summaryrefslogtreecommitdiff
path: root/libdiskfs/dir-lookup.c
blob: 24388cc998851b0267fb0bcab8dc520205b26701 (plain)
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
/* libdiskfs implementation of fs.defs:dir_lookup
   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997 Free Software Foundation

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program 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
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <sys/file.h>
#include <hurd/fsys.h>
#include <hurd/paths.h>

#include "priv.h"
#include "fs_S.h"

/* XXX - Temporary hack; this belongs in a header file, probably types.h. */
#define major(x) ((int)(((unsigned) (x) >> 8) & 0xff))
#define minor(x) ((int)((x) & 0xff))

/* Implement dir_lookup as described in <hurd/fs.defs>. */
kern_return_t
diskfs_S_dir_lookup (struct protid *dircred,
		     char *path,
		     int flags,
		     mode_t mode,
		     enum retry_type *retry,
		     char *retryname,
		     file_t *returned_port,
		     mach_msg_type_name_t *returned_port_poly)
{
  struct node *dnp;
  struct node *np;
  int nsymlink = 0;
  char *nextname;
  int nextnamelen;
  error_t error = 0;
  char *pathbuf = 0;
  int pathbuflen = 0;
  int newnamelen;
  int create, excl;
  int lastcomp = 0;
  int newnode = 0;
  struct dirstat *ds = 0;
  int mustbedir = 0;
  int amt;
  int type;
  struct protid *newpi;
  unsigned depth;		/* Depth of DNP below FS root.  */

  if (!dircred)
    return EOPNOTSUPP;

  /* XXX - EXLOCK & SHLOCK are temporary until they get added to O_HURD. */
  flags &= O_HURD | O_EXLOCK | O_SHLOCK;  

  create = (flags & O_CREAT);
  excl = (flags & O_EXCL);

  /* Skip leading slashes */
  while (path[0] == '/')
    path++;

  *returned_port_poly = MACH_MSG_TYPE_MAKE_SEND;
  *retry = FS_RETRY_NORMAL;
  retryname[0] = '\0';

  /* How far beneath root we are; this changes as we traverse the path.  */
  depth = dircred->po->depth;

  if (path[0] == '\0')
    {
      mustbedir = 1;

      /* Set things up in the state expected by the code from gotit: on. */
      dnp = 0;
      np = dircred->po->np;
      mutex_lock (&np->lock);
      diskfs_nref (np);
      goto gotit;
    }

  dnp = dircred->po->np;

  mutex_lock (&dnp->lock);
  np = 0;

  diskfs_nref (dnp);		/* acquire a reference for later diskfs_nput */

  do
    {
      assert (!lastcomp);
      
      /* Find the name of the next pathname component */
      nextname = index (path, '/');

      if (nextname)
	{
	  *nextname++ = '\0';
	  while (*nextname == '/')
	    nextname++;
	  if (*nextname == '\0')
	    {
	      /* These are the rules for filenames ending in /. */
	      nextname = 0;
	      lastcomp = 1;
	      mustbedir = 1;
	      create = 0;
	    }
	  else
	    lastcomp = 0;
	}
      else
	lastcomp = 1;
	  
      np = 0;

      /* diskfs_lookup the next pathname component */
      if (lastcomp && create)
	{
	  assert (!ds);
	  ds = alloca (diskfs_dirstat_size);
	  error = diskfs_lookup (dnp, path, CREATE, &np, ds, dircred, depth, &depth);
	}
      else
	error = diskfs_lookup (dnp, path, LOOKUP, &np, 0, dircred, depth, &depth);

      if (lastcomp && create && excl && (!error || error == EAGAIN))
	error = EEXIST;

      /* If we get an error we're done */
      if (error == EAGAIN)
	{
	  if (dircred->po->dotdotport != MACH_PORT_NULL)
	    {
	      *retry = FS_RETRY_REAUTH;
	      *returned_port = dircred->po->dotdotport;
	      *returned_port_poly = MACH_MSG_TYPE_COPY_SEND;
	      if (!lastcomp)
		strcpy (retryname, nextname);
	      error = 0;
	      goto out;
	    }
	  else
	    {
	      error = 0;
	      np = dnp;
	      diskfs_nref (np);
	    }
	}

      /* Create the new node if necessary */
      if (lastcomp && create)
	{
	  if (error == ENOENT)
	    {
	      mode &= ~(S_IFMT | S_ISPARE | S_ISVTX);
	      mode |= S_IFREG;
	      error = diskfs_create_node (dnp, path, mode, &np, dircred, ds);
	      if (diskfs_synchronous)
		{
		  diskfs_file_update (dnp, 1);
		  diskfs_file_update (np, 1);
		}
	      newnode = 1;
	    }
	  else
	    diskfs_drop_dirstat (dnp, ds);
	}
      
      if (error)
	goto out;

      /* If this is translated, start the translator (if necessary)
	 and return.  */
      if ((((flags & O_NOTRANS) == 0) || !lastcomp)
	  && ((np->dn_stat.st_mode & S_IPTRANS)
	      || S_ISFIFO (np->dn_stat.st_mode)
	      || S_ISCHR (np->dn_stat.st_mode)
	      || S_ISBLK (np->dn_stat.st_mode)
	      || fshelp_translated (&np->transbox)))
	{
	  mach_port_t dirport;
	  struct diskfs_trans_callback_cookie2 cookie2 =
	    { dircred->po->dotdotport, depth };
	  
	  /* A callback function for short-circuited translators.
	     Symlink & ifsock are handled elsewhere.  */
	  error_t short_circuited_callback1 (void *cookie1, void *cookie2,
					     uid_t *uid, gid_t *gid,
					     char **argz, int *argz_len)
	    {
	      struct node *node = cookie1;

	      switch (node->dn_stat.st_mode & S_IFMT)
		{
		case S_IFCHR:
		case S_IFBLK:
		  asprintf (argz, "%s%c%d%c%d",
			    (S_ISCHR (node->dn_stat.st_mode)
			     ? _HURD_CHRDEV : _HURD_BLKDEV),
			    0, major (node->dn_stat.st_rdev),
			    0, minor (node->dn_stat.st_rdev));
		  *argz_len = strlen (*argz) + 1;
		  *argz_len += strlen (*argz + *argz_len) + 1;
		  *argz_len += strlen (*argz + *argz_len) + 1;
		  break;
		case S_IFIFO:
		  asprintf (argz, "%s", _HURD_FIFO);
		  *argz_len = strlen (*argz) + 1;
		  break;
		default:
		  return ENOENT;
		}

	      *uid = node->dn_stat.st_uid;
	      *gid = node->dn_stat.st_gid;

	      return 0;
	    }

	  /* Create an unauthenticated port for DNP, and then
	     unlock it. */
	  error = 
	    diskfs_create_protid (diskfs_make_peropen (dnp, 0,
						       dircred->po->dotdotport,
						       depth),
				  iohelp_create_iouser (make_idvec (), 
							make_idvec ()),
				  &newpi);
	  if (error)
	    goto out;

	  dirport = ports_get_right (newpi);
	  mach_port_insert_right (mach_task_self (), dirport, dirport,
				  MACH_MSG_TYPE_MAKE_SEND);
	  ports_port_deref (newpi);
	  if (np != dnp)
	    mutex_unlock (&dnp->lock);

	  error = fshelp_fetch_root (&np->transbox, &cookie2,
				     dirport, dircred->user,
				     lastcomp ? flags : 0,
				     ((np->dn_stat.st_mode & S_IPTRANS)
				      ? _diskfs_translator_callback1
				      : short_circuited_callback1),
				     _diskfs_translator_callback2,
				     retry, retryname, returned_port);

	  /* fetch_root copies DIRPORT for success, so we always should
	     deallocate our send right.  */
	  mach_port_deallocate (mach_task_self (), dirport);

	  if (error != ENOENT)
	    {
	      diskfs_nrele (dnp);
	      diskfs_nput (np);
	      *returned_port_poly = MACH_MSG_TYPE_MOVE_SEND;
	      if (!lastcomp && !error)
		{
		  strcat (retryname, "/");
		  strcat (retryname, nextname);
		}
	      return error;
	    }

	  /* ENOENT means there was a hiccup, and the translator
	     vanished while NP was unlocked inside fshelp_fetch_root.
	     Reacquire the locks, and continue as normal. */
	  error = 0;
	  if (np != dnp)
	    {
	      if (!strcmp (path, ".."))
		mutex_lock (&dnp->lock);
	      else
		{
		  mutex_unlock (&np->lock);
		  mutex_lock (&dnp->lock);
		  mutex_lock (&np->lock);
		}
	    }
	}
      
      if (S_ISLNK (np->dn_stat.st_mode)
	  && !(lastcomp && (flags & (O_NOLINK|O_NOTRANS))))
	{
	  /* Handle symlink interpretation */

	  if (nsymlink++ > diskfs_maxsymlinks)
	    {
	      error = ELOOP;
	      goto out;
	    }
	      
	  nextnamelen = nextname ? strlen (nextname) + 1 : 0;
	  newnamelen = nextnamelen + np->dn_stat.st_size + 1;
	  if (pathbuflen < newnamelen)
	    {
	      pathbuf = alloca (newnamelen);
	      pathbuflen = newnamelen;
	    }
	      
	  if (diskfs_read_symlink_hook)
	    error = (*diskfs_read_symlink_hook)(np, pathbuf);
	  if (!diskfs_read_symlink_hook || error == EINVAL)
	    error = diskfs_node_rdwr (np, pathbuf, 
				      0, np->dn_stat.st_size, 0, 
				      dircred, &amt);
	  if (error)
	    goto out;
	      
	  if (nextname)
	    {
	      pathbuf[np->dn_stat.st_size] = '/';
	      bcopy (nextname, pathbuf + np->dn_stat.st_size + 1, 
		     nextnamelen - 1);
	    }
	  pathbuf[nextnamelen + np->dn_stat.st_size] = '\0';

	  if (pathbuf[0] == '/')
	    {
	      /* Punt to the caller.  */
	      *retry = FS_RETRY_MAGICAL;
	      *returned_port = MACH_PORT_NULL;
	      strcpy (retryname, pathbuf);
	      goto out;
	    }
	  
	  path = pathbuf;
	  if (lastcomp)
	    {
	      lastcomp = 0;
	      /* Symlinks to nonexistent files aren't allowed to cause
		 creation, so clear the flag here. */
	      create = 0;
	    }
	  diskfs_nput (np);
	  np = 0;
	}
      else
	{
	  /* Handle normal nodes */
	  path = nextname;
	  if (np == dnp)
	    diskfs_nrele (dnp);
	  else
	    diskfs_nput (dnp);
	  if (!lastcomp)
	    {
	      dnp = np;
	      np = 0;
	    }
	  else
	    dnp = 0;
	}
    } while (path && *path);
  
  /* At this point, np is the node to return.  If newnode is set, then
     we just created this node.  */

 gotit:
  type = np->dn_stat.st_mode & S_IFMT;

  if (mustbedir && type != S_IFDIR)
    {
      error = ENOTDIR;
      goto out;
    }
  
  if (!newnode)
    /* Check permissions on existing nodes, but not new ones. */
    {
      if ((type == S_IFSOCK || type == S_IFBLK || type == S_IFLNK
	   || type == S_IFCHR || type == S_IFIFO)
	  && (flags & (O_READ|O_WRITE|O_EXEC)))
	error = EOPNOTSUPP;

      if (!error && (flags & O_READ))
	error = fshelp_access (&np->dn_stat, S_IREAD, dircred->user);

      if (!error && (flags & O_EXEC))
	error = fshelp_access (&np->dn_stat, S_IEXEC, dircred->user);

      if (!error && (flags & O_WRITE))
	{
	  if (type == S_IFDIR)
	    error = EISDIR;
	  else if (diskfs_check_readonly ())
	    error = EROFS;
	  else
	    error = fshelp_access (&np->dn_stat, S_IWRITE, dircred->user);
	}

      if (error)
	goto out;
    }
    
  if ((flags & O_NOATIME) 
      && (fshelp_isowner (&np->dn_stat, dircred->user) == EPERM))
    flags &= ~O_NOATIME;
      
  error =
    diskfs_create_protid (diskfs_make_peropen (np, 
					       (flags &~OPENONLY_STATE_MODES), 
					       dircred->po->dotdotport,
					       depth),
			  dircred->user, &newpi);

  if (! error)
    {
      if (flags & O_EXLOCK)
	error = fshelp_acquire_lock (&np->userlock, &newpi->po->lock_status,
				     &np->lock, LOCK_EX);
      else if (flags & O_SHLOCK)
	error = fshelp_acquire_lock (&np->userlock, &newpi->po->lock_status,
				     &np->lock, LOCK_SH);
      if (error)
	ports_port_deref (newpi); /* Get rid of NEWPI.  */
    }
  
  if (! error)
    {
      *returned_port = ports_get_right (newpi);
      ports_port_deref (newpi);
    }
  
 out:
  if (np)
    if (dnp == np)
      diskfs_nrele (np);
    else
      diskfs_nput (np);
  if (dnp)
    diskfs_nput (dnp);

  return error;
}