gdb/inflow.c

   1 /* Low level interface to ptrace, for GDB when running under Unix.
   2    Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   3    1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
   4    2009 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "frame.h"
  23 #include "inferior.h"
  24 #include "command.h"
  25 #include "serial.h"
  26 #include "terminal.h"
  27 #include "target.h"
  28 #include "gdbthread.h"
  29
  30 #include "gdb_string.h"
  31 #include <signal.h>
  32 #include <fcntl.h>
  33 #include "gdb_select.h"
  34
  35 #include "inflow.h"
  36
  37 #ifdef HAVE_SYS_IOCTL_H
  38 #include <sys/ioctl.h>
  39 #endif
  40
  41 #ifndef O_NOCTTY
  42 #define O_NOCTTY 0
  43 #endif
  44
  45 #if defined (SIGIO) && defined (FASYNC) && defined (FD_SET) && defined (F_SETOWN)
  46 static void handle_sigio (int);
  47 #endif
  48
  49 extern void _initialize_inflow (void);
  50
  51 static void pass_signal (int);
  52
  53 static void kill_command (char *, int);
  54
  55 static void terminal_ours_1 (int);
  56 \f
  57 /* Record terminal status separately for debugger and inferior.  */
  58
  59 static struct serial *stdin_serial;
  60
  61 /* TTY state for the inferior.  We save it whenever the inferior stops, and
  62    restore it when it resumes.  */
  63 static serial_ttystate inferior_ttystate;
  64
  65 /* Our own tty state, which we restore every time we need to deal with the
  66    terminal.  We only set it once, when GDB first starts.  The settings of
  67    flags which readline saves and restores and unimportant.  */
  68 static serial_ttystate our_ttystate;
  69
  70 /* fcntl flags for us and the inferior.  Saved and restored just like
  71    {our,inferior}_ttystate.  */
  72 static int tflags_inferior;
  73 static int tflags_ours;
  74
  75 #ifdef PROCESS_GROUP_TYPE
  76 /* Process group for us and the inferior.  Saved and restored just like
  77    {our,inferior}_ttystate.  */
  78 PROCESS_GROUP_TYPE our_process_group;
  79 PROCESS_GROUP_TYPE inferior_process_group;
  80 #endif
  81
  82 /* While the inferior is running, we want SIGINT and SIGQUIT to go to the
  83    inferior only.  If we have job control, that takes care of it.  If not,
  84    we save our handlers in these two variables and set SIGINT and SIGQUIT
  85    to SIG_IGN.  */
  86
  87 static void (*sigint_ours) ();
  88 static void (*sigquit_ours) ();
  89
  90 /* The name of the tty (from the `tty' command) that we gave to the inferior
  91    when it was last started.  */
  92
  93 static const char *inferior_thisrun_terminal;
  94
  95 /* Nonzero if our terminal settings are in effect.  Zero if the
  96    inferior's settings are in effect.  Ignored if !gdb_has_a_terminal
  97    ().  */
  98
  99 int terminal_is_ours;
 100
 101 #ifdef PROCESS_GROUP_TYPE
 102 static PROCESS_GROUP_TYPE
 103 gdb_getpgrp (void)
 104 {
 105   int process_group = -1;
 106 #ifdef HAVE_TERMIOS
 107   process_group = tcgetpgrp (0);
 108 #endif
 109 #ifdef HAVE_TERMIO
 110   process_group = getpgrp ();
 111 #endif
 112 #ifdef HAVE_SGTTY
 113   ioctl (0, TIOCGPGRP, &process_group);
 114 #endif
 115   return process_group;
 116 }
 117 #endif
 118
 119 enum
 120   {
 121     yes, no, have_not_checked
 122   }
 123 gdb_has_a_terminal_flag = have_not_checked;
 124
 125 /* Does GDB have a terminal (on stdin)?  */
 126 int
 127 gdb_has_a_terminal (void)
 128 {
 129   switch (gdb_has_a_terminal_flag)
 130     {
 131     case yes:
 132       return 1;
 133     case no:
 134       return 0;
 135     case have_not_checked:
 136       /* Get all the current tty settings (including whether we have a
 137          tty at all!).  Can't do this in _initialize_inflow because
 138          serial_fdopen() won't work until the serial_ops_list is
 139          initialized.  */
 140
 141 #ifdef F_GETFL
 142       tflags_ours = fcntl (0, F_GETFL, 0);
 143 #endif
 144
 145       gdb_has_a_terminal_flag = no;
 146       if (stdin_serial != NULL)
 147         {
 148           our_ttystate = serial_get_tty_state (stdin_serial);
 149
 150           if (our_ttystate != NULL)
 151             {
 152               gdb_has_a_terminal_flag = yes;
 153 #ifdef PROCESS_GROUP_TYPE
 154               our_process_group = gdb_getpgrp ();
 155 #endif
 156             }
 157         }
 158
 159       return gdb_has_a_terminal_flag == yes;
 160     default:
 161       /* "Can't happen".  */
 162       return 0;
 163     }
 164 }
 165
 166 /* Macro for printing errors from ioctl operations */
 167
 168 #define OOPSY(what)     \
 169   if (result == -1)     \
 170     fprintf_unfiltered(gdb_stderr, "[%s failed in terminal_inferior: %s]\n", \
 171             what, safe_strerror (errno))
 172
 173 static void terminal_ours_1 (int);
 174
 175 /* Initialize the terminal settings we record for the inferior,
 176    before we actually run the inferior.  */
 177
 178 void
 179 terminal_init_inferior_with_pgrp (int pgrp)
 180 {
 181   if (gdb_has_a_terminal ())
 182     {
 183       /* We could just as well copy our_ttystate (if we felt like
 184          adding a new function serial_copy_tty_state()).  */
 185       if (inferior_ttystate)
 186         xfree (inferior_ttystate);
 187       inferior_ttystate = serial_get_tty_state (stdin_serial);
 188
 189 #ifdef PROCESS_GROUP_TYPE
 190       inferior_process_group = pgrp;
 191 #endif
 192
 193       /* Make sure that next time we call terminal_inferior (which will be
 194          before the program runs, as it needs to be), we install the new
 195          process group.  */
 196       terminal_is_ours = 1;
 197     }
 198 }
 199
 200 /* Save the terminal settings again.  This is necessary for the TUI
 201    when it switches to TUI or non-TUI mode;  curses changes the terminal
 202    and gdb must be able to restore it correctly.  */
 203
 204 void
 205 terminal_save_ours (void)
 206 {
 207   if (gdb_has_a_terminal ())
 208     {
 209       /* We could just as well copy our_ttystate (if we felt like adding
 210          a new function serial_copy_tty_state).  */
 211       if (our_ttystate)
 212         xfree (our_ttystate);
 213       our_ttystate = serial_get_tty_state (stdin_serial);
 214     }
 215 }
 216
 217 void
 218 terminal_init_inferior (void)
 219 {
 220 #ifdef PROCESS_GROUP_TYPE
 221   /* This is for Lynx, and should be cleaned up by having Lynx be a separate
 222      debugging target with a version of target_terminal_init_inferior which
 223      passes in the process group to a generic routine which does all the work
 224      (and the non-threaded child_terminal_init_inferior can just pass in
 225      inferior_ptid to the same routine).  */
 226   /* We assume INFERIOR_PID is also the child's process group.  */
 227   terminal_init_inferior_with_pgrp (PIDGET (inferior_ptid));
 228 #endif /* PROCESS_GROUP_TYPE */
 229 }
 230
 231 /* Put the inferior's terminal settings into effect.
 232    This is preparation for starting or resuming the inferior.  */
 233
 234 void
 235 terminal_inferior (void)
 236 {
 237   if (gdb_has_a_terminal () && terminal_is_ours
 238       && inferior_ttystate != NULL
 239       && inferior_thisrun_terminal == 0)
 240     {
 241       int result;
 242
 243 #ifdef F_GETFL
 244       /* Is there a reason this is being done twice?  It happens both
 245          places we use F_SETFL, so I'm inclined to think perhaps there
 246          is some reason, however perverse.  Perhaps not though...  */
 247       result = fcntl (0, F_SETFL, tflags_inferior);
 248       result = fcntl (0, F_SETFL, tflags_inferior);
 249       OOPSY ("fcntl F_SETFL");
 250 #endif
 251
 252       /* Because we were careful to not change in or out of raw mode in
 253          terminal_ours, we will not change in our out of raw mode with
 254          this call, so we don't flush any input.  */
 255       result = serial_set_tty_state (stdin_serial, inferior_ttystate);
 256       OOPSY ("setting tty state");
 257
 258       if (!job_control)
 259         {
 260           sigint_ours = (void (*)()) signal (SIGINT, SIG_IGN);
 261 #ifdef SIGQUIT
 262           sigquit_ours = (void (*)()) signal (SIGQUIT, SIG_IGN);
 263 #endif
 264         }
 265
 266       /* If attach_flag is set, we don't know whether we are sharing a
 267          terminal with the inferior or not.  (attaching a process
 268          without a terminal is one case where we do not; attaching a
 269          process which we ran from the same shell as GDB via `&' is
 270          one case where we do, I think (but perhaps this is not
 271          `sharing' in the sense that we need to save and restore tty
 272          state)).  I don't know if there is any way to tell whether we
 273          are sharing a terminal.  So what we do is to go through all
 274          the saving and restoring of the tty state, but ignore errors
 275          setting the process group, which will happen if we are not
 276          sharing a terminal).  */
 277
 278       if (job_control)
 279         {
 280           struct inferior *inf = current_inferior ();
 281 #ifdef HAVE_TERMIOS
 282           result = tcsetpgrp (0, inferior_process_group);
 283           if (!inf->attach_flag)
 284             OOPSY ("tcsetpgrp");
 285 #endif
 286
 287 #ifdef HAVE_SGTTY
 288           result = ioctl (0, TIOCSPGRP, &inferior_process_group);
 289           if (!inf->attach_flag)
 290             OOPSY ("TIOCSPGRP");
 291 #endif
 292         }
 293
 294     }
 295   terminal_is_ours = 0;
 296 }
 297
 298 /* Put some of our terminal settings into effect,
 299    enough to get proper results from our output,
 300    but do not change into or out of RAW mode
 301    so that no input is discarded.
 302
 303    After doing this, either terminal_ours or terminal_inferior
 304    should be called to get back to a normal state of affairs.  */
 305
 306 void
 307 terminal_ours_for_output (void)
 308 {
 309   terminal_ours_1 (1);
 310 }
 311
 312 /* Put our terminal settings into effect.
 313    First record the inferior's terminal settings
 314    so they can be restored properly later.  */
 315
 316 void
 317 terminal_ours (void)
 318 {
 319   terminal_ours_1 (0);
 320 }
 321
 322 /* output_only is not used, and should not be used unless we introduce
 323    separate terminal_is_ours and terminal_is_ours_for_output
 324    flags.  */
 325
 326 static void
 327 terminal_ours_1 (int output_only)
 328 {
 329   /* Checking inferior_thisrun_terminal is necessary so that
 330      if GDB is running in the background, it won't block trying
 331      to do the ioctl()'s below.  Checking gdb_has_a_terminal
 332      avoids attempting all the ioctl's when running in batch.  */
 333   if (inferior_thisrun_terminal != 0 || gdb_has_a_terminal () == 0)
 334     return;
 335
 336   if (!terminal_is_ours)
 337     {
 338       struct inferior *inf = current_inferior ();
 339
 340 #ifdef SIGTTOU
 341       /* Ignore this signal since it will happen when we try to set the
 342          pgrp.  */
 343       void (*osigttou) () = NULL;
 344 #endif
 345       int result;
 346
 347       terminal_is_ours = 1;
 348
 349 #ifdef SIGTTOU
 350       if (job_control)
 351         osigttou = (void (*)()) signal (SIGTTOU, SIG_IGN);
 352 #endif
 353
 354       if (inferior_ttystate)
 355         xfree (inferior_ttystate);
 356       inferior_ttystate = serial_get_tty_state (stdin_serial);
 357
 358 #ifdef PROCESS_GROUP_TYPE
 359       if (!inf->attach_flag)
 360         /* If setpgrp failed in terminal_inferior, this would give us
 361            our process group instead of the inferior's.  See
 362            terminal_inferior for details.  */
 363         inferior_process_group = gdb_getpgrp ();
 364 #endif
 365
 366       /* Here we used to set ICANON in our ttystate, but I believe this
 367          was an artifact from before when we used readline.  Readline sets
 368          the tty state when it needs to.
 369          FIXME-maybe: However, query() expects non-raw mode and doesn't
 370          use readline.  Maybe query should use readline (on the other hand,
 371          this only matters for HAVE_SGTTY, not termio or termios, I think).  */
 372
 373       /* Set tty state to our_ttystate.  We don't change in our out of raw
 374          mode, to avoid flushing input.  We need to do the same thing
 375          regardless of output_only, because we don't have separate
 376          terminal_is_ours and terminal_is_ours_for_output flags.  It's OK,
 377          though, since readline will deal with raw mode when/if it needs to.
 378        */
 379
 380       serial_noflush_set_tty_state (stdin_serial, our_ttystate,
 381                                     inferior_ttystate);
 382
 383       if (job_control)
 384         {
 385 #ifdef HAVE_TERMIOS
 386           result = tcsetpgrp (0, our_process_group);
 387 #if 0
 388           /* This fails on Ultrix with EINVAL if you run the testsuite
 389              in the background with nohup, and then log out.  GDB never
 390              used to check for an error here, so perhaps there are other
 391              such situations as well.  */
 392           if (result == -1)
 393             fprintf_unfiltered (gdb_stderr, "[tcsetpgrp failed in terminal_ours: %s]\n",
 394                                 safe_strerror (errno));
 395 #endif
 396 #endif /* termios */
 397
 398 #ifdef HAVE_SGTTY
 399           result = ioctl (0, TIOCSPGRP, &our_process_group);
 400 #endif
 401         }
 402
 403 #ifdef SIGTTOU
 404       if (job_control)
 405         signal (SIGTTOU, osigttou);
 406 #endif
 407
 408       if (!job_control)
 409         {
 410           signal (SIGINT, sigint_ours);
 411 #ifdef SIGQUIT
 412           signal (SIGQUIT, sigquit_ours);
 413 #endif
 414         }
 415
 416 #ifdef F_GETFL
 417       tflags_inferior = fcntl (0, F_GETFL, 0);
 418
 419       /* Is there a reason this is being done twice?  It happens both
 420          places we use F_SETFL, so I'm inclined to think perhaps there
 421          is some reason, however perverse.  Perhaps not though...  */
 422       result = fcntl (0, F_SETFL, tflags_ours);
 423       result = fcntl (0, F_SETFL, tflags_ours);
 424 #endif
 425     }
 426 }
 427
 428 void
 429 term_info (char *arg, int from_tty)
 430 {
 431   target_terminal_info (arg, from_tty);
 432 }
 433
 434 void
 435 child_terminal_info (char *args, int from_tty)
 436 {
 437   if (!gdb_has_a_terminal ())
 438     {
 439       printf_filtered (_("This GDB does not control a terminal.\n"));
 440       return;
 441     }
 442
 443   printf_filtered (_("Inferior's terminal status (currently saved by GDB):\n"));
 444
 445   /* First the fcntl flags.  */
 446   {
 447     int flags;
 448
 449     flags = tflags_inferior;
 450
 451     printf_filtered ("File descriptor flags = ");
 452
 453 #ifndef O_ACCMODE
 454 #define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
 455 #endif
 456     /* (O_ACCMODE) parens are to avoid Ultrix header file bug */
 457     switch (flags & (O_ACCMODE))
 458       {
 459       case O_RDONLY:
 460         printf_filtered ("O_RDONLY");
 461         break;
 462       case O_WRONLY:
 463         printf_filtered ("O_WRONLY");
 464         break;
 465       case O_RDWR:
 466         printf_filtered ("O_RDWR");
 467         break;
 468       }
 469     flags &= ~(O_ACCMODE);
 470
 471 #ifdef O_NONBLOCK
 472     if (flags & O_NONBLOCK)
 473       printf_filtered (" | O_NONBLOCK");
 474     flags &= ~O_NONBLOCK;
 475 #endif
 476
 477 #if defined (O_NDELAY)
 478     /* If O_NDELAY and O_NONBLOCK are defined to the same thing, we will
 479        print it as O_NONBLOCK, which is good cause that is what POSIX
 480        has, and the flag will already be cleared by the time we get here.  */
 481     if (flags & O_NDELAY)
 482       printf_filtered (" | O_NDELAY");
 483     flags &= ~O_NDELAY;
 484 #endif
 485
 486     if (flags & O_APPEND)
 487       printf_filtered (" | O_APPEND");
 488     flags &= ~O_APPEND;
 489
 490 #if defined (O_BINARY)
 491     if (flags & O_BINARY)
 492       printf_filtered (" | O_BINARY");
 493     flags &= ~O_BINARY;
 494 #endif
 495
 496     if (flags)
 497       printf_filtered (" | 0x%x", flags);
 498     printf_filtered ("\n");
 499   }
 500
 501 #ifdef PROCESS_GROUP_TYPE
 502   printf_filtered ("Process group = %d\n",
 503                    (int) inferior_process_group);
 504 #endif
 505
 506   serial_print_tty_state (stdin_serial, inferior_ttystate, gdb_stdout);
 507 }
 508 \f
 509 /* NEW_TTY_PREFORK is called before forking a new child process,
 510    so we can record the state of ttys in the child to be formed.
 511    TTYNAME is null if we are to share the terminal with gdb;
 512    or points to a string containing the name of the desired tty.
 513
 514    NEW_TTY is called in new child processes under Unix, which will
 515    become debugger target processes.  This actually switches to
 516    the terminal specified in the NEW_TTY_PREFORK call.  */
 517
 518 void
 519 new_tty_prefork (const char *ttyname)
 520 {
 521   /* Save the name for later, for determining whether we and the child
 522      are sharing a tty.  */
 523   inferior_thisrun_terminal = ttyname;
 524 }
 525
 526
 527 /* If RESULT, assumed to be the return value from a system call, is
 528    negative, print the error message indicated by errno and exit.
 529    MSG should identify the operation that failed.  */
 530 static void
 531 check_syscall (const char *msg, int result)
 532 {
 533   if (result < 0)
 534     {
 535       print_sys_errmsg (msg, errno);
 536       _exit (1);
 537     }
 538 }
 539
 540 void
 541 new_tty (void)
 542 {
 543   int tty;
 544
 545   if (inferior_thisrun_terminal == 0)
 546     return;
 547 #if !defined(__GO32__) && !defined(_WIN32)
 548 #ifdef TIOCNOTTY
 549   /* Disconnect the child process from our controlling terminal.  On some
 550      systems (SVR4 for example), this may cause a SIGTTOU, so temporarily
 551      ignore SIGTTOU. */
 552   tty = open ("/dev/tty", O_RDWR);
 553   if (tty > 0)
 554     {
 555       void (*osigttou) ();
 556
 557       osigttou = (void (*)()) signal (SIGTTOU, SIG_IGN);
 558       ioctl (tty, TIOCNOTTY, 0);
 559       close (tty);
 560       signal (SIGTTOU, osigttou);
 561     }
 562 #endif
 563
 564   /* Now open the specified new terminal.  */
 565   tty = open (inferior_thisrun_terminal, O_RDWR | O_NOCTTY);
 566   check_syscall (inferior_thisrun_terminal, tty);
 567
 568   /* Avoid use of dup2; doesn't exist on all systems.  */
 569   if (tty != 0)
 570     {
 571       close (0);
 572       check_syscall ("dup'ing tty into fd 0", dup (tty));
 573     }
 574   if (tty != 1)
 575     {
 576       close (1);
 577       check_syscall ("dup'ing tty into fd 1", dup (tty));
 578     }
 579   if (tty != 2)
 580     {
 581       close (2);
 582       check_syscall ("dup'ing tty into fd 2", dup (tty));
 583     }
 584
 585 #ifdef TIOCSCTTY
 586   /* Make tty our new controlling terminal.  */
 587   if (ioctl (tty, TIOCSCTTY, 0) == -1)
 588     /* Mention GDB in warning because it will appear in the inferior's
 589        terminal instead of GDB's.  */
 590     warning ("GDB: Failed to set controlling terminal: %s",
 591              safe_strerror (errno));
 592 #endif
 593
 594   if (tty > 2)
 595     close (tty);
 596 #endif /* !go32 && !win32 */
 597 }
 598 \f
 599 /* Kill the inferior process.  Make us have no inferior.  */
 600
 601 static void
 602 kill_command (char *arg, int from_tty)
 603 {
 604   /* FIXME:  This should not really be inferior_ptid (or target_has_execution).
 605      It should be a distinct flag that indicates that a target is active, cuz
 606      some targets don't have processes! */
 607
 608   if (ptid_equal (inferior_ptid, null_ptid))
 609     error (_("The program is not being run."));
 610   if (!query ("Kill the program being debugged? "))
 611     error (_("Not confirmed."));
 612   target_kill ();
 613
 614   /* If the current target interface claims there's still execution,
 615      then don't mess with threads of other processes.  */
 616   if (!target_has_execution)
 617     {
 618       init_thread_list ();              /* Destroy thread info */
 619
 620       /* Killing off the inferior can leave us with a core file.  If
 621          so, print the state we are left in.  */
 622       if (target_has_stack)
 623         {
 624           printf_filtered (_("In %s,\n"), target_longname);
 625           print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
 626         }
 627     }
 628   bfd_cache_close_all ();
 629 }
 630 \f
 631 /* Call set_sigint_trap when you need to pass a signal on to an attached
 632    process when handling SIGINT */
 633
 634 static void
 635 pass_signal (int signo)
 636 {
 637 #ifndef _WIN32
 638   kill (PIDGET (inferior_ptid), SIGINT);
 639 #endif
 640 }
 641
 642 static void (*osig) ();
 643
 644 void
 645 set_sigint_trap (void)
 646 {
 647   struct inferior *inf = current_inferior ();
 648   if (inf->attach_flag || inferior_thisrun_terminal)
 649     {
 650       osig = (void (*)()) signal (SIGINT, pass_signal);
 651     }
 652 }
 653
 654 void
 655 clear_sigint_trap (void)
 656 {
 657   struct inferior *inf = current_inferior ();
 658   if (inf->attach_flag || inferior_thisrun_terminal)
 659     {
 660       signal (SIGINT, osig);
 661     }
 662 }
 663 \f
 664
 665 /* Create a new session if the inferior will run in a different tty.
 666    A session is UNIX's way of grouping processes that share a controlling
 667    terminal, so a new one is needed if the inferior terminal will be
 668    different from GDB's.
 669
 670    Returns the session id of the new session, 0 if no session was created
 671    or -1 if an error occurred.  */
 672 pid_t
 673 create_tty_session (void)
 674 {
 675 #ifdef HAVE_SETSID
 676   pid_t ret;
 677
 678   if (!job_control || inferior_thisrun_terminal == 0)
 679     return 0;
 680
 681   ret = setsid ();
 682   if (ret == -1)
 683     warning ("Failed to create new terminal session: setsid: %s",
 684              safe_strerror (errno));
 685
 686   return ret;
 687 #else
 688   return 0;
 689 #endif /* HAVE_SETSID */
 690 }
 691
 692 /* This is here because this is where we figure out whether we (probably)
 693    have job control.  Just using job_control only does part of it because
 694    setpgid or setpgrp might not exist on a system without job control.
 695    It might be considered misplaced (on the other hand, process groups and
 696    job control are closely related to ttys).
 697
 698    For a more clean implementation, in libiberty, put a setpgid which merely
 699    calls setpgrp and a setpgrp which does nothing (any system with job control
 700    will have one or the other).  */
 701 int
 702 gdb_setpgid (void)
 703 {
 704   int retval = 0;
 705
 706   if (job_control)
 707     {
 708 #if defined (HAVE_TERMIOS) || defined (TIOCGPGRP)
 709 #ifdef HAVE_SETPGID
 710       /* The call setpgid (0, 0) is supposed to work and mean the same
 711          thing as this, but on Ultrix 4.2A it fails with EPERM (and
 712          setpgid (getpid (), getpid ()) succeeds).  */
 713       retval = setpgid (getpid (), getpid ());
 714 #else
 715 #ifdef HAVE_SETPGRP
 716 #ifdef SETPGRP_VOID
 717       retval = setpgrp ();
 718 #else
 719       retval = setpgrp (getpid (), getpid ());
 720 #endif
 721 #endif /* HAVE_SETPGRP */
 722 #endif /* HAVE_SETPGID */
 723 #endif /* defined (HAVE_TERMIOS) || defined (TIOCGPGRP) */
 724     }
 725
 726   return retval;
 727 }
 728
 729 /* Get all the current tty settings (including whether we have a
 730    tty at all!).  We can't do this in _initialize_inflow because
 731    serial_fdopen() won't work until the serial_ops_list is
 732    initialized, but we don't want to do it lazily either, so
 733    that we can guarantee stdin_serial is opened if there is
 734    a terminal.  */
 735 void
 736 initialize_stdin_serial (void)
 737 {
 738   stdin_serial = serial_fdopen (0);
 739 }
 740
 741 void
 742 _initialize_inflow (void)
 743 {
 744   add_info ("terminal", term_info,
 745             _("Print inferior's saved terminal status."));
 746
 747   add_com ("kill", class_run, kill_command,
 748            _("Kill execution of program being debugged."));
 749
 750   inferior_ptid = null_ptid;
 751
 752   terminal_is_ours = 1;
 753
 754   /* OK, figure out whether we have job control.  If neither termios nor
 755      sgtty (i.e. termio or go32), leave job_control 0.  */
 756
 757 #if defined (HAVE_TERMIOS)
 758   /* Do all systems with termios have the POSIX way of identifying job
 759      control?  I hope so.  */
 760 #ifdef _POSIX_JOB_CONTROL
 761   job_control = 1;
 762 #else
 763 #ifdef _SC_JOB_CONTROL
 764   job_control = sysconf (_SC_JOB_CONTROL);
 765 #else
 766   job_control = 0;              /* have to assume the worst */
 767 #endif /* _SC_JOB_CONTROL */
 768 #endif /* _POSIX_JOB_CONTROL */
 769 #endif /* HAVE_TERMIOS */
 770
 771 #ifdef HAVE_SGTTY
 772 #ifdef TIOCGPGRP
 773   job_control = 1;
 774 #else
 775   job_control = 0;
 776 #endif /* TIOCGPGRP */
 777 #endif /* sgtty */
 778 }