aboutsummaryrefslogtreecommitdiff
path: root/gdb/linux-fork.c
diff options
context:
space:
mode:
authorAlan Modra <amodra@gmail.com>2009-05-12 09:07:37 +0000
committerAlan Modra <amodra@gmail.com>2009-05-12 09:07:37 +0000
commit78e82dc3f166e9c5bcea5440ddd49e846c3dcc04 (patch)
tree00cf36ebdc7d048ed6ad3281fa205a37039812aa /gdb/linux-fork.c
parent2d90c72afecf3529ed5e08ed3d53e66aff4cb06a (diff)
downloadgdb-78e82dc3f166e9c5bcea5440ddd49e846c3dcc04.zip
gdb-78e82dc3f166e9c5bcea5440ddd49e846c3dcc04.tar.gz
gdb-78e82dc3f166e9c5bcea5440ddd49e846c3dcc04.tar.bz2
* objcopy.c (set_long_section_mode): Check input_bfd is coff
before accessing coff specific fields of bfd.
Diffstat (limited to 'gdb/linux-fork.c')
0 files changed, 0 insertions, 0 deletions
/a> 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 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218
/* Multi-process/thread control for GDB, the GNU debugger.

   Copyright (C) 1986-2019 Free Software Foundation, Inc.

   Contributed by Lynx Real-Time Systems, Inc.  Los Gatos, CA.

   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "symtab.h"
#include "frame.h"
#include "inferior.h"
#include "gdbsupport/environ.h"
#include "value.h"
#include "target.h"
#include "gdbthread.h"
#include "command.h"
#include "gdbcmd.h"
#include "regcache.h"
#include "btrace.h"

#include <ctype.h>
#include <sys/types.h>
#include <signal.h>
#include "ui-out.h"
#include "observable.h"
#include "annotate.h"
#include "cli/cli-decode.h"
#include "cli/cli-option.h"
#include "gdb_regex.h"
#include "cli/cli-utils.h"
#include "thread-fsm.h"
#include "tid-parse.h"
#include <algorithm>
#include "gdbsupport/gdb_optional.h"
#include "inline-frame.h"
#include "stack.h"

/* Definition of struct thread_info exported to gdbthread.h.  */

/* Prototypes for local functions.  */

static int highest_thread_num;

/* True if any thread is, or may be executing.  We need to track this
   separately because until we fully sync the thread list, we won't
   know whether the target is fully stopped, even if we see stop
   events for all known threads, because any of those threads may have
   spawned new threads we haven't heard of yet.  */
static int threads_executing;

static int thread_alive (struct thread_info *);

/* RAII type used to increase / decrease the refcount of each thread
   in a given list of threads.  */

class scoped_inc_dec_ref
{
public:
  explicit scoped_inc_dec_ref (const std::vector<thread_info *> &thrds)
    : m_thrds (thrds)
  {
    for (thread_info *thr : m_thrds)
      thr->incref ();
  }

  ~scoped_inc_dec_ref ()
  {
    for (thread_info *thr : m_thrds)
      thr->decref ();
  }

private:
  const std::vector<thread_info *> &m_thrds;
};


struct thread_info*
inferior_thread (void)
{
  struct thread_info *tp = find_thread_ptid (inferior_ptid);
  gdb_assert (tp);
  return tp;
}

/* Delete the breakpoint pointed at by BP_P, if there's one.  */

static void
delete_thread_breakpoint (struct breakpoint **bp_p)
{
  if (*bp_p != NULL)
    {
      delete_breakpoint (*bp_p);
      *bp_p = NULL;
    }
}

void
delete_step_resume_breakpoint (struct thread_info *tp)
{
  if (tp != NULL)
    delete_thread_breakpoint (&tp->control.step_resume_breakpoint);
}

void
delete_exception_resume_breakpoint (struct thread_info *tp)
{
  if (tp != NULL)
    delete_thread_breakpoint (&tp->control.exception_resume_breakpoint);
}

/* See gdbthread.h.  */

void
delete_single_step_breakpoints (struct thread_info *tp)
{
  if (tp != NULL)
    delete_thread_breakpoint (&tp->control.single_step_breakpoints);
}

/* Delete the breakpoint pointed at by BP_P at the next stop, if
   there's one.  */

static void
delete_at_next_stop (struct breakpoint **bp)
{
  if (*bp != NULL)
    {
      (*bp)->disposition = disp_del_at_next_stop;
      *bp = NULL;
    }
}

/* See gdbthread.h.  */

int
thread_has_single_step_breakpoints_set (struct thread_info *tp)
{
  return tp->control.single_step_breakpoints != NULL;
}

/* See gdbthread.h.  */

int
thread_has_single_step_breakpoint_here (struct thread_info *tp,
					const address_space *aspace,
					CORE_ADDR addr)
{
  struct breakpoint *ss_bps = tp->control.single_step_breakpoints;

  return (ss_bps != NULL
	  && breakpoint_has_location_inserted_here (ss_bps, aspace, addr));
}

/* See gdbthread.h.  */

void
thread_cancel_execution_command (struct thread_info *thr)
{
  if (thr->thread_fsm != NULL)
    {
      thr->thread_fsm->clean_up (thr);
      delete thr->thread_fsm;
      thr->thread_fsm = NULL;
    }
}

static void
clear_thread_inferior_resources (struct thread_info *tp)
{
  /* NOTE: this will take care of any left-over step_resume breakpoints,
     but not any user-specified thread-specific breakpoints.  We can not
     delete the breakpoint straight-off, because the inferior might not
     be stopped at the moment.  */
  delete_at_next_stop (&tp->control.step_resume_breakpoint);
  delete_at_next_stop (&tp->control.exception_resume_breakpoint);
  delete_at_next_stop (&tp->control.single_step_breakpoints);

  delete_longjmp_breakpoint_at_next_stop (tp->global_num);

  bpstat_clear (&tp->control.stop_bpstat);

  btrace_teardown (tp);

  thread_cancel_execution_command (tp);

  clear_inline_frame_state (tp->ptid);
}

/* Set the TP's state as exited.  */

static void
set_thread_exited (thread_info *tp, int silent)
{
  /* Dead threads don't need to step-over.  Remove from queue.  */
  if (tp->step_over_next != NULL)
    thread_step_over_chain_remove (tp);

  if (tp->state != THREAD_EXITED)
    {
      gdb::observers::thread_exit.notify (tp, silent);

      /* Tag it as exited.  */
      tp->state = THREAD_EXITED;

      /* Clear breakpoints, etc. associated with this thread.  */
      clear_thread_inferior_resources (tp);
    }
}

void
init_thread_list (void)
{
  highest_thread_num = 0;

  for (thread_info *tp : all_threads_safe ())
    {
      inferior *inf = tp->inf;

      if (tp->deletable ())
	delete tp;
      else
	set_thread_exited (tp, 1);

      inf->thread_list = NULL;
    }
}

/* Allocate a new thread of inferior INF with target id PTID and add
   it to the thread list.  */

static struct thread_info *
new_thread (struct inferior *inf, ptid_t ptid)
{
  thread_info *tp = new thread_info (inf, ptid);

  if (inf->thread_list == NULL)
    inf->thread_list = tp;
  else
    {
      struct thread_info *last;

      for (last = inf->thread_list; last->next != NULL; last = last->next)
	;
      last->next = tp;
    }

  return tp;
}

struct thread_info *
add_thread_silent (ptid_t ptid)
{
  struct inferior *inf = find_inferior_ptid (ptid);
  gdb_assert (inf != NULL);

  thread_info *tp = find_thread_ptid (inf, ptid);
  if (tp)
    /* Found an old thread with the same id.  It has to be dead,
       otherwise we wouldn't be adding a new thread with the same id.
       The OS is reusing this id --- delete it, and recreate a new
       one.  */
    {
      /* In addition to deleting the thread, if this is the current
	 thread, then we need to take care that delete_thread doesn't
	 really delete the thread if it is inferior_ptid.  Create a
	 new template thread in the list with an invalid ptid, switch
	 to it, delete the original thread, reset the new thread's
	 ptid, and switch to it.  */

      if (inferior_ptid == ptid)
	{
	  thread_info *new_thr = new_thread (inf, null_ptid);

	  /* Make switch_to_thread not read from the thread.  */
	  new_thr->state = THREAD_EXITED;
	  switch_to_no_thread ();

	  /* Now we can delete it.  */
	  delete_thread (tp);

	  /* Now reset its ptid, and reswitch inferior_ptid to it.  */
	  new_thr->ptid = ptid;
	  new_thr->state = THREAD_STOPPED;
	  switch_to_thread (new_thr);

	  gdb::observers::new_thread.notify (new_thr);

	  /* All done.  */
	  return new_thr;
	}
      else
	/* Just go ahead and delete it.  */
	delete_thread (tp);
    }

  tp = new_thread (inf, ptid);
  gdb::observers::new_thread.notify (tp);

  return tp;
}

struct thread_info *
add_thread_with_info (ptid_t ptid, private_thread_info *priv)
{
  struct thread_info *result = add_thread_silent (ptid);

  result->priv.reset (priv);

  if (print_thread_events)
    printf_unfiltered (_("[New %s]\n"), target_pid_to_str (ptid).c_str ());

  annotate_new_thread ();
  return result;
}

struct thread_info *
add_thread (ptid_t ptid)
{
  return add_thread_with_info (ptid, NULL);
}

private_thread_info::~private_thread_info () = default;

thread_info::thread_info (struct inferior *inf_, ptid_t ptid_)
  : ptid (ptid_), inf (inf_)
{
  gdb_assert (inf_ != NULL);

  this->global_num = ++highest_thread_num;
  this->per_inf_num = ++inf_->highest_thread_num;

  /* Nothing to follow yet.  */
  memset (&this->pending_follow, 0, sizeof (this->pending_follow));
  this->pending_follow.kind = TARGET_WAITKIND_SPURIOUS;
  this->suspend.waitstatus.kind = TARGET_WAITKIND_IGNORE;
}

thread_info::~thread_info ()
{
  xfree (this->name);
}

/* See gdbthread.h.  */

bool
thread_info::deletable () const
{
  /* If this is the current thread, or there's code out there that
     relies on it existing (refcount > 0) we can't delete yet.  */
  return refcount () == 0 && ptid != inferior_ptid;
}

/* Add TP to the end of the step-over chain LIST_P.  */

static void
step_over_chain_enqueue (struct thread_info **list_p, struct thread_info *tp)
{
  gdb_assert (tp->step_over_next == NULL);
  gdb_assert (tp->step_over_prev == NULL);

  if (*list_p == NULL)
    {
      *list_p = tp;
      tp->step_over_prev = tp->step_over_next = tp;
    }
  else
    {
      struct thread_info *head = *list_p;
      struct thread_info *tail = head->step_over_prev;

      tp->step_over_prev = tail;
      tp->step_over_next = head;
      head->step_over_prev = tp;
      tail->step_over_next = tp;
    }
}

/* Remove TP from step-over chain LIST_P.  */

static void
step_over_chain_remove (struct thread_info **list_p, struct thread_info *tp)
{
  gdb_assert (tp->step_over_next != NULL);
  gdb_assert (tp->step_over_prev != NULL);

  if (*list_p == tp)
    {
      if (tp == tp->step_over_next)
	*list_p = NULL;
      else
	*list_p = tp->step_over_next;
    }

  tp->step_over_prev->step_over_next = tp->step_over_next;
  tp->step_over_next->step_over_prev = tp->step_over_prev;
  tp->step_over_prev = tp->step_over_next = NULL;
}

/* See gdbthread.h.  */

struct thread_info *
thread_step_over_chain_next (struct thread_info *tp)
{
  struct thread_info *next = tp->step_over_next;

  return (next == step_over_queue_head ? NULL : next);
}

/* See gdbthread.h.  */

int
thread_is_in_step_over_chain (struct thread_info *tp)
{
  return (tp->step_over_next != NULL);
}

/* See gdbthread.h.  */

void
thread_step_over_chain_enqueue (struct thread_info *tp)
{
  step_over_chain_enqueue (&step_over_queue_head, tp);
}

/* See gdbthread.h.  */

void
thread_step_over_chain_remove (struct thread_info *tp)
{
  step_over_chain_remove (&step_over_queue_head, tp);
}

/* Delete the thread referenced by THR.  If SILENT, don't notifyi
   the observer of this exit.
   
   THR must not be NULL or a failed assertion will be raised.  */

static void
delete_thread_1 (thread_info *thr, bool silent)
{
  gdb_assert (thr != nullptr);

  struct thread_info *tp, *tpprev = NULL;

  for (tp = thr->inf->thread_list; tp; tpprev = tp, tp = tp->next)
    if (tp == thr)
      break;

  if (!tp)
    return;

  set_thread_exited (tp, silent);

  if (!tp->deletable ())
    {
       /* Will be really deleted some other time.  */
       return;
     }

  if (tpprev)
    tpprev->next = tp->next;
  else
    tp->inf->thread_list = tp->next;

  delete tp;
}

/* Delete thread THREAD and notify of thread exit.  If this is the
   current thread, don't actually delete it, but tag it as exited and
   do the notification.  If this is the user selected thread, clear
   it.  */

void
delete_thread (thread_info *thread)
{
  delete_thread_1 (thread, false /* not silent */);
}

void
delete_thread_silent (thread_info *thread)
{
  delete_thread_1 (thread, true /* silent */);
}

struct thread_info *
find_thread_global_id (int global_id)
{
  for (thread_info *tp : all_threads ())
    if (tp->global_num == global_id)
      return tp;

  return NULL;
}

static struct thread_info *
find_thread_id (struct inferior *inf, int thr_num)
{
  for (thread_info *tp : inf->threads ())
    if (tp->per_inf_num == thr_num)
      return tp;

  return NULL;
}

/* Find a thread_info by matching PTID.  */

struct thread_info *
find_thread_ptid (ptid_t ptid)
{
  inferior *inf = find_inferior_ptid (ptid);
  if (inf == NULL)
    return NULL;
  return find_thread_ptid (inf, ptid);
}

/* See gdbthread.h.  */

struct thread_info *
find_thread_ptid (inferior *inf, ptid_t ptid)
{
  for (thread_info *tp : inf->threads ())
    if (tp->ptid == ptid)
      return tp;

  return NULL;
}

/* See gdbthread.h.  */

struct thread_info *
find_thread_by_handle (gdb::array_view<const gdb_byte> handle,
		       struct inferior *inf)
{
  return target_thread_handle_to_thread_info (handle.data (),
					      handle.size (),
					      inf);
}

/*
 * Thread iterator function.
 *
 * Calls a callback function once for each thread, so long as
 * the callback function returns false.  If the callback function
 * returns true, the iteration will end and the current thread
 * will be returned.  This can be useful for implementing a
 * search for a thread with arbitrary attributes, or for applying
 * some operation to every thread.
 *
 * FIXME: some of the existing functionality, such as
 * "Thread apply all", might be rewritten using this functionality.
 */

struct thread_info *
iterate_over_threads (int (*callback) (struct thread_info *, void *),
		      void *data)
{
  for (thread_info *tp : all_threads_safe ())
    if ((*callback) (tp, data))
      return tp;

  return NULL;
}

/* See gdbthread.h.  */

bool
any_thread_p ()
{
  for (thread_info *tp ATTRIBUTE_UNUSED : all_threads ())
    return true;
  return false;
}

int
thread_count (void)
{
  auto rng = all_threads ();
  return std::distance (rng.begin (), rng.end ());
}

/* Return the number of non-exited threads in the thread list.  */

static int
live_threads_count (void)
{
  auto rng = all_non_exited_threads ();
  return std::distance (rng.begin (), rng.end ());
}

int
valid_global_thread_id (int global_id)
{
  for (thread_info *tp : all_threads ())
    if (tp->global_num == global_id)
      return 1;

  return 0;
}

int
in_thread_list (ptid_t ptid)
{
  return find_thread_ptid (ptid) != nullptr;
}

/* Finds the first thread of the inferior.  */

thread_info *
first_thread_of_inferior (inferior *inf)
{
  return inf->thread_list;
}

thread_info *
any_thread_of_inferior (inferior *inf)
{
  gdb_assert (inf->pid != 0);

  /* Prefer the current thread.  */
  if (inf == current_inferior ())
    return inferior_thread ();

  for (thread_info *tp : inf->non_exited_threads ())
    return tp;

  return NULL;
}

thread_info *
any_live_thread_of_inferior (inferior *inf)
{
  struct thread_info *curr_tp = NULL;
  struct thread_info *tp_executing = NULL;

  gdb_assert (inf != NULL && inf->pid != 0);

  /* Prefer the current thread if it's not executing.  */
  if (inferior_ptid != null_ptid && current_inferior () == inf)
    {
      /* If the current thread is dead, forget it.  If it's not
	 executing, use it.  Otherwise, still choose it (below), but
	 only if no other non-executing thread is found.  */
      curr_tp = inferior_thread ();
      if (curr_tp->state == THREAD_EXITED)
	curr_tp = NULL;
      else if (!curr_tp->executing)
	return curr_tp;
    }

  for (thread_info *tp : inf->non_exited_threads ())
    {
      if (!tp->executing)
	return tp;

      tp_executing = tp;
    }

  /* If both the current thread and all live threads are executing,
     prefer the current thread.  */
  if (curr_tp != NULL)
    return curr_tp;

  /* Otherwise, just return an executing thread, if any.  */
  return tp_executing;
}

/* Return true if TP is an active thread.  */
static int
thread_alive (struct thread_info *tp)
{
  if (tp->state == THREAD_EXITED)
    return 0;
  if (!target_thread_alive (tp->ptid))
    return 0;
  return 1;
}

/* See gdbthreads.h.  */

void
prune_threads (void)
{
  for (thread_info *tp : all_threads_safe ())
    if (!thread_alive (tp))
      delete_thread (tp);
}

/* See gdbthreads.h.  */

void
delete_exited_threads (void)
{
  for (thread_info *tp : all_threads_safe ())
    if (tp->state == THREAD_EXITED)
      delete_thread (tp);
}

/* Return true value if stack temporaies are enabled for the thread
   TP.  */

bool
thread_stack_temporaries_enabled_p (thread_info *tp)
{
  if (tp == NULL)
    return false;
  else
    return tp->stack_temporaries_enabled;
}

/* Push V on to the stack temporaries of the thread with id PTID.  */

void
push_thread_stack_temporary (thread_info *tp, struct value *v)
{
  gdb_assert (tp != NULL && tp->stack_temporaries_enabled);
  tp->stack_temporaries.push_back (v);
}

/* Return true if VAL is among the stack temporaries of the thread
   TP.  Return false otherwise.  */

bool
value_in_thread_stack_temporaries (struct value *val, thread_info *tp)
{
  gdb_assert (tp != NULL && tp->stack_temporaries_enabled);
  for (value *v : tp->stack_temporaries)
    if (v == val)
      return true;

  return false;
}

/* Return the last of the stack temporaries for thread with id PTID.
   Return NULL if there are no stack temporaries for the thread.  */

value *
get_last_thread_stack_temporary (thread_info *tp)
{
  struct value *lastval = NULL;

  gdb_assert (tp != NULL);
  if (!tp->stack_temporaries.empty ())
    lastval = tp->stack_temporaries.back ();

  return lastval;
}

void
thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid)
{
  struct inferior *inf;
  struct thread_info *tp;

  /* It can happen that what we knew as the target inferior id
     changes.  E.g, target remote may only discover the remote process
     pid after adding the inferior to GDB's list.  */
  inf = find_inferior_ptid (old_ptid);
  inf->pid = new_ptid.pid ();

  tp = find_thread_ptid (inf, old_ptid);
  tp->ptid = new_ptid;

  gdb::observers::thread_ptid_changed.notify (old_ptid, new_ptid);
}

/* See gdbthread.h.  */

void
set_resumed (ptid_t ptid, int resumed)
{
  for (thread_info *tp : all_non_exited_threads (ptid))
    tp->resumed = resumed;
}

/* Helper for set_running, that marks one thread either running or
   stopped.  */

static int
set_running_thread (struct thread_info *tp, int running)
{
  int started = 0;

  if (running && tp->state == THREAD_STOPPED)
    started = 1;
  tp->state = running ? THREAD_RUNNING : THREAD_STOPPED;

  if (!running)
    {
      /* If the thread is now marked stopped, remove it from
	 the step-over queue, so that we don't try to resume
	 it until the user wants it to.  */
      if (tp->step_over_next != NULL)
	thread_step_over_chain_remove (tp);
    }

  return started;
}

/* See gdbthread.h.  */

void
thread_info::set_running (bool running)
{
  if (set_running_thread (this, running))
    gdb::observers::target_resumed.notify (this->ptid);
}

void
set_running (ptid_t ptid, int running)
{
  /* We try not to notify the observer if no thread has actually
     changed the running state -- merely to reduce the number of
     messages to the MI frontend.  A frontend is supposed to handle
     multiple *running notifications just fine.  */
  bool any_started = false;

  for (thread_info *tp : all_non_exited_threads (ptid))
    if (set_running_thread (tp, running))
      any_started = true;

  if (any_started)
    gdb::observers::target_resumed.notify (ptid);
}


/* Helper for set_executing.  Set's the thread's 'executing' field
   from EXECUTING, and if EXECUTING is true also clears the thread's
   stop_pc.  */

static void
set_executing_thread (thread_info *thr, bool executing)
{
  thr->executing = executing;
  if (executing)
    thr->suspend.stop_pc = ~(CORE_ADDR) 0;
}

void
set_executing (ptid_t ptid, int executing)
{
  for (thread_info *tp : all_non_exited_threads (ptid))
    set_executing_thread (tp, executing);

  /* It only takes one running thread to spawn more threads.  */
  if (executing)
    threads_executing = 1;
  /* Only clear the flag if the caller is telling us everything is
     stopped.  */
  else if (minus_one_ptid == ptid)
    threads_executing = 0;
}

/* See gdbthread.h.  */

int
threads_are_executing (void)
{
  return threads_executing;
}

void
set_stop_requested (ptid_t ptid, int stop)
{
  for (thread_info *tp : all_non_exited_threads (ptid))
    tp->stop_requested = stop;

  /* Call the stop requested observer so other components of GDB can
     react to this request.  */
  if (stop)
    gdb::observers::thread_stop_requested.notify (ptid);
}

void
finish_thread_state (ptid_t ptid)
{
  bool any_started = false;

  for (thread_info *tp : all_non_exited_threads (ptid))
    if (set_running_thread (tp, tp->executing))
      any_started = true;

  if (any_started)
    gdb::observers::target_resumed.notify (ptid);
}

/* See gdbthread.h.  */

void
validate_registers_access (void)
{
  /* No selected thread, no registers.  */
  if (inferior_ptid == null_ptid)
    error (_("No thread selected."));

  thread_info *tp = inferior_thread ();

  /* Don't try to read from a dead thread.  */
  if (tp->state == THREAD_EXITED)
    error (_("The current thread has terminated"));

  /* ... or from a spinning thread.  FIXME: This isn't actually fully
     correct.  It'll allow an user-requested access (e.g., "print $pc"
     at the prompt) when a thread is not executing for some internal
     reason, but is marked running from the user's perspective.  E.g.,
     the thread is waiting for its turn in the step-over queue.  */
  if (tp->executing)
    error (_("Selected thread is running."));
}

/* See gdbthread.h.  */

bool
can_access_registers_thread (thread_info *thread)
{
  /* No thread, no registers.  */
  if (thread == NULL)
    return false;

  /* Don't try to read from a dead thread.  */
  if (thread->state == THREAD_EXITED)
    return false;

  /* ... or from a spinning thread.  FIXME: see validate_registers_access.  */
  if (thread->executing)
    return false;

  return true;
}

int
pc_in_thread_step_range (CORE_ADDR pc, struct thread_info *thread)
{
  return (pc >= thread->control.step_range_start
	  && pc < thread->control.step_range_end);
}

/* Helper for print_thread_info.  Returns true if THR should be
   printed.  If REQUESTED_THREADS, a list of GDB ids/ranges, is not
   NULL, only print THR if its ID is included in the list.  GLOBAL_IDS
   is true if REQUESTED_THREADS is list of global IDs, false if a list
   of per-inferior thread ids.  If PID is not -1, only print THR if it
   is a thread from the process PID.  Otherwise, threads from all
   attached PIDs are printed.  If both REQUESTED_THREADS is not NULL
   and PID is not -1, then the thread is printed if it belongs to the
   specified process.  Otherwise, an error is raised.  */

static int
should_print_thread (const char *requested_threads, int default_inf_num,
		     int global_ids, int pid, struct thread_info *thr)
{
  if (requested_threads != NULL && *requested_threads != '\0')
    {
      int in_list;

      if (global_ids)
	in_list = number_is_in_list (requested_threads, thr->global_num);
      else
	in_list = tid_is_in_list (requested_threads, default_inf_num,
				  thr->inf->num, thr->per_inf_num);
      if (!in_list)
	return 0;
    }

  if (pid != -1 && thr->ptid.pid () != pid)
    {
      if (requested_threads != NULL && *requested_threads != '\0')
	error (_("Requested thread not found in requested process"));
      return 0;
    }

  if (thr->state == THREAD_EXITED)
    return 0;

  return 1;
}

/* Return the string to display in "info threads"'s "Target Id"
   column, for TP.  */

static std::string
thread_target_id_str (thread_info *tp)
{
  std::string target_id = target_pid_to_str (tp->ptid);
  const char *extra_info = target_extra_thread_info (tp);
  const char *name = tp->name != nullptr ? tp->name : target_thread_name (tp);

  if (extra_info != nullptr && name != nullptr)
    return string_printf ("%s \"%s\" (%s)", target_id.c_str (), name,
			  extra_info);
  else if (extra_info != nullptr)
    return string_printf ("%s (%s)", target_id.c_str (), extra_info);
  else if (name != nullptr)
    return string_printf ("%s \"%s\"", target_id.c_str (), name);
  else
    return target_id;
}

/* Like print_thread_info, but in addition, GLOBAL_IDS indicates
   whether REQUESTED_THREADS is a list of global or per-inferior
   thread ids.  */

static void
print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
		     int global_ids, int pid,
		     int show_global_ids)
{
  int default_inf_num = current_inferior ()->num;

  update_thread_list ();

  /* Whether we saw any thread.  */
  bool any_thread = false;
  /* Whether the current thread is exited.  */
  bool current_exited = false;

  thread_info *current_thread = (inferior_ptid != null_ptid
				 ? inferior_thread () : NULL);

  {
    /* For backward compatibility, we make a list for MI.  A table is
       preferable for the CLI, though, because it shows table
       headers.  */
    gdb::optional<ui_out_emit_list> list_emitter;
    gdb::optional<ui_out_emit_table> table_emitter;

    if (uiout->is_mi_like_p ())
      list_emitter.emplace (uiout, "threads");
    else
      {
	int n_threads = 0;
	/* The width of the "Target Id" column.  Grown below to
	   accommodate the largest entry.  */
	size_t target_id_col_width = 17;

	for (thread_info *tp : all_threads ())
	  {
	    if (!should_print_thread (requested_threads, default_inf_num,
				      global_ids, pid, tp))
	      continue;

	    if (!uiout->is_mi_like_p ())
	      {
		target_id_col_width
		  = std::max (target_id_col_width,
			      thread_target_id_str (tp).size ());
	      }

	    ++n_threads;
	  }

	if (n_threads == 0)
	  {
	    if (requested_threads == NULL || *requested_threads == '\0')
	      uiout->message (_("No threads.\n"));
	    else
	      uiout->message (_("No threads match '%s'.\n"),
			      requested_threads);
	    return;
	  }

	table_emitter.emplace (uiout, show_global_ids ? 5 : 4,
			       n_threads, "threads");

	uiout->table_header (1, ui_left, "current", "");
	uiout->table_header (4, ui_left, "id-in-tg", "Id");
	if (show_global_ids)
	  uiout->table_header (4, ui_left, "id", "GId");
	uiout->table_header (target_id_col_width, ui_left,
			     "target-id", "Target Id");
	uiout->table_header (1, ui_left, "frame", "Frame");
	uiout->table_body ();
      }

    /* We'll be switching threads temporarily.  */
    scoped_restore_current_thread restore_thread;

    for (inferior *inf : all_inferiors ())
      for (thread_info *tp : inf->threads ())
      {
	int core;

	any_thread = true;
	if (tp == current_thread && tp->state == THREAD_EXITED)
	  current_exited = true;

	if (!should_print_thread (requested_threads, default_inf_num,
				  global_ids, pid, tp))
	  continue;

	ui_out_emit_tuple tuple_emitter (uiout, NULL);

	if (!uiout->is_mi_like_p ())
	  {
	    if (tp == current_thread)
	      uiout->field_string ("current", "*");
	    else
	      uiout->field_skip ("current");

	    uiout->field_string ("id-in-tg", print_thread_id (tp));
	  }

	if (show_global_ids || uiout->is_mi_like_p ())
	  uiout->field_signed ("id", tp->global_num);

	/* For the CLI, we stuff everything into the target-id field.
	   This is a gross hack to make the output come out looking
	   correct.  The underlying problem here is that ui-out has no
	   way to specify that a field's space allocation should be
	   shared by several fields.  For MI, we do the right thing
	   instead.  */

	if (uiout->is_mi_like_p ())
	  {
	    uiout->field_string ("target-id", target_pid_to_str (tp->ptid));

	    const char *extra_info = target_extra_thread_info (tp);
	    if (extra_info != nullptr)
	      uiout->field_string ("details", extra_info);

	    const char *name = (tp->name != nullptr
				? tp->name
				: target_thread_name (tp));
	    if (name != NULL)
	      uiout->field_string ("name", name);
	  }
	else
	  {
	    uiout->field_string ("target-id",
				 thread_target_id_str (tp).c_str ());
	  }

	if (tp->state == THREAD_RUNNING)
	  uiout->text ("(running)\n");
	else
	  {
	    /* The switch below puts us at the top of the stack (leaf
	       frame).  */
	    switch_to_thread (tp);
	    print_stack_frame (get_selected_frame (NULL),
			       /* For MI output, print frame level.  */
			       uiout->is_mi_like_p (),
			       LOCATION, 0);
	  }

	if (uiout->is_mi_like_p ())
	  {
	    const char *state = "stopped";

	    if (tp->state == THREAD_RUNNING)
	      state = "running";
	    uiout->field_string ("state", state);
	  }

	core = target_core_of_thread (tp->ptid);
	if (uiout->is_mi_like_p () && core != -1)
	  uiout->field_signed ("core", core);
      }

    /* This end scope restores the current thread and the frame
       selected before the "info threads" command, and it finishes the
       ui-out list or table.  */
  }

  if (pid == -1 && requested_threads == NULL)
    {
      if (uiout->is_mi_like_p () && inferior_ptid != null_ptid)
	uiout->field_signed ("current-thread-id", current_thread->global_num);

      if (inferior_ptid != null_ptid && current_exited)
	uiout->message ("\n\
The current thread <Thread ID %s> has terminated.  See `help thread'.\n",
			print_thread_id (inferior_thread ()));
      else if (any_thread && inferior_ptid == null_ptid)
	uiout->message ("\n\
No selected thread.  See `help thread'.\n");
    }
}

/* See gdbthread.h.  */

void
print_thread_info (struct ui_out *uiout, const char *requested_threads,
		   int pid)
{
  print_thread_info_1 (uiout, requested_threads, 1, pid, 0);
}

/* The options for the "info threads" command.  */

struct info_threads_opts
{
  /* For "-gid".  */
  int show_global_ids = 0;
};

static const gdb::option::option_def info_threads_option_defs[] = {

  gdb::option::flag_option_def<info_threads_opts> {
    "gid",
    [] (info_threads_opts *opts) { return &opts->show_global_ids; },
    N_("Show global thread IDs."),
  },

};

/* Create an option_def_group for the "info threads" options, with
   IT_OPTS as context.  */

static inline gdb::option::option_def_group
make_info_threads_options_def_group (info_threads_opts *it_opts)
{
  return {{info_threads_option_defs}, it_opts};
}

/* Implementation of the "info threads" command.

   Note: this has the drawback that it _really_ switches
	 threads, which frees the frame cache.  A no-side
	 effects info-threads command would be nicer.  */

static void
info_threads_command (const char *arg, int from_tty)
{
  info_threads_opts it_opts;

  auto grp = make_info_threads_options_def_group (&it_opts);
  gdb::option::process_options
    (&arg, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR, grp);

  print_thread_info_1 (current_uiout, arg, 0, -1, it_opts.show_global_ids);
}

/* Completer for the "info threads" command.  */

static void
info_threads_command_completer (struct cmd_list_element *ignore,
				completion_tracker &tracker,
				const char *text, const char *word_ignored)
{
  const auto grp = make_info_threads_options_def_group (nullptr);

  if (gdb::option::complete_options
      (tracker, &text, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR, grp))
    return;

  /* Convenience to let the user know what the option can accept.  */
  if (*text == '\0')
    {
      gdb::option::complete_on_all_options (tracker, grp);
      /* Keep this "ID" in sync with what "help info threads"
	 says.  */
      tracker.add_completion (make_unique_xstrdup ("ID"));
    }
}

/* See gdbthread.h.  */

void
switch_to_thread_no_regs (struct thread_info *thread)
{
  struct inferior *inf = thread->inf;

  set_current_program_space (inf->pspace);
  set_current_inferior (inf);

  inferior_ptid = thread->ptid;
}

/* See gdbthread.h.  */

void
switch_to_no_thread ()
{
  if (inferior_ptid == null_ptid)
    return;

  inferior_ptid = null_ptid;
  reinit_frame_cache ();
}

/* See gdbthread.h.  */

void
switch_to_thread (thread_info *thr)
{
  gdb_assert (thr != NULL);

  if (inferior_ptid == thr->ptid)
    return;

  switch_to_thread_no_regs (thr);

  reinit_frame_cache ();
}

/* See gdbsupport/common-gdbthread.h.  */

void
switch_to_thread (ptid_t ptid)
{
  thread_info *thr = find_thread_ptid (ptid);
  switch_to_thread (thr);
}

static void
restore_selected_frame (struct frame_id a_frame_id, int frame_level)
{
  struct frame_info *frame = NULL;
  int count;

  /* This means there was no selected frame.  */
  if (frame_level == -1)
    {
      select_frame (NULL);
      return;
    }

  gdb_assert (frame_level >= 0);

  /* Restore by level first, check if the frame id is the same as
     expected.  If that fails, try restoring by frame id.  If that
     fails, nothing to do, just warn the user.  */

  count = frame_level;
  frame = find_relative_frame (get_current_frame (), &count);
  if (count == 0
      && frame != NULL
      /* The frame ids must match - either both valid or both outer_frame_id.
	 The latter case is not failsafe, but since it's highly unlikely
	 the search by level finds the wrong frame, it's 99.9(9)% of
	 the time (for all practical purposes) safe.  */
      && frame_id_eq (get_frame_id (frame), a_frame_id))
    {
      /* Cool, all is fine.  */
      select_frame (frame);
      return;
    }

  frame = frame_find_by_id (a_frame_id);
  if (frame != NULL)
    {
      /* Cool, refound it.  */
      select_frame (frame);
      return;
    }

  /* Nothing else to do, the frame layout really changed.  Select the
     innermost stack frame.  */
  select_frame (get_current_frame ());

  /* Warn the user.  */
  if (frame_level > 0 && !current_uiout->is_mi_like_p ())
    {
      warning (_("Couldn't restore frame #%d in "
		 "current thread.  Bottom (innermost) frame selected:"),
	       frame_level);
      /* For MI, we should probably have a notification about
	 current frame change.  But this error is not very
	 likely, so don't bother for now.  */
      print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC, 1);
    }
}

scoped_restore_current_thread::~scoped_restore_current_thread ()
{
  /* If an entry of thread_info was previously selected, it won't be
     deleted because we've increased its refcount.  The thread represented
     by this thread_info entry may have already exited (due to normal exit,
     detach, etc), so the thread_info.state is THREAD_EXITED.  */
  if (m_thread != NULL
      /* If the previously selected thread belonged to a process that has
	 in the mean time exited (or killed, detached, etc.), then don't revert
	 back to it, but instead simply drop back to no thread selected.  */
      && m_inf->pid != 0)
    switch_to_thread (m_thread);
  else
    {
      switch_to_no_thread ();
      set_current_inferior (m_inf);
    }

  /* The running state of the originally selected thread may have
     changed, so we have to recheck it here.  */
  if (inferior_ptid != null_ptid
      && m_was_stopped
      && m_thread->state == THREAD_STOPPED
      && target_has_registers
      && target_has_stack
      && target_has_memory)
    restore_selected_frame (m_selected_frame_id, m_selected_frame_level);

  if (m_thread != NULL)
    m_thread->decref ();
  m_inf->decref ();
}

scoped_restore_current_thread::scoped_restore_current_thread ()
{
  m_thread = NULL;
  m_inf = current_inferior ();

  if (inferior_ptid != null_ptid)
    {
      thread_info *tp = inferior_thread ();
      struct frame_info *frame;

      m_was_stopped = tp->state == THREAD_STOPPED;
      if (m_was_stopped
	  && target_has_registers
	  && target_has_stack
	  && target_has_memory)
	{
	  /* When processing internal events, there might not be a
	     selected frame.  If we naively call get_selected_frame
	     here, then we can end up reading debuginfo for the
	     current frame, but we don't generally need the debuginfo
	     at this point.  */
	  frame = get_selected_frame_if_set ();
	}
      else
	frame = NULL;

      m_selected_frame_id = get_frame_id (frame);
      m_selected_frame_level = frame_relative_level (frame);

      tp->incref ();
      m_thread = tp;
    }

  m_inf->incref ();
}

/* See gdbthread.h.  */

int
show_thread_that_caused_stop (void)
{
  return highest_thread_num > 1;
}

/* See gdbthread.h.  */

int
show_inferior_qualified_tids (void)
{
  return (inferior_list->next != NULL || inferior_list->num != 1);
}

/* See gdbthread.h.  */

const char *
print_thread_id (struct thread_info *thr)
{
  char *s = get_print_cell ();

  if (show_inferior_qualified_tids ())
    xsnprintf (s, PRINT_CELL_SIZE, "%d.%d", thr->inf->num, thr->per_inf_num);
  else
    xsnprintf (s, PRINT_CELL_SIZE, "%d", thr->per_inf_num);
  return s;
}

/* Sort an array of struct thread_info pointers by thread ID (first by
   inferior number, and then by per-inferior thread number).  Sorts in
   ascending order.  */

static bool
tp_array_compar_ascending (const thread_info *a, const thread_info *b)
{
  if (a->inf->num != b->inf->num)
    return a->inf->num < b->inf->num;

  return (a->per_inf_num < b->per_inf_num);
}

/* Sort an array of struct thread_info pointers by thread ID (first by
   inferior number, and then by per-inferior thread number).  Sorts in
   descending order.  */

static bool
tp_array_compar_descending (const thread_info *a, const thread_info *b)
{
  if (a->inf->num != b->inf->num)
    return a->inf->num > b->inf->num;

  return (a->per_inf_num > b->per_inf_num);
}

/* Switch to thread THR and execute CMD.
   FLAGS.QUIET controls the printing of the thread information.
   FLAGS.CONT and FLAGS.SILENT control how to handle errors.  */

static void
thr_try_catch_cmd (thread_info *thr, const char *cmd, int from_tty,
		   const qcs_flags &flags)
{
  switch_to_thread (thr);
  try
    {
      std::string cmd_result = execute_command_to_string
	(cmd, from_tty, gdb_stdout->term_out ());
      if (!flags.silent || cmd_result.length () > 0)
	{
	  if (!flags.quiet)
	    printf_filtered (_("\nThread %s (%s):\n"),
			     print_thread_id (thr),
			     target_pid_to_str (inferior_ptid).c_str ());
	  printf_filtered ("%s", cmd_result.c_str ());
	}
    }
  catch (const gdb_exception_error &ex)
    {
      if (!flags.silent)
	{
	  if (!flags.quiet)
	    printf_filtered (_("\nThread %s (%s):\n"),
			     print_thread_id (thr),
			     target_pid_to_str (inferior_ptid).c_str ());
	  if (flags.cont)
	    printf_filtered ("%s\n", ex.what ());
	  else
	    throw;
	}
    }
}

/* Option definition of "thread apply"'s "-ascending" option.  */

static const gdb::option::flag_option_def<> ascending_option_def = {
  "ascending",
  N_("\
Call COMMAND for all threads in ascending order.\n\
The default is descending order."),
};

/* The qcs command line flags for the "thread apply" commands.  Keep
   this in sync with the "frame apply" commands.  */

using qcs_flag_option_def
  = gdb::option::flag_option_def<qcs_flags>;

static const gdb::option::option_def thr_qcs_flags_option_defs[] = {
  qcs_flag_option_def {
    "q", [] (qcs_flags *opt) { return &opt->quiet; },
    N_("Disables printing the thread information."),
  },

  qcs_flag_option_def {
    "c", [] (qcs_flags *opt) { return &opt->cont; },
    N_("Print any error raised by COMMAND and continue."),
  },

  qcs_flag_option_def {
    "s", [] (qcs_flags *opt) { return &opt->silent; },
    N_("Silently ignore any errors or empty output produced by COMMAND."),
  },
};

/* Create an option_def_group for the "thread apply all" options, with
   ASCENDING and FLAGS as context.  */

static inline std::array<gdb::option::option_def_group, 2>
make_thread_apply_all_options_def_group (int *ascending,
					 qcs_flags *flags)
{
  return {{
    { {ascending_option_def.def ()}, ascending},
    { {thr_qcs_flags_option_defs}, flags },
  }};
}

/* Create an option_def_group for the "thread apply" options, with
   FLAGS as context.  */

static inline gdb::option::option_def_group
make_thread_apply_options_def_group (qcs_flags *flags)
{
  return {{thr_qcs_flags_option_defs}, flags};
}

/* Apply a GDB command to a list of threads.  List syntax is a whitespace
   separated list of numbers, or ranges, or the keyword `all'.  Ranges consist
   of two numbers separated by a hyphen.  Examples:

   thread apply 1 2 7 4 backtrace       Apply backtrace cmd to threads 1,2,7,4
   thread apply 2-7 9 p foo(1)  Apply p foo(1) cmd to threads 2->7 & 9
   thread apply all x/i $pc   Apply x/i $pc cmd to all threads.  */

static void
thread_apply_all_command (const char *cmd, int from_tty)
{
  int ascending = false;
  qcs_flags flags;

  auto group = make_thread_apply_all_options_def_group (&ascending,
							&flags);
  gdb::option::process_options
    (&cmd, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_OPERAND, group);

  validate_flags_qcs ("thread apply all", &flags);

  if (cmd == NULL || *cmd == '\000')
    error (_("Please specify a command at the end of 'thread apply all'"));

  update_thread_list ();

  int tc = live_threads_count ();
  if (tc != 0)
    {
      /* Save a copy of the thread list and increment each thread's
	 refcount while executing the command in the context of each
	 thread, in case the command is one that wipes threads.  E.g.,
	 detach, kill, disconnect, etc., or even normally continuing
	 over an inferior or thread exit.  */
      std::vector<thread_info *> thr_list_cpy;
      thr_list_cpy.reserve (tc);

      for (thread_info *tp : all_non_exited_threads ())
	thr_list_cpy.push_back (tp);
      gdb_assert (thr_list_cpy.size () == tc);

      /* Increment the refcounts, and restore them back on scope
	 exit.  */
      scoped_inc_dec_ref inc_dec_ref (thr_list_cpy);

      auto *sorter = (ascending
		      ? tp_array_compar_ascending
		      : tp_array_compar_descending);
      std::sort (thr_list_cpy.begin (), thr_list_cpy.end (), sorter);

      scoped_restore_current_thread restore_thread;

      for (thread_info *thr : thr_list_cpy)
	if (thread_alive (thr))
	  thr_try_catch_cmd (thr, cmd, from_tty, flags);
    }
}

/* Completer for "thread apply [ID list]".  */

static void
thread_apply_command_completer (cmd_list_element *ignore,
				completion_tracker &tracker,
				const char *text, const char * /*word*/)
{
  /* Don't leave this to complete_options because there's an early
     return below.  */
  tracker.set_use_custom_word_point (true);

  tid_range_parser parser;
  parser.init (text, current_inferior ()->num);

  try
    {
      while (!parser.finished ())
	{
	  int inf_num, thr_start, thr_end;

	  if (!parser.get_tid_range (&inf_num, &thr_start, &thr_end))
	    break;

	  if (parser.in_star_range () || parser.in_thread_range ())
	    parser.skip_range ();
	}
    }
  catch (const gdb_exception_error &ex)
    {
      /* get_tid_range throws if it parses a negative number, for
	 example.  But a seemingly negative number may be the start of
	 an option instead.  */
    }

  const char *cmd = parser.cur_tok ();

  if (cmd == text)
    {
      /* No thread ID list yet.  */
      return;
    }

  /* Check if we're past a valid thread ID list already.  */
  if (parser.finished ()
      && cmd > text && !isspace (cmd[-1]))
    return;

  /* We're past the thread ID list, advance word point.  */
  tracker.advance_custom_word_point_by (cmd - text);
  text = cmd;

  const auto group = make_thread_apply_options_def_group (nullptr);
  if (gdb::option::complete_options
      (tracker, &text, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_OPERAND, group))
    return;

  complete_nested_command_line (tracker, text);
}

/* Completer for "thread apply all".  */

static void
thread_apply_all_command_completer (cmd_list_element *ignore,
				    completion_tracker &tracker,
				    const char *text, const char *word)
{
  const auto group = make_thread_apply_all_options_def_group (nullptr,
							      nullptr);
  if (gdb::option::complete_options
      (tracker, &text, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_OPERAND, group))
    return;

  complete_nested_command_line (tracker, text);
}

/* Implementation of the "thread apply" command.  */

static void
thread_apply_command (const char *tidlist, int from_tty)
{
  qcs_flags flags;
  const char *cmd = NULL;
  tid_range_parser parser;

  if (tidlist == NULL || *tidlist == '\000')
    error (_("Please specify a thread ID list"));

  parser.init (tidlist, current_inferior ()->num);
  while (!parser.finished ())
    {
      int inf_num, thr_start, thr_end;

      if (!parser.get_tid_range (&inf_num, &thr_start, &thr_end))
	break;
    }

  cmd = parser.cur_tok ();

  auto group = make_thread_apply_options_def_group (&flags);
  gdb::option::process_options
    (&cmd, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_OPERAND, group);

  validate_flags_qcs ("thread apply", &flags);

  if (*cmd == '\0')
    error (_("Please specify a command following the thread ID list"));

  if (tidlist == cmd || isdigit (cmd[0]))
    invalid_thread_id_error (cmd);

  scoped_restore_current_thread restore_thread;

  parser.init (tidlist, current_inferior ()->num);
  while (!parser.finished ())
    {
      struct thread_info *tp = NULL;
      struct inferior *inf;
      int inf_num, thr_num;

      parser.get_tid (&inf_num, &thr_num);
      inf = find_inferior_id (inf_num);
      if (inf != NULL)
	tp = find_thread_id (inf, thr_num);

      if (parser.in_star_range ())
	{
	  if (inf == NULL)
	    {
	      warning (_("Unknown inferior %d"), inf_num);
	      parser.skip_range ();
	      continue;
	    }

	  /* No use looking for threads past the highest thread number
	     the inferior ever had.  */
	  if (thr_num >= inf->highest_thread_num)
	    parser.skip_range ();

	  /* Be quiet about unknown threads numbers.  */
	  if (tp == NULL)
	    continue;
	}

      if (tp == NULL)
	{
	  if (show_inferior_qualified_tids () || parser.tid_is_qualified ())
	    warning (_("Unknown thread %d.%d"), inf_num, thr_num);
	  else
	    warning (_("Unknown thread %d"), thr_num);
	  continue;
	}

      if (!thread_alive (tp))
	{
	  warning (_("Thread %s has terminated."), print_thread_id (tp));
	  continue;
	}

      thr_try_catch_cmd (tp, cmd, from_tty, flags);
    }
}


/* Implementation of the "taas" command.  */

static void
taas_command (const char *cmd, int from_tty)
{
  std::string expanded = std::string ("thread apply all -s ") + cmd;
  execute_command (expanded.c_str (), from_tty);
}

/* Implementation of the "tfaas" command.  */

static void
tfaas_command (const char *cmd, int from_tty)
{
  std::string expanded
    = std::string ("thread apply all -s -- frame apply all -s ") + cmd;
  execute_command (expanded.c_str (), from_tty);
}

/* Switch to the specified thread, or print the current thread.  */

void
thread_command (const char *tidstr, int from_tty)
{
  if (tidstr == NULL)
    {
      if (inferior_ptid == null_ptid)
	error (_("No thread selected"));

      if (target_has_stack)
	{
	  struct thread_info *tp = inferior_thread ();

	  if (tp->state == THREAD_EXITED)
	    printf_filtered (_("[Current thread is %s (%s) (exited)]\n"),
			     print_thread_id (tp),
			     target_pid_to_str (inferior_ptid).c_str ());
	  else
	    printf_filtered (_("[Current thread is %s (%s)]\n"),
			     print_thread_id (tp),
			     target_pid_to_str (inferior_ptid).c_str ());
	}
      else
	error (_("No stack."));
    }
  else
    {
      ptid_t previous_ptid = inferior_ptid;

      thread_select (tidstr, parse_thread_id (tidstr, NULL));

      /* Print if the thread has not changed, otherwise an event will
	 be sent.  */
      if (inferior_ptid == previous_ptid)
	{
	  print_selected_thread_frame (current_uiout,
				       USER_SELECTED_THREAD
				       | USER_SELECTED_FRAME);
	}
      else
	{
	  gdb::observers::user_selected_context_changed.notify
	    (USER_SELECTED_THREAD | USER_SELECTED_FRAME);
	}
    }
}

/* Implementation of `thread name'.  */

static void
thread_name_command (const char *arg, int from_tty)
{
  struct thread_info *info;

  if (inferior_ptid == null_ptid)
    error (_("No thread selected"));

  arg = skip_spaces (arg);

  info = inferior_thread ();
  xfree (info->name);
  info->name = arg ? xstrdup (arg) : NULL;
}

/* Find thread ids with a name, target pid, or extra info matching ARG.  */

static void
thread_find_command (const char *arg, int from_tty)
{
  const char *tmp;
  unsigned long match = 0;

  if (arg == NULL || *arg == '\0')
    error (_("Command requires an argument."));

  tmp = re_comp (arg);
  if (tmp != 0)
    error (_("Invalid regexp (%s): %s"), tmp, arg);

  update_thread_list ();
  for (thread_info *tp : all_threads ())
    {
      if (tp->name != NULL && re_exec (tp->name))
	{
	  printf_filtered (_("Thread %s has name '%s'\n"),
			   print_thread_id (tp), tp->name);
	  match++;
	}

      tmp = target_thread_name (tp);
      if (tmp != NULL && re_exec (tmp))
	{
	  printf_filtered (_("Thread %s has target name '%s'\n"),
			   print_thread_id (tp), tmp);
	  match++;
	}

      std::string name = target_pid_to_str (tp->ptid);
      if (!name.empty () && re_exec (name.c_str ()))
	{
	  printf_filtered (_("Thread %s has target id '%s'\n"),
			   print_thread_id (tp), name.c_str ());
	  match++;
	}

      tmp = target_extra_thread_info (tp);
      if (tmp != NULL && re_exec (tmp))
	{
	  printf_filtered (_("Thread %s has extra info '%s'\n"),
			   print_thread_id (tp), tmp);
	  match++;
	}
    }
  if (!match)
    printf_filtered (_("No threads match '%s'\n"), arg);
}

/* Print notices when new threads are attached and detached.  */
int print_thread_events = 1;
static void
show_print_thread_events (struct ui_file *file, int from_tty,
			  struct cmd_list_element *c, const char *value)
{
  fprintf_filtered (file,
		    _("Printing of thread events is %s.\n"),
		    value);
}

/* See gdbthread.h.  */

void
thread_select (const char *tidstr, thread_info *tp)
{
  if (!thread_alive (tp))
    error (_("Thread ID %s has terminated."), tidstr);

  switch_to_thread (tp);

  annotate_thread_changed ();

  /* Since the current thread may have changed, see if there is any
     exited thread we can now delete.  */
  prune_threads ();
}

/* Print thread and frame switch command response.  */

void
print_selected_thread_frame (struct ui_out *uiout,
			     user_selected_what selection)
{
  struct thread_info *tp = inferior_thread ();

  if (selection & USER_SELECTED_THREAD)
    {
      if (uiout->is_mi_like_p ())
	{
	  uiout->field_signed ("new-thread-id",
			       inferior_thread ()->global_num);
	}
      else
	{
	  uiout->text ("[Switching to thread ");
	  uiout->field_string ("new-thread-id", print_thread_id (tp));
	  uiout->text (" (");
	  uiout->text (target_pid_to_str (inferior_ptid).c_str ());
	  uiout->text (")]");
	}
    }

  if (tp->state == THREAD_RUNNING)
    {
      if (selection & USER_SELECTED_THREAD)
	uiout->text ("(running)\n");
    }
  else if (selection & USER_SELECTED_FRAME)
    {
      if (selection & USER_SELECTED_THREAD)
	uiout->text ("\n");

      if (has_stack_frames ())
	print_stack_frame_to_uiout (uiout, get_selected_frame (NULL),
				    1, SRC_AND_LOC, 1);
    }
}

/* Update the 'threads_executing' global based on the threads we know
   about right now.  */

static void
update_threads_executing (void)
{
  threads_executing = 0;
  for (thread_info *tp : all_non_exited_threads ())
    {
      if (tp->executing)
	{
	  threads_executing = 1;
	  break;
	}
    }
}

void
update_thread_list (void)
{
  target_update_thread_list ();
  update_threads_executing ();
}

/* Return a new value for the selected thread's id.  Return a value of
   0 if no thread is selected.  If GLOBAL is true, return the thread's
   global number.  Otherwise return the per-inferior number.  */

static struct value *
thread_num_make_value_helper (struct gdbarch *gdbarch, int global)
{
  int int_val;

  if (inferior_ptid == null_ptid)
    int_val = 0;
  else
    {
      thread_info *tp = inferior_thread ();
      if (global)
	int_val = tp->global_num;
      else
	int_val = tp->per_inf_num;
    }

  return value_from_longest (builtin_type (gdbarch)->builtin_int, int_val);
}

/* Return a new value for the selected thread's per-inferior thread
   number.  Return a value of 0 if no thread is selected, or no
   threads exist.  */

static struct value *
thread_id_per_inf_num_make_value (struct gdbarch *gdbarch,
				  struct internalvar *var,
				  void *ignore)
{
  return thread_num_make_value_helper (gdbarch, 0);
}

/* Return a new value for the selected thread's global id.  Return a
   value of 0 if no thread is selected, or no threads exist.  */

static struct value *
global_thread_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
			     void *ignore)
{
  return thread_num_make_value_helper (gdbarch, 1);
}

/* Commands with a prefix of `thread'.  */
struct cmd_list_element *thread_cmd_list = NULL;

/* Implementation of `thread' variable.  */

static const struct internalvar_funcs thread_funcs =
{
  thread_id_per_inf_num_make_value,
  NULL,
  NULL
};

/* Implementation of `gthread' variable.  */

static const struct internalvar_funcs gthread_funcs =
{
  global_thread_id_make_value,
  NULL,
  NULL
};

void
_initialize_thread (void)
{
  static struct cmd_list_element *thread_apply_list = NULL;
  cmd_list_element *c;

  const auto info_threads_opts = make_info_threads_options_def_group (nullptr);

  /* Note: keep this "ID" in sync with what "info threads [TAB]"
     suggests.  */
  static std::string info_threads_help
    = gdb::option::build_help (_("\
Display currently known threads.\n\
Usage: info threads [OPTION]... [ID]...\n\
\n\
Options:\n\
%OPTIONS%\
If ID is given, it is a space-separated list of IDs of threads to display.\n\
Otherwise, all threads are displayed."),
			       info_threads_opts);

  c = add_info ("threads", info_threads_command, info_threads_help.c_str ());
  set_cmd_completer_handle_brkchars (c, info_threads_command_completer);

  add_prefix_cmd ("thread", class_run, thread_command, _("\
Use this command to switch between threads.\n\
The new thread ID must be currently known."),
		  &thread_cmd_list, "thread ", 1, &cmdlist);

#define THREAD_APPLY_OPTION_HELP "\
Prints per-inferior thread number and target system's thread id\n\
followed by COMMAND output.\n\
\n\
By default, an error raised during the execution of COMMAND\n\
aborts \"thread apply\".\n\
\n\
Options:\n\
%OPTIONS%"

  const auto thread_apply_opts = make_thread_apply_options_def_group (nullptr);

  static std::string thread_apply_help = gdb::option::build_help (_("\
Apply a command to a list of threads.\n\
Usage: thread apply ID... [OPTION]... COMMAND\n\
ID is a space-separated list of IDs of threads to apply COMMAND on.\n"
THREAD_APPLY_OPTION_HELP),
			       thread_apply_opts);

  c = add_prefix_cmd ("apply", class_run, thread_apply_command,
		      thread_apply_help.c_str (),
		      &thread_apply_list, "thread apply ", 1,
		      &thread_cmd_list);
  set_cmd_completer_handle_brkchars (c, thread_apply_command_completer);

  const auto thread_apply_all_opts
    = make_thread_apply_all_options_def_group (nullptr, nullptr);

  static std::string thread_apply_all_help = gdb::option::build_help (_("\
Apply a command to all threads.\n\
\n\
Usage: thread apply all [OPTION]... COMMAND\n"
THREAD_APPLY_OPTION_HELP),
			       thread_apply_all_opts);

  c = add_cmd ("all", class_run, thread_apply_all_command,
	       thread_apply_all_help.c_str (),
	       &thread_apply_list);
  set_cmd_completer_handle_brkchars (c, thread_apply_all_command_completer);

  c = add_com ("taas", class_run, taas_command, _("\
Apply a command to all threads (ignoring errors and empty output).\n\
Usage: taas [OPTION]... COMMAND\n\
shortcut for 'thread apply all -s [OPTION]... COMMAND'\n\
See \"help thread apply all\" for available options."));
  set_cmd_completer_handle_brkchars (c, thread_apply_all_command_completer);

  c = add_com ("tfaas", class_run, tfaas_command, _("\
Apply a command to all frames of all threads (ignoring errors and empty output).\n\
Usage: tfaas [OPTION]... COMMAND\n\
shortcut for 'thread apply all -s -- frame apply all -s [OPTION]... COMMAND'\n\
See \"help frame apply all\" for available options."));
  set_cmd_completer_handle_brkchars (c, frame_apply_all_cmd_completer);

  add_cmd ("name", class_run, thread_name_command,
	   _("Set the current thread's name.\n\
Usage: thread name [NAME]\n\
If NAME is not given, then any existing name is removed."), &thread_cmd_list);

  add_cmd ("find", class_run, thread_find_command, _("\
Find threads that match a regular expression.\n\
Usage: thread find REGEXP\n\
Will display thread ids whose name, target ID, or extra info matches REGEXP."),
	   &thread_cmd_list);

  add_com_alias ("t", "thread", class_run, 1);

  add_setshow_boolean_cmd ("thread-events", no_class,
			   &print_thread_events, _("\
Set printing of thread events (such as thread start and exit)."), _("\
Show printing of thread events (such as thread start and exit)."), NULL,
			   NULL,
			   show_print_thread_events,
			   &setprintlist, &showprintlist);

  create_internalvar_type_lazy ("_thread", &thread_funcs, NULL);
  create_internalvar_type_lazy ("_gthread", &gthread_funcs, NULL);
}