gdb/inflow.c

   1 /* Low level interface to ptrace, for GDB when running under Unix.
   2    Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   3    1996, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "frame.h"
  24 #include "inferior.h"
  25 #include "command.h"
  26 #include "serial.h"
  27 #include "terminal.h"
  28 #include "target.h"
  29 #include "gdbthread.h"
  30
  31 #include "gdb_string.h"
  32 #include <signal.h>
  33 #include <fcntl.h>
  34 #ifdef HAVE_SYS_SELECT_H
  35 #include <sys/select.h>
  36 #endif
  37
  38 #ifdef HAVE_TERMIOS
  39 #define PROCESS_GROUP_TYPE pid_t
  40 #endif
  41
  42 #ifdef HAVE_TERMIO
  43 #define PROCESS_GROUP_TYPE int
  44 #endif
  45
  46 #ifdef HAVE_SGTTY
  47 #ifdef SHORT_PGRP
  48 /* This is only used for the ultra.  Does it have pid_t?  */
  49 #define PROCESS_GROUP_TYPE short
  50 #else
  51 #define PROCESS_GROUP_TYPE int
  52 #endif
  53 #endif /* sgtty */
  54
  55 #ifdef HAVE_SYS_IOCTL_H
  56 #include <sys/ioctl.h>
  57 #endif
  58
  59 #if defined (SIGIO) && defined (FASYNC) && defined (FD_SET) && defined (F_SETOWN)
  60 static void handle_sigio (int);
  61 #endif
  62
  63 extern void _initialize_inflow (void);
  64
  65 static void pass_signal (int);
  66
  67 static void kill_command (char *, int);
  68
  69 static void terminal_ours_1 (int);
  70 \f
  71 /* Record terminal status separately for debugger and inferior.  */
  72
  73 static struct serial *stdin_serial;
  74
  75 /* TTY state for the inferior.  We save it whenever the inferior stops, and
  76    restore it when it resumes.  */
  77 static serial_ttystate inferior_ttystate;
  78
  79 /* Our own tty state, which we restore every time we need to deal with the
  80    terminal.  We only set it once, when GDB first starts.  The settings of
  81    flags which readline saves and restores and unimportant.  */
  82 static serial_ttystate our_ttystate;
  83
  84 /* fcntl flags for us and the inferior.  Saved and restored just like
  85    {our,inferior}_ttystate.  */
  86 static int tflags_inferior;
  87 static int tflags_ours;
  88
  89 #ifdef PROCESS_GROUP_TYPE
  90 /* Process group for us and the inferior.  Saved and restored just like
  91    {our,inferior}_ttystate.  */
  92 PROCESS_GROUP_TYPE our_process_group;
  93 PROCESS_GROUP_TYPE inferior_process_group;
  94 #endif
  95
  96 /* While the inferior is running, we want SIGINT and SIGQUIT to go to the
  97    inferior only.  If we have job control, that takes care of it.  If not,
  98    we save our handlers in these two variables and set SIGINT and SIGQUIT
  99    to SIG_IGN.  */
 100
 101 static void (*sigint_ours) ();
 102 static void (*sigquit_ours) ();
 103
 104 /* The name of the tty (from the `tty' command) that we gave to the inferior
 105    when it was last started.  */
 106
 107 static char *inferior_thisrun_terminal;
 108
 109 /* Nonzero if our terminal settings are in effect.  Zero if the
 110    inferior's settings are in effect.  Ignored if !gdb_has_a_terminal
 111    ().  */
 112
 113 int terminal_is_ours;
 114
 115 enum
 116   {
 117     yes, no, have_not_checked
 118   }
 119 gdb_has_a_terminal_flag = have_not_checked;
 120
 121 /* Does GDB have a terminal (on stdin)?  */
 122 int
 123 gdb_has_a_terminal (void)
 124 {
 125   switch (gdb_has_a_terminal_flag)
 126     {
 127     case yes:
 128       return 1;
 129     case no:
 130       return 0;
 131     case have_not_checked:
 132       /* Get all the current tty settings (including whether we have a
 133          tty at all!).  Can't do this in _initialize_inflow because
 134          serial_fdopen() won't work until the serial_ops_list is
 135          initialized.  */
 136
 137 #ifdef F_GETFL
 138       tflags_ours = fcntl (0, F_GETFL, 0);
 139 #endif
 140
 141       gdb_has_a_terminal_flag = no;
 142       stdin_serial = serial_fdopen (0);
 143       if (stdin_serial != NULL)
 144         {
 145           our_ttystate = serial_get_tty_state (stdin_serial);
 146
 147           if (our_ttystate != NULL)
 148             {
 149               gdb_has_a_terminal_flag = yes;
 150 #ifdef HAVE_TERMIOS
 151               our_process_group = tcgetpgrp (0);
 152 #endif
 153 #ifdef HAVE_TERMIO
 154               our_process_group = getpgrp ();
 155 #endif
 156 #ifdef HAVE_SGTTY
 157               ioctl (0, TIOCGPGRP, &our_process_group);
 158 #endif
 159             }
 160         }
 161
 162       return gdb_has_a_terminal_flag == yes;
 163     default:
 164       /* "Can't happen".  */
 165       return 0;
 166     }
 167 }
 168
 169 /* Macro for printing errors from ioctl operations */
 170
 171 #define OOPSY(what)     \
 172   if (result == -1)     \
 173     fprintf_unfiltered(gdb_stderr, "[%s failed in terminal_inferior: %s]\n", \
 174             what, safe_strerror (errno))
 175
 176 static void terminal_ours_1 (int);
 177
 178 /* Initialize the terminal settings we record for the inferior,
 179    before we actually run the inferior.  */
 180
 181 void
 182 terminal_init_inferior_with_pgrp (int pgrp)
 183 {
 184   if (gdb_has_a_terminal ())
 185     {
 186       /* We could just as well copy our_ttystate (if we felt like
 187          adding a new function serial_copy_tty_state()).  */
 188       if (inferior_ttystate)
 189         xfree (inferior_ttystate);
 190       inferior_ttystate = serial_get_tty_state (stdin_serial);
 191
 192 #ifdef PROCESS_GROUP_TYPE
 193       inferior_process_group = pgrp;
 194 #endif
 195
 196       /* Make sure that next time we call terminal_inferior (which will be
 197          before the program runs, as it needs to be), we install the new
 198          process group.  */
 199       terminal_is_ours = 1;
 200     }
 201 }
 202
 203 /* Save the terminal settings again.  This is necessary for the TUI
 204    when it switches to TUI or non-TUI mode;  curses changes the terminal
 205    and gdb must be able to restore it correctly.  */
 206
 207 void
 208 terminal_save_ours (void)
 209 {
 210   if (gdb_has_a_terminal ())
 211     {
 212       /* We could just as well copy our_ttystate (if we felt like adding
 213          a new function serial_copy_tty_state).  */
 214       if (our_ttystate)
 215         xfree (our_ttystate);
 216       our_ttystate = serial_get_tty_state (stdin_serial);
 217     }
 218 }
 219
 220 void
 221 terminal_init_inferior (void)
 222 {
 223 #ifdef PROCESS_GROUP_TYPE
 224   /* This is for Lynx, and should be cleaned up by having Lynx be a separate
 225      debugging target with a version of target_terminal_init_inferior which
 226      passes in the process group to a generic routine which does all the work
 227      (and the non-threaded child_terminal_init_inferior can just pass in
 228      inferior_ptid to the same routine).  */
 229   /* We assume INFERIOR_PID is also the child's process group.  */
 230   terminal_init_inferior_with_pgrp (PIDGET (inferior_ptid));
 231 #endif /* PROCESS_GROUP_TYPE */
 232 }
 233
 234 /* Put the inferior's terminal settings into effect.
 235    This is preparation for starting or resuming the inferior.  */
 236
 237 void
 238 terminal_inferior (void)
 239 {
 240   if (gdb_has_a_terminal () && terminal_is_ours
 241       && inferior_thisrun_terminal == 0)
 242     {
 243       int result;
 244
 245 #ifdef F_GETFL
 246       /* Is there a reason this is being done twice?  It happens both
 247          places we use F_SETFL, so I'm inclined to think perhaps there
 248          is some reason, however perverse.  Perhaps not though...  */
 249       result = fcntl (0, F_SETFL, tflags_inferior);
 250       result = fcntl (0, F_SETFL, tflags_inferior);
 251       OOPSY ("fcntl F_SETFL");
 252 #endif
 253
 254       /* Because we were careful to not change in or out of raw mode in
 255          terminal_ours, we will not change in our out of raw mode with
 256          this call, so we don't flush any input.  */
 257       result = serial_set_tty_state (stdin_serial, inferior_ttystate);
 258       OOPSY ("setting tty state");
 259
 260       if (!job_control)
 261         {
 262           sigint_ours = (void (*)()) signal (SIGINT, SIG_IGN);
 263 #ifdef SIGQUIT
 264           sigquit_ours = (void (*)()) signal (SIGQUIT, SIG_IGN);
 265 #endif
 266         }
 267
 268       /* If attach_flag is set, we don't know whether we are sharing a
 269          terminal with the inferior or not.  (attaching a process
 270          without a terminal is one case where we do not; attaching a
 271          process which we ran from the same shell as GDB via `&' is
 272          one case where we do, I think (but perhaps this is not
 273          `sharing' in the sense that we need to save and restore tty
 274          state)).  I don't know if there is any way to tell whether we
 275          are sharing a terminal.  So what we do is to go through all
 276          the saving and restoring of the tty state, but ignore errors
 277          setting the process group, which will happen if we are not
 278          sharing a terminal).  */
 279
 280       if (job_control)
 281         {
 282 #ifdef HAVE_TERMIOS
 283           result = tcsetpgrp (0, inferior_process_group);
 284           if (!attach_flag)
 285             OOPSY ("tcsetpgrp");
 286 #endif
 287
 288 #ifdef HAVE_SGTTY
 289           result = ioctl (0, TIOCSPGRP, &inferior_process_group);
 290           if (!attach_flag)
 291             OOPSY ("TIOCSPGRP");
 292 #endif
 293         }
 294
 295     }
 296   terminal_is_ours = 0;
 297 }
 298
 299 /* Put some of our terminal settings into effect,
 300    enough to get proper results from our output,
 301    but do not change into or out of RAW mode
 302    so that no input is discarded.
 303
 304    After doing this, either terminal_ours or terminal_inferior
 305    should be called to get back to a normal state of affairs.  */
 306
 307 void
 308 terminal_ours_for_output (void)
 309 {
 310   terminal_ours_1 (1);
 311 }
 312
 313 /* Put our terminal settings into effect.
 314    First record the inferior's terminal settings
 315    so they can be restored properly later.  */
 316
 317 void
 318 terminal_ours (void)
 319 {
 320   terminal_ours_1 (0);
 321 }
 322
 323 /* output_only is not used, and should not be used unless we introduce
 324    separate terminal_is_ours and terminal_is_ours_for_output
 325    flags.  */
 326
 327 static void
 328 terminal_ours_1 (int output_only)
 329 {
 330   /* Checking inferior_thisrun_terminal is necessary so that
 331      if GDB is running in the background, it won't block trying
 332      to do the ioctl()'s below.  Checking gdb_has_a_terminal
 333      avoids attempting all the ioctl's when running in batch.  */
 334   if (inferior_thisrun_terminal != 0 || gdb_has_a_terminal () == 0)
 335     return;
 336
 337   if (!terminal_is_ours)
 338     {
 339 #ifdef SIGTTOU
 340       /* Ignore this signal since it will happen when we try to set the
 341          pgrp.  */
 342       void (*osigttou) () = NULL;
 343 #endif
 344       int result;
 345
 346       terminal_is_ours = 1;
 347
 348 #ifdef SIGTTOU
 349       if (job_control)
 350         osigttou = (void (*)()) signal (SIGTTOU, SIG_IGN);
 351 #endif
 352
 353       if (inferior_ttystate)
 354         xfree (inferior_ttystate);
 355       inferior_ttystate = serial_get_tty_state (stdin_serial);
 356 #ifdef HAVE_TERMIOS
 357       inferior_process_group = tcgetpgrp (0);
 358 #endif
 359 #ifdef HAVE_TERMIO
 360       inferior_process_group = getpgrp ();
 361 #endif
 362 #ifdef HAVE_SGTTY
 363       ioctl (0, TIOCGPGRP, &inferior_process_group);
 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       result = result;          /* lint */
 427     }
 428 }
 429
 430 /* ARGSUSED */
 431 void
 432 term_info (char *arg, int from_tty)
 433 {
 434   target_terminal_info (arg, from_tty);
 435 }
 436
 437 /* ARGSUSED */
 438 void
 439 child_terminal_info (char *args, int from_tty)
 440 {
 441   if (!gdb_has_a_terminal ())
 442     {
 443       printf_filtered ("This GDB does not control a terminal.\n");
 444       return;
 445     }
 446
 447   printf_filtered ("Inferior's terminal status (currently saved by GDB):\n");
 448
 449   /* First the fcntl flags.  */
 450   {
 451     int flags;
 452
 453     flags = tflags_inferior;
 454
 455     printf_filtered ("File descriptor flags = ");
 456
 457 #ifndef O_ACCMODE
 458 #define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
 459 #endif
 460     /* (O_ACCMODE) parens are to avoid Ultrix header file bug */
 461     switch (flags & (O_ACCMODE))
 462       {
 463       case O_RDONLY:
 464         printf_filtered ("O_RDONLY");
 465         break;
 466       case O_WRONLY:
 467         printf_filtered ("O_WRONLY");
 468         break;
 469       case O_RDWR:
 470         printf_filtered ("O_RDWR");
 471         break;
 472       }
 473     flags &= ~(O_ACCMODE);
 474
 475 #ifdef O_NONBLOCK
 476     if (flags & O_NONBLOCK)
 477       printf_filtered (" | O_NONBLOCK");
 478     flags &= ~O_NONBLOCK;
 479 #endif
 480
 481 #if defined (O_NDELAY)
 482     /* If O_NDELAY and O_NONBLOCK are defined to the same thing, we will
 483        print it as O_NONBLOCK, which is good cause that is what POSIX
 484        has, and the flag will already be cleared by the time we get here.  */
 485     if (flags & O_NDELAY)
 486       printf_filtered (" | O_NDELAY");
 487     flags &= ~O_NDELAY;
 488 #endif
 489
 490     if (flags & O_APPEND)
 491       printf_filtered (" | O_APPEND");
 492     flags &= ~O_APPEND;
 493
 494 #if defined (O_BINARY)
 495     if (flags & O_BINARY)
 496       printf_filtered (" | O_BINARY");
 497     flags &= ~O_BINARY;
 498 #endif
 499
 500     if (flags)
 501       printf_filtered (" | 0x%x", flags);
 502     printf_filtered ("\n");
 503   }
 504
 505 #ifdef PROCESS_GROUP_TYPE
 506   printf_filtered ("Process group = %d\n",
 507                    (int) inferior_process_group);
 508 #endif
 509
 510   serial_print_tty_state (stdin_serial, inferior_ttystate, gdb_stdout);
 511 }
 512 \f
 513 /* NEW_TTY_PREFORK is called before forking a new child process,
 514    so we can record the state of ttys in the child to be formed.
 515    TTYNAME is null if we are to share the terminal with gdb;
 516    or points to a string containing the name of the desired tty.
 517
 518    NEW_TTY is called in new child processes under Unix, which will
 519    become debugger target processes.  This actually switches to
 520    the terminal specified in the NEW_TTY_PREFORK call.  */
 521
 522 void
 523 new_tty_prefork (char *ttyname)
 524 {
 525   /* Save the name for later, for determining whether we and the child
 526      are sharing a tty.  */
 527   inferior_thisrun_terminal = ttyname;
 528 }
 529
 530 void
 531 new_tty (void)
 532 {
 533   register int tty;
 534
 535   if (inferior_thisrun_terminal == 0)
 536     return;
 537 #if !defined(__GO32__) && !defined(_WIN32)
 538 #ifdef TIOCNOTTY
 539   /* Disconnect the child process from our controlling terminal.  On some
 540      systems (SVR4 for example), this may cause a SIGTTOU, so temporarily
 541      ignore SIGTTOU. */
 542   tty = open ("/dev/tty", O_RDWR);
 543   if (tty > 0)
 544     {
 545       void (*osigttou) ();
 546
 547       osigttou = (void (*)()) signal (SIGTTOU, SIG_IGN);
 548       ioctl (tty, TIOCNOTTY, 0);
 549       close (tty);
 550       signal (SIGTTOU, osigttou);
 551     }
 552 #endif
 553
 554   /* Now open the specified new terminal.  */
 555
 556 #ifdef USE_O_NOCTTY
 557   tty = open (inferior_thisrun_terminal, O_RDWR | O_NOCTTY);
 558 #else
 559   tty = open (inferior_thisrun_terminal, O_RDWR);
 560 #endif
 561   if (tty == -1)
 562     {
 563       print_sys_errmsg (inferior_thisrun_terminal, errno);
 564       _exit (1);
 565     }
 566
 567   /* Avoid use of dup2; doesn't exist on all systems.  */
 568   if (tty != 0)
 569     {
 570       close (0);
 571       dup (tty);
 572     }
 573   if (tty != 1)
 574     {
 575       close (1);
 576       dup (tty);
 577     }
 578   if (tty != 2)
 579     {
 580       close (2);
 581       dup (tty);
 582     }
 583   if (tty > 2)
 584     close (tty);
 585 #endif /* !go32 && !win32 */
 586 }
 587 \f
 588 /* Kill the inferior process.  Make us have no inferior.  */
 589
 590 /* ARGSUSED */
 591 static void
 592 kill_command (char *arg, int from_tty)
 593 {
 594   /* FIXME:  This should not really be inferior_ptid (or target_has_execution).
 595      It should be a distinct flag that indicates that a target is active, cuz
 596      some targets don't have processes! */
 597
 598   if (ptid_equal (inferior_ptid, null_ptid))
 599     error ("The program is not being run.");
 600   if (!query ("Kill the program being debugged? "))
 601     error ("Not confirmed.");
 602   target_kill ();
 603
 604   init_thread_list ();          /* Destroy thread info */
 605
 606   /* Killing off the inferior can leave us with a core file.  If so,
 607      print the state we are left in.  */
 608   if (target_has_stack)
 609     {
 610       printf_filtered ("In %s,\n", target_longname);
 611       if (deprecated_selected_frame == NULL)
 612         fputs_filtered ("No selected stack frame.\n", gdb_stdout);
 613       else
 614         print_stack_frame (deprecated_selected_frame,
 615                            frame_relative_level (deprecated_selected_frame), 1);
 616     }
 617 }
 618 \f
 619 /* Call set_sigint_trap when you need to pass a signal on to an attached
 620    process when handling SIGINT */
 621
 622 /* ARGSUSED */
 623 static void
 624 pass_signal (int signo)
 625 {
 626 #ifndef _WIN32
 627   kill (PIDGET (inferior_ptid), SIGINT);
 628 #endif
 629 }
 630
 631 static void (*osig) ();
 632
 633 void
 634 set_sigint_trap (void)
 635 {
 636   if (attach_flag || inferior_thisrun_terminal)
 637     {
 638       osig = (void (*)()) signal (SIGINT, pass_signal);
 639     }
 640 }
 641
 642 void
 643 clear_sigint_trap (void)
 644 {
 645   if (attach_flag || inferior_thisrun_terminal)
 646     {
 647       signal (SIGINT, osig);
 648     }
 649 }
 650 \f
 651 #if defined (SIGIO) && defined (FASYNC) && defined (FD_SET) && defined (F_SETOWN)
 652 static void (*old_sigio) ();
 653
 654 static void
 655 handle_sigio (int signo)
 656 {
 657   int numfds;
 658   fd_set readfds;
 659
 660   signal (SIGIO, handle_sigio);
 661
 662   FD_ZERO (&readfds);
 663   FD_SET (target_activity_fd, &readfds);
 664   numfds = select (target_activity_fd + 1, &readfds, NULL, NULL, NULL);
 665   if (numfds >= 0 && FD_ISSET (target_activity_fd, &readfds))
 666     {
 667 #ifndef _WIN32
 668       if ((*target_activity_function) ())
 669         kill (PIDGET (inferior_ptid), SIGINT);
 670 #endif
 671     }
 672 }
 673
 674 static int old_fcntl_flags;
 675
 676 void
 677 set_sigio_trap (void)
 678 {
 679   if (target_activity_function)
 680     {
 681       old_sigio = (void (*)()) signal (SIGIO, handle_sigio);
 682       fcntl (target_activity_fd, F_SETOWN, getpid ());
 683       old_fcntl_flags = fcntl (target_activity_fd, F_GETFL, 0);
 684       fcntl (target_activity_fd, F_SETFL, old_fcntl_flags | FASYNC);
 685     }
 686 }
 687
 688 void
 689 clear_sigio_trap (void)
 690 {
 691   if (target_activity_function)
 692     {
 693       signal (SIGIO, old_sigio);
 694       fcntl (target_activity_fd, F_SETFL, old_fcntl_flags);
 695     }
 696 }
 697 #else /* No SIGIO.  */
 698 void
 699 set_sigio_trap (void)
 700 {
 701   if (target_activity_function)
 702     internal_error (__FILE__, __LINE__, "failed internal consistency check");
 703 }
 704
 705 void
 706 clear_sigio_trap (void)
 707 {
 708   if (target_activity_function)
 709     internal_error (__FILE__, __LINE__, "failed internal consistency check");
 710 }
 711 #endif /* No SIGIO.  */
 712 \f
 713
 714 /* This is here because this is where we figure out whether we (probably)
 715    have job control.  Just using job_control only does part of it because
 716    setpgid or setpgrp might not exist on a system without job control.
 717    It might be considered misplaced (on the other hand, process groups and
 718    job control are closely related to ttys).
 719
 720    For a more clean implementation, in libiberty, put a setpgid which merely
 721    calls setpgrp and a setpgrp which does nothing (any system with job control
 722    will have one or the other).  */
 723 int
 724 gdb_setpgid (void)
 725 {
 726   int retval = 0;
 727
 728   if (job_control)
 729     {
 730 #if defined (HAVE_TERMIOS) || defined (TIOCGPGRP)
 731 #ifdef HAVE_SETPGID
 732       /* The call setpgid (0, 0) is supposed to work and mean the same
 733          thing as this, but on Ultrix 4.2A it fails with EPERM (and
 734          setpgid (getpid (), getpid ()) succeeds).  */
 735       retval = setpgid (getpid (), getpid ());
 736 #else
 737 #ifdef HAVE_SETPGRP
 738 #ifdef SETPGRP_VOID
 739       retval = setpgrp ();
 740 #else
 741       retval = setpgrp (getpid (), getpid ());
 742 #endif
 743 #endif /* HAVE_SETPGRP */
 744 #endif /* HAVE_SETPGID */
 745 #endif /* defined (HAVE_TERMIOS) || defined (TIOCGPGRP) */
 746     }
 747
 748   return retval;
 749 }
 750
 751 void
 752 _initialize_inflow (void)
 753 {
 754   add_info ("terminal", term_info,
 755             "Print inferior's saved terminal status.");
 756
 757   add_com ("kill", class_run, kill_command,
 758            "Kill execution of program being debugged.");
 759
 760   inferior_ptid = null_ptid;
 761
 762   terminal_is_ours = 1;
 763
 764   /* OK, figure out whether we have job control.  If neither termios nor
 765      sgtty (i.e. termio or go32), leave job_control 0.  */
 766
 767 #if defined (HAVE_TERMIOS)
 768   /* Do all systems with termios have the POSIX way of identifying job
 769      control?  I hope so.  */
 770 #ifdef _POSIX_JOB_CONTROL
 771   job_control = 1;
 772 #else
 773 #ifdef _SC_JOB_CONTROL
 774   job_control = sysconf (_SC_JOB_CONTROL);
 775 #else
 776   job_control = 0;              /* have to assume the worst */
 777 #endif /* _SC_JOB_CONTROL */
 778 #endif /* _POSIX_JOB_CONTROL */
 779 #endif /* HAVE_TERMIOS */
 780
 781 #ifdef HAVE_SGTTY
 782 #ifdef TIOCGPGRP
 783   job_control = 1;
 784 #else
 785   job_control = 0;
 786 #endif /* TIOCGPGRP */
 787 #endif /* sgtty */
 788 }