aboutsummaryrefslogtreecommitdiff
path: root/gdb/symfile.c
blob: 52028238f09ae67ede9164e6c093050e7410f2e4 (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
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
/* Generic symbol file reading for the GNU debugger, GDB.
   Copyright 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
   Contributed by Cygnus Support, using pieces from other GDB modules.

This file is part of GDB.

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 of the License, 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 "defs.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "gdbcore.h"
#include "frame.h"
#include "target.h"
#include "value.h"
#include "symfile.h"
#include "objfiles.h"
#include "gdbcmd.h"
#include "breakpoint.h"
#include "language.h"
#include "complaints.h"
#include "demangle.h"
#include "inferior.h" /* for write_pc */

#include <obstack.h>
#include <assert.h>

#include <sys/types.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <ctype.h>

#ifndef O_BINARY
#define O_BINARY 0
#endif

/* Global variables owned by this file */

int readnow_symbol_files;		/* Read full symbols immediately */

struct complaint oldsyms_complaint = {
  "Replacing old symbols for `%s'", 0, 0
};

struct complaint empty_symtab_complaint = {
  "Empty symbol table found for `%s'", 0, 0
};

/* External variables and functions referenced. */

extern int info_verbose;

/* Functions this file defines */

static void
set_initial_language PARAMS ((void));

static void
load_command PARAMS ((char *, int));

static void
add_symbol_file_command PARAMS ((char *, int));

static void
cashier_psymtab PARAMS ((struct partial_symtab *));

static int
compare_psymbols PARAMS ((const void *, const void *));

static int
compare_symbols PARAMS ((const void *, const void *));

static bfd *
symfile_bfd_open PARAMS ((char *));

static void
find_sym_fns PARAMS ((struct objfile *));

/* List of all available sym_fns.  On gdb startup, each object file reader
   calls add_symtab_fns() to register information on each format it is
   prepared to read. */

static struct sym_fns *symtab_fns = NULL;

/* Structures with which to manage partial symbol allocation.  */

struct psymbol_allocation_list global_psymbols = {0}, static_psymbols = {0};

/* Flag for whether user will be reloading symbols multiple times.
   Defaults to ON for VxWorks, otherwise OFF.  */

#ifdef SYMBOL_RELOADING_DEFAULT
int symbol_reloading = SYMBOL_RELOADING_DEFAULT;
#else
int symbol_reloading = 0;
#endif


/* Since this function is called from within qsort, in an ANSI environment
   it must conform to the prototype for qsort, which specifies that the
   comparison function takes two "void *" pointers. */

static int
compare_symbols (s1p, s2p)
     const PTR s1p;
     const PTR s2p;
{
  register struct symbol **s1, **s2;

  s1 = (struct symbol **) s1p;
  s2 = (struct symbol **) s2p;

  return (STRCMP (SYMBOL_NAME (*s1), SYMBOL_NAME (*s2)));
}

/*

LOCAL FUNCTION

	compare_psymbols -- compare two partial symbols by name

DESCRIPTION

	Given pointer to two partial symbol table entries, compare
	them by name and return -N, 0, or +N (ala strcmp).  Typically
	used by sorting routines like qsort().

NOTES

	Does direct compare of first two characters before punting
	and passing to strcmp for longer compares.  Note that the
	original version had a bug whereby two null strings or two
	identically named one character strings would return the
	comparison of memory following the null byte.

 */

static int
compare_psymbols (s1p, s2p)
     const PTR s1p;
     const PTR s2p;
{
  register char *st1 = SYMBOL_NAME ((struct partial_symbol *) s1p);
  register char *st2 = SYMBOL_NAME ((struct partial_symbol *) s2p);

  if ((st1[0] - st2[0]) || !st1[0])
    {
      return (st1[0] - st2[0]);
    }
  else if ((st1[1] - st2[1]) || !st1[1])
    {
      return (st1[1] - st2[1]);
    }
  else
    {
      return (STRCMP (st1 + 2, st2 + 2));
    }
}

void
sort_pst_symbols (pst)
     struct partial_symtab *pst;
{
  /* Sort the global list; don't sort the static list */

  qsort (pst -> objfile -> global_psymbols.list + pst -> globals_offset,
	 pst -> n_global_syms, sizeof (struct partial_symbol),
	 compare_psymbols);
}

/* Call sort_block_syms to sort alphabetically the symbols of one block.  */

void
sort_block_syms (b)
     register struct block *b;
{
  qsort (&BLOCK_SYM (b, 0), BLOCK_NSYMS (b),
	 sizeof (struct symbol *), compare_symbols);
}

/* Call sort_symtab_syms to sort alphabetically
   the symbols of each block of one symtab.  */

void
sort_symtab_syms (s)
     register struct symtab *s;
{
  register struct blockvector *bv;
  int nbl;
  int i;
  register struct block *b;

  if (s == 0)
    return;
  bv = BLOCKVECTOR (s);
  nbl = BLOCKVECTOR_NBLOCKS (bv);
  for (i = 0; i < nbl; i++)
    {
      b = BLOCKVECTOR_BLOCK (bv, i);
      if (BLOCK_SHOULD_SORT (b))
	sort_block_syms (b);
    }
}

/* Make a copy of the string at PTR with SIZE characters in the symbol obstack
   (and add a null character at the end in the copy).
   Returns the address of the copy.  */

char *
obsavestring (ptr, size, obstackp)
     char *ptr;
     int size;
     struct obstack *obstackp;
{
  register char *p = (char *) obstack_alloc (obstackp, size + 1);
  /* Open-coded memcpy--saves function call time.
     These strings are usually short.  */
  {
    register char *p1 = ptr;
    register char *p2 = p;
    char *end = ptr + size;
    while (p1 != end)
      *p2++ = *p1++;
  }
  p[size] = 0;
  return p;
}

/* Concatenate strings S1, S2 and S3; return the new string.
   Space is found in the symbol_obstack.  */

char *
obconcat (obstackp, s1, s2, s3)
     struct obstack *obstackp;
     const char *s1, *s2, *s3;
{
  register int len = strlen (s1) + strlen (s2) + strlen (s3) + 1;
  register char *val = (char *) obstack_alloc (obstackp, len);
  strcpy (val, s1);
  strcat (val, s2);
  strcat (val, s3);
  return val;
}

/* Get the symbol table that corresponds to a partial_symtab.
   This is fast after the first time you do it.  In fact, there
   is an even faster macro PSYMTAB_TO_SYMTAB that does the fast
   case inline.  */

struct symtab *
psymtab_to_symtab (pst)
     register struct partial_symtab *pst;
{
  /* If it's been looked up before, return it. */
  if (pst->symtab)
    return pst->symtab;

  /* If it has not yet been read in, read it.  */
  if (!pst->readin)
    { 
      (*pst->read_symtab) (pst);
    }

  return pst->symtab;
}

/* Initialize entry point information for this objfile. */

void
init_entry_point_info (objfile)
     struct objfile *objfile;
{
  /* Save startup file's range of PC addresses to help blockframe.c
     decide where the bottom of the stack is.  */

  if (bfd_get_file_flags (objfile -> obfd) & EXEC_P)
    {
      /* Executable file -- record its entry point so we'll recognize
	 the startup file because it contains the entry point.  */
      objfile -> ei.entry_point = bfd_get_start_address (objfile -> obfd);
    }
  else
    {
      /* Examination of non-executable.o files.  Short-circuit this stuff.  */
      /* ~0 will not be in any file, we hope.  */
      objfile -> ei.entry_point = ~0;
      /* set the startup file to be an empty range.  */
      objfile -> ei.entry_file_lowpc = 0;
      objfile -> ei.entry_file_highpc = 0;
    }
}

/* Get current entry point address.  */

CORE_ADDR
entry_point_address()
{
  return symfile_objfile ? symfile_objfile->ei.entry_point : 0;
}

/* Remember the lowest-addressed loadable section we've seen.  
   This function is called via bfd_map_over_sections.  */

#if 0 	/* Not used yet */
static void
find_lowest_section (abfd, sect, obj)
     bfd *abfd;
     asection *sect;
     PTR obj;
{
  asection **lowest = (asection **)obj;

  if (0 == (bfd_get_section_flags (abfd, sect) & SEC_LOAD))
    return;
  if (!*lowest)
    *lowest = sect;		/* First loadable section */
  else if (bfd_section_vma (abfd, *lowest) >= bfd_section_vma (abfd, sect))
    *lowest = sect;		/* A lower loadable section */
}
#endif 

/* Process a symbol file, as either the main file or as a dynamically
   loaded file.

   NAME is the file name (which will be tilde-expanded and made
   absolute herein) (but we don't free or modify NAME itself).
   FROM_TTY says how verbose to be.  MAINLINE specifies whether this
   is the main symbol file, or whether it's an extra symbol file such
   as dynamically loaded code.  If !mainline, ADDR is the address
   where the text segment was loaded.  If VERBO, the caller has printed
   a verbose message about the symbol reading (and complaints can be
   more terse about it).  */

void
syms_from_objfile (objfile, addr, mainline, verbo)
     struct objfile *objfile;
     CORE_ADDR addr;
     int mainline;
     int verbo;
{
  struct section_offsets *section_offsets;
  asection *lowest_sect;
  struct cleanup *old_chain;

  init_entry_point_info (objfile);
  find_sym_fns (objfile);

  /* Make sure that partially constructed symbol tables will be cleaned up
     if an error occurs during symbol reading.  */
  old_chain = make_cleanup (free_objfile, objfile);

  if (mainline) 
    {
      /* We will modify the main symbol table, make sure that all its users
	 will be cleaned up if an error occurs during symbol reading.  */
      make_cleanup (clear_symtab_users, 0);

      /* Since no error yet, throw away the old symbol table.  */

      if (symfile_objfile != NULL)
	{
	  free_objfile (symfile_objfile);
	  symfile_objfile = NULL;
	}

      /* Currently we keep symbols from the add-symbol-file command.
	 If the user wants to get rid of them, they should do "symbol-file"
	 without arguments first.  Not sure this is the best behavior
	 (PR 2207).  */

      (*objfile -> sf -> sym_new_init) (objfile);
    }

  /* Convert addr into an offset rather than an absolute address.
     We find the lowest address of a loaded segment in the objfile,
     and assume that <addr> is where that got loaded.  Due to historical
     precedent, we warn if that doesn't happen to be the ".text"
     segment.  */

  if (mainline)
    {
      addr = 0;		/* No offset from objfile addresses.  */
    }
  else
    {
      lowest_sect = bfd_get_section_by_name (objfile->obfd, ".text");
#if 0
      lowest_sect = 0;
      bfd_map_over_sections (objfile->obfd, find_lowest_section,
			     (PTR) &lowest_sect);
#endif

      if (lowest_sect == 0)
	warning ("no loadable sections found in added symbol-file %s",
		 objfile->name);
      else if (0 == bfd_get_section_name (objfile->obfd, lowest_sect)
	       || !STREQ (".text",
			      bfd_get_section_name (objfile->obfd, lowest_sect)))
	warning ("Lowest section in %s is %s at 0x%lx",
		 objfile->name,
		 bfd_section_name (objfile->obfd, lowest_sect),
		 (unsigned long) bfd_section_vma (objfile->obfd, lowest_sect));

      if (lowest_sect)
	addr -= bfd_section_vma (objfile->obfd, lowest_sect);
    }

  /* Initialize symbol reading routines for this objfile, allow complaints to
     appear for this new file, and record how verbose to be, then do the
     initial symbol reading for this file. */

  (*objfile -> sf -> sym_init) (objfile);
  clear_complaints (1, verbo);

  section_offsets = (*objfile -> sf -> sym_offsets) (objfile, addr);
  objfile->section_offsets = section_offsets;

#ifndef IBM6000_TARGET
  /* This is a SVR4/SunOS specific hack, I think.  In any event, it
     screws RS/6000.  sym_offsets should be doing this sort of thing,
     because it knows the mapping between bfd sections and
     section_offsets.  */
  /* This is a hack.  As far as I can tell, section offsets are not
     target dependent.  They are all set to addr with a couple of
     exceptions.  The exceptions are sysvr4 shared libraries, whose
     offsets are kept in solib structures anyway and rs6000 xcoff
     which handles shared libraries in a completely unique way.

     Section offsets are built similarly, except that they are built
     by adding addr in all cases because there is no clear mapping
     from section_offsets into actual sections.  Note that solib.c
     has a different algorythm for finding section offsets.

     These should probably all be collapsed into some target
     independent form of shared library support.  FIXME.  */

  if (addr)
    {
      struct obj_section *s;

      for (s = objfile->sections; s < objfile->sections_end; ++s)
	{
	  s->addr -= s->offset;
	  s->addr += addr;
	  s->endaddr -= s->offset;
	  s->endaddr += addr;
	  s->offset += addr;
	}
    }
#endif /* not IBM6000_TARGET */

  (*objfile -> sf -> sym_read) (objfile, section_offsets, mainline);

  /* Don't allow char * to have a typename (else would get caddr_t).
     Ditto void *.  FIXME: Check whether this is now done by all the
     symbol readers themselves (many of them now do), and if so remove
     it from here.  */

  TYPE_NAME (lookup_pointer_type (builtin_type_char)) = 0;
  TYPE_NAME (lookup_pointer_type (builtin_type_void)) = 0;

  /* Mark the objfile has having had initial symbol read attempted.  Note
     that this does not mean we found any symbols... */

  objfile -> flags |= OBJF_SYMS;

  /* Discard cleanups as symbol reading was successful.  */

  discard_cleanups (old_chain);
}

/* Perform required actions after either reading in the initial
   symbols for a new objfile, or mapping in the symbols from a reusable
   objfile. */
   
void
new_symfile_objfile (objfile, mainline, verbo)
     struct objfile *objfile;
     int mainline;
     int verbo;
{

  /* If this is the main symbol file we have to clean up all users of the
     old main symbol file. Otherwise it is sufficient to fixup all the
     breakpoints that may have been redefined by this symbol file.  */
  if (mainline)
    {
      /* OK, make it the "real" symbol file.  */
      symfile_objfile = objfile;

      clear_symtab_users ();
    }
  else
    {
      breakpoint_re_set ();
    }

  /* We're done reading the symbol file; finish off complaints.  */
  clear_complaints (0, verbo);
}

/* Process a symbol file, as either the main file or as a dynamically
   loaded file.

   NAME is the file name (which will be tilde-expanded and made
   absolute herein) (but we don't free or modify NAME itself).
   FROM_TTY says how verbose to be.  MAINLINE specifies whether this
   is the main symbol file, or whether it's an extra symbol file such
   as dynamically loaded code.  If !mainline, ADDR is the address
   where the text segment was loaded.

   Upon success, returns a pointer to the objfile that was added.
   Upon failure, jumps back to command level (never returns). */

struct objfile *
symbol_file_add (name, from_tty, addr, mainline, mapped, readnow)
     char *name;
     int from_tty;
     CORE_ADDR addr;
     int mainline;
     int mapped;
     int readnow;
{
  struct objfile *objfile;
  struct partial_symtab *psymtab;
  bfd *abfd;

  /* Open a bfd for the file, and give user a chance to burp if we'd be
     interactively wiping out any existing symbols.  */

  abfd = symfile_bfd_open (name);

  if ((have_full_symbols () || have_partial_symbols ())
      && mainline
      && from_tty
      && !query ("Load new symbol table from \"%s\"? ", name))
      error ("Not confirmed.");

  objfile = allocate_objfile (abfd, mapped);

  /* If the objfile uses a mapped symbol file, and we have a psymtab for
     it, then skip reading any symbols at this time. */

  if ((objfile -> flags & OBJF_MAPPED) && (objfile -> flags & OBJF_SYMS))
    {
      /* We mapped in an existing symbol table file that already has had
	 initial symbol reading performed, so we can skip that part.  Notify
	 the user that instead of reading the symbols, they have been mapped.
	 */
      if (from_tty || info_verbose)
	{
	  printf_filtered ("Mapped symbols for %s...", name);
	  wrap_here ("");
	  gdb_flush (gdb_stdout);
	}
      init_entry_point_info (objfile);
      find_sym_fns (objfile);
    }
  else
    {
      /* We either created a new mapped symbol table, mapped an existing
	 symbol table file which has not had initial symbol reading
	 performed, or need to read an unmapped symbol table. */
      if (from_tty || info_verbose)
	{
	  printf_filtered ("Reading symbols from %s...", name);
	  wrap_here ("");
	  gdb_flush (gdb_stdout);
	}
      syms_from_objfile (objfile, addr, mainline, from_tty);
    }      

  /* We now have at least a partial symbol table.  Check to see if the
     user requested that all symbols be read on initial access via either
     the gdb startup command line or on a per symbol file basis.  Expand
     all partial symbol tables for this objfile if so. */

  if (readnow || readnow_symbol_files)
    {
      if (from_tty || info_verbose)
	{
	  printf_filtered ("expanding to full symbols...");
	  wrap_here ("");
	  gdb_flush (gdb_stdout);
	}

      for (psymtab = objfile -> psymtabs;
	   psymtab != NULL;
	   psymtab = psymtab -> next)
	{
	  psymtab_to_symtab (psymtab);
	}
    }

  if (from_tty || info_verbose)
    {
      printf_filtered ("done.\n");
      gdb_flush (gdb_stdout);
    }

  new_symfile_objfile (objfile, mainline, from_tty);
      
  /* Getting new symbols may change our opinion about what is
     frameless.  */

  reinit_frame_cache ();

  return (objfile);
}

/* This is the symbol-file command.  Read the file, analyze its symbols,
   and add a struct symtab to a symtab list.  */

void
symbol_file_command (args, from_tty)
     char *args;
     int from_tty;
{
  char **argv;
  char *name = NULL;
  struct cleanup *cleanups;
  int mapped = 0;
  int readnow = 0;

  dont_repeat ();

  if (args == NULL)
    {
      if ((have_full_symbols () || have_partial_symbols ())
	  && from_tty
	  && !query ("Discard symbol table from `%s'? ",
		     symfile_objfile -> name))
	error ("Not confirmed.");
      free_all_objfiles ();
      symfile_objfile = NULL;
      if (from_tty)
	{
	  printf_unfiltered ("No symbol file now.\n");
	}
    }
  else
    {
      if ((argv = buildargv (args)) == NULL)
	{
	  nomem (0);
	}
      cleanups = make_cleanup (freeargv, (char *) argv);
      while (*argv != NULL)
	{
	  if (STREQ (*argv, "-mapped"))
	    {
	      mapped = 1;
	    }
	  else if (STREQ (*argv, "-readnow"))
	    {
	      readnow = 1;
	    }
	  else if (**argv == '-')
	    {
	      error ("unknown option `%s'", *argv);
	    }
	  else
	    {
	      name = *argv;
	    }
	  argv++;
	}

      if (name == NULL)
	{
	  error ("no symbol file name was specified");
	}
      else
	{
	  symbol_file_add (name, from_tty, (CORE_ADDR)0, 1, mapped, readnow);
	  set_initial_language ();
	}
      do_cleanups (cleanups);
    }
}

/* Set the initial language.

   A better solution would be to record the language in the psymtab when reading
   partial symbols, and then use it (if known) to set the language.  This would
   be a win for formats that encode the language in an easily discoverable place,
   such as DWARF.  For stabs, we can jump through hoops looking for specially
   named symbols or try to intuit the language from the specific type of stabs
   we find, but we can't do that until later when we read in full symbols.
   FIXME.  */

static void
set_initial_language ()
{
  struct partial_symtab *pst;
  enum language lang = language_unknown;  	

  pst = find_main_psymtab ();
  if (pst != NULL)
    {
      if (pst -> filename != NULL)
	{
	  lang = deduce_language_from_filename (pst -> filename);
        }
      if (lang == language_unknown)
	{
	    /* Make C the default language */
	    lang = language_c;
	}
      set_language (lang);
      expected_language = current_language;	/* Don't warn the user */
    }
}

/* Open file specified by NAME and hand it off to BFD for preliminary
   analysis.  Result is a newly initialized bfd *, which includes a newly
   malloc'd` copy of NAME (tilde-expanded and made absolute).
   In case of trouble, error() is called.  */

static bfd *
symfile_bfd_open (name)
     char *name;
{
  bfd *sym_bfd;
  int desc;
  char *absolute_name;

  name = tilde_expand (name);	/* Returns 1st new malloc'd copy */

  /* Look down path for it, allocate 2nd new malloc'd copy.  */
  desc = openp (getenv ("PATH"), 1, name, O_RDONLY | O_BINARY, 0, &absolute_name);
  if (desc < 0)
    {
      make_cleanup (free, name);
      perror_with_name (name);
    }
  free (name);			/* Free 1st new malloc'd copy */
  name = absolute_name;		/* Keep 2nd malloc'd copy in bfd */
				/* It'll be freed in free_objfile(). */

  sym_bfd = bfd_fdopenr (name, gnutarget, desc);
  if (!sym_bfd)
    {
      close (desc);
      make_cleanup (free, name);
      error ("\"%s\": can't open to read symbols: %s.", name,
	     bfd_errmsg (bfd_error));
    }
  sym_bfd->cacheable = true;

  if (!bfd_check_format (sym_bfd, bfd_object))
    {
      bfd_close (sym_bfd);	/* This also closes desc */
      make_cleanup (free, name);
      error ("\"%s\": can't read symbols: %s.", name,
	     bfd_errmsg (bfd_error));
    }

  return (sym_bfd);
}

/* Link a new symtab_fns into the global symtab_fns list.  Called on gdb
   startup by the _initialize routine in each object file format reader,
   to register information about each format the the reader is prepared
   to handle. */

void
add_symtab_fns (sf)
     struct sym_fns *sf;
{
  sf->next = symtab_fns;
  symtab_fns = sf;
}


/* Initialize to read symbols from the symbol file sym_bfd.  It either
   returns or calls error().  The result is an initialized struct sym_fns
   in the objfile structure, that contains cached information about the
   symbol file.  */

static void
find_sym_fns (objfile)
     struct objfile *objfile;
{
  struct sym_fns *sf;
  enum bfd_flavour our_flavour = bfd_get_flavour (objfile -> obfd);

  /* Special kludge for RS/6000.  See xcoffread.c.  */
  if (STREQ (bfd_get_target (objfile -> obfd), "aixcoff-rs6000"))
    our_flavour = (enum bfd_flavour)-1;

  for (sf = symtab_fns; sf != NULL; sf = sf -> next)
    {
      if (our_flavour == sf -> sym_flavour)
	{
	  objfile -> sf = sf;
	  return;
	}
    }
  error ("I'm sorry, Dave, I can't do that.  Symbol format `%s' unknown.",
	 bfd_get_target (objfile -> obfd));
}

/* This function runs the load command of our current target.  */

static void
load_command (arg, from_tty)
     char *arg;
     int from_tty;
{
  target_load (arg, from_tty);
}

/* This version of "load" should be usable for any target.  Currently
   it is just used for remote targets, not inftarg.c or core files,
   on the theory that only in that case is it useful.

   Avoiding xmodem and the like seems like a win (a) because we don't have
   to worry about finding it, and (b) On VMS, fork() is very slow and so
   we don't want to run a subprocess.  On the other hand, I'm not sure how
   performance compares.  */
void
generic_load (filename, from_tty)
    char *filename;
    int from_tty;
{
  struct cleanup *old_cleanups;
  asection *s;
  bfd *loadfile_bfd = bfd_openr (filename, gnutarget);
  if (loadfile_bfd == NULL)
    {
      perror_with_name (filename);
      return;
    }
  old_cleanups = make_cleanup (bfd_close, loadfile_bfd);

  if (!bfd_check_format (loadfile_bfd, bfd_object)) 
    {
      error ("\"%s\" is not an object file: %s", filename,
	     bfd_errmsg (bfd_error));
    }
  
  for (s = loadfile_bfd->sections; s; s = s->next) 
    {
      if (s->flags & SEC_LOAD) 
	{
	  bfd_size_type size;

	  size = bfd_get_section_size_before_reloc (s);
	  if (size > 0)
	    {
	      char *buffer;
	      struct cleanup *old_chain;
	      bfd_vma vma;

	      buffer = xmalloc (size);
	      old_chain = make_cleanup (free, buffer);

	      vma = bfd_get_section_vma (loadfile_bfd, s);

	      /* Is this really necessary?  I guess it gives the user something
		 to look at during a long download.  */
	      printf_filtered ("Loading section %s, size 0x%lx vma 0x%lx\n",
			       bfd_get_section_name (loadfile_bfd, s),
			       (unsigned long) size, (unsigned long) vma);

	      bfd_get_section_contents (loadfile_bfd, s, buffer, 0, size);

	      target_write_memory (vma, buffer, size);

	      do_cleanups (old_chain);
	    }
	}
    }

  /* We were doing this in remote-mips.c, I suspect it is right
     for other targets too.  */
  write_pc (loadfile_bfd->start_address);

  /* FIXME: are we supposed to call symbol_file_add or not?  According to
     a comment from remote-mips.c (where a call to symbol_file_add was
     commented out), making the call confuses GDB if more than one file is
     loaded in.  remote-nindy.c had no call to symbol_file_add, but remote-vx.c
     does.  */

  do_cleanups (old_cleanups);
}

/* This function allows the addition of incrementally linked object files.
   It does not modify any state in the target, only in the debugger.  */

/* ARGSUSED */
static void
add_symbol_file_command (args, from_tty)
     char *args;
     int from_tty;
{
  char *name = NULL;
  CORE_ADDR text_addr;
  char *arg;
  int readnow = 0;
  int mapped = 0;
  
  dont_repeat ();

  if (args == NULL)
    {
      error ("add-symbol-file takes a file name and an address");
    }

  /* Make a copy of the string that we can safely write into. */

  args = strdup (args);
  make_cleanup (free, args);

  /* Pick off any -option args and the file name. */

  while ((*args != '\000') && (name == NULL))
    {
      while (isspace (*args)) {args++;}
      arg = args;
      while ((*args != '\000') && !isspace (*args)) {args++;}
      if (*args != '\000')
	{
	  *args++ = '\000';
	}
      if (*arg != '-')
	{
	  name = arg;
	}
      else if (STREQ (arg, "-mapped"))
	{
	  mapped = 1;
	}
      else if (STREQ (arg, "-readnow"))
	{
	  readnow = 1;
	}
      else
	{
	  error ("unknown option `%s'", arg);
	}
    }

  /* After picking off any options and the file name, args should be
     left pointing at the remainder of the command line, which should
     be the address expression to evaluate. */

  if ((name == NULL) || (*args == '\000') )
    {
      error ("add-symbol-file takes a file name and an address");
    }
  name = tilde_expand (name);
  make_cleanup (free, name);

  text_addr = parse_and_eval_address (args);

  if (!query ("add symbol table from file \"%s\" at text_addr = %s?\n",
	      name, local_hex_string ((unsigned long)text_addr)))
    error ("Not confirmed.");

  symbol_file_add (name, 0, text_addr, 0, mapped, readnow);
}

/* Re-read symbols if a symbol-file has changed.  */
void
reread_symbols ()
{
  struct objfile *objfile;
  long new_modtime;
  int reread_one = 0;
  struct stat new_statbuf;
  int res;

  /* With the addition of shared libraries, this should be modified,
     the load time should be saved in the partial symbol tables, since
     different tables may come from different source files.  FIXME.
     This routine should then walk down each partial symbol table
     and see if the symbol table that it originates from has been changed */

  for (objfile = object_files; objfile; objfile = objfile->next) {
    if (objfile->obfd) {
#ifdef IBM6000_TARGET
     /* If this object is from a shared library, then you should
        stat on the library name, not member name. */

     if (objfile->obfd->my_archive)
       res = stat (objfile->obfd->my_archive->filename, &new_statbuf);
     else
#endif
      res = stat (objfile->name, &new_statbuf);
      if (res != 0) {
	/* FIXME, should use print_sys_errmsg but it's not filtered. */
	printf_filtered ("`%s' has disappeared; keeping its symbols.\n",
			 objfile->name);
	continue;
      }
      new_modtime = new_statbuf.st_mtime;
      if (new_modtime != objfile->mtime)
	{
	  struct cleanup *old_cleanups;
	  struct section_offsets *offsets;
	  int num_offsets;
	  int section_offsets_size;

	  printf_filtered ("`%s' has changed; re-reading symbols.\n",
			   objfile->name);

	  /* There are various functions like symbol_file_add,
	     symfile_bfd_open, syms_from_objfile, etc., which might
	     appear to do what we want.  But they have various other
	     effects which we *don't* want.  So we just do stuff
	     ourselves.  We don't worry about mapped files (for one thing,
	     any mapped file will be out of date).  */

	  /* If we get an error, blow away this objfile (not sure if
	     that is the correct response for things like shared
	     libraries).  */
	  old_cleanups = make_cleanup (free_objfile, objfile);
	  /* We need to do this whenever any symbols go away.  */
	  make_cleanup (clear_symtab_users, 0);

	  /* Clean up any state BFD has sitting around.  We don't need
	     to close the descriptor but BFD lacks a way of closing the
	     BFD without closing the descriptor.  */
	  if (!bfd_close (objfile->obfd))
	    error ("Can't close BFD for %s.", objfile->name);
	  objfile->obfd = bfd_openr (objfile->name, gnutarget);
	  if (objfile->obfd == NULL)
	    error ("Can't open %s to read symbols.", objfile->name);
	  /* bfd_openr sets cacheable to true, which is what we want.  */
	  if (!bfd_check_format (objfile->obfd, bfd_object))
	    error ("Can't read symbols from %s: %s.", objfile->name,
		   bfd_errmsg (bfd_error));

	  /* Save the offsets, we will nuke them with the rest of the
	     psymbol_obstack.  */
	  num_offsets = objfile->num_sections;
	  section_offsets_size =
	    sizeof (struct section_offsets)
	      + sizeof (objfile->section_offsets->offsets) * num_offsets;
	  offsets = (struct section_offsets *) alloca (section_offsets_size);
	  memcpy (offsets, objfile->section_offsets, section_offsets_size);

	  /* Nuke all the state that we will re-read.  Much of the following
	     code which sets things to NULL really is necessary to tell
	     other parts of GDB that there is nothing currently there.  */

	  /* FIXME: Do we have to free a whole linked list, or is this
	     enough?  */
	  if (objfile->global_psymbols.list)
	    mfree (objfile->md, objfile->global_psymbols.list);
	  objfile->global_psymbols.list = NULL;
	  objfile->global_psymbols.size = 0;
	  if (objfile->static_psymbols.list)
	    mfree (objfile->md, objfile->static_psymbols.list);
	  objfile->static_psymbols.list = NULL;
	  objfile->static_psymbols.size = 0;

	  /* Free the obstacks for non-reusable objfiles */
	  obstack_free (&objfile -> psymbol_obstack, 0);
	  obstack_free (&objfile -> symbol_obstack, 0);
	  obstack_free (&objfile -> type_obstack, 0);
	  objfile->sections = NULL;
	  objfile->symtabs = NULL;
	  objfile->psymtabs = NULL;
	  objfile->free_psymtabs = NULL;
	  objfile->msymbols = NULL;
	  objfile->minimal_symbol_count= 0;
	  objfile->fundamental_types = NULL;
	  if (objfile -> sf != NULL)
	    {
	      (*objfile -> sf -> sym_finish) (objfile);
	    }

	  /* We never make this a mapped file.  */
	  objfile -> md = NULL;
	  /* obstack_specify_allocation also initializes the obstack so
	     it is empty.  */
	  obstack_specify_allocation (&objfile -> psymbol_obstack, 0, 0,
				      xmalloc, free);
	  obstack_specify_allocation (&objfile -> symbol_obstack, 0, 0,
				      xmalloc, free);
	  obstack_specify_allocation (&objfile -> type_obstack, 0, 0,
				      xmalloc, free);
	  if (build_objfile_section_table (objfile))
	    {
	      error ("Can't find the file sections in `%s': %s", 
		     objfile -> name, bfd_errmsg (bfd_error));
	    }

	  /* We use the same section offsets as from last time.  I'm not
	     sure whether that is always correct for shared libraries.  */
	  objfile->section_offsets = (struct section_offsets *)
	    obstack_alloc (&objfile -> psymbol_obstack, section_offsets_size);
	  memcpy (objfile->section_offsets, offsets, section_offsets_size);
	  objfile->num_sections = num_offsets;

	  /* What the hell is sym_new_init for, anyway?  The concept of
	     distinguishing between the main file and additional files
	     in this way seems rather dubious.  */
	  if (objfile == symfile_objfile)
	    (*objfile->sf->sym_new_init) (objfile);

	  (*objfile->sf->sym_init) (objfile);
	  clear_complaints (1, 1);
	  /* The "mainline" parameter is a hideous hack; I think leaving it
	     zero is OK since dbxread.c also does what it needs to do if
	     objfile->global_psymbols.size is 0.  */
	  (*objfile->sf->sym_read) (objfile, objfile->section_offsets, 0);
	  objfile -> flags |= OBJF_SYMS;

	  /* We're done reading the symbol file; finish off complaints.  */
	  clear_complaints (0, 1);

	  /* Getting new symbols may change our opinion about what is
	     frameless.  */

	  reinit_frame_cache ();

	  /* Discard cleanups as symbol reading was successful.  */
	  discard_cleanups (old_cleanups);

	  /* If the mtime has changed between the time we set new_modtime
	     and now, we *want* this to be out of date, so don't call stat
	     again now.  */
	  objfile->mtime = new_modtime;
	  reread_one = 1;
	}
    }
  }

  if (reread_one)
    clear_symtab_users ();
}


enum language
deduce_language_from_filename (filename)
     char *filename;
{
  char *c;
  
  if (0 == filename) 
    ; /* Get default */
  else if (0 == (c = strrchr (filename, '.')))
    ; /* Get default. */
  else if (STREQ(c,".mod"))
    return language_m2;
  else if (STREQ(c,".c"))
    return language_c;
  else if (STREQ (c,".cc") || STREQ (c,".C") || STREQ (c, ".cxx"))
    return language_cplus;
  else if (STREQ (c,".ch") || STREQ (c,".c186") || STREQ (c,".c286"))
    return language_chill;

  return language_unknown;		/* default */
}

/* allocate_symtab:

   Allocate and partly initialize a new symbol table.  Return a pointer
   to it.  error() if no space.

   Caller must set these fields:
	LINETABLE(symtab)
	symtab->blockvector
	symtab->dirname
	symtab->free_code
	symtab->free_ptr
	initialize any EXTRA_SYMTAB_INFO
	possibly free_named_symtabs (symtab->filename);
 */

struct symtab *
allocate_symtab (filename, objfile)
     char *filename;
     struct objfile *objfile;
{
  register struct symtab *symtab;

  symtab = (struct symtab *)
    obstack_alloc (&objfile -> symbol_obstack, sizeof (struct symtab));
  memset (symtab, 0, sizeof (*symtab));
  symtab -> filename = obsavestring (filename, strlen (filename),
				     &objfile -> symbol_obstack);
  symtab -> fullname = NULL;
  symtab -> language = deduce_language_from_filename (filename);

  /* Hook it to the objfile it comes from */

  symtab -> objfile = objfile;
  symtab -> next = objfile -> symtabs;
  objfile -> symtabs = symtab;

#ifdef INIT_EXTRA_SYMTAB_INFO
  INIT_EXTRA_SYMTAB_INFO (symtab);
#endif

  return (symtab);
}

struct partial_symtab *
allocate_psymtab (filename, objfile)
     char *filename;
     struct objfile *objfile;
{
  struct partial_symtab *psymtab;

  if (objfile -> free_psymtabs)
    {
      psymtab = objfile -> free_psymtabs;
      objfile -> free_psymtabs = psymtab -> next;
    }
  else
    psymtab = (struct partial_symtab *)
      obstack_alloc (&objfile -> psymbol_obstack,
		     sizeof (struct partial_symtab));

  memset (psymtab, 0, sizeof (struct partial_symtab));
  psymtab -> filename = obsavestring (filename, strlen (filename),
				      &objfile -> psymbol_obstack);
  psymtab -> symtab = NULL;

  /* Hook it to the objfile it comes from */

  psymtab -> objfile = objfile;
  psymtab -> next = objfile -> psymtabs;
  objfile -> psymtabs = psymtab;
  
  return (psymtab);
}


/* Reset all data structures in gdb which may contain references to symbol
   table date.  */

void
clear_symtab_users ()
{
  /* Someday, we should do better than this, by only blowing away
     the things that really need to be blown.  */
  clear_value_history ();
  clear_displays ();
  clear_internalvars ();
  breakpoint_re_set ();
  set_default_breakpoint (0, 0, 0, 0);
  current_source_symtab = 0;
  current_source_line = 0;
  clear_pc_function_cache ();
}

/* clear_symtab_users_once:

   This function is run after symbol reading, or from a cleanup.
   If an old symbol table was obsoleted, the old symbol table
   has been blown away, but the other GDB data structures that may 
   reference it have not yet been cleared or re-directed.  (The old
   symtab was zapped, and the cleanup queued, in free_named_symtab()
   below.)

   This function can be queued N times as a cleanup, or called
   directly; it will do all the work the first time, and then will be a
   no-op until the next time it is queued.  This works by bumping a
   counter at queueing time.  Much later when the cleanup is run, or at
   the end of symbol processing (in case the cleanup is discarded), if
   the queued count is greater than the "done-count", we do the work
   and set the done-count to the queued count.  If the queued count is
   less than or equal to the done-count, we just ignore the call.  This
   is needed because reading a single .o file will often replace many
   symtabs (one per .h file, for example), and we don't want to reset
   the breakpoints N times in the user's face.

   The reason we both queue a cleanup, and call it directly after symbol
   reading, is because the cleanup protects us in case of errors, but is
   discarded if symbol reading is successful.  */

#if 0
/* FIXME:  As free_named_symtabs is currently a big noop this function
   is no longer needed.  */
static void
clear_symtab_users_once PARAMS ((void));

static int clear_symtab_users_queued;
static int clear_symtab_users_done;

static void
clear_symtab_users_once ()
{
  /* Enforce once-per-`do_cleanups'-semantics */
  if (clear_symtab_users_queued <= clear_symtab_users_done)
    return;
  clear_symtab_users_done = clear_symtab_users_queued;

  clear_symtab_users ();
}
#endif

/* Delete the specified psymtab, and any others that reference it.  */

static void
cashier_psymtab (pst)
     struct partial_symtab *pst;
{
  struct partial_symtab *ps, *pprev = NULL;
  int i;

  /* Find its previous psymtab in the chain */
  for (ps = pst->objfile->psymtabs; ps; ps = ps->next) {
    if (ps == pst)
      break;
    pprev = ps;
  }

  if (ps) {
    /* Unhook it from the chain.  */
    if (ps == pst->objfile->psymtabs)
      pst->objfile->psymtabs = ps->next;
    else
      pprev->next = ps->next;

    /* FIXME, we can't conveniently deallocate the entries in the
       partial_symbol lists (global_psymbols/static_psymbols) that
       this psymtab points to.  These just take up space until all
       the psymtabs are reclaimed.  Ditto the dependencies list and
       filename, which are all in the psymbol_obstack.  */

    /* We need to cashier any psymtab that has this one as a dependency... */
again:
    for (ps = pst->objfile->psymtabs; ps; ps = ps->next) {
      for (i = 0; i < ps->number_of_dependencies; i++) {
	if (ps->dependencies[i] == pst) {
	  cashier_psymtab (ps);
	  goto again;		/* Must restart, chain has been munged. */
	}
      }
    }
  }
}

/* If a symtab or psymtab for filename NAME is found, free it along
   with any dependent breakpoints, displays, etc.
   Used when loading new versions of object modules with the "add-file"
   command.  This is only called on the top-level symtab or psymtab's name;
   it is not called for subsidiary files such as .h files.

   Return value is 1 if we blew away the environment, 0 if not.
   FIXME.  The return valu appears to never be used.

   FIXME.  I think this is not the best way to do this.  We should
   work on being gentler to the environment while still cleaning up
   all stray pointers into the freed symtab.  */

int
free_named_symtabs (name)
     char *name;
{
#if 0
  /* FIXME:  With the new method of each objfile having it's own
     psymtab list, this function needs serious rethinking.  In particular,
     why was it ever necessary to toss psymtabs with specific compilation
     unit filenames, as opposed to all psymtabs from a particular symbol
     file?  -- fnf
     Well, the answer is that some systems permit reloading of particular
     compilation units.  We want to blow away any old info about these
     compilation units, regardless of which objfiles they arrived in. --gnu.  */

  register struct symtab *s;
  register struct symtab *prev;
  register struct partial_symtab *ps;
  struct blockvector *bv;
  int blewit = 0;

  /* We only wack things if the symbol-reload switch is set.  */
  if (!symbol_reloading)
    return 0;

  /* Some symbol formats have trouble providing file names... */
  if (name == 0 || *name == '\0')
    return 0;

  /* Look for a psymtab with the specified name.  */

again2:
  for (ps = partial_symtab_list; ps; ps = ps->next) {
    if (STREQ (name, ps->filename)) {
      cashier_psymtab (ps);	/* Blow it away...and its little dog, too.  */
      goto again2;		/* Must restart, chain has been munged */
    }
  }

  /* Look for a symtab with the specified name.  */

  for (s = symtab_list; s; s = s->next)
    {
      if (STREQ (name, s->filename))
	break;
      prev = s;
    }

  if (s)
    {
      if (s == symtab_list)
	symtab_list = s->next;
      else
	prev->next = s->next;

      /* For now, queue a delete for all breakpoints, displays, etc., whether
	 or not they depend on the symtab being freed.  This should be
	 changed so that only those data structures affected are deleted.  */

      /* But don't delete anything if the symtab is empty.
	 This test is necessary due to a bug in "dbxread.c" that
	 causes empty symtabs to be created for N_SO symbols that
	 contain the pathname of the object file.  (This problem
	 has been fixed in GDB 3.9x).  */

      bv = BLOCKVECTOR (s);
      if (BLOCKVECTOR_NBLOCKS (bv) > 2
	  || BLOCK_NSYMS (BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK))
	  || BLOCK_NSYMS (BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK)))
	{
	  complain (&oldsyms_complaint, name);

	  clear_symtab_users_queued++;
	  make_cleanup (clear_symtab_users_once, 0);
	  blewit = 1;
	} else {
	  complain (&empty_symtab_complaint, name);
	}

      free_symtab (s);
    }
  else
    {
      /* It is still possible that some breakpoints will be affected
	 even though no symtab was found, since the file might have
	 been compiled without debugging, and hence not be associated
	 with a symtab.  In order to handle this correctly, we would need
	 to keep a list of text address ranges for undebuggable files.
	 For now, we do nothing, since this is a fairly obscure case.  */
      ;
    }

  /* FIXME, what about the minimal symbol table? */
  return blewit;
#else
  return (0);
#endif
}

/* Allocate and partially fill a partial symtab.  It will be
   completely filled at the end of the symbol list.

   SYMFILE_NAME is the name of the symbol-file we are reading from, and ADDR
   is the address relative to which its symbols are (incremental) or 0
   (normal). */


struct partial_symtab *
start_psymtab_common (objfile, section_offsets,
		      filename, textlow, global_syms, static_syms)
     struct objfile *objfile;
     struct section_offsets *section_offsets;
     char *filename;
     CORE_ADDR textlow;
     struct partial_symbol *global_syms;
     struct partial_symbol *static_syms;
{
  struct partial_symtab *psymtab;

  psymtab = allocate_psymtab (filename, objfile);
  psymtab -> section_offsets = section_offsets;
  psymtab -> textlow = textlow;
  psymtab -> texthigh = psymtab -> textlow;  /* default */
  psymtab -> globals_offset = global_syms - objfile -> global_psymbols.list;
  psymtab -> statics_offset = static_syms - objfile -> static_psymbols.list;
  return (psymtab);
}

/* Debugging versions of functions that are usually inline macros
   (see symfile.h).  */

#if !INLINE_ADD_PSYMBOL

/* Add a symbol with a long value to a psymtab.
   Since one arg is a struct, we pass in a ptr and deref it (sigh).  */

void
add_psymbol_to_list (name, namelength, namespace, class, list, val, language,
		     objfile)
     char *name;
     int namelength;
     enum namespace namespace;
     enum address_class class;
     struct psymbol_allocation_list *list;
     long val;
     enum language language;
     struct objfile *objfile;
{
  register struct partial_symbol *psym;
  register char *demangled_name;

  if (list->next >= list->list + list->size)
    {
      extend_psymbol_list (list,objfile);
    }
  psym = list->next++;
  
  SYMBOL_NAME (psym) =
    (char *) obstack_alloc (&objfile->psymbol_obstack, namelength + 1);
  memcpy (SYMBOL_NAME (psym), name, namelength);
  SYMBOL_NAME (psym)[namelength] = '\0';
  SYMBOL_VALUE (psym) = val;
  SYMBOL_LANGUAGE (psym) = language;
  PSYMBOL_NAMESPACE (psym) = namespace;
  PSYMBOL_CLASS (psym) = class;
  SYMBOL_INIT_DEMANGLED_NAME (psym, &objfile->psymbol_obstack);
}

/* Add a symbol with a CORE_ADDR value to a psymtab. */

void
add_psymbol_addr_to_list (name, namelength, namespace, class, list, val,
			  language, objfile)
     char *name;
     int namelength;
     enum namespace namespace;
     enum address_class class;
     struct psymbol_allocation_list *list;
     CORE_ADDR val;
     enum language language;
     struct objfile *objfile;
{
  register struct partial_symbol *psym;
  register char *demangled_name;

  if (list->next >= list->list + list->size)
    {
      extend_psymbol_list (list,objfile);
    }
  psym = list->next++;
  
  SYMBOL_NAME (psym) =
    (char *) obstack_alloc (&objfile->psymbol_obstack, namelength + 1);
  memcpy (SYMBOL_NAME (psym), name, namelength);
  SYMBOL_NAME (psym)[namelength] = '\0';
  SYMBOL_VALUE_ADDRESS (psym) = val;
  SYMBOL_LANGUAGE (psym) = language;
  PSYMBOL_NAMESPACE (psym) = namespace;
  PSYMBOL_CLASS (psym) = class;
  SYMBOL_INIT_DEMANGLED_NAME (psym, &objfile->psymbol_obstack);
}

#endif /* !INLINE_ADD_PSYMBOL */


void
_initialize_symfile ()
{
  struct cmd_list_element *c;
  
  c = add_cmd ("symbol-file", class_files, symbol_file_command,
   "Load symbol table from executable file FILE.\n\
The `file' command can also load symbol tables, as well as setting the file\n\
to execute.", &cmdlist);
  c->completer = filename_completer;

  c = add_cmd ("add-symbol-file", class_files, add_symbol_file_command,
   "Load the symbols from FILE, assuming FILE has been dynamically loaded.\n\
The second argument provides the starting address of the file's text.",
	       &cmdlist);
  c->completer = filename_completer;

  c = add_cmd ("load", class_files, load_command,
   "Dynamically load FILE into the running program, and record its symbols\n\
for access from GDB.", &cmdlist);
  c->completer = filename_completer;

  add_show_from_set
    (add_set_cmd ("symbol-reloading", class_support, var_boolean,
		  (char *)&symbol_reloading,
	  "Set dynamic symbol table reloading multiple times in one run.",
		  &setlist),
     &showlist);

}