aboutsummaryrefslogtreecommitdiff
path: root/src/gdbmopen.c
blob: 80474a6eea692ec596ae0745a7946dab61b2d6bf (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
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
540
541
542
543
544
545
546
547
548
/* gdbmopen.c - Open the dbm file and initialize data structures for use. */

/* This file is part of GDBM, the GNU data base manager.
   Copyright (C) 1990-1991, 1993, 2007, 2011, 2013, 2016-2017 Free
   Software Foundation, Inc.

   GDBM 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 3, or (at your option)
   any later version.

   GDBM 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 GDBM. If not, see <http://www.gnu.org/licenses/>.   */

/* Include system configuration before all else. */
#include "autoconf.h"

#include "gdbmdefs.h"

/* Determine our native magic number and bail if we can't. */
#if SIZEOF_OFF_T == 4
# define GDBM_MAGIC	GDBM_MAGIC32
#elif SIZEOF_OFF_T == 8
# define GDBM_MAGIC	GDBM_MAGIC64
#else
# error "Unsupported off_t size, contact GDBM maintainer.  What crazy system is this?!?"
#endif

static void
compute_directory_size (GDBM_FILE dbf, blksize_t block_size,
			int *ret_dir_size, int *ret_dir_bits)
{
  /* Create the initial hash table directory.  */
  int dir_size = 8 * sizeof (off_t);
  int dir_bits = 3;

  while (dir_size < block_size && dir_bits < GDBM_HASH_BITS - 3)
    {
      dir_size <<= 1;
      dir_bits++;
    }

  *ret_dir_size = dir_size;
  *ret_dir_bits = dir_bits;
}

GDBM_FILE 
gdbm_fd_open (int fd, const char *file_name, int block_size,
	      int flags, void (*fatal_func) (const char *))
{
  GDBM_FILE dbf;		/* The record to return. */
  struct stat file_stat;	/* Space for the stat information. */
  off_t       file_pos;		/* Used with seeks. */
  int 	      index;		/* Used as a loop index. */
  
  /* Initialize the gdbm_errno variable. */
  gdbm_set_errno (NULL, GDBM_NO_ERROR, FALSE);

  /* Get the status of the file. */
  if (fstat (fd, &file_stat))
    {
      if (flags & GDBM_CLOERROR)
	SAVE_ERRNO (close (fd));
      GDBM_SET_ERRNO2 (NULL, GDBM_FILE_STAT_ERROR, FALSE, GDBM_DEBUG_OPEN);
      return NULL;
    }
  
  /* Allocate new info structure. */
  dbf = (GDBM_FILE) malloc (sizeof (*dbf));
  if (dbf == NULL)
    {
      if (flags & GDBM_CLOERROR)
	SAVE_ERRNO (close (fd));
      GDBM_SET_ERRNO2 (NULL, GDBM_MALLOC_ERROR, FALSE, GDBM_DEBUG_OPEN);
      return NULL;
    }

  dbf->desc = fd;
  
  /* Initialize some fields for known values.  This is done so gdbm_close
     will work if called before allocating some structures. */
  dbf->dir  = NULL;
  dbf->bucket = NULL;
  dbf->header = NULL;
  dbf->bucket_cache = NULL;
  dbf->cache_size = 0;

  dbf->memory_mapping = FALSE;
  dbf->mapped_size_max = SIZE_T_MAX;
  dbf->mapped_region = NULL;
  dbf->mapped_size = 0;
  dbf->mapped_pos = 0;
  dbf->mapped_off = 0;
  
  /* Save name of file. */
  dbf->name = strdup (file_name);
  if (dbf->name == NULL)
    {
      if (flags & GDBM_CLOERROR)
	close (fd);
      free (dbf);
      GDBM_SET_ERRNO2 (NULL, GDBM_MALLOC_ERROR, FALSE, GDBM_DEBUG_OPEN);
      return NULL;
    }

  /* Initialize the fatal error routine. */
  dbf->fatal_err = fatal_func;

  dbf->fast_write = TRUE;	/* Default to setting fast_write. */
  dbf->file_locking = TRUE;	/* Default to doing file locking. */
  dbf->central_free = FALSE;	/* Default to not using central_free. */
  dbf->coalesce_blocks = FALSE; /* Default to not coalesce blocks. */

  dbf->need_recovery = FALSE;
  dbf->last_error = GDBM_NO_ERROR;
  dbf->last_syserror = 0;
  dbf->last_errstr = NULL;
  
  /* GDBM_FAST used to determine whether or not we set fast_write. */
  if (flags & GDBM_SYNC)
    {
      /* If GDBM_SYNC has been requested, don't do fast_write. */
      dbf->fast_write = FALSE;
    }
  if (flags & GDBM_NOLOCK)
    {
      dbf->file_locking = FALSE;
    }

  dbf->cloexec = !!(flags & GDBM_CLOEXEC);
  
  /* Zero-length file can't be a reader... */
  if (((flags & GDBM_OPENMASK) == GDBM_READER) && (file_stat.st_size == 0))
    {
      if (flags & GDBM_CLOERROR)
	close (dbf->desc);
      free (dbf->name);
      free (dbf);
      GDBM_SET_ERRNO2 (NULL, GDBM_EMPTY_DATABASE, FALSE, GDBM_DEBUG_OPEN);
      return NULL;
    }

  /* Record the kind of user. */
  dbf->read_write = (flags & GDBM_OPENMASK);

  /* Lock the file in the appropriate way. */
  if (dbf->file_locking)
    {
      if (_gdbm_lock_file (dbf) == -1)
	{
	  if (flags & GDBM_CLOERROR)
	    close (dbf->desc);
	  free (dbf->name);
	  free (dbf);
          GDBM_SET_ERRNO2 (NULL,
			   (flags & GDBM_OPENMASK) == GDBM_READER
			     ? GDBM_CANT_BE_READER : GDBM_CANT_BE_WRITER,
			   FALSE,
			   GDBM_DEBUG_OPEN);
	  return NULL;
	}
    }

  /* If we do have a write lock and it was a GDBM_NEWDB, it is 
     now time to truncate the file. */
  if ((flags & GDBM_OPENMASK) == GDBM_NEWDB && file_stat.st_size != 0)
    {
      TRUNCATE (dbf);
      fstat (dbf->desc, &file_stat);
    }

  /* Decide if this is a new file or an old file. */
  if (file_stat.st_size == 0)
    {
      /* This is a new file.  Create an empty database.  */
      int dir_size, dir_bits;
      
      /* Start with the blocksize. */
      if (block_size < GDBM_MIN_BLOCK_SIZE)
	{
	  block_size = STATBLKSIZE (file_stat);
	  flags &= ~GDBM_BSEXACT;
	}
      compute_directory_size (dbf, block_size, &dir_size, &dir_bits);
      GDBM_DEBUG (GDBM_DEBUG_OPEN, "%s: computed dir_size=%d, dir_bits=%d",
		  dbf->name, dir_size, dir_bits);
      /* Check for correct block_size. */
      if (dir_size != block_size)
	{
	  if (flags & GDBM_BSEXACT)
	    {
	      if (!(flags & GDBM_CLOERROR))
		dbf->desc = -1;
	      gdbm_close (dbf);
	      GDBM_SET_ERRNO2 (NULL, GDBM_BLOCK_SIZE_ERROR, FALSE,
			       GDBM_DEBUG_OPEN);
	      return NULL;
	    }
	  else
	    block_size = dir_size;
	}
      GDBM_DEBUG (GDBM_DEBUG_OPEN, "%s: block_size=%d", dbf->name, block_size);
      
      /* Get space for the file header. It will be written to disk, so
         make sure there's no garbage in it. */
      dbf->header = (gdbm_file_header *) calloc (1, block_size);
      if (dbf->header == NULL)
	{
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  gdbm_close (dbf);
	  GDBM_SET_ERRNO2 (NULL, GDBM_MALLOC_ERROR, FALSE, GDBM_DEBUG_OPEN);
	  return NULL;
	}

      /* Set the magic number and the block_size. */
      dbf->header->header_magic = GDBM_MAGIC;
      dbf->header->block_size = block_size;
      dbf->header->dir_size = dir_size;
      dbf->header->dir_bits = dir_bits;

      /* Allocate the space for the directory. */
      dbf->dir = (off_t *) malloc (dbf->header->dir_size);
      if (dbf->dir == NULL)
	{
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  gdbm_close (dbf);
	  GDBM_SET_ERRNO2 (NULL, GDBM_MALLOC_ERROR, FALSE, GDBM_DEBUG_OPEN);
	  return NULL;
	}
      dbf->header->dir = dbf->header->block_size;

      /* Create the first and only hash bucket. */
      dbf->header->bucket_elems =
	(dbf->header->block_size - sizeof (hash_bucket))
	/ sizeof (bucket_element) + 1;
      dbf->header->bucket_size  = dbf->header->block_size;
      dbf->bucket = (hash_bucket *) malloc (dbf->header->bucket_size);
      if (dbf->bucket == NULL)
	{
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  gdbm_close (dbf);
	  GDBM_SET_ERRNO2 (NULL, GDBM_MALLOC_ERROR, FALSE, GDBM_DEBUG_OPEN);
	  return NULL;
	}
      _gdbm_new_bucket (dbf, dbf->bucket, 0);
      dbf->bucket->av_count = 1;
      dbf->bucket->bucket_avail[0].av_adr = 3*dbf->header->block_size;
      dbf->bucket->bucket_avail[0].av_size = dbf->header->block_size;

      /* Set table entries to point to hash buckets. */
      for (index = 0; index < GDBM_DIR_COUNT (dbf); index++)
	dbf->dir[index] = 2*dbf->header->block_size;

      /* Initialize the active avail block. */
      dbf->header->avail.size
	= ( (dbf->header->block_size - sizeof (gdbm_file_header))
	 / sizeof (avail_elem)) + 1;
      dbf->header->avail.count = 0;
      dbf->header->avail.next_block = 0;
      dbf->header->next_block  = 4*dbf->header->block_size;

      /* Write initial configuration to the file. */
      /* Block 0 is the file header and active avail block. */
      if (_gdbm_full_write (dbf, dbf->header, dbf->header->block_size))
	{
	  GDBM_DEBUG (GDBM_DEBUG_OPEN|GDBM_DEBUG_ERR,
		      "%s: error writing header: %s",
		      dbf->name, gdbm_db_strerror (dbf));
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  return NULL;
	}

      /* Block 1 is the initial bucket directory. */
      if (_gdbm_full_write (dbf, dbf->dir, dbf->header->dir_size))
	{
	  GDBM_DEBUG (GDBM_DEBUG_OPEN|GDBM_DEBUG_ERR,
		      "%s: error writing directory: %s",
		      dbf->name, gdbm_db_strerror (dbf));	  
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  return NULL;
	}

      /* Block 2 is the only bucket. */
      if (_gdbm_full_write (dbf, dbf->bucket, dbf->header->bucket_size))
	{
	  GDBM_DEBUG (GDBM_DEBUG_OPEN|GDBM_DEBUG_ERR,
		      "%s: error writing bucket: %s",
		      dbf->name, gdbm_db_strerror (dbf));	  
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  return NULL;
	}

      /* Wait for initial configuration to be written to disk. */
      __fsync (dbf);

      free (dbf->bucket);
    }
  else
    {
      /* This is an old database.  Read in the information from the file
	 header and initialize the hash directory. */

      gdbm_file_header partial_header;  /* For the first part of it. */

      /* Read the partial file header. */
      if (_gdbm_full_read (dbf, &partial_header, sizeof (gdbm_file_header)))
	{
	  GDBM_DEBUG (GDBM_DEBUG_ERR|GDBM_DEBUG_OPEN,
		      "%s: error reading partial header: %s",
		      dbf->name, gdbm_db_strerror (dbf));
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  return NULL;
	}

      /* Is the magic number good? */
      if (partial_header.header_magic != GDBM_MAGIC
	  && partial_header.header_magic != GDBM_OMAGIC)
	{
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  gdbm_close (dbf);
	  switch (partial_header.header_magic)
	    {
	      case GDBM_OMAGIC_SWAP:
	      case GDBM_MAGIC32_SWAP:
	      case GDBM_MAGIC64_SWAP:
		GDBM_SET_ERRNO2 (NULL, GDBM_BYTE_SWAPPED, FALSE,
				 GDBM_DEBUG_OPEN);
		break;
	      case GDBM_MAGIC32:
	      case GDBM_MAGIC64:
		GDBM_SET_ERRNO2 (NULL, GDBM_BAD_FILE_OFFSET, FALSE,
				 GDBM_DEBUG_OPEN);
		break;
	      default:
		GDBM_SET_ERRNO2 (NULL, GDBM_BAD_MAGIC_NUMBER, FALSE,
				 GDBM_DEBUG_OPEN);
	    }
	  return NULL;
	}

      /* It is a good database, read the entire header. */
      dbf->header = (gdbm_file_header *) malloc (partial_header.block_size);
      if (dbf->header == NULL)
	{
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  GDBM_SET_ERRNO2 (NULL, GDBM_MALLOC_ERROR, FALSE, GDBM_DEBUG_OPEN);
	  return NULL;
	}
      memcpy (dbf->header, &partial_header, sizeof (gdbm_file_header));
      if (_gdbm_full_read (dbf, &dbf->header->avail.av_table[1],
			   dbf->header->block_size - sizeof (gdbm_file_header)))
	{
	  GDBM_DEBUG (GDBM_DEBUG_ERR|GDBM_DEBUG_OPEN,
		      "%s: error reading av_table: %s",
		      dbf->name, gdbm_db_strerror (dbf));
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  return NULL;
	}
	
      /* Allocate space for the hash table directory.  */
      dbf->dir = (off_t *) malloc (dbf->header->dir_size);
      if (dbf->dir == NULL)
	{
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  gdbm_close (dbf);
	  GDBM_SET_ERRNO2 (NULL, GDBM_MALLOC_ERROR, FALSE, GDBM_DEBUG_OPEN);
	  return NULL;
	}

      /* Read the hash table directory. */
      file_pos = __lseek (dbf, dbf->header->dir, SEEK_SET);
      if (file_pos != dbf->header->dir)
	{
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  GDBM_SET_ERRNO2 (NULL, GDBM_FILE_SEEK_ERROR, FALSE, GDBM_DEBUG_OPEN);
	  return NULL;
	}

      if (_gdbm_full_read (dbf, dbf->dir, dbf->header->dir_size))
	{
	  GDBM_DEBUG (GDBM_DEBUG_ERR|GDBM_DEBUG_OPEN,
		      "%s: error reading dir: %s",
		      dbf->name, gdbm_db_strerror (dbf));
	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  return NULL;
	}

    }

#if HAVE_MMAP
  if (!(flags & GDBM_NOMMAP))
    {
      if (_gdbm_mapped_init (dbf) == 0)
	dbf->memory_mapping = TRUE;
      else
	{
	  /* gdbm_errno should already be set. */
	  GDBM_DEBUG (GDBM_DEBUG_ERR|GDBM_DEBUG_OPEN,
		      "%s: _gdbm_mapped_init failed: %s",
		      dbf->name, strerror (errno));

	  if (!(flags & GDBM_CLOERROR))
	    dbf->desc = -1;
	  SAVE_ERRNO (gdbm_close (dbf));
	  return NULL;
	}
    }
#endif

  /* Finish initializing dbf. */
  dbf->last_read = -1;
  dbf->bucket = NULL;
  dbf->bucket_dir = 0;
  dbf->cache_entry = NULL;
  dbf->header_changed = FALSE;
  dbf->directory_changed = FALSE;
  dbf->bucket_changed = FALSE;
  dbf->second_changed = FALSE;

  GDBM_DEBUG (GDBM_DEBUG_ALL, "%s: opened successfully", dbf->name);

  /* Everything is fine, return the pointer to the file
     information structure.  */
  return dbf;
}
  
/* Initialize dbm system.  FILE is a pointer to the file name.  If the file
   has a size of zero bytes, a file initialization procedure is performed,
   setting up the initial structure in the file.  BLOCK_SIZE is used during
   initialization to determine the size of various constructs.  If the value
   is less than GDBM_MIN_BLOCK_SIZE, the file system blocksize is used,
   otherwise the value of BLOCK_SIZE is used.  BLOCK_SIZE is ignored if the
   file has previously initialized.  If FLAGS is set to GDBM_READ the user
   wants to just read the database and any call to dbm_store or dbm_delete
   will fail. Many readers can access the database at the same time.  If FLAGS
   is set to GDBM_WRITE, the user wants both read and write access to the
   database and requires exclusive access.  If FLAGS is GDBM_WRCREAT, the user
   wants both read and write access to the database and if the database does
   not exist, create a new one.  If FLAGS is GDBM_NEWDB, the user want a
   new database created, regardless of whether one existed, and wants read
   and write access to the new database.  Any error detected will cause a 
   return value of null and an approprate value will be in gdbm_errno.  If
   no errors occur, a pointer to the "gdbm file descriptor" will be
   returned. */
   

GDBM_FILE 
gdbm_open (const char *file, int block_size, int flags, int mode,
     	   void (*fatal_func) (const char *))
{
  int fd;
  /* additional bits for open(2) flags */
  int fbits = 0;

  switch (flags & GDBM_OPENMASK)
    {
      case GDBM_READER:
	fbits = O_RDONLY;
	break;

      case GDBM_WRITER:
	fbits = O_RDWR;
	break;

      case GDBM_NEWDB:
	fbits = O_RDWR|O_CREAT;
	break;

      default:
	fbits = O_RDWR|O_CREAT;
    }
  if (flags & GDBM_CLOEXEC)
    fbits |= O_CLOEXEC;
  
  fd = open (file, fbits, mode);
  if (fd < 0)
    {
      GDBM_SET_ERRNO2 (NULL, GDBM_FILE_OPEN_ERROR, FALSE, GDBM_DEBUG_OPEN);
      return NULL;
    }
  return gdbm_fd_open (fd, file, block_size, flags | GDBM_CLOERROR,
		       fatal_func);
}

/* Initialize the bucket cache. */
int
_gdbm_init_cache (GDBM_FILE dbf, size_t size)
{
  int index;

  if (dbf->bucket_cache == NULL)
    {
      dbf->bucket_cache = GDBM_DEBUG_ALLOC ("_gdbm_init_cache:malloc-failure",
	                      malloc (sizeof(cache_elem) * size));
      if (dbf->bucket_cache == NULL)
        {
          GDBM_SET_ERRNO (dbf, GDBM_MALLOC_ERROR, TRUE);
          return -1;
        }
      dbf->cache_size = size;

      for (index = 0; index < size; index++)
        {
	  (dbf->bucket_cache[index]).ca_bucket = 
	    GDBM_DEBUG_ALLOC ("_gdbm_init_cache:bucket-malloc-failure",
	                      malloc (dbf->header->bucket_size));
          if ((dbf->bucket_cache[index]).ca_bucket == NULL)
	    {
              GDBM_SET_ERRNO (dbf, GDBM_MALLOC_ERROR, TRUE);
	      return -1;
            }
          (dbf->bucket_cache[index]).ca_adr = 0;
          (dbf->bucket_cache[index]).ca_changed = FALSE;
          (dbf->bucket_cache[index]).ca_data.hash_val = -1;
          (dbf->bucket_cache[index]).ca_data.elem_loc = -1;
          (dbf->bucket_cache[index]).ca_data.dptr = NULL;
        }
      dbf->bucket = dbf->bucket_cache[0].ca_bucket;
      dbf->cache_entry = &dbf->bucket_cache[0];
    }
  return 0;
}

Return to:

Send suggestions and report system problems to the System administrator.