summary refs log tree commit diff
path: root/sysdeps/posix/getcwd.c
blob: 911cbfab5db11a29d90ec366b9b0ba423f825341 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
/* Copyright (C) 1991-2012 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

/* Wants:
   AC_STDC_HEADERS
   AC_DIR_HEADER
   AC_UNISTD_H
   AC_MEMORY_H
   AC_CONST
   AC_ALLOCA
 */

/* AIX requires this to be the first thing in the file.  */
#if defined _AIX && !defined __GNUC__
 #pragma alloca
#endif

#ifdef	HAVE_CONFIG_H
# include "config.h"
#endif

#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifdef	STDC_HEADERS
# include <stddef.h>
#endif

#if !defined __GNU_LIBRARY__ && !defined STDC_HEADERS
extern int errno;
#endif
#ifndef __set_errno
# define __set_errno(val) errno = (val)
#endif

#ifndef	NULL
# define NULL	0
#endif

#if defined USGr3 && !defined DIRENT
# define DIRENT
#endif /* USGr3 */
#if defined Xenix && !defined SYSNDIR
# define SYSNDIR
#endif /* Xenix */

#if defined POSIX || defined DIRENT || defined __GNU_LIBRARY__
# include <dirent.h>
# ifndef __GNU_LIBRARY__
#  define D_NAMLEN(d) strlen((d)->d_name)
# else
#  define HAVE_D_NAMLEN
#  define D_NAMLEN(d) ((d)->d_namlen)
# endif
#else /* not POSIX or DIRENT */
# define dirent		direct
# define D_NAMLEN(d)	((d)->d_namlen)
# define HAVE_D_NAMLEN
# if defined USG && !defined sgi
#  if defined SYSNDIR
#   include <sys/ndir.h>
#  else /* Not SYSNDIR */
#   include "ndir.h"
#  endif /* SYSNDIR */
# else /* not USG */
#  include <sys/dir.h>
# endif /* USG */
#endif /* POSIX or DIRENT or __GNU_LIBRARY__ */

#if defined HAVE_UNISTD_H || defined __GNU_LIBRARY__
# include <unistd.h>
#endif

#if defined STDC_HEADERS || defined __GNU_LIBRARY__ || defined POSIX
# include <stdlib.h>
# include <string.h>
# define ANSI_STRING
#else	/* No standard headers.  */

# ifdef	USG

#  include <string.h>
#  ifdef NEED_MEMORY_H
#   include <memory.h>
#  endif
#  define	ANSI_STRING

# else	/* Not USG.  */

#  ifdef NeXT

#   include <string.h>

#  else	/* Not NeXT.  */

#   include <strings.h>

#   ifndef bcmp
extern int bcmp ();
#   endif
#   ifndef bzero
extern void bzero ();
#   endif
#   ifndef bcopy
extern void bcopy ();
#   endif

#  endif /* NeXT. */

# endif	/* USG.  */

extern char *malloc (), *realloc ();
extern void free ();

#endif /* Standard headers.  */

#ifndef	ANSI_STRING
# define memcpy(d, s, n)	bcopy((s), (d), (n))
# define memmove memcpy
#endif	/* Not ANSI_STRING.  */

#ifndef MAX
# define MAX(a, b) ((a) < (b) ? (b) : (a))
#endif

#ifdef _LIBC
# ifndef mempcpy
#  define mempcpy __mempcpy
# endif
# define HAVE_MEMPCPY	1
#endif

#if !defined __alloca && !defined __GNU_LIBRARY__

# ifdef	__GNUC__
#  undef alloca
#  define alloca(n)	__builtin_alloca (n)
# else	/* Not GCC.  */
#  if	defined sparc || defined HAVE_ALLOCA_H
#   include <alloca.h>
#  else	/* Not sparc or HAVE_ALLOCA_H.  */
#   ifndef _AIX
extern char *alloca ();
#   endif /* Not _AIX.  */
#  endif /* sparc or HAVE_ALLOCA_H.  */
# endif	/* GCC.  */

# define __alloca	alloca

#endif

#if defined HAVE_LIMITS_H || defined STDC_HEADERS || defined __GNU_LIBRARY__
# include <limits.h>
#else
# include <sys/param.h>
#endif

#if defined _LIBC
# include <not-cancel.h>
# include <kernel-features.h>
#else
# define openat64_not_cancel_3(dfd, name, mode) openat64 (dfd, name, mode)
# define close_not_cancel_no_status(fd) close (fd)
#endif

#ifndef PATH_MAX
# ifdef	MAXPATHLEN
#  define PATH_MAX MAXPATHLEN
# else
#  define PATH_MAX 1024
# endif
#endif

#if !defined STDC_HEADERS && !defined __GNU_LIBRARY__
# undef	size_t
# define size_t	unsigned int
#endif

#ifndef __GNU_LIBRARY__
# define __lstat64	stat64
#endif

#ifndef _LIBC
# define __getcwd getcwd
#endif

#ifndef GETCWD_RETURN_TYPE
# define GETCWD_RETURN_TYPE char *
#endif

#ifdef __ASSUME_ATFCTS
# define __have_atfcts 1
#elif defined NOT_IN_libc && defined IS_IN_rtld
static int __rtld_have_atfcts;
# define __have_atfcts __rtld_have_atfcts
#endif

/* Get the pathname of the current working directory, and put it in SIZE
   bytes of BUF.  Returns NULL if the directory couldn't be determined or
   SIZE was too small.  If successful, returns BUF.  In GNU, if BUF is
   NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
   unless SIZE == 0, in which case it is as big as necessary.  */

GETCWD_RETURN_TYPE
__getcwd (buf, size)
     char *buf;
     size_t size;
{
#ifndef __ASSUME_ATFCTS
  static const char dots[]
    = "../../../../../../../../../../../../../../../../../../../../../../../\
../../../../../../../../../../../../../../../../../../../../../../../../../../\
../../../../../../../../../../../../../../../../../../../../../../../../../..";
  const char *dotp = &dots[sizeof (dots)];
  const char *dotlist = dots;
  size_t dotsize = sizeof (dots) - 1;
#endif
  int prev_errno = errno;
  DIR *dirstream = NULL;
  bool fd_needs_closing = false;
  int fd = AT_FDCWD;

  char *path;
#ifndef NO_ALLOCATION
  size_t allocated = size;
  if (size == 0)
    {
      if (buf != NULL)
	{
	  __set_errno (EINVAL);
	  return NULL;
	}

      allocated = PATH_MAX + 1;
    }

  if (buf == NULL)
    {
      path = malloc (allocated);
      if (path == NULL)
	return NULL;
    }
  else
#else
# define allocated size
#endif
    path = buf;

  char *pathp = path + allocated;
  *--pathp = '\0';

  struct stat64 st;
  if (__lstat64 (".", &st) < 0)
    goto lose;
  dev_t thisdev = st.st_dev;
  ino_t thisino = st.st_ino;

  if (__lstat64 ("/", &st) < 0)
    goto lose;
  dev_t rootdev = st.st_dev;
  ino_t rootino = st.st_ino;

  while (!(thisdev == rootdev && thisino == rootino))
    {
      if (__have_atfcts >= 0)
	{
	  int mode = O_RDONLY;
#ifdef O_CLOEXEC
	  mode |= O_CLOEXEC;
#endif
	  fd = openat64_not_cancel_3 (fd, "..", mode);
	}
      else
	fd = -1;
      if (fd >= 0)
	{
	  fd_needs_closing = true;
	  if (__fstat64 (fd, &st) < 0)
	    goto lose;
	}
#ifndef __ASSUME_ATFCTS
      else if (errno == ENOSYS)
	{
	  __have_atfcts = -1;

	  /* Look at the parent directory.  */
	  if (dotp == dotlist)
	    {
# ifdef NO_ALLOCATION
	      __set_errno (ENOMEM);
	      goto lose;
# else
	      /* My, what a deep directory tree you have, Grandma.  */
	      char *new;
	      if (dotlist == dots)
		{
		  new = malloc (dotsize * 2 + 1);
		  if (new == NULL)
		    goto lose;
#  ifdef HAVE_MEMPCPY
		  dotp = mempcpy (new, dots, dotsize);
#  else
		  memcpy (new, dots, dotsize);
		  dotp = &new[dotsize];
#  endif
		}
	      else
		{
		  new = realloc ((__ptr_t) dotlist, dotsize * 2 + 1);
		  if (new == NULL)
		    goto lose;
		  dotp = &new[dotsize];
		}
#  ifdef HAVE_MEMPCPY
	      *((char *) mempcpy ((char *) dotp, new, dotsize)) = '\0';
	      dotsize *= 2;
#  else
	      memcpy ((char *) dotp, new, dotsize);
	      dotsize *= 2;
	      new[dotsize] = '\0';
#  endif
	      dotlist = new;
# endif
	    }

	  dotp -= 3;

	  /* Figure out if this directory is a mount point.  */
	  if (__lstat64 (dotp, &st) < 0)
	    goto lose;
	}
#endif
      else
	goto lose;

      if (dirstream && __closedir (dirstream) != 0)
	{
	  dirstream = NULL;
	  goto lose;
       }

      dev_t dotdev = st.st_dev;
      ino_t dotino = st.st_ino;
      bool mount_point = dotdev != thisdev;

      /* Search for the last directory.  */
      if (__have_atfcts >= 0)
	dirstream = __fdopendir (fd);
#ifndef __ASSUME_ATFCTS
      else
	dirstream = __opendir (dotp);
#endif
      if (dirstream == NULL)
	goto lose;
      fd_needs_closing = false;

      struct dirent *d;
      bool use_d_ino = true;
      while (1)
	{
	  /* Clear errno to distinguish EOF from error if readdir returns
	     NULL.  */
	  __set_errno (0);
	  d = __readdir (dirstream);
	  if (d == NULL)
	    {
	      if (errno == 0)
		{
		  /* When we've iterated through all directory entries
		     without finding one with a matching d_ino, rewind the
		     stream and consider each name again, but this time, using
		     lstat64.  This is necessary in a chroot on at least one
		     system.  */
		  if (use_d_ino)
		    {
		      use_d_ino = false;
		      rewinddir (dirstream);
		      continue;
		    }

		  /* EOF on dirstream, which means that the current directory
		     has been removed.  */
		  __set_errno (ENOENT);
		}
	      goto lose;
	    }

#ifdef _DIRENT_HAVE_D_TYPE
	  if (d->d_type != DT_DIR && d->d_type != DT_UNKNOWN)
	    continue;
#endif
	  if (d->d_name[0] == '.'
	      && (d->d_name[1] == '\0'
		  || (d->d_name[1] == '.' && d->d_name[2] == '\0')))
	    continue;
	  if (use_d_ino && !mount_point && (ino_t) d->d_ino != thisino)
	    continue;

	  if (__have_atfcts >= 0)
	    {
	      /* We don't fail here if we cannot stat64() a directory entry.
		 This can happen when (network) filesystems fail.  If this
		 entry is in fact the one we are looking for we will find
		 out soon as we reach the end of the directory without
		 having found anything.  */
	      if (__fstatat64 (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0)
		continue;
	    }
#ifndef __ASSUME_ATFCTS
	  else
	    {
	      char name[dotlist + dotsize - dotp + 1 + _D_ALLOC_NAMLEN (d)];
# ifdef HAVE_MEMPCPY
	      char *tmp = mempcpy (name, dotp, dotlist + dotsize - dotp);
	      *tmp++ = '/';
	      strcpy (tmp, d->d_name);
# else
	      memcpy (name, dotp, dotlist + dotsize - dotp);
	      name[dotlist + dotsize - dotp] = '/';
	      strcpy (&name[dotlist + dotsize - dotp + 1], d->d_name);
# endif
	      /* We don't fail here if we cannot stat64() a directory entry.
		 This can happen when (network) filesystems fail.  If this
		 entry is in fact the one we are looking for we will find
		 out soon as we reach the end of the directory without
		 having found anything.  */
	      if (__lstat64 (name, &st) < 0)
		continue;
	    }
#endif
	  if (S_ISDIR (st.st_mode)
	      && st.st_dev == thisdev && st.st_ino == thisino)
	    break;
	}

      size_t namlen = _D_EXACT_NAMLEN (d);

      if ((size_t) (pathp - path) <= namlen)
	{
#ifndef NO_ALLOCATION
	  if (size == 0)
	    {
	      size_t oldsize = allocated;

	      allocated = 2 * MAX (allocated, namlen);
	      char *tmp = realloc (path, allocated);
	      if (tmp == NULL)
		goto lose;

	      /* Move current contents up to the end of the buffer.
		 This is guaranteed to be non-overlapping.  */
	      pathp = memcpy (tmp + allocated - (path + oldsize - pathp),
			      tmp + (pathp - path),
			      path + oldsize - pathp);
	      path = tmp;
	    }
	  else
#endif
	    {
	      __set_errno (ERANGE);
	      goto lose;
	    }
	}
      pathp -= namlen;
      (void) memcpy (pathp, d->d_name, namlen);
      *--pathp = '/';

      thisdev = dotdev;
      thisino = dotino;
    }

  if (dirstream != NULL && __closedir (dirstream) != 0)
    {
      dirstream = NULL;
      goto lose;
    }

  if (pathp == &path[allocated - 1])
    *--pathp = '/';

#ifndef __ASSUME_ATFCTS
  if (dotlist != dots)
    free ((__ptr_t) dotlist);
#endif

  size_t used = path + allocated - pathp;
  memmove (path, pathp, used);

  if (size == 0)
    /* Ensure that the buffer is only as large as necessary.  */
    buf = realloc (path, used);

  if (buf == NULL)
    /* Either buf was NULL all along, or `realloc' failed but
       we still have the original string.  */
    buf = path;

  /* Restore errno on successful return.  */
  __set_errno (prev_errno);

  return buf;

 lose:;
  int save_errno = errno;
#ifndef __ASSUME_ATFCTS
  if (dotlist != dots)
    free ((__ptr_t) dotlist);
#endif
  if (dirstream != NULL)
    __closedir (dirstream);
  if (fd_needs_closing)
    close_not_cancel_no_status (fd);
#ifndef NO_ALLOCATION
  if (buf == NULL)
    free (path);
#endif
  __set_errno (save_errno);
  return NULL;
}

#if defined _LIBC && !defined __getcwd
weak_alias (__getcwd, getcwd)
#endif