summaryrefslogtreecommitdiff
path: root/gdb/solib.c
blob: d5afd5a951c6df934750b502f027bdd4ab89ab5a (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
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
/* Handle SunOS and SVR4 shared libraries for GDB, the GNU Debugger.
   Copyright 1990, 91, 92, 93, 94, 95, 96, 98, 1999
   Free Software Foundation, Inc.

   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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */


#include "defs.h"

/* This file is only compilable if link.h is available. */

#ifdef HAVE_LINK_H

#include <sys/types.h>
#include <signal.h>
#include "gdb_string.h"
#include <sys/param.h>
#include <fcntl.h>

#ifndef SVR4_SHARED_LIBS
 /* SunOS shared libs need the nlist structure.  */
#include <a.out.h>
#else
#include "elf/external.h"
#endif

#include <link.h>

#include "symtab.h"
#include "bfd.h"
#include "symfile.h"
#include "objfiles.h"
#include "gdbcore.h"
#include "command.h"
#include "target.h"
#include "frame.h"
#include "gdb_regex.h"
#include "inferior.h"
#include "environ.h"
#include "language.h"
#include "gdbcmd.h"

#define MAX_PATH_SIZE 512	/* FIXME: Should be dynamic */

/* On SVR4 systems, a list of symbols in the dynamic linker where
   GDB can try to place a breakpoint to monitor shared library
   events.

   If none of these symbols are found, or other errors occur, then
   SVR4 systems will fall back to using a symbol as the "startup
   mapping complete" breakpoint address.  */

#ifdef SVR4_SHARED_LIBS
static char *solib_break_names[] =
{
  "r_debug_state",
  "_r_debug_state",
  "_dl_debug_state",
  "rtld_db_dlactivity",
  NULL
};
#endif

#define BKPT_AT_SYMBOL 1

#if defined (BKPT_AT_SYMBOL) && defined (SVR4_SHARED_LIBS)
static char *bkpt_names[] =
{
#ifdef SOLIB_BKPT_NAME
  SOLIB_BKPT_NAME,		/* Prefer configured name if it exists. */
#endif
  "_start",
  "main",
  NULL
};
#endif

/* Symbols which are used to locate the base of the link map structures. */

#ifndef SVR4_SHARED_LIBS
static char *debug_base_symbols[] =
{
  "_DYNAMIC",
  "_DYNAMIC__MGC",
  NULL
};
#endif

static char *main_name_list[] =
{
  "main_$main",
  NULL
};

/* local data declarations */

/* Macro to extract an address from a solib structure.
   When GDB is configured for some 32-bit targets (e.g. Solaris 2.7
   sparc), BFD is configured to handle 64-bit targets, so CORE_ADDR is
   64 bits.  We have to extract only the significant bits of addresses
   to get the right address when accessing the core file BFD.  */

#define SOLIB_EXTRACT_ADDRESS(member) \
  extract_address (&member, sizeof (member))

#ifndef SVR4_SHARED_LIBS

#define LM_ADDR(so) (SOLIB_EXTRACT_ADDRESS ((so) -> lm.lm_addr))
#define LM_NEXT(so) (SOLIB_EXTRACT_ADDRESS ((so) -> lm.lm_next))
#define LM_NAME(so) (SOLIB_EXTRACT_ADDRESS ((so) -> lm.lm_name))
/* Test for first link map entry; first entry is a shared library. */
#define IGNORE_FIRST_LINK_MAP_ENTRY(so) (0)
static struct link_dynamic dynamic_copy;
static struct link_dynamic_2 ld_2_copy;
static struct ld_debug debug_copy;
static CORE_ADDR debug_addr;
static CORE_ADDR flag_addr;

#else /* SVR4_SHARED_LIBS */

#define LM_ADDR(so) (SOLIB_EXTRACT_ADDRESS ((so) -> lm.l_addr))
#define LM_NEXT(so) (SOLIB_EXTRACT_ADDRESS ((so) -> lm.l_next))
#define LM_NAME(so) (SOLIB_EXTRACT_ADDRESS ((so) -> lm.l_name))
/* Test for first link map entry; first entry is the exec-file. */
#define IGNORE_FIRST_LINK_MAP_ENTRY(so) \
  (SOLIB_EXTRACT_ADDRESS ((so) -> lm.l_prev) == 0)
static struct r_debug debug_copy;
char shadow_contents[BREAKPOINT_MAX];	/* Stash old bkpt addr contents */

#endif /* !SVR4_SHARED_LIBS */

struct so_list
  {
    /* The following fields of the structure come directly from the
       dynamic linker's tables in the inferior, and are initialized by
       current_sos.  */

    struct so_list *next;	/* next structure in linked list */
    struct link_map lm;		/* copy of link map from inferior */
    CORE_ADDR lmaddr;		/* addr in inferior lm was read from */

    /* Shared object file name, exactly as it appears in the
       inferior's link map.  This may be a relative path, or something
       which needs to be looked up in LD_LIBRARY_PATH, etc.  We use it
       to tell which entries in the inferior's dynamic linker's link
       map we've already loaded.  */
    char so_original_name[MAX_PATH_SIZE];

    /* shared object file name, expanded to something GDB can open */
    char so_name[MAX_PATH_SIZE];

    /* The following fields of the structure are built from
       information gathered from the shared object file itself, and
       are initialized when we actually add it to our symbol tables.  */

    bfd *abfd;
    CORE_ADDR lmend;		/* upper addr bound of mapped object */
    char symbols_loaded;	/* flag: symbols read in yet? */
    char from_tty;		/* flag: print msgs? */
    struct objfile *objfile;	/* objfile for loaded lib */
    struct section_table *sections;
    struct section_table *sections_end;
    struct section_table *textsection;
  };

static struct so_list *so_list_head;	/* List of known shared objects */
static CORE_ADDR debug_base;	/* Base of dynamic linker structures */
static CORE_ADDR breakpoint_addr;	/* Address where end bkpt is set */

static int solib_cleanup_queued = 0;	/* make_run_cleanup called */

extern int fdmatch (int, int);	/* In libiberty */

/* Local function prototypes */

static void do_clear_solib (PTR);

static int match_main (char *);

static void special_symbol_handling (void);

static void sharedlibrary_command (char *, int);

static int enable_break (void);

static void info_sharedlibrary_command (char *, int);

static int symbol_add_stub (PTR);

static CORE_ADDR first_link_map_member (void);

static CORE_ADDR locate_base (void);

static int solib_map_sections (PTR);

#ifdef SVR4_SHARED_LIBS

static CORE_ADDR elf_locate_base (void);

#else

static struct so_list *current_sos (void);
static void free_so (struct so_list *node);

static int disable_break (void);

static void allocate_rt_common_objfile (void);

static void
solib_add_common_symbols (CORE_ADDR);

#endif

void _initialize_solib (void);

/* If non-zero, this is a prefix that will be added to the front of the name
   shared libraries with an absolute filename for loading.  */
static char *solib_absolute_prefix = NULL;

/* If non-empty, this is a search path for loading non-absolute shared library
   symbol files.  This takes precedence over the environment variables PATH
   and LD_LIBRARY_PATH.  */
static char *solib_search_path = NULL;

/*

   LOCAL FUNCTION

   solib_map_sections -- open bfd and build sections for shared lib

   SYNOPSIS

   static int solib_map_sections (struct so_list *so)

   DESCRIPTION

   Given a pointer to one of the shared objects in our list
   of mapped objects, use the recorded name to open a bfd
   descriptor for the object, build a section table, and then
   relocate all the section addresses by the base address at
   which the shared object was mapped.

   FIXMES

   In most (all?) cases the shared object file name recorded in the
   dynamic linkage tables will be a fully qualified pathname.  For
   cases where it isn't, do we really mimic the systems search
   mechanism correctly in the below code (particularly the tilde
   expansion stuff?).
 */

static int
solib_map_sections (arg)
     PTR arg;
{
  struct so_list *so = (struct so_list *) arg;	/* catch_errors bogon */
  char *filename;
  char *scratch_pathname;
  int scratch_chan;
  struct section_table *p;
  struct cleanup *old_chain;
  bfd *abfd;

  filename = tilde_expand (so->so_name);

  if (solib_absolute_prefix && ROOTED_P (filename))
    /* Prefix shared libraries with absolute filenames with
       SOLIB_ABSOLUTE_PREFIX.  */
    {
      char *pfxed_fn;
      int pfx_len;

      pfx_len = strlen (solib_absolute_prefix);

      /* Remove trailing slashes.  */
      while (pfx_len > 0 && SLASH_P (solib_absolute_prefix[pfx_len - 1]))
	pfx_len--;

      pfxed_fn = xmalloc (pfx_len + strlen (filename) + 1);
      strcpy (pfxed_fn, solib_absolute_prefix);
      strcat (pfxed_fn, filename);
      free (filename);

      filename = pfxed_fn;
    }

  old_chain = make_cleanup (free, filename);

  scratch_chan = -1;

  if (solib_search_path)
    scratch_chan = openp (solib_search_path,
			  1, filename, O_RDONLY, 0, &scratch_pathname);
  if (scratch_chan < 0)
    scratch_chan = openp (get_in_environ (inferior_environ, "PATH"),
			  1, filename, O_RDONLY, 0, &scratch_pathname);
  if (scratch_chan < 0)
    {
      scratch_chan = openp (get_in_environ
			    (inferior_environ, "LD_LIBRARY_PATH"),
			    1, filename, O_RDONLY, 0, &scratch_pathname);
    }
  if (scratch_chan < 0)
    {
      perror_with_name (filename);
    }
  /* Leave scratch_pathname allocated.  abfd->name will point to it.  */

  abfd = bfd_fdopenr (scratch_pathname, gnutarget, scratch_chan);
  if (!abfd)
    {
      close (scratch_chan);
      error ("Could not open `%s' as an executable file: %s",
	     scratch_pathname, bfd_errmsg (bfd_get_error ()));
    }
  /* Leave bfd open, core_xfer_memory and "info files" need it.  */
  so->abfd = abfd;
  abfd->cacheable = true;

  /* copy full path name into so_name, so that later symbol_file_add can find
     it */
  if (strlen (scratch_pathname) >= MAX_PATH_SIZE)
    error ("Full path name length of shared library exceeds MAX_PATH_SIZE in so_list structure.");
  strcpy (so->so_name, scratch_pathname);

  if (!bfd_check_format (abfd, bfd_object))
    {
      error ("\"%s\": not in executable format: %s.",
	     scratch_pathname, bfd_errmsg (bfd_get_error ()));
    }
  if (build_section_table (abfd, &so->sections, &so->sections_end))
    {
      error ("Can't find the file sections in `%s': %s",
	     bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
    }

  for (p = so->sections; p < so->sections_end; p++)
    {
      /* Relocate the section binding addresses as recorded in the shared
         object's file by the base address to which the object was actually
         mapped. */
      p->addr += LM_ADDR (so);
      p->endaddr += LM_ADDR (so);
      so->lmend = max (p->endaddr, so->lmend);
      if (STREQ (p->the_bfd_section->name, ".text"))
	{
	  so->textsection = p;
	}
    }

  /* Free the file names, close the file now.  */
  do_cleanups (old_chain);

  return (1);
}

#ifndef SVR4_SHARED_LIBS

/* Allocate the runtime common object file.  */

static void
allocate_rt_common_objfile ()
{
  struct objfile *objfile;
  struct objfile *last_one;

  objfile = (struct objfile *) xmalloc (sizeof (struct objfile));
  memset (objfile, 0, sizeof (struct objfile));
  objfile->md = NULL;
  obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0,
			      xmalloc, free);
  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);
  objfile->name = mstrsave (objfile->md, "rt_common");

  /* Add this file onto the tail of the linked list of other such files. */

  objfile->next = NULL;
  if (object_files == NULL)
    object_files = objfile;
  else
    {
      for (last_one = object_files;
	   last_one->next;
	   last_one = last_one->next);
      last_one->next = objfile;
    }

  rt_common_objfile = objfile;
}

/* Read all dynamically loaded common symbol definitions from the inferior
   and put them into the minimal symbol table for the runtime common
   objfile.  */

static void
solib_add_common_symbols (rtc_symp)
     CORE_ADDR rtc_symp;
{
  struct rtc_symb inferior_rtc_symb;
  struct nlist inferior_rtc_nlist;
  int len;
  char *name;

  /* Remove any runtime common symbols from previous runs.  */

  if (rt_common_objfile != NULL && rt_common_objfile->minimal_symbol_count)
    {
      obstack_free (&rt_common_objfile->symbol_obstack, 0);
      obstack_specify_allocation (&rt_common_objfile->symbol_obstack, 0, 0,
				  xmalloc, free);
      rt_common_objfile->minimal_symbol_count = 0;
      rt_common_objfile->msymbols = NULL;
    }

  init_minimal_symbol_collection ();
  make_cleanup_discard_minimal_symbols ();

  while (rtc_symp)
    {
      read_memory (rtc_symp,
		   (char *) &inferior_rtc_symb,
		   sizeof (inferior_rtc_symb));
      read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_sp),
		   (char *) &inferior_rtc_nlist,
		   sizeof (inferior_rtc_nlist));
      if (inferior_rtc_nlist.n_type == N_COMM)
	{
	  /* FIXME: The length of the symbol name is not available, but in the
	     current implementation the common symbol is allocated immediately
	     behind the name of the symbol. */
	  len = inferior_rtc_nlist.n_value - inferior_rtc_nlist.n_un.n_strx;

	  name = xmalloc (len);
	  read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_nlist.n_un.n_name),
		       name, len);

	  /* Allocate the runtime common objfile if necessary. */
	  if (rt_common_objfile == NULL)
	    allocate_rt_common_objfile ();

	  prim_record_minimal_symbol (name, inferior_rtc_nlist.n_value,
				      mst_bss, rt_common_objfile);
	  free (name);
	}
      rtc_symp = SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_next);
    }

  /* Install any minimal symbols that have been collected as the current
     minimal symbols for the runtime common objfile.  */

  install_minimal_symbols (rt_common_objfile);
}

#endif /* SVR4_SHARED_LIBS */


#ifdef SVR4_SHARED_LIBS

static CORE_ADDR bfd_lookup_symbol (bfd *, char *);

/*

   LOCAL FUNCTION

   bfd_lookup_symbol -- lookup the value for a specific symbol

   SYNOPSIS

   CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)

   DESCRIPTION

   An expensive way to lookup the value of a single symbol for
   bfd's that are only temporary anyway.  This is used by the
   shared library support to find the address of the debugger
   interface structures in the shared library.

   Note that 0 is specifically allowed as an error return (no
   such symbol).
 */

static CORE_ADDR
bfd_lookup_symbol (abfd, symname)
     bfd *abfd;
     char *symname;
{
  unsigned int storage_needed;
  asymbol *sym;
  asymbol **symbol_table;
  unsigned int number_of_symbols;
  unsigned int i;
  struct cleanup *back_to;
  CORE_ADDR symaddr = 0;

  storage_needed = bfd_get_symtab_upper_bound (abfd);

  if (storage_needed > 0)
    {
      symbol_table = (asymbol **) xmalloc (storage_needed);
      back_to = make_cleanup (free, (PTR) symbol_table);
      number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);

      for (i = 0; i < number_of_symbols; i++)
	{
	  sym = *symbol_table++;
	  if (STREQ (sym->name, symname))
	    {
	      /* Bfd symbols are section relative. */
	      symaddr = sym->value + sym->section->vma;
	      break;
	    }
	}
      do_cleanups (back_to);
    }
  return (symaddr);
}

#ifdef HANDLE_SVR4_EXEC_EMULATORS

/*
   Solaris BCP (the part of Solaris which allows it to run SunOS4
   a.out files) throws in another wrinkle. Solaris does not fill
   in the usual a.out link map structures when running BCP programs,
   the only way to get at them is via groping around in the dynamic
   linker.
   The dynamic linker and it's structures are located in the shared
   C library, which gets run as the executable's "interpreter" by
   the kernel.

   Note that we can assume nothing about the process state at the time
   we need to find these structures.  We may be stopped on the first
   instruction of the interpreter (C shared library), the first
   instruction of the executable itself, or somewhere else entirely
   (if we attached to the process for example).
 */

static char *debug_base_symbols[] =
{
  "r_debug",			/* Solaris 2.3 */
  "_r_debug",			/* Solaris 2.1, 2.2 */
  NULL
};

static int look_for_base (int, CORE_ADDR);

/*

   LOCAL FUNCTION

   look_for_base -- examine file for each mapped address segment

   SYNOPSYS

   static int look_for_base (int fd, CORE_ADDR baseaddr)

   DESCRIPTION

   This function is passed to proc_iterate_over_mappings, which
   causes it to get called once for each mapped address space, with
   an open file descriptor for the file mapped to that space, and the
   base address of that mapped space.

   Our job is to find the debug base symbol in the file that this
   fd is open on, if it exists, and if so, initialize the dynamic
   linker structure base address debug_base.

   Note that this is a computationally expensive proposition, since
   we basically have to open a bfd on every call, so we specifically
   avoid opening the exec file.
 */

static int
look_for_base (fd, baseaddr)
     int fd;
     CORE_ADDR baseaddr;
{
  bfd *interp_bfd;
  CORE_ADDR address = 0;
  char **symbolp;

  /* If the fd is -1, then there is no file that corresponds to this
     mapped memory segment, so skip it.  Also, if the fd corresponds
     to the exec file, skip it as well. */

  if (fd == -1
      || (exec_bfd != NULL
	  && fdmatch (fileno ((FILE *) (exec_bfd->iostream)), fd)))
    {
      return (0);
    }

  /* Try to open whatever random file this fd corresponds to.  Note that
     we have no way currently to find the filename.  Don't gripe about
     any problems we might have, just fail. */

  if ((interp_bfd = bfd_fdopenr ("unnamed", gnutarget, fd)) == NULL)
    {
      return (0);
    }
  if (!bfd_check_format (interp_bfd, bfd_object))
    {
      /* FIXME-leak: on failure, might not free all memory associated with
         interp_bfd.  */
      bfd_close (interp_bfd);
      return (0);
    }

  /* Now try to find our debug base symbol in this file, which we at
     least know to be a valid ELF executable or shared library. */

  for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++)
    {
      address = bfd_lookup_symbol (interp_bfd, *symbolp);
      if (address != 0)
	{
	  break;
	}
    }
  if (address == 0)
    {
      /* FIXME-leak: on failure, might not free all memory associated with
         interp_bfd.  */
      bfd_close (interp_bfd);
      return (0);
    }

  /* Eureka!  We found the symbol.  But now we may need to relocate it
     by the base address.  If the symbol's value is less than the base
     address of the shared library, then it hasn't yet been relocated
     by the dynamic linker, and we have to do it ourself.  FIXME: Note
     that we make the assumption that the first segment that corresponds
     to the shared library has the base address to which the library
     was relocated. */

  if (address < baseaddr)
    {
      address += baseaddr;
    }
  debug_base = address;
  /* FIXME-leak: on failure, might not free all memory associated with
     interp_bfd.  */
  bfd_close (interp_bfd);
  return (1);
}
#endif /* HANDLE_SVR4_EXEC_EMULATORS */

/*

   LOCAL FUNCTION

   elf_locate_base -- locate the base address of dynamic linker structs
   for SVR4 elf targets.

   SYNOPSIS

   CORE_ADDR elf_locate_base (void)

   DESCRIPTION

   For SVR4 elf targets the address of the dynamic linker's runtime
   structure is contained within the dynamic info section in the
   executable file.  The dynamic section is also mapped into the
   inferior address space.  Because the runtime loader fills in the
   real address before starting the inferior, we have to read in the
   dynamic info section from the inferior address space.
   If there are any errors while trying to find the address, we
   silently return 0, otherwise the found address is returned.

 */

static CORE_ADDR
elf_locate_base ()
{
  sec_ptr dyninfo_sect;
  int dyninfo_sect_size;
  CORE_ADDR dyninfo_addr;
  char *buf;
  char *bufend;
  int arch_size;

  /* Find the start address of the .dynamic section.  */
  dyninfo_sect = bfd_get_section_by_name (exec_bfd, ".dynamic");
  if (dyninfo_sect == NULL)
    return 0;
  dyninfo_addr = bfd_section_vma (exec_bfd, dyninfo_sect);

  /* Read in .dynamic section, silently ignore errors.  */
  dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect);
  buf = alloca (dyninfo_sect_size);
  if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size))
    return 0;

  /* Find the DT_DEBUG entry in the the .dynamic section.
     For mips elf we look for DT_MIPS_RLD_MAP, mips elf apparently has
     no DT_DEBUG entries.  */

  arch_size = bfd_get_arch_size (exec_bfd);
  if (arch_size == -1)	/* failure */
    return 0;

  if (arch_size == 32)
    { /* 32-bit elf */
      for (bufend = buf + dyninfo_sect_size;
	   buf < bufend;
	   buf += sizeof (Elf32_External_Dyn))
	{
	  Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf;
	  long dyn_tag;
	  CORE_ADDR dyn_ptr;

	  dyn_tag = bfd_h_get_32 (exec_bfd, (bfd_byte *) x_dynp->d_tag);
	  if (dyn_tag == DT_NULL)
	    break;
	  else if (dyn_tag == DT_DEBUG)
	    {
	      dyn_ptr = bfd_h_get_32 (exec_bfd, 
				      (bfd_byte *) x_dynp->d_un.d_ptr);
	      return dyn_ptr;
	    }
#ifdef DT_MIPS_RLD_MAP
	  else if (dyn_tag == DT_MIPS_RLD_MAP)
	    {
	      char pbuf[TARGET_PTR_BIT / HOST_CHAR_BIT];

	      /* DT_MIPS_RLD_MAP contains a pointer to the address
		 of the dynamic link structure.  */
	      dyn_ptr = bfd_h_get_32 (exec_bfd, 
				      (bfd_byte *) x_dynp->d_un.d_ptr);
	      if (target_read_memory (dyn_ptr, pbuf, sizeof (pbuf)))
		return 0;
	      return extract_unsigned_integer (pbuf, sizeof (pbuf));
	    }
#endif
	}
    }
  else /* 64-bit elf */
    {
      for (bufend = buf + dyninfo_sect_size;
	   buf < bufend;
	   buf += sizeof (Elf64_External_Dyn))
	{
	  Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf;
	  long dyn_tag;
	  CORE_ADDR dyn_ptr;

	  dyn_tag = bfd_h_get_64 (exec_bfd, (bfd_byte *) x_dynp->d_tag);
	  if (dyn_tag == DT_NULL)
	    break;
	  else if (dyn_tag == DT_DEBUG)
	    {
	      dyn_ptr = bfd_h_get_64 (exec_bfd, 
				      (bfd_byte *) x_dynp->d_un.d_ptr);
	      return dyn_ptr;
	    }
	}
    }

  /* DT_DEBUG entry not found.  */
  return 0;
}

#endif /* SVR4_SHARED_LIBS */

/*

   LOCAL FUNCTION

   locate_base -- locate the base address of dynamic linker structs

   SYNOPSIS

   CORE_ADDR locate_base (void)

   DESCRIPTION

   For both the SunOS and SVR4 shared library implementations, if the
   inferior executable has been linked dynamically, there is a single
   address somewhere in the inferior's data space which is the key to
   locating all of the dynamic linker's runtime structures.  This
   address is the value of the debug base symbol.  The job of this
   function is to find and return that address, or to return 0 if there
   is no such address (the executable is statically linked for example).

   For SunOS, the job is almost trivial, since the dynamic linker and
   all of it's structures are statically linked to the executable at
   link time.  Thus the symbol for the address we are looking for has
   already been added to the minimal symbol table for the executable's
   objfile at the time the symbol file's symbols were read, and all we
   have to do is look it up there.  Note that we explicitly do NOT want
   to find the copies in the shared library.

   The SVR4 version is a bit more complicated because the address
   is contained somewhere in the dynamic info section.  We have to go
   to a lot more work to discover the address of the debug base symbol.
   Because of this complexity, we cache the value we find and return that
   value on subsequent invocations.  Note there is no copy in the
   executable symbol tables.

 */

static CORE_ADDR
locate_base ()
{

#ifndef SVR4_SHARED_LIBS

  struct minimal_symbol *msymbol;
  CORE_ADDR address = 0;
  char **symbolp;

  /* For SunOS, we want to limit the search for the debug base symbol to the
     executable being debugged, since there is a duplicate named symbol in the
     shared library.  We don't want the shared library versions. */

  for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++)
    {
      msymbol = lookup_minimal_symbol (*symbolp, NULL, symfile_objfile);
      if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0))
	{
	  address = SYMBOL_VALUE_ADDRESS (msymbol);
	  return (address);
	}
    }
  return (0);

#else /* SVR4_SHARED_LIBS */

  /* Check to see if we have a currently valid address, and if so, avoid
     doing all this work again and just return the cached address.  If
     we have no cached address, try to locate it in the dynamic info
     section for ELF executables.  */

  if (debug_base == 0)
    {
      if (exec_bfd != NULL
	  && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour)
	debug_base = elf_locate_base ();
#ifdef HANDLE_SVR4_EXEC_EMULATORS
      /* Try it the hard way for emulated executables.  */
      else if (inferior_pid != 0 && target_has_execution)
	proc_iterate_over_mappings (look_for_base);
#endif
    }
  return (debug_base);

#endif /* !SVR4_SHARED_LIBS */

}

/*

   LOCAL FUNCTION

   first_link_map_member -- locate first member in dynamic linker's map

   SYNOPSIS

   static CORE_ADDR first_link_map_member (void)

   DESCRIPTION

   Find the first element in the inferior's dynamic link map, and
   return its address in the inferior.  This function doesn't copy the
   link map entry itself into our address space; current_sos actually
   does the reading.  */

static CORE_ADDR
first_link_map_member ()
{
  CORE_ADDR lm = 0;

#ifndef SVR4_SHARED_LIBS

  read_memory (debug_base, (char *) &dynamic_copy, sizeof (dynamic_copy));
  if (dynamic_copy.ld_version >= 2)
    {
      /* It is a version that we can deal with, so read in the secondary
         structure and find the address of the link map list from it. */
      read_memory (SOLIB_EXTRACT_ADDRESS (dynamic_copy.ld_un.ld_2),
		   (char *) &ld_2_copy, sizeof (struct link_dynamic_2));
      lm = SOLIB_EXTRACT_ADDRESS (ld_2_copy.ld_loaded);
    }

#else /* SVR4_SHARED_LIBS */

  read_memory (debug_base, (char *) &debug_copy, sizeof (struct r_debug));
  /* FIXME:  Perhaps we should validate the info somehow, perhaps by
     checking r_version for a known version number, or r_state for
     RT_CONSISTENT. */
  lm = SOLIB_EXTRACT_ADDRESS (debug_copy.r_map);

#endif /* !SVR4_SHARED_LIBS */

  return (lm);
}

#ifdef SVR4_SHARED_LIBS
/*

  LOCAL FUNCTION

  open_symbol_file_object

  SYNOPSIS

  void open_symbol_file_object (int from_tty)

  DESCRIPTION

  If no open symbol file, attempt to locate and open the main symbol
  file.  On SVR4 systems, this is the first link map entry.  If its
  name is here, we can open it.  Useful when attaching to a process
  without first loading its symbol file.

 */

static int
open_symbol_file_object (from_ttyp)
     int *from_ttyp;	/* sneak past catch_errors */
{
  CORE_ADDR lm;
  struct link_map lmcopy;
  char *filename;
  int errcode;

  if (symfile_objfile)
    if (!query ("Attempt to reload symbols from process? "))
      return 0;

  if ((debug_base = locate_base ()) == 0)
    return 0;	/* failed somehow... */

  /* First link map member should be the executable.  */
  if ((lm = first_link_map_member ()) == 0)
    return 0;	/* failed somehow... */

  /* Read from target memory to GDB.  */
  read_memory (lm, (void *) &lmcopy, sizeof (lmcopy));

  if (lmcopy.l_name == 0)
    return 0;	/* no filename.  */

  /* Now fetch the filename from target memory.  */
  target_read_string (SOLIB_EXTRACT_ADDRESS (lmcopy.l_name), &filename, 
		      MAX_PATH_SIZE - 1, &errcode);
  if (errcode)
    {
      warning ("failed to read exec filename from attached file: %s",
	       safe_strerror (errcode));
      return 0;
    }

  make_cleanup (free, filename);
  /* Have a pathname: read the symbol file.  */
  symbol_file_command (filename, *from_ttyp);

  return 1;
}
#endif /* SVR4_SHARED_LIBS */


/* LOCAL FUNCTION

   free_so --- free a `struct so_list' object

   SYNOPSIS

   void free_so (struct so_list *so)

   DESCRIPTION

   Free the storage associated with the `struct so_list' object SO.
   If we have opened a BFD for SO, close it.  

   The caller is responsible for removing SO from whatever list it is
   a member of.  If we have placed SO's sections in some target's
   section table, the caller is responsible for removing them.

   This function doesn't mess with objfiles at all.  If there is an
   objfile associated with SO that needs to be removed, the caller is
   responsible for taking care of that.  */

static void
free_so (struct so_list *so)
{
  char *bfd_filename = 0;

  if (so->sections)
    free (so->sections);
      
  if (so->abfd)
    {
      bfd_filename = bfd_get_filename (so->abfd);
      if (! bfd_close (so->abfd))
	warning ("cannot close \"%s\": %s",
		 bfd_filename, bfd_errmsg (bfd_get_error ()));
    }

  if (bfd_filename)
    free (bfd_filename);

  free (so);
}


/* On some systems, the only way to recognize the link map entry for
   the main executable file is by looking at its name.  Return
   non-zero iff SONAME matches one of the known main executable names.  */

static int
match_main (soname)
     char *soname;
{
  char **mainp;

  for (mainp = main_name_list; *mainp != NULL; mainp++)
    {
      if (strcmp (soname, *mainp) == 0)
	return (1);
    }

  return (0);
}


/* LOCAL FUNCTION

   current_sos -- build a list of currently loaded shared objects

   SYNOPSIS

   struct so_list *current_sos ()

   DESCRIPTION

   Build a list of `struct so_list' objects describing the shared
   objects currently loaded in the inferior.  This list does not
   include an entry for the main executable file.

   Note that we only gather information directly available from the
   inferior --- we don't examine any of the shared library files
   themselves.  The declaration of `struct so_list' says which fields
   we provide values for.  */

static struct so_list *
current_sos ()
{
  CORE_ADDR lm;
  struct so_list *head = 0;
  struct so_list **link_ptr = &head;

  /* Make sure we've looked up the inferior's dynamic linker's base
     structure.  */
  if (! debug_base)
    {
      debug_base = locate_base ();

      /* If we can't find the dynamic linker's base structure, this
	 must not be a dynamically linked executable.  Hmm.  */
      if (! debug_base)
	return 0;
    }

  /* Walk the inferior's link map list, and build our list of
     `struct so_list' nodes.  */
  lm = first_link_map_member ();  
  while (lm)
    {
      struct so_list *new
	= (struct so_list *) xmalloc (sizeof (struct so_list));
      struct cleanup *old_chain = make_cleanup (free, new);
      memset (new, 0, sizeof (*new));

      new->lmaddr = lm;
      read_memory (lm, (char *) &(new->lm), sizeof (struct link_map));

      lm = LM_NEXT (new);

      /* For SVR4 versions, the first entry in the link map is for the
         inferior executable, so we must ignore it.  For some versions of
         SVR4, it has no name.  For others (Solaris 2.3 for example), it
         does have a name, so we can no longer use a missing name to
         decide when to ignore it. */
      if (IGNORE_FIRST_LINK_MAP_ENTRY (new))
	free_so (new);
      else
	{
	  int errcode;
	  char *buffer;

	  /* Extract this shared object's name.  */
	  target_read_string (LM_NAME (new), &buffer,
			      MAX_PATH_SIZE - 1, &errcode);
	  if (errcode != 0)
	    {
	      warning ("current_sos: Can't read pathname for load map: %s\n",
		       safe_strerror (errcode));
	    }
	  else
	    {
	      strncpy (new->so_name, buffer, MAX_PATH_SIZE - 1);
	      new->so_name[MAX_PATH_SIZE - 1] = '\0';
	      free (buffer);
	      strcpy (new->so_original_name, new->so_name);
	    }

	  /* If this entry has no name, or its name matches the name
	     for the main executable, don't include it in the list.  */
	  if (! new->so_name[0]
	      || match_main (new->so_name))
	    free_so (new);
	  else
	    {
	      new->next = 0;
	      *link_ptr = new;
	      link_ptr = &new->next;
	    }
	}

      discard_cleanups (old_chain);
    }

  return head;
}


/* A small stub to get us past the arg-passing pinhole of catch_errors.  */

static int
symbol_add_stub (arg)
     PTR arg;
{
  register struct so_list *so = (struct so_list *) arg;  /* catch_errs bogon */
  struct section_addr_info *sap;
  CORE_ADDR lowest_addr = 0;
  int lowest_index;
  asection *lowest_sect = NULL;

  /* Have we already loaded this shared object?  */
  ALL_OBJFILES (so->objfile)
    {
      if (strcmp (so->objfile->name, so->so_name) == 0)
	return 1;
    }

  /* Find the shared object's text segment.  */
  if (so->textsection)
    {
      lowest_addr = so->textsection->addr;
      lowest_sect = bfd_get_section_by_name (so->abfd, ".text");
      lowest_index = lowest_sect->index;
    }
  else if (so->abfd != NULL)
    {
      /* If we didn't find a mapped non zero sized .text section, set
         up lowest_addr so that the relocation in symbol_file_add does
         no harm.  */
      lowest_sect = bfd_get_section_by_name (so->abfd, ".text");
      if (lowest_sect == NULL)
	bfd_map_over_sections (so->abfd, find_lowest_section,
			       (PTR) &lowest_sect);
      if (lowest_sect)
	{
	  lowest_addr = bfd_section_vma (so->abfd, lowest_sect)
	    + LM_ADDR (so);
	  lowest_index = lowest_sect->index;
	}
    }

  sap = build_section_addr_info_from_section_table (so->sections,
                                                    so->sections_end);

  sap->other[lowest_index].addr = lowest_addr;

  so->objfile = symbol_file_add (so->so_name, so->from_tty,
				 sap, 0, OBJF_SHARED);
  free_section_addr_info (sap);

  return (1);
}


/* LOCAL FUNCTION

   update_solib_list --- synchronize GDB's shared object list with inferior's

   SYNOPSIS

   void update_solib_list (int from_tty, struct target_ops *TARGET)

   Extract the list of currently loaded shared objects from the
   inferior, and compare it with the list of shared objects currently
   in GDB's so_list_head list.  Edit so_list_head to bring it in sync
   with the inferior's new list.

   If we notice that the inferior has unloaded some shared objects,
   free any symbolic info GDB had read about those shared objects.

   Don't load symbolic info for any new shared objects; just add them
   to the list, and leave their symbols_loaded flag clear.

   If FROM_TTY is non-null, feel free to print messages about what
   we're doing.

   If TARGET is non-null, add the sections of all new shared objects
   to TARGET's section table.  Note that this doesn't remove any
   sections for shared objects that have been unloaded, and it
   doesn't check to see if the new shared objects are already present in
   the section table.  But we only use this for core files and
   processes we've just attached to, so that's okay.  */

void
update_solib_list (int from_tty, struct target_ops *target)
{
  struct so_list *inferior = current_sos ();
  struct so_list *gdb, **gdb_link;

#ifdef SVR4_SHARED_LIBS
  /* If we are attaching to a running process for which we 
     have not opened a symbol file, we may be able to get its 
     symbols now!  */
  if (attach_flag &&
      symfile_objfile == NULL)
    catch_errors (open_symbol_file_object, (PTR) &from_tty, 
		  "Error reading attached process's symbol file.\n",
		  RETURN_MASK_ALL);

#endif SVR4_SHARED_LIBS

  /* Since this function might actually add some elements to the
     so_list_head list, arrange for it to be cleaned up when
     appropriate.  */
  if (!solib_cleanup_queued)
    {
      make_run_cleanup (do_clear_solib, NULL);
      solib_cleanup_queued = 1;
    }

  /* GDB and the inferior's dynamic linker each maintain their own
     list of currently loaded shared objects; we want to bring the
     former in sync with the latter.  Scan both lists, seeing which
     shared objects appear where.  There are three cases:

     - A shared object appears on both lists.  This means that GDB
     knows about it already, and it's still loaded in the inferior.
     Nothing needs to happen.

     - A shared object appears only on GDB's list.  This means that
     the inferior has unloaded it.  We should remove the shared
     object from GDB's tables.

     - A shared object appears only on the inferior's list.  This
     means that it's just been loaded.  We should add it to GDB's
     tables.

     So we walk GDB's list, checking each entry to see if it appears
     in the inferior's list too.  If it does, no action is needed, and
     we remove it from the inferior's list.  If it doesn't, the
     inferior has unloaded it, and we remove it from GDB's list.  By
     the time we're done walking GDB's list, the inferior's list
     contains only the new shared objects, which we then add.  */

  gdb = so_list_head;
  gdb_link = &so_list_head;
  while (gdb)
    {
      struct so_list *i = inferior;
      struct so_list **i_link = &inferior;

      /* Check to see whether the shared object *gdb also appears in
	 the inferior's current list.  */
      while (i)
	{
	  if (! strcmp (gdb->so_original_name, i->so_original_name))
	    break;

	  i_link = &i->next;
	  i = *i_link;
	}

      /* If the shared object appears on the inferior's list too, then
         it's still loaded, so we don't need to do anything.  Delete
         it from the inferior's list, and leave it on GDB's list.  */
      if (i)
	{
	  *i_link = i->next;
	  free_so (i);
	  gdb_link = &gdb->next;
	  gdb = *gdb_link;
	}

      /* If it's not on the inferior's list, remove it from GDB's tables.  */
      else
	{
	  *gdb_link = gdb->next;

	  /* Unless the user loaded it explicitly, free SO's objfile.  */
	  if (gdb->objfile && ! (gdb->objfile->flags & OBJF_USERLOADED))
	    free_objfile (gdb->objfile);

	  /* Some targets' section tables might be referring to
	     sections from so->abfd; remove them.  */
	  remove_target_sections (gdb->abfd);

	  free_so (gdb);
	  gdb = *gdb_link;
	}
    }

  /* Now the inferior's list contains only shared objects that don't
     appear in GDB's list --- those that are newly loaded.  Add them
     to GDB's shared object list.  */
  if (inferior)
    {
      struct so_list *i;

      /* Add the new shared objects to GDB's list.  */
      *gdb_link = inferior;

      /* Fill in the rest of each of the `struct so_list' nodes.  */
      for (i = inferior; i; i = i->next)
	{
	  i->from_tty = from_tty;

	  /* Fill in the rest of the `struct so_list' node.  */
	  catch_errors (solib_map_sections, i,
			"Error while mapping shared library sections:\n",
			RETURN_MASK_ALL);
	}

      /* If requested, add the shared objects' sections to the the
	 TARGET's section table.  */
      if (target)
	{
	  int new_sections;

	  /* Figure out how many sections we'll need to add in total.  */
	  new_sections = 0;
	  for (i = inferior; i; i = i->next)
	    new_sections += (i->sections_end - i->sections);

	  if (new_sections > 0)
	    {
	      int space = target_resize_to_sections (target, new_sections);

	      for (i = inferior; i; i = i->next)
		{
		  int count = (i->sections_end - i->sections);
		  memcpy (target->to_sections + space,
			  i->sections,
			  count * sizeof (i->sections[0]));
		  space += count;
		}
	    }
	}
    }
}


/* GLOBAL FUNCTION

   solib_add -- read in symbol info for newly added shared libraries

   SYNOPSIS

   void solib_add (char *pattern, int from_tty, struct target_ops *TARGET)

   DESCRIPTION

   Read in symbolic information for any shared objects whose names
   match PATTERN.  (If we've already read a shared object's symbol
   info, leave it alone.)  If PATTERN is zero, read them all.

   FROM_TTY and TARGET are as described for update_solib_list, above.  */

void
solib_add (char *pattern, int from_tty, struct target_ops *target)
{
  struct so_list *gdb;

  if (pattern)
    {
      char *re_err = re_comp (pattern);

      if (re_err)
	error ("Invalid regexp: %s", re_err);
    }

  update_solib_list (from_tty, target);

  /* Walk the list of currently loaded shared libraries, and read
     symbols for any that match the pattern --- or any whose symbols
     aren't already loaded, if no pattern was given.  */
  {
    int any_matches = 0;
    int loaded_any_symbols = 0;

    for (gdb = so_list_head; gdb; gdb = gdb->next)
      if (! pattern || re_exec (gdb->so_name))
	{
	  any_matches = 1;

	  if (gdb->symbols_loaded)
	    {
	      if (from_tty)
		printf_unfiltered ("Symbols already loaded for %s\n",
				   gdb->so_name);
	    }
	  else
	    {
	      if (catch_errors
		  (symbol_add_stub, gdb,
		   "Error while reading shared library symbols:\n",
		   RETURN_MASK_ALL))
		{
		  if (from_tty)
		    printf_unfiltered ("Loaded symbols for %s\n",
				       gdb->so_name);
		  gdb->symbols_loaded = 1;
		  loaded_any_symbols = 1;
		}
	    }
	}

    if (from_tty && pattern && ! any_matches)
      printf_unfiltered
	("No loaded shared libraries match the pattern `%s'.\n", pattern);

    if (loaded_any_symbols)
      {
	/* Getting new symbols may change our opinion about what is
	   frameless.  */
	reinit_frame_cache ();

	special_symbol_handling ();
      }
  }
}


/*

   LOCAL FUNCTION

   info_sharedlibrary_command -- code for "info sharedlibrary"

   SYNOPSIS

   static void info_sharedlibrary_command ()

   DESCRIPTION

   Walk through the shared library list and print information
   about each attached library.
 */

static void
info_sharedlibrary_command (ignore, from_tty)
     char *ignore;
     int from_tty;
{
  register struct so_list *so = NULL;	/* link map state variable */
  int header_done = 0;
  int addr_width;
  char *addr_fmt;
  int arch_size;

  if (exec_bfd == NULL)
    {
      printf_unfiltered ("No executable file.\n");
      return;
    }

  arch_size = bfd_get_arch_size (exec_bfd);
  /* Default to 32-bit in case of failure (non-elf). */
  if (arch_size == 32 || arch_size == -1)
    {
      addr_width = 8 + 4;
      addr_fmt = "08l";
    }
  else if (arch_size == 64)
    {
      addr_width = 16 + 4;
      addr_fmt = "016l";
    }

  update_solib_list (from_tty, 0);

  for (so = so_list_head; so; so = so->next)
    {
      if (so->so_name[0])
	{
	  if (!header_done)
	    {
	      printf_unfiltered ("%-*s%-*s%-12s%s\n", addr_width, "From",
				 addr_width, "To", "Syms Read",
				 "Shared Object Library");
	      header_done++;
	    }

	  printf_unfiltered ("%-*s", addr_width,
		      local_hex_string_custom ((unsigned long) LM_ADDR (so),
					       addr_fmt));
	  printf_unfiltered ("%-*s", addr_width,
			 local_hex_string_custom ((unsigned long) so->lmend,
						  addr_fmt));
	  printf_unfiltered ("%-12s", so->symbols_loaded ? "Yes" : "No");
	  printf_unfiltered ("%s\n", so->so_name);
	}
    }
  if (so_list_head == NULL)
    {
      printf_unfiltered ("No shared libraries loaded at this time.\n");
    }
}

/*

   GLOBAL FUNCTION

   solib_address -- check to see if an address is in a shared lib

   SYNOPSIS

   char * solib_address (CORE_ADDR address)

   DESCRIPTION

   Provides a hook for other gdb routines to discover whether or
   not a particular address is within the mapped address space of
   a shared library.  Any address between the base mapping address
   and the first address beyond the end of the last mapping, is
   considered to be within the shared library address space, for
   our purposes.

   For example, this routine is called at one point to disable
   breakpoints which are in shared libraries that are not currently
   mapped in.
 */

char *
solib_address (address)
     CORE_ADDR address;
{
  register struct so_list *so = 0;	/* link map state variable */

  for (so = so_list_head; so; so = so->next)
    {
      if (LM_ADDR (so) <= address && address < so->lmend)
	return (so->so_name);
    }

  return (0);
}

/* Called by free_all_symtabs */

void
clear_solib ()
{
  /* This function is expected to handle ELF shared libraries.  It is
     also used on Solaris, which can run either ELF or a.out binaries
     (for compatibility with SunOS 4), both of which can use shared
     libraries.  So we don't know whether we have an ELF executable or
     an a.out executable until the user chooses an executable file.

     ELF shared libraries don't get mapped into the address space
     until after the program starts, so we'd better not try to insert
     breakpoints in them immediately.  We have to wait until the
     dynamic linker has loaded them; we'll hit a bp_shlib_event
     breakpoint (look for calls to create_solib_event_breakpoint) when
     it's ready.

     SunOS shared libraries seem to be different --- they're present
     as soon as the process begins execution, so there's no need to
     put off inserting breakpoints.  There's also nowhere to put a
     bp_shlib_event breakpoint, so if we put it off, we'll never get
     around to it.

     So: disable breakpoints only if we're using ELF shared libs.  */
  if (exec_bfd != NULL
      && bfd_get_flavour (exec_bfd) != bfd_target_aout_flavour)
    disable_breakpoints_in_shlibs (1);

  while (so_list_head)
    {
      struct so_list *so = so_list_head;
      so_list_head = so->next;
      free_so (so);
    }

  debug_base = 0;
}

static void
do_clear_solib (dummy)
     PTR dummy;
{
  solib_cleanup_queued = 0;
  clear_solib ();
}

#ifdef SVR4_SHARED_LIBS

/* Return 1 if PC lies in the dynamic symbol resolution code of the
   SVR4 run time loader.  */

static CORE_ADDR interp_text_sect_low;
static CORE_ADDR interp_text_sect_high;
static CORE_ADDR interp_plt_sect_low;
static CORE_ADDR interp_plt_sect_high;

int
in_svr4_dynsym_resolve_code (pc)
     CORE_ADDR pc;
{
  return ((pc >= interp_text_sect_low && pc < interp_text_sect_high)
	  || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high)
	  || in_plt_section (pc, NULL));
}
#endif

/*

   LOCAL FUNCTION

   disable_break -- remove the "mapping changed" breakpoint

   SYNOPSIS

   static int disable_break ()

   DESCRIPTION

   Removes the breakpoint that gets hit when the dynamic linker
   completes a mapping change.

 */

#ifndef SVR4_SHARED_LIBS

static int
disable_break ()
{
  int status = 1;

#ifndef SVR4_SHARED_LIBS

  int in_debugger = 0;

  /* Read the debugger structure from the inferior to retrieve the
     address of the breakpoint and the original contents of the
     breakpoint address.  Remove the breakpoint by writing the original
     contents back. */

  read_memory (debug_addr, (char *) &debug_copy, sizeof (debug_copy));

  /* Set `in_debugger' to zero now. */

  write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger));

  breakpoint_addr = SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_bp_addr);
  write_memory (breakpoint_addr, (char *) &debug_copy.ldd_bp_inst,
		sizeof (debug_copy.ldd_bp_inst));

#else /* SVR4_SHARED_LIBS */

  /* Note that breakpoint address and original contents are in our address
     space, so we just need to write the original contents back. */

  if (memory_remove_breakpoint (breakpoint_addr, shadow_contents) != 0)
    {
      status = 0;
    }

#endif /* !SVR4_SHARED_LIBS */

  /* For the SVR4 version, we always know the breakpoint address.  For the
     SunOS version we don't know it until the above code is executed.
     Grumble if we are stopped anywhere besides the breakpoint address. */

  if (stop_pc != breakpoint_addr)
    {
      warning ("stopped at unknown breakpoint while handling shared libraries");
    }

  return (status);
}

#endif /* #ifdef SVR4_SHARED_LIBS */

/*

   LOCAL FUNCTION

   enable_break -- arrange for dynamic linker to hit breakpoint

   SYNOPSIS

   int enable_break (void)

   DESCRIPTION

   Both the SunOS and the SVR4 dynamic linkers have, as part of their
   debugger interface, support for arranging for the inferior to hit
   a breakpoint after mapping in the shared libraries.  This function
   enables that breakpoint.

   For SunOS, there is a special flag location (in_debugger) which we
   set to 1.  When the dynamic linker sees this flag set, it will set
   a breakpoint at a location known only to itself, after saving the
   original contents of that place and the breakpoint address itself,
   in it's own internal structures.  When we resume the inferior, it
   will eventually take a SIGTRAP when it runs into the breakpoint.
   We handle this (in a different place) by restoring the contents of
   the breakpointed location (which is only known after it stops),
   chasing around to locate the shared libraries that have been
   loaded, then resuming.

   For SVR4, the debugger interface structure contains a member (r_brk)
   which is statically initialized at the time the shared library is
   built, to the offset of a function (_r_debug_state) which is guaran-
   teed to be called once before mapping in a library, and again when
   the mapping is complete.  At the time we are examining this member,
   it contains only the unrelocated offset of the function, so we have
   to do our own relocation.  Later, when the dynamic linker actually
   runs, it relocates r_brk to be the actual address of _r_debug_state().

   The debugger interface structure also contains an enumeration which
   is set to either RT_ADD or RT_DELETE prior to changing the mapping,
   depending upon whether or not the library is being mapped or unmapped,
   and then set to RT_CONSISTENT after the library is mapped/unmapped.
 */

static int
enable_break ()
{
  int success = 0;

#ifndef SVR4_SHARED_LIBS

  int j;
  int in_debugger;

  /* Get link_dynamic structure */

  j = target_read_memory (debug_base, (char *) &dynamic_copy,
			  sizeof (dynamic_copy));
  if (j)
    {
      /* unreadable */
      return (0);
    }

  /* Calc address of debugger interface structure */

  debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd);

  /* Calc address of `in_debugger' member of debugger interface structure */

  flag_addr = debug_addr + (CORE_ADDR) ((char *) &debug_copy.ldd_in_debugger -
					(char *) &debug_copy);

  /* Write a value of 1 to this member.  */

  in_debugger = 1;
  write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger));
  success = 1;

#else /* SVR4_SHARED_LIBS */

#ifdef BKPT_AT_SYMBOL

  struct minimal_symbol *msymbol;
  char **bkpt_namep;
  asection *interp_sect;

  /* First, remove all the solib event breakpoints.  Their addresses
     may have changed since the last time we ran the program.  */
  remove_solib_event_breakpoints ();

#ifdef SVR4_SHARED_LIBS
  interp_text_sect_low = interp_text_sect_high = 0;
  interp_plt_sect_low = interp_plt_sect_high = 0;

  /* Find the .interp section; if not found, warn the user and drop
     into the old breakpoint at symbol code.  */
  interp_sect = bfd_get_section_by_name (exec_bfd, ".interp");
  if (interp_sect)
    {
      unsigned int interp_sect_size;
      char *buf;
      CORE_ADDR load_addr;
      bfd *tmp_bfd;
      CORE_ADDR sym_addr = 0;

      /* Read the contents of the .interp section into a local buffer;
         the contents specify the dynamic linker this program uses.  */
      interp_sect_size = bfd_section_size (exec_bfd, interp_sect);
      buf = alloca (interp_sect_size);
      bfd_get_section_contents (exec_bfd, interp_sect,
				buf, 0, interp_sect_size);

      /* Now we need to figure out where the dynamic linker was
         loaded so that we can load its symbols and place a breakpoint
         in the dynamic linker itself.

         This address is stored on the stack.  However, I've been unable
         to find any magic formula to find it for Solaris (appears to
         be trivial on GNU/Linux).  Therefore, we have to try an alternate
         mechanism to find the dynamic linker's base address.  */
      tmp_bfd = bfd_openr (buf, gnutarget);
      if (tmp_bfd == NULL)
	goto bkpt_at_symbol;

      /* Make sure the dynamic linker's really a useful object.  */
      if (!bfd_check_format (tmp_bfd, bfd_object))
	{
	  warning ("Unable to grok dynamic linker %s as an object file", buf);
	  bfd_close (tmp_bfd);
	  goto bkpt_at_symbol;
	}

      /* We find the dynamic linker's base address by examining the
         current pc (which point at the entry point for the dynamic
         linker) and subtracting the offset of the entry point.  */
      load_addr = read_pc () - tmp_bfd->start_address;

      /* Record the relocated start and end address of the dynamic linker
         text and plt section for in_svr4_dynsym_resolve_code.  */
      interp_sect = bfd_get_section_by_name (tmp_bfd, ".text");
      if (interp_sect)
	{
	  interp_text_sect_low =
	    bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
	  interp_text_sect_high =
	    interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect);
	}
      interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt");
      if (interp_sect)
	{
	  interp_plt_sect_low =
	    bfd_section_vma (tmp_bfd, interp_sect) + load_addr;
	  interp_plt_sect_high =
	    interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect);
	}

      /* Now try to set a breakpoint in the dynamic linker.  */
      for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++)
	{
	  sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep);
	  if (sym_addr != 0)
	    break;
	}

      /* We're done with the temporary bfd.  */
      bfd_close (tmp_bfd);

      if (sym_addr != 0)
	{
	  create_solib_event_breakpoint (load_addr + sym_addr);
	  return 1;
	}

      /* For whatever reason we couldn't set a breakpoint in the dynamic
         linker.  Warn and drop into the old code.  */
    bkpt_at_symbol:
      warning ("Unable to find dynamic linker breakpoint function.\nGDB will be unable to debug shared library initializers\nand track explicitly loaded dynamic code.");
    }
#endif

  /* Scan through the list of symbols, trying to look up the symbol and
     set a breakpoint there.  Terminate loop when we/if we succeed. */

  breakpoint_addr = 0;
  for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++)
    {
      msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile);
      if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0))
	{
	  create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol));
	  return 1;
	}
    }

  /* Nothing good happened.  */
  success = 0;

#endif /* BKPT_AT_SYMBOL */

#endif /* !SVR4_SHARED_LIBS */

  return (success);
}

/*

   GLOBAL FUNCTION

   solib_create_inferior_hook -- shared library startup support

   SYNOPSIS

   void solib_create_inferior_hook()

   DESCRIPTION

   When gdb starts up the inferior, it nurses it along (through the
   shell) until it is ready to execute it's first instruction.  At this
   point, this function gets called via expansion of the macro
   SOLIB_CREATE_INFERIOR_HOOK.

   For SunOS executables, this first instruction is typically the
   one at "_start", or a similar text label, regardless of whether
   the executable is statically or dynamically linked.  The runtime
   startup code takes care of dynamically linking in any shared
   libraries, once gdb allows the inferior to continue.

   For SVR4 executables, this first instruction is either the first
   instruction in the dynamic linker (for dynamically linked
   executables) or the instruction at "start" for statically linked
   executables.  For dynamically linked executables, the system
   first exec's /lib/libc.so.N, which contains the dynamic linker,
   and starts it running.  The dynamic linker maps in any needed
   shared libraries, maps in the actual user executable, and then
   jumps to "start" in the user executable.

   For both SunOS shared libraries, and SVR4 shared libraries, we
   can arrange to cooperate with the dynamic linker to discover the
   names of shared libraries that are dynamically linked, and the
   base addresses to which they are linked.

   This function is responsible for discovering those names and
   addresses, and saving sufficient information about them to allow
   their symbols to be read at a later time.

   FIXME

   Between enable_break() and disable_break(), this code does not
   properly handle hitting breakpoints which the user might have
   set in the startup code or in the dynamic linker itself.  Proper
   handling will probably have to wait until the implementation is
   changed to use the "breakpoint handler function" method.

   Also, what if child has exit()ed?  Must exit loop somehow.
 */

void
solib_create_inferior_hook ()
{
  /* If we are using the BKPT_AT_SYMBOL code, then we don't need the base
     yet.  In fact, in the case of a SunOS4 executable being run on
     Solaris, we can't get it yet.  current_sos will get it when it needs
     it.  */
#if !(defined (SVR4_SHARED_LIBS) && defined (BKPT_AT_SYMBOL))
  if ((debug_base = locate_base ()) == 0)
    {
      /* Can't find the symbol or the executable is statically linked. */
      return;
    }
#endif

  if (!enable_break ())
    {
      warning ("shared library handler failed to enable breakpoint");
      return;
    }

#if !defined(SVR4_SHARED_LIBS) || defined(_SCO_DS)
  /* SCO and SunOS need the loop below, other systems should be using the
     special shared library breakpoints and the shared library breakpoint
     service routine.

     Now run the target.  It will eventually hit the breakpoint, at
     which point all of the libraries will have been mapped in and we
     can go groveling around in the dynamic linker structures to find
     out what we need to know about them. */

  clear_proceed_status ();
  stop_soon_quietly = 1;
  stop_signal = TARGET_SIGNAL_0;
  do
    {
      target_resume (-1, 0, stop_signal);
      wait_for_inferior ();
    }
  while (stop_signal != TARGET_SIGNAL_TRAP);
  stop_soon_quietly = 0;

#if !defined(_SCO_DS)
  /* We are now either at the "mapping complete" breakpoint (or somewhere
     else, a condition we aren't prepared to deal with anyway), so adjust
     the PC as necessary after a breakpoint, disable the breakpoint, and
     add any shared libraries that were mapped in. */

  if (DECR_PC_AFTER_BREAK)
    {
      stop_pc -= DECR_PC_AFTER_BREAK;
      write_register (PC_REGNUM, stop_pc);
    }

  if (!disable_break ())
    {
      warning ("shared library handler failed to disable breakpoint");
    }

  if (auto_solib_add)
    solib_add ((char *) 0, 0, (struct target_ops *) 0);
#endif /* ! _SCO_DS */
#endif
}

/*

   LOCAL FUNCTION

   special_symbol_handling -- additional shared library symbol handling

   SYNOPSIS

   void special_symbol_handling ()

   DESCRIPTION

   Once the symbols from a shared object have been loaded in the usual
   way, we are called to do any system specific symbol handling that 
   is needed.

   For SunOS4, this consists of grunging around in the dynamic
   linkers structures to find symbol definitions for "common" symbols
   and adding them to the minimal symbol table for the runtime common
   objfile.

 */

static void
special_symbol_handling ()
{
#ifndef SVR4_SHARED_LIBS
  int j;

  if (debug_addr == 0)
    {
      /* Get link_dynamic structure */

      j = target_read_memory (debug_base, (char *) &dynamic_copy,
			      sizeof (dynamic_copy));
      if (j)
	{
	  /* unreadable */
	  return;
	}

      /* Calc address of debugger interface structure */
      /* FIXME, this needs work for cross-debugging of core files
         (byteorder, size, alignment, etc).  */

      debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd);
    }

  /* Read the debugger structure from the inferior, just to make sure
     we have a current copy. */

  j = target_read_memory (debug_addr, (char *) &debug_copy,
			  sizeof (debug_copy));
  if (j)
    return;			/* unreadable */

  /* Get common symbol definitions for the loaded object. */

  if (debug_copy.ldd_cp)
    {
      solib_add_common_symbols (SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_cp));
    }

#endif /* !SVR4_SHARED_LIBS */
}


/*

   LOCAL FUNCTION

   sharedlibrary_command -- handle command to explicitly add library

   SYNOPSIS

   static void sharedlibrary_command (char *args, int from_tty)

   DESCRIPTION

 */

static void
sharedlibrary_command (args, from_tty)
     char *args;
     int from_tty;
{
  dont_repeat ();
  solib_add (args, from_tty, (struct target_ops *) 0);
}

#endif /* HAVE_LINK_H */

void
_initialize_solib ()
{
#ifdef HAVE_LINK_H

  add_com ("sharedlibrary", class_files, sharedlibrary_command,
	   "Load shared object library symbols for files matching REGEXP.");
  add_info ("sharedlibrary", info_sharedlibrary_command,
	    "Status of loaded shared object libraries.");

  add_show_from_set
    (add_set_cmd ("auto-solib-add", class_support, var_zinteger,
		  (char *) &auto_solib_add,
		  "Set autoloading of shared library symbols.\n\
If nonzero, symbols from all shared object libraries will be loaded\n\
automatically when the inferior begins execution or when the dynamic linker\n\
informs gdb that a new library has been loaded.  Otherwise, symbols\n\
must be loaded manually, using `sharedlibrary'.",
		  &setlist),
     &showlist);

  add_show_from_set
    (add_set_cmd ("solib-absolute-prefix", class_support, var_filename,
		  (char *) &solib_absolute_prefix,
		  "Set prefix for loading absolute shared library symbol files.\n\
For other (relative) files, you can add values using `set solib-search-path'.",
		  &setlist),
     &showlist);
  add_show_from_set
    (add_set_cmd ("solib-search-path", class_support, var_string,
		  (char *) &solib_search_path,
		  "Set the search path for loading non-absolute shared library symbol files.\n\
This takes precedence over the environment variables PATH and LD_LIBRARY_PATH.",
		  &setlist),
     &showlist);

#endif /* HAVE_LINK_H */
}