1/* Return the canonical absolute name of a given file.
2   Copyright (C) 1996-2005 Free Software Foundation, Inc.
3
4   This program is free software; you can redistribute it and/or modify
5   it under the terms of the GNU General Public License as published by
6   the Free Software Foundation; either version 2, or (at your option)
7   any later version.
8
9   This program is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12   GNU General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this program; see the file COPYING.
16   If not, write to the Free Software Foundation,
17   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
18
19#ifdef HAVE_CONFIG_H
20# include <config.h>
21#endif
22
23#include "canonicalize.h"
24
25#ifdef STDC_HEADERS
26# include <stdlib.h>
27#else
28void free ();
29#endif
30
31#if defined STDC_HEADERS || defined HAVE_STRING_H
32# include <string.h>
33#else
34# include <strings.h>
35#endif
36
37#if HAVE_SYS_PARAM_H
38# include <sys/param.h>
39#endif
40
41#include <sys/stat.h>
42
43#if HAVE_UNISTD_H
44# include <unistd.h>
45#endif
46
47#include <errno.h>
48#include <stddef.h>
49
50#include "cycle-check.h"
51#include "filenamecat.h"
52#include "stat-macros.h"
53#include "xalloc.h"
54#include "xgetcwd.h"
55
56#ifndef __set_errno
57# define __set_errno(Val) errno = (Val)
58#endif
59
60#include "pathmax.h"
61#include "xreadlink.h"
62
63#if !HAVE_CANONICALIZE_FILE_NAME
64/* Return the canonical absolute name of file NAME.  A canonical name
65   does not contain any `.', `..' components nor any repeated file name
66   separators ('/') or symlinks.  All components must exist.
67   The result is malloc'd.  */
68
69char *
70canonicalize_file_name (const char *name)
71{
72# if HAVE_RESOLVEPATH
73
74  char *resolved, *extra_buf = NULL;
75  size_t resolved_size;
76  ssize_t resolved_len;
77
78  if (name == NULL)
79    {
80      __set_errno (EINVAL);
81      return NULL;
82    }
83
84  if (name[0] == '\0')
85    {
86      __set_errno (ENOENT);
87      return NULL;
88    }
89
90  /* All known hosts with resolvepath (e.g. Solaris 7) don't turn
91     relative names into absolute ones, so prepend the working
92     directory if the file name is not absolute.  */
93  if (name[0] != '/')
94    {
95      char *wd;
96
97      if (!(wd = xgetcwd ()))
98	return NULL;
99
100      extra_buf = file_name_concat (wd, name, NULL);
101      name = extra_buf;
102      free (wd);
103    }
104
105  resolved_size = strlen (name);
106  while (1)
107    {
108      resolved_size = 2 * resolved_size + 1;
109      resolved = xmalloc (resolved_size);
110      resolved_len = resolvepath (name, resolved, resolved_size);
111      if (resolved_len < 0)
112	{
113	  free (resolved);
114	  free (extra_buf);
115	  return NULL;
116	}
117      if (resolved_len < resolved_size)
118	break;
119      free (resolved);
120    }
121
122  free (extra_buf);
123
124  /* NUL-terminate the resulting name.  */
125  resolved[resolved_len] = '\0';
126
127  return resolved;
128
129# else
130
131  return canonicalize_filename_mode (name, CAN_EXISTING);
132
133# endif /* !HAVE_RESOLVEPATH */
134}
135#endif /* !HAVE_CANONICALIZE_FILE_NAME */
136
137/* Return the canonical absolute name of file NAME.  A canonical name
138   does not contain any `.', `..' components nor any repeated file name
139   separators ('/') or symlinks.  Whether components must exist
140   or not depends on canonicalize mode.  The result is malloc'd.  */
141
142char *
143canonicalize_filename_mode (const char *name, canonicalize_mode_t can_mode)
144{
145  char *rname, *dest, *extra_buf = NULL;
146  char const *start;
147  char const *end;
148  char const *rname_limit;
149  size_t extra_len = 0;
150  struct cycle_check_state cycle_state;
151
152  if (name == NULL)
153    {
154      __set_errno (EINVAL);
155      return NULL;
156    }
157
158  if (name[0] == '\0')
159    {
160      __set_errno (ENOENT);
161      return NULL;
162    }
163
164  if (name[0] != '/')
165    {
166      rname = xgetcwd ();
167      if (!rname)
168	return NULL;
169      dest = strchr (rname, '\0');
170      if (dest - rname < PATH_MAX)
171	{
172	  char *p = xrealloc (rname, PATH_MAX);
173	  dest = p + (dest - rname);
174	  rname = p;
175	  rname_limit = rname + PATH_MAX;
176	}
177      else
178	{
179	  rname_limit = dest;
180	}
181    }
182  else
183    {
184      rname = xmalloc (PATH_MAX);
185      rname_limit = rname + PATH_MAX;
186      rname[0] = '/';
187      dest = rname + 1;
188    }
189
190  cycle_check_init (&cycle_state);
191  for (start = end = name; *start; start = end)
192    {
193      /* Skip sequence of multiple file name separators.  */
194      while (*start == '/')
195	++start;
196
197      /* Find end of component.  */
198      for (end = start; *end && *end != '/'; ++end)
199	/* Nothing.  */;
200
201      if (end - start == 0)
202	break;
203      else if (end - start == 1 && start[0] == '.')
204	/* nothing */;
205      else if (end - start == 2 && start[0] == '.' && start[1] == '.')
206	{
207	  /* Back up to previous component, ignore if at root already.  */
208	  if (dest > rname + 1)
209	    while ((--dest)[-1] != '/');
210	}
211      else
212	{
213	  struct stat st;
214
215	  if (dest[-1] != '/')
216	    *dest++ = '/';
217
218	  if (dest + (end - start) >= rname_limit)
219	    {
220	      ptrdiff_t dest_offset = dest - rname;
221	      size_t new_size = rname_limit - rname;
222
223	      if (end - start + 1 > PATH_MAX)
224		new_size += end - start + 1;
225	      else
226		new_size += PATH_MAX;
227	      rname = xrealloc (rname, new_size);
228	      rname_limit = rname + new_size;
229
230	      dest = rname + dest_offset;
231	    }
232
233	  dest = memcpy (dest, start, end - start);
234	  dest += end - start;
235	  *dest = '\0';
236
237	  if (lstat (rname, &st) != 0)
238	    {
239	      if (can_mode == CAN_EXISTING)
240		goto error;
241	      if (can_mode == CAN_ALL_BUT_LAST && *end)
242		goto error;
243	      st.st_mode = 0;
244	    }
245
246	  if (S_ISLNK (st.st_mode))
247	    {
248	      char *buf;
249	      size_t n, len;
250
251	      if (cycle_check (&cycle_state, &st))
252		{
253		  __set_errno (ELOOP);
254		  if (can_mode == CAN_MISSING)
255		    continue;
256		  else
257		    goto error;
258		}
259
260	      buf = xreadlink (rname, st.st_size);
261	      if (!buf)
262		{
263		  if (can_mode == CAN_MISSING)
264		    continue;
265		  else
266		    goto error;
267		}
268
269	      n = strlen (buf);
270	      len = strlen (end);
271
272	      if (!extra_len)
273		{
274		  extra_len =
275		    ((n + len + 1) > PATH_MAX) ? (n + len + 1) : PATH_MAX;
276		  extra_buf = xmalloc (extra_len);
277		}
278	      else if ((n + len + 1) > extra_len)
279		{
280		  extra_len = n + len + 1;
281		  extra_buf = xrealloc (extra_buf, extra_len);
282		}
283
284	      /* Careful here, end may be a pointer into extra_buf... */
285	      memmove (&extra_buf[n], end, len + 1);
286	      name = end = memcpy (extra_buf, buf, n);
287
288	      if (buf[0] == '/')
289		dest = rname + 1;	/* It's an absolute symlink */
290	      else
291		/* Back up to previous component, ignore if at root already: */
292		if (dest > rname + 1)
293		  while ((--dest)[-1] != '/');
294
295	      free (buf);
296	    }
297	  else
298	    {
299	      if (!S_ISDIR (st.st_mode) && *end && (can_mode != CAN_MISSING))
300		{
301		  errno = ENOTDIR;
302		  goto error;
303		}
304	    }
305	}
306    }
307  if (dest > rname + 1 && dest[-1] == '/')
308    --dest;
309  *dest = '\0';
310
311  free (extra_buf);
312  return rname;
313
314error:
315  free (extra_buf);
316  free (rname);
317  return NULL;
318}
319