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 "lrealpath.h"
38
39 #ifdef HAVE_LIMITS_H
40 #include <limits.h>
41 #endif
42 #ifdef HAVE_STDLIB_H
43 #include <stdlib.h>
44 #endif
45 #ifdef HAVE_UNISTD_H
46 #include <unistd.h>
47 #endif
48 #ifdef HAVE_STRING_H
49 #include <string.h>
50 #endif
51
52 /* On GNU libc systems the declaration is only visible with _GNU_SOURCE. */
53 #if defined(HAVE_CANONICALIZE_FILE_NAME) \
54 && defined(NEED_DECLARATION_CANONICALIZE_FILE_NAME)
55 extern char *canonicalize_file_name (const char *);
56 #endif
57
58 #if defined(HAVE_REALPATH)
59 # if defined (PATH_MAX)
60 # define REALPATH_LIMIT PATH_MAX
61 # else
62 # if defined (MAXPATHLEN)
63 # define REALPATH_LIMIT MAXPATHLEN
64 # endif
65 # endif
66 #else
67 /* cygwin has realpath, so it won't get here. */
68 # if defined (_WIN32)
69 # define WIN32_LEAN_AND_MEAN
70 # include <windows.h> /* for GetFullPathName */
71 # endif
72 #endif
73
74 char *
lrealpath(const char * filename)75 lrealpath (const char *filename)
76 {
77 /* Method 1: The system has a compile time upper bound on a filename
78 path. Use that and realpath() to canonicalize the name. This is
79 the most common case. Note that, if there isn't a compile time
80 upper bound, you want to avoid realpath() at all costs. */
81 #if defined(REALPATH_LIMIT)
82 {
83 char buf[REALPATH_LIMIT];
84 const char *rp = realpath (filename, buf);
85 if (rp == NULL)
86 rp = filename;
87 return strdup (rp);
88 }
89 /* REALPATH_LIMIT */
90
91 /* Method 2: The host system (i.e., GNU) has the function
92 canonicalize_file_name() which malloc's a chunk of memory and
93 returns that, use that. */
94 #elif defined(HAVE_CANONICALIZE_FILE_NAME)
95 {
96 char *rp = canonicalize_file_name (filename);
97 if (rp == NULL)
98 return strdup (filename);
99 else
100 return rp;
101 }
102 /* HAVE_CANONICALIZE_FILE_NAME */
103
104 /* Method 3: Now we're getting desperate! The system doesn't have a
105 compile time buffer size and no alternative function. Query the
106 OS, using pathconf(), for the buffer limit. Care is needed
107 though, some systems do not limit PATH_MAX (return -1 for
108 pathconf()) making it impossible to pass a correctly sized buffer
109 to realpath() (it could always overflow). On those systems, we
110 skip this. */
111 #elif defined (HAVE_REALPATH) && defined (HAVE_UNISTD_H)
112 {
113 /* Find out the max path size. */
114 long path_max = pathconf ("/", _PC_PATH_MAX);
115 if (path_max > 0)
116 {
117 /* PATH_MAX is bounded. */
118 char *buf, *rp, *ret;
119 buf = (char *) malloc (path_max);
120 if (buf == NULL)
121 return NULL;
122 rp = realpath (filename, buf);
123 ret = strdup (rp ? rp : filename);
124 free (buf);
125 return ret;
126 }
127 else
128 {
129 return NULL;
130 }
131 }
132 /* HAVE_REALPATH && HAVE_UNISTD_H */
133
134 /* The MS Windows method. If we don't have realpath, we assume we
135 don't have symlinks and just canonicalize to a Windows absolute
136 path. GetFullPath converts ../ and ./ in relative paths to
137 absolute paths, filling in current drive if one is not given
138 or using the current directory of a specified drive (eg, "E:foo").
139 It also converts all forward slashes to back slashes. */
140 #elif defined (_WIN32)
141 {
142 char buf[MAX_PATH];
143 char* basename;
144 DWORD len = GetFullPathName (filename, MAX_PATH, buf, &basename);
145 if (len == 0 || len > MAX_PATH - 1)
146 return strdup (filename);
147 else
148 {
149 /* The file system is case-preserving but case-insensitive,
150 Canonicalize to lowercase, using the codepage associated
151 with the process locale. */
152 CharLowerBuff (buf, len);
153 return strdup (buf);
154 }
155 }
156 #else
157
158 /* This system is a lost cause, just duplicate the filename. */
159 return strdup (filename);
160 #endif
161 }
162