.  */
  69. # if defined (_WIN32)
  70. #  define WIN32_LEAN_AND_MEAN
  71. #  include <windows.h> /* for GetFullPathName */
  72. # endif
  73. #endif
  74.  
  75. char *
  76. lrealpath (const char *filename)
  77. {
  78.   /* Method 1: The system has a compile time upper bound on a filename
  79.      path.  Use that and realpath() to canonicalize the name.  This is
  80.      the most common case.  Note that, if there isn't a compile time
  81.      upper bound, you want to avoid realpath() at all costs.  */
  82. #if defined(REALPATH_LIMIT)
  83.   {
  84.     char buf[REALPATH_LIMIT];
  85.     const char *rp = realpath (filename, buf);
  86.     if (rp == NULL)
  87.       rp = filename;
  88.     return strdup (rp);
  89.   }
  90. #endif /* REALPATH_LIMIT */
  91.  
  92.   /* Method 2: The host system (i.e., GNU) has the function
  93.      canonicalize_file_name() which malloc's a chunk of memory and
  94.      returns that, use that.  */
  95. #if defined(HAVE_CANONICALIZE_FILE_NAME)
  96.   {
  97.     char *rp = canonicalize_file_name (filename);
  98.     if (rp == NULL)
  99.       return strdup (filename);
  100.     else
  101.       return rp;
  102.   }
  103. #endif
  104.  
  105.   /* Method 3: Now we're getting desperate!  The system doesn't have a
  106.      compile time buffer size and no alternative function.  Query the
  107.      OS, using pathconf(), for the buffer limit.  Care is needed
  108.      though, some systems do not limit PATH_MAX (return -1 for
  109.      pathconf()) making it impossible to pass a correctly sized buffer
  110.      to realpath() (it could always overflow).  On those systems, we
  111.      skip this.  */
  112. #if defined (HAVE_REALPATH) && defined (HAVE_UNISTD_H)
  113.   {
  114.     /* Find out the max path size.  */
  115.     long path_max = pathconf ("/", _PC_PATH_MAX);
  116.     if (path_max > 0)
  117.       {
  118.         /* PATH_MAX is bounded.  */
  119.         char *buf, *rp, *ret;
  120.         buf = (char *) malloc (path_max);
  121.         if (buf == NULL)
  122.           return NULL;
  123.         rp = realpath (filename, buf);
  124.         ret = strdup (rp ? rp : filename);
  125.         free (buf);
  126.         return ret;
  127.       }
  128.   }
  129. #endif
  130.  
  131.   /* The MS Windows method.  If we don't have realpath, we assume we
  132.      don't have symlinks and just canonicalize to a Windows absolute
  133.      path.  GetFullPath converts ../ and ./ in relative paths to
  134.      absolute paths, filling in current drive if one is not given
  135.      or using the current directory of a specified drive (eg, "E:foo").
  136.      It also converts all forward slashes to back slashes.  */
  137. #if defined (_WIN32)
  138.   {
  139.     char buf[MAX_PATH];
  140.     char* basename;
  141.     DWORD len = GetFullPathName (filename, MAX_PATH, buf, &basename);
  142.     if (len == 0 || len > MAX_PATH - 1)
  143.       return strdup (filename);
  144.     else
  145.       {
  146.         /* The file system is case-preserving but case-insensitive,
  147.            Canonicalize to lowercase, using the codepage associated
  148.            with the process locale.  */
  149.         CharLowerBuff (buf, len);
  150.         return strdup (buf);
  151.       }
  152.   }
  153. #endif
  154.  
  155.   /* This system is a lost cause, just duplicate the filename.  */
  156.   return strdup (filename);
  157. }
  158.