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
27Given a pointer to a string containing a pathname, returns a canonical
28version of the filename.  Symlinks will be resolved, and ``.'' and ``..''
29components 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)
56extern 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
75char *
76lrealpath (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