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 #include "observer.h"
  30
  31 #include "gdb_string.h"
  32 #include <signal.h>
  33 #include <fcntl.h>
  34 #include "gdb_select.h"
  35
  36 #include "inflow.h"
  37
  38 #ifdef HAVE_SYS_IOCTL_H
  39 #include <sys/ioctl.h>
  40 #endif
  41
  42 #ifndef O_NOCTTY
  43 #define O_NOCTTY 0
  44 #endif
  45
  46 #if defined (SIGIO) && defined (FASYNC) && defined (FD_SET) && defined (F_SETOWN)
  47 static void handle_sigio (int);
  48 #endif
  49
  50 extern void _initialize_inflow (void);
  51
  52 static void pass_signal (int);
  53
  54 static void kill_command (char *, int);
  55
  56 static void terminal_ours_1 (int);
  57 \f
  58 /* Record terminal status separately for debugger and inferior.  */
  59
  60 static struct serial *stdin_serial;
  61
  62 /* Terminal related info we need to keep track of.  Each inferior
  63    holds an instance of this structure --- we save it whenever the
  64    corresponding inferior stops, and restore it to the foreground
  65    inferior when it resumes.  */
  66 struct terminal_info
  67 {
  68   /* The name of the tty (from the `tty' command) that we gave to the
  69      inferior when it was started.  */
  70   char *run_terminal;
  71
  72   /* TTY state.  We save it whenever the inferior stops, and restore
  73      it when it resumes.  */
  74   serial_ttystate ttystate;
  75
  76 #ifdef PROCESS_GROUP_TYPE
  77   /* Process group.  Saved and restored just like ttystate.  */
  78   PROCESS_GROUP_TYPE process_group;
  79 #endif
  80
  81   /* fcntl flags.  Saved and restored just like ttystate.  */
  82   int tflags;
  83 };
  84
  85 /* Our own tty state, which we restore every time we need to deal with
  86    the terminal.  This is only set once, when GDB first starts.  The
  87    settings of flags which readline saves and restores and
  88    unimportant.  */
  89 static struct terminal_info our_terminal_info;
  90
  91 #ifdef PROCESS_GROUP_TYPE
  92
  93 /* Return the process group of the current inferior.  */
  94
  95 PROCESS_GROUP_TYPE
  96 inferior_process_group (void)
  97 {
  98   return current_inferior ()->terminal_info->process_group;
  99 }
 100 #endif
 101
 102 /* While the inferior is running, we want SIGINT and SIGQUIT to go to the
 103    inferior only.  If we have job control, that takes care of it.  If not,
 104    we save our handlers in these two variables and set SIGINT and SIGQUIT
 105    to SIG_IGN.  */
 106
 107 static void (*sigint_ours) ();
 108 static void (*sigquit_ours) ();
 109
 110 /* The name of the tty (from the `tty' command) that we're giving to
 111    the inferior when starting it up.  This is only (and should only
 112    be) used as a transient global by new_tty_prefork,
 113    create_tty_session, new_tty and new_tty_postfork, all called from
 114    fork_inferior, while forking a new child.  */
 115 static const char *inferior_thisrun_terminal;
 116
 117 /* Nonzero if our terminal settings are in effect.  Zero if the
 118    inferior's settings are in effect.  Ignored if !gdb_has_a_terminal
 119    ().  */
 120
 121 int terminal_is_ours;
 122
 123 #ifdef PROCESS_GROUP_TYPE
 124 static PROCESS_GROUP_TYPE
 125 gdb_getpgrp (void)
 126 {
 127   int process_group = -1;
 128 #ifdef HAVE_TERMIOS
 129   process_group = tcgetpgrp (0);
 130 #endif
 131 #ifdef HAVE_TERMIO
 132   process_group = getpgrp ();
 133 #endif
 134 #ifdef HAVE_SGTTY
 135   ioctl (0, TIOCGPGRP, &process_group);
 136 #endif
 137   return process_group;
 138 }
 139 #endif
 140
 141 enum
 142   {
 143     yes, no, have_not_checked
 144   }
 145 gdb_has_a_terminal_flag = have_not_checked;
 146
 147 /* Does GDB have a terminal (on stdin)?  */
 148 int
 149 gdb_has_a_terminal (void)
 150 {
 151   switch (gdb_has_a_terminal_flag)
 152     {
 153     case yes:
 154       return 1;
 155     case no:
 156       return 0;
 157     case have_not_checked:
 158       /* Get all the current tty settings (including whether we have a
 159          tty at all!).  Can't do this in _initialize_inflow because
 160          serial_fdopen() won't work until the serial_ops_list is
 161          initialized.  */
 162
 163 #ifdef F_GETFL
 164       our_terminal_info.tflags = fcntl (0, F_GETFL, 0);
 165 #endif
 166
 167       gdb_has_a_terminal_flag = no;
 168       if (stdin_serial != NULL)
 169         {
 170           our_terminal_info.ttystate = serial_get_tty_state (stdin_serial);
 171
 172           if (our_terminal_info.ttystate != NULL)
 173             {
 174               gdb_has_a_terminal_flag = yes;
 175 #ifdef PROCESS_GROUP_TYPE
 176               our_terminal_info.process_group = gdb_getpgrp ();
 177 #endif
 178             }
 179         }
 180
 181       return gdb_has_a_terminal_flag == yes;
 182     default:
 183       /* "Can't happen".  */
 184       return 0;
 185     }
 186 }
 187
 188 /* Macro for printing errors from ioctl operations */
 189
 190 #define OOPSY(what)     \
 191   if (result == -1)     \
 192     fprintf_unfiltered(gdb_stderr, "[%s failed in terminal_inferior: %s]\n", \
 193             what, safe_strerror (errno))
 194
 195 static void terminal_ours_1 (int);
 196
 197 /* Initialize the terminal settings we record for the inferior,
 198    before we actually run the inferior.  */
 199
 200 void
 201 terminal_init_inferior_with_pgrp (int pgrp)
 202 {
 203   if (gdb_has_a_terminal ())
 204     {
 205       struct inferior *inf = current_inferior ();
 206
 207       /* We could just as well copy our_ttystate (if we felt like
 208          adding a new function serial_copy_tty_state()).  */
 209       xfree (inf->terminal_info->ttystate);
 210       inf->terminal_info->ttystate
 211         = serial_get_tty_state (stdin_serial);
 212
 213 #ifdef PROCESS_GROUP_TYPE
 214       inf->terminal_info->process_group = pgrp;
 215 #endif
 216
 217       /* Make sure that next time we call terminal_inferior (which will be
 218          before the program runs, as it needs to be), we install the new
 219          process group.  */
 220       terminal_is_ours = 1;
 221     }
 222 }
 223
 224 /* Save the terminal settings again.  This is necessary for the TUI
 225    when it switches to TUI or non-TUI mode;  curses changes the terminal
 226    and gdb must be able to restore it correctly.  */
 227
 228 void
 229 terminal_save_ours (void)
 230 {
 231   if (gdb_has_a_terminal ())
 232     {
 233       /* We could just as well copy our_ttystate (if we felt like adding
 234          a new function serial_copy_tty_state).  */
 235       xfree (our_terminal_info.ttystate);
 236       our_terminal_info.ttystate = serial_get_tty_state (stdin_serial);
 237     }
 238 }
 239
 240 void
 241 terminal_init_inferior (void)
 242 {
 243 #ifdef PROCESS_GROUP_TYPE
 244   /* This is for Lynx, and should be cleaned up by having Lynx be a separate
 245      debugging target with a version of target_terminal_init_inferior which
 246      passes in the process group to a generic routine which does all the work
 247      (and the non-threaded child_terminal_init_inferior can just pass in
 248      inferior_ptid to the same routine).  */
 249   /* We assume INFERIOR_PID is also the child's process group.  */
 250   terminal_init_inferior_with_pgrp (PIDGET (inferior_ptid));
 251 #endif /* PROCESS_GROUP_TYPE */
 252 }
 253
 254 /* Put the inferior's terminal settings into effect.
 255    This is preparation for starting or resuming the inferior.  */
 256
 257 void
 258 terminal_inferior (void)
 259 {
 260   struct inferior *inf;
 261
 262   if (!terminal_is_ours)
 263     return;
 264
 265   inf = current_inferior ();
 266
 267   if (gdb_has_a_terminal ()
 268       && inf->terminal_info->ttystate != NULL
 269       && inf->terminal_info->run_terminal == NULL)
 270     {
 271       int result;
 272
 273 #ifdef F_GETFL
 274       /* Is there a reason this is being done twice?  It happens both
 275          places we use F_SETFL, so I'm inclined to think perhaps there
 276          is some reason, however perverse.  Perhaps not though...  */
 277       result = fcntl (0, F_SETFL, inf->terminal_info->tflags);
 278       result = fcntl (0, F_SETFL, inf->terminal_info->tflags);
 279       OOPSY ("fcntl F_SETFL");
 280 #endif
 281
 282       /* Because we were careful to not change in or out of raw mode in
 283          terminal_ours, we will not change in our out of raw mode with
 284          this call, so we don't flush any input.  */
 285       result = serial_set_tty_state (stdin_serial,
 286                                      inf->terminal_info->ttystate);
 287       OOPSY ("setting tty state");
 288
 289       if (!job_control)
 290         {
 291           sigint_ours = (void (*)()) signal (SIGINT, SIG_IGN);
 292 #ifdef SIGQUIT
 293           sigquit_ours = (void (*)()) signal (SIGQUIT, SIG_IGN);
 294 #endif
 295         }
 296
 297       /* If attach_flag is set, we don't know whether we are sharing a
 298          terminal with the inferior or not.  (attaching a process
 299          without a terminal is one case where we do not; attaching a
 300          process which we ran from the same shell as GDB via `&' is
 301          one case where we do, I think (but perhaps this is not
 302          `sharing' in the sense that we need to save and restore tty
 303          state)).  I don't know if there is any way to tell whether we
 304          are sharing a terminal.  So what we do is to go through all
 305          the saving and restoring of the tty state, but ignore errors
 306          setting the process group, which will happen if we are not
 307          sharing a terminal).  */
 308
 309       if (job_control)
 310         {
 311 #ifdef HAVE_TERMIOS
 312           result = tcsetpgrp (0, inf->terminal_info->process_group);
 313           if (!inf->attach_flag)
 314             OOPSY ("tcsetpgrp");
 315 #endif
 316
 317 #ifdef HAVE_SGTTY
 318           result = ioctl (0, TIOCSPGRP, &inf->terminal_info->process_group);
 319           if (!inf->attach_flag)
 320             OOPSY ("TIOCSPGRP");
 321 #endif
 322         }
 323
 324     }
 325   terminal_is_ours = 0;
 326 }
 327
 328 /* Put some of our terminal settings into effect,
 329    enough to get proper results from our output,
 330    but do not change into or out of RAW mode
 331    so that no input is discarded.
 332
 333    After doing this, either terminal_ours or terminal_inferior
 334    should be called to get back to a normal state of affairs.  */
 335
 336 void
 337 terminal_ours_for_output (void)
 338 {
 339   terminal_ours_1 (1);
 340 }
 341
 342 /* Put our terminal settings into effect.
 343    First record the inferior's terminal settings
 344    so they can be restored properly later.  */
 345
 346 void
 347 terminal_ours (void)
 348 {
 349   terminal_ours_1 (0);
 350 }
 351
 352 /* output_only is not used, and should not be used unless we introduce
 353    separate terminal_is_ours and terminal_is_ours_for_output
 354    flags.  */
 355
 356 static void
 357 terminal_ours_1 (int output_only)
 358 {
 359   struct inferior *inf;
 360
 361   if (terminal_is_ours)
 362     return;
 363
 364   terminal_is_ours = 1;
 365
 366   /* Checking inferior->run_terminal is necessary so that
 367      if GDB is running in the background, it won't block trying
 368      to do the ioctl()'s below.  Checking gdb_has_a_terminal
 369      avoids attempting all the ioctl's when running in batch.  */
 370
 371   inf = current_inferior ();
 372
 373   if (inf->terminal_info->run_terminal != NULL || gdb_has_a_terminal () == 0)
 374     return;
 375
 376     {
 377 #ifdef SIGTTOU
 378       /* Ignore this signal since it will happen when we try to set the
 379          pgrp.  */
 380       void (*osigttou) () = NULL;
 381 #endif
 382       int result;
 383
 384 #ifdef SIGTTOU
 385       if (job_control)
 386         osigttou = (void (*)()) signal (SIGTTOU, SIG_IGN);
 387 #endif
 388
 389       xfree (inf->terminal_info->ttystate);
 390       inf->terminal_info->ttystate = serial_get_tty_state (stdin_serial);
 391
 392 #ifdef PROCESS_GROUP_TYPE
 393       if (!inf->attach_flag)
 394         /* If setpgrp failed in terminal_inferior, this would give us
 395            our process group instead of the inferior's.  See
 396            terminal_inferior for details.  */
 397         inf->terminal_info->process_group = gdb_getpgrp ();
 398 #endif
 399
 400       /* Here we used to set ICANON in our ttystate, but I believe this
 401          was an artifact from before when we used readline.  Readline sets
 402          the tty state when it needs to.
 403          FIXME-maybe: However, query() expects non-raw mode and doesn't
 404          use readline.  Maybe query should use readline (on the other hand,
 405          this only matters for HAVE_SGTTY, not termio or termios, I think).  */
 406
 407       /* Set tty state to our_ttystate.  We don't change in our out of raw
 408          mode, to avoid flushing input.  We need to do the same thing
 409          regardless of output_only, because we don't have separate
 410          terminal_is_ours and terminal_is_ours_for_output flags.  It's OK,
 411          though, since readline will deal with raw mode when/if it needs to.
 412        */
 413
 414       serial_noflush_set_tty_state (stdin_serial, our_terminal_info.ttystate,
 415                                     inf->terminal_info->ttystate);
 416
 417       if (job_control)
 418         {
 419 #ifdef HAVE_TERMIOS
 420           result = tcsetpgrp (0, our_terminal_info.process_group);
 421 #if 0
 422           /* This fails on Ultrix with EINVAL if you run the testsuite
 423              in the background with nohup, and then log out.  GDB never
 424              used to check for an error here, so perhaps there are other
 425              such situations as well.  */
 426           if (result == -1)
 427             fprintf_unfiltered (gdb_stderr, "[tcsetpgrp failed in terminal_ours: %s]\n",
 428                                 safe_strerror (errno));
 429 #endif
 430 #endif /* termios */
 431
 432 #ifdef HAVE_SGTTY
 433           result = ioctl (0, TIOCSPGRP, &our_terminal_info.process_group);
 434 #endif
 435         }
 436
 437 #ifdef SIGTTOU
 438       if (job_control)
 439         signal (SIGTTOU, osigttou);
 440 #endif
 441
 442       if (!job_control)
 443         {
 444           signal (SIGINT, sigint_ours);
 445 #ifdef SIGQUIT
 446           signal (SIGQUIT, sigquit_ours);
 447 #endif
 448         }
 449
 450 #ifdef F_GETFL
 451       inf->terminal_info->tflags = fcntl (0, F_GETFL, 0);
 452
 453       /* Is there a reason this is being done twice?  It happens both
 454          places we use F_SETFL, so I'm inclined to think perhaps there
 455          is some reason, however perverse.  Perhaps not though...  */
 456       result = fcntl (0, F_SETFL, our_terminal_info.tflags);
 457       result = fcntl (0, F_SETFL, our_terminal_info.tflags);
 458 #endif
 459     }
 460 }
 461
 462 /* This is a "new_inferior" observer.  It's business is to allocate
 463    the TERMINAL_INFO member of the inferior structure.  This field is
 464    private to inflow.c, and its type is opaque to the rest of GDB.
 465    PID is the target pid of the inferior that has just been added to
 466    the inferior list.  */
 467
 468 static void
 469 inflow_new_inferior (int pid)
 470 {
 471   struct inferior *inf = find_inferior_pid (pid);
 472
 473   inf->terminal_info = XZALLOC (struct terminal_info);
 474 }
 475
 476 /* This is a "inferior_exit" observer.  Releases the TERMINAL_INFO member
 477    of the inferior structure.  This field is private to inflow.c, and
 478    its type is opaque to the rest of GDB.  PID is the target pid of
 479    the inferior that is about to be removed from the inferior
 480    list.  */
 481
 482 static void
 483 inflow_inferior_exit (int pid)
 484 {
 485   struct inferior *inf = find_inferior_pid (pid);
 486
 487   xfree (inf->terminal_info->run_terminal);
 488   xfree (inf->terminal_info);
 489   inf->terminal_info = NULL;
 490 }
 491
 492 void
 493 copy_terminal_info (struct inferior *to, struct inferior *from)
 494 {
 495   *to->terminal_info = *from->terminal_info;
 496   if (from->terminal_info->run_terminal)
 497     to->terminal_info->run_terminal = from->terminal_info->run_terminal;
 498 }
 499
 500 void
 501 term_info (char *arg, int from_tty)
 502 {
 503   target_terminal_info (arg, from_tty);
 504 }
 505
 506 void
 507 child_terminal_info (char *args, int from_tty)
 508 {
 509   struct inferior *inf;
 510
 511   if (!gdb_has_a_terminal ())
 512     {
 513       printf_filtered (_("This GDB does not control a terminal.\n"));
 514       return;
 515     }
 516
 517   if (ptid_equal (inferior_ptid, null_ptid))
 518     return;
 519
 520   inf = current_inferior ();
 521
 522   printf_filtered (_("Inferior's terminal status (currently saved by GDB):\n"));
 523
 524   /* First the fcntl flags.  */
 525   {
 526     int flags;
 527
 528     flags = inf->terminal_info->tflags;
 529
 530     printf_filtered ("File descriptor flags = ");
 531
 532 #ifndef O_ACCMODE
 533 #define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
 534 #endif
 535     /* (O_ACCMODE) parens are to avoid Ultrix header file bug */
 536     switch (flags & (O_ACCMODE))
 537       {
 538       case O_RDONLY:
 539         printf_filtered ("O_RDONLY");
 540         break;
 541       case O_WRONLY:
 542         printf_filtered ("O_WRONLY");
 543         break;
 544       case O_RDWR:
 545         printf_filtered ("O_RDWR");
 546         break;
 547       }
 548     flags &= ~(O_ACCMODE);
 549
 550 #ifdef O_NONBLOCK
 551     if (flags & O_NONBLOCK)
 552       printf_filtered (" | O_NONBLOCK");
 553     flags &= ~O_NONBLOCK;
 554 #endif
 555
 556 #if defined (O_NDELAY)
 557     /* If O_NDELAY and O_NONBLOCK are defined to the same thing, we will
 558        print it as O_NONBLOCK, which is good cause that is what POSIX
 559        has, and the flag will already be cleared by the time we get here.  */
 560     if (flags & O_NDELAY)
 561       printf_filtered (" | O_NDELAY");
 562     flags &= ~O_NDELAY;
 563 #endif
 564
 565     if (flags & O_APPEND)
 566       printf_filtered (" | O_APPEND");
 567     flags &= ~O_APPEND;
 568
 569 #if defined (O_BINARY)
 570     if (flags & O_BINARY)
 571       printf_filtered (" | O_BINARY");
 572     flags &= ~O_BINARY;
 573 #endif
 574
 575     if (flags)
 576       printf_filtered (" | 0x%x", flags);
 577     printf_filtered ("\n");
 578   }
 579
 580 #ifdef PROCESS_GROUP_TYPE
 581   printf_filtered ("Process group = %d\n",
 582                    (int) inf->terminal_info->process_group);
 583 #endif
 584
 585   serial_print_tty_state (stdin_serial,
 586                           inf->terminal_info->ttystate,
 587                           gdb_stdout);
 588 }
 589 \f
 590 /* NEW_TTY_PREFORK is called before forking a new child process,
 591    so we can record the state of ttys in the child to be formed.
 592    TTYNAME is null if we are to share the terminal with gdb;
 593    or points to a string containing the name of the desired tty.
 594
 595    NEW_TTY is called in new child processes under Unix, which will
 596    become debugger target processes.  This actually switches to
 597    the terminal specified in the NEW_TTY_PREFORK call.  */
 598
 599 void
 600 new_tty_prefork (const char *ttyname)
 601 {
 602   /* Save the name for later, for determining whether we and the child
 603      are sharing a tty.  */
 604   inferior_thisrun_terminal = ttyname;
 605 }
 606
 607
 608 /* If RESULT, assumed to be the return value from a system call, is
 609    negative, print the error message indicated by errno and exit.
 610    MSG should identify the operation that failed.  */
 611 static void
 612 check_syscall (const char *msg, int result)
 613 {
 614   if (result < 0)
 615     {
 616       print_sys_errmsg (msg, errno);
 617       _exit (1);
 618     }
 619 }
 620
 621 void
 622 new_tty (void)
 623 {
 624   int tty;
 625
 626   if (inferior_thisrun_terminal == 0)
 627     return;
 628 #if !defined(__GO32__) && !defined(_WIN32)
 629 #ifdef TIOCNOTTY
 630   /* Disconnect the child process from our controlling terminal.  On some
 631      systems (SVR4 for example), this may cause a SIGTTOU, so temporarily
 632      ignore SIGTTOU. */
 633   tty = open ("/dev/tty", O_RDWR);
 634   if (tty > 0)
 635     {
 636       void (*osigttou) ();
 637
 638       osigttou = (void (*)()) signal (SIGTTOU, SIG_IGN);
 639       ioctl (tty, TIOCNOTTY, 0);
 640       close (tty);
 641       signal (SIGTTOU, osigttou);
 642     }
 643 #endif
 644
 645   /* Now open the specified new terminal.  */
 646   tty = open (inferior_thisrun_terminal, O_RDWR | O_NOCTTY);
 647   check_syscall (inferior_thisrun_terminal, tty);
 648
 649   /* Avoid use of dup2; doesn't exist on all systems.  */
 650   if (tty != 0)
 651     {
 652       close (0);
 653       check_syscall ("dup'ing tty into fd 0", dup (tty));
 654     }
 655   if (tty != 1)
 656     {
 657       close (1);
 658       check_syscall ("dup'ing tty into fd 1", dup (tty));
 659     }
 660   if (tty != 2)
 661     {
 662       close (2);
 663       check_syscall ("dup'ing tty into fd 2", dup (tty));
 664     }
 665
 666 #ifdef TIOCSCTTY
 667   /* Make tty our new controlling terminal.  */
 668   if (ioctl (tty, TIOCSCTTY, 0) == -1)
 669     /* Mention GDB in warning because it will appear in the inferior's
 670        terminal instead of GDB's.  */
 671     warning ("GDB: Failed to set controlling terminal: %s",
 672              safe_strerror (errno));
 673 #endif
 674
 675   if (tty > 2)
 676     close (tty);
 677 #endif /* !go32 && !win32 */
 678 }
 679
 680 /* NEW_TTY_POSTFORK is called after forking a new child process, and
 681    adding it to the inferior table, to store the TTYNAME being used by
 682    the child, or null if it sharing the terminal with gdb.  */
 683
 684 void
 685 new_tty_postfork (void)
 686 {
 687   /* Save the name for later, for determining whether we and the child
 688      are sharing a tty.  */
 689
 690   if (inferior_thisrun_terminal)
 691     current_inferior ()->terminal_info->run_terminal
 692       = xstrdup (inferior_thisrun_terminal);
 693
 694   inferior_thisrun_terminal = NULL;
 695 }
 696
 697 \f
 698 /* Call set_sigint_trap when you need to pass a signal on to an attached
 699    process when handling SIGINT */
 700
 701 static void
 702 pass_signal (int signo)
 703 {
 704 #ifndef _WIN32
 705   kill (PIDGET (inferior_ptid), SIGINT);
 706 #endif
 707 }
 708
 709 static void (*osig) ();
 710 static int osig_set;
 711
 712 void
 713 set_sigint_trap (void)
 714 {
 715   struct inferior *inf = current_inferior ();
 716   if (inf->attach_flag || inf->terminal_info->run_terminal)
 717     {
 718       osig = (void (*)()) signal (SIGINT, pass_signal);
 719       osig_set = 1;
 720     }
 721   else
 722     osig_set = 0;
 723 }
 724
 725 void
 726 clear_sigint_trap (void)
 727 {
 728   if (osig_set)
 729     {
 730       signal (SIGINT, osig);
 731       osig_set = 0;
 732     }
 733 }
 734 \f
 735
 736 /* Create a new session if the inferior will run in a different tty.
 737    A session is UNIX's way of grouping processes that share a controlling
 738    terminal, so a new one is needed if the inferior terminal will be
 739    different from GDB's.
 740
 741    Returns the session id of the new session, 0 if no session was created
 742    or -1 if an error occurred.  */
 743 pid_t
 744 create_tty_session (void)
 745 {
 746 #ifdef HAVE_SETSID
 747   pid_t ret;
 748
 749   if (!job_control || inferior_thisrun_terminal == 0)
 750     return 0;
 751
 752   ret = setsid ();
 753   if (ret == -1)
 754     warning ("Failed to create new terminal session: setsid: %s",
 755              safe_strerror (errno));
 756
 757   return ret;
 758 #else
 759   return 0;
 760 #endif /* HAVE_SETSID */
 761 }
 762
 763 /* This is here because this is where we figure out whether we (probably)
 764    have job control.  Just using job_control only does part of it because
 765    setpgid or setpgrp might not exist on a system without job control.
 766    It might be considered misplaced (on the other hand, process groups and
 767    job control are closely related to ttys).
 768
 769    For a more clean implementation, in libiberty, put a setpgid which merely
 770    calls setpgrp and a setpgrp which does nothing (any system with job control
 771    will have one or the other).  */
 772 int
 773 gdb_setpgid (void)
 774 {
 775   int retval = 0;
 776
 777   if (job_control)
 778     {
 779 #if defined (HAVE_TERMIOS) || defined (TIOCGPGRP)
 780 #ifdef HAVE_SETPGID
 781       /* The call setpgid (0, 0) is supposed to work and mean the same
 782          thing as this, but on Ultrix 4.2A it fails with EPERM (and
 783          setpgid (getpid (), getpid ()) succeeds).  */
 784       retval = setpgid (getpid (), getpid ());
 785 #else
 786 #ifdef HAVE_SETPGRP
 787 #ifdef SETPGRP_VOID
 788       retval = setpgrp ();
 789 #else
 790       retval = setpgrp (getpid (), getpid ());
 791 #endif
 792 #endif /* HAVE_SETPGRP */
 793 #endif /* HAVE_SETPGID */
 794 #endif /* defined (HAVE_TERMIOS) || defined (TIOCGPGRP) */
 795     }
 796
 797   return retval;
 798 }
 799
 800 /* Get all the current tty settings (including whether we have a
 801    tty at all!).  We can't do this in _initialize_inflow because
 802    serial_fdopen() won't work until the serial_ops_list is
 803    initialized, but we don't want to do it lazily either, so
 804    that we can guarantee stdin_serial is opened if there is
 805    a terminal.  */
 806 void
 807 initialize_stdin_serial (void)
 808 {
 809   stdin_serial = serial_fdopen (0);
 810 }
 811
 812 void
 813 _initialize_inflow (void)
 814 {
 815   add_info ("terminal", term_info,
 816             _("Print inferior's saved terminal status."));
 817
 818   terminal_is_ours = 1;
 819
 820   /* OK, figure out whether we have job control.  If neither termios nor
 821      sgtty (i.e. termio or go32), leave job_control 0.  */
 822
 823 #if defined (HAVE_TERMIOS)
 824   /* Do all systems with termios have the POSIX way of identifying job
 825      control?  I hope so.  */
 826 #ifdef _POSIX_JOB_CONTROL
 827   job_control = 1;
 828 #else
 829 #ifdef _SC_JOB_CONTROL
 830   job_control = sysconf (_SC_JOB_CONTROL);
 831 #else
 832   job_control = 0;              /* have to assume the worst */
 833 #endif /* _SC_JOB_CONTROL */
 834 #endif /* _POSIX_JOB_CONTROL */
 835 #endif /* HAVE_TERMIOS */
 836
 837 #ifdef HAVE_SGTTY
 838 #ifdef TIOCGPGRP
 839   job_control = 1;
 840 #else
 841   job_control = 0;
 842 #endif /* TIOCGPGRP */
 843 #endif /* sgtty */
 844
 845   observer_attach_new_inferior (inflow_new_inferior);
 846   observer_attach_inferior_exit (inflow_inferior_exit);
 847 }