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, 2010 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 extern void _initialize_inflow (void);
  47
  48 static void pass_signal (int);
  49
  50 static void terminal_ours_1 (int);
  51 \f
  52 /* Record terminal status separately for debugger and inferior.  */
  53
  54 static struct serial *stdin_serial;
  55
  56 /* Terminal related info we need to keep track of.  Each inferior
  57    holds an instance of this structure --- we save it whenever the
  58    corresponding inferior stops, and restore it to the foreground
  59    inferior when it resumes.  */
  60 struct terminal_info
  61 {
  62   /* The name of the tty (from the `tty' command) that we gave to the
  63      inferior when it was started.  */
  64   char *run_terminal;
  65
  66   /* TTY state.  We save it whenever the inferior stops, and restore
  67      it when it resumes.  */
  68   serial_ttystate ttystate;
  69
  70 #ifdef PROCESS_GROUP_TYPE
  71   /* Process group.  Saved and restored just like ttystate.  */
  72   PROCESS_GROUP_TYPE process_group;
  73 #endif
  74
  75   /* fcntl flags.  Saved and restored just like ttystate.  */
  76   int tflags;
  77 };
  78
  79 /* Our own tty state, which we restore every time we need to deal with
  80    the terminal.  This is only set once, when GDB first starts.  The
  81    settings of flags which readline saves and restores and
  82    unimportant.  */
  83 static struct terminal_info our_terminal_info;
  84
  85 static struct terminal_info *get_inflow_inferior_data (struct inferior *);
  86
  87 #ifdef PROCESS_GROUP_TYPE
  88
  89 /* Return the process group of the current inferior.  */
  90
  91 PROCESS_GROUP_TYPE
  92 inferior_process_group (void)
  93 {
  94   return get_inflow_inferior_data (current_inferior ())->process_group;
  95 }
  96 #endif
  97
  98 /* While the inferior is running, we want SIGINT and SIGQUIT to go to the
  99    inferior only.  If we have job control, that takes care of it.  If not,
 100    we save our handlers in these two variables and set SIGINT and SIGQUIT
 101    to SIG_IGN.  */
 102
 103 static void (*sigint_ours) ();
 104 static void (*sigquit_ours) ();
 105
 106 /* The name of the tty (from the `tty' command) that we're giving to
 107    the inferior when starting it up.  This is only (and should only
 108    be) used as a transient global by new_tty_prefork,
 109    create_tty_session, new_tty and new_tty_postfork, all called from
 110    fork_inferior, while forking a new child.  */
 111 static const char *inferior_thisrun_terminal;
 112
 113 /* Nonzero if our terminal settings are in effect.  Zero if the
 114    inferior's settings are in effect.  Ignored if !gdb_has_a_terminal
 115    ().  */
 116
 117 int terminal_is_ours;
 118
 119 #ifdef PROCESS_GROUP_TYPE
 120 static PROCESS_GROUP_TYPE
 121 gdb_getpgrp (void)
 122 {
 123   int process_group = -1;
 124 #ifdef HAVE_TERMIOS
 125   process_group = tcgetpgrp (0);
 126 #endif
 127 #ifdef HAVE_TERMIO
 128   process_group = getpgrp ();
 129 #endif
 130 #ifdef HAVE_SGTTY
 131   ioctl (0, TIOCGPGRP, &process_group);
 132 #endif
 133   return process_group;
 134 }
 135 #endif
 136
 137 enum
 138   {
 139     yes, no, have_not_checked
 140   }
 141 gdb_has_a_terminal_flag = have_not_checked;
 142
 143 /* Does GDB have a terminal (on stdin)?  */
 144 int
 145 gdb_has_a_terminal (void)
 146 {
 147   switch (gdb_has_a_terminal_flag)
 148     {
 149     case yes:
 150       return 1;
 151     case no:
 152       return 0;
 153     case have_not_checked:
 154       /* Get all the current tty settings (including whether we have a
 155          tty at all!).  Can't do this in _initialize_inflow because
 156          serial_fdopen() won't work until the serial_ops_list is
 157          initialized.  */
 158
 159 #ifdef F_GETFL
 160       our_terminal_info.tflags = fcntl (0, F_GETFL, 0);
 161 #endif
 162
 163       gdb_has_a_terminal_flag = no;
 164       if (stdin_serial != NULL)
 165         {
 166           our_terminal_info.ttystate = serial_get_tty_state (stdin_serial);
 167
 168           if (our_terminal_info.ttystate != NULL)
 169             {
 170               gdb_has_a_terminal_flag = yes;
 171 #ifdef PROCESS_GROUP_TYPE
 172               our_terminal_info.process_group = gdb_getpgrp ();
 173 #endif
 174             }
 175         }
 176
 177       return gdb_has_a_terminal_flag == yes;
 178     default:
 179       /* "Can't happen".  */
 180       return 0;
 181     }
 182 }
 183
 184 /* Macro for printing errors from ioctl operations */
 185
 186 #define OOPSY(what)     \
 187   if (result == -1)     \
 188     fprintf_unfiltered(gdb_stderr, "[%s failed in terminal_inferior: %s]\n", \
 189             what, safe_strerror (errno))
 190
 191 static void terminal_ours_1 (int);
 192
 193 /* Initialize the terminal settings we record for the inferior,
 194    before we actually run the inferior.  */
 195
 196 void
 197 terminal_init_inferior_with_pgrp (int pgrp)
 198 {
 199   if (gdb_has_a_terminal ())
 200     {
 201       struct inferior *inf = current_inferior ();
 202       struct terminal_info *tinfo = get_inflow_inferior_data (inf);
 203
 204       /* We could just as well copy our_ttystate (if we felt like
 205          adding a new function serial_copy_tty_state()).  */
 206       xfree (tinfo->ttystate);
 207       tinfo->ttystate = serial_get_tty_state (stdin_serial);
 208
 209 #ifdef PROCESS_GROUP_TYPE
 210       tinfo->process_group = pgrp;
 211 #endif
 212
 213       /* Make sure that next time we call terminal_inferior (which will be
 214          before the program runs, as it needs to be), we install the new
 215          process group.  */
 216       terminal_is_ours = 1;
 217     }
 218 }
 219
 220 /* Save the terminal settings again.  This is necessary for the TUI
 221    when it switches to TUI or non-TUI mode;  curses changes the terminal
 222    and gdb must be able to restore it correctly.  */
 223
 224 void
 225 terminal_save_ours (void)
 226 {
 227   if (gdb_has_a_terminal ())
 228     {
 229       /* We could just as well copy our_ttystate (if we felt like adding
 230          a new function serial_copy_tty_state).  */
 231       xfree (our_terminal_info.ttystate);
 232       our_terminal_info.ttystate = serial_get_tty_state (stdin_serial);
 233     }
 234 }
 235
 236 void
 237 terminal_init_inferior (void)
 238 {
 239 #ifdef PROCESS_GROUP_TYPE
 240   /* This is for Lynx, and should be cleaned up by having Lynx be a separate
 241      debugging target with a version of target_terminal_init_inferior which
 242      passes in the process group to a generic routine which does all the work
 243      (and the non-threaded child_terminal_init_inferior can just pass in
 244      inferior_ptid to the same routine).  */
 245   /* We assume INFERIOR_PID is also the child's process group.  */
 246   terminal_init_inferior_with_pgrp (PIDGET (inferior_ptid));
 247 #endif /* PROCESS_GROUP_TYPE */
 248 }
 249
 250 /* Put the inferior's terminal settings into effect.
 251    This is preparation for starting or resuming the inferior.  */
 252
 253 void
 254 terminal_inferior (void)
 255 {
 256   struct inferior *inf;
 257   struct terminal_info *tinfo;
 258
 259   if (!terminal_is_ours)
 260     return;
 261
 262   inf = current_inferior ();
 263   tinfo = get_inflow_inferior_data (inf);
 264
 265   if (gdb_has_a_terminal ()
 266       && tinfo->ttystate != NULL
 267       && tinfo->run_terminal == NULL)
 268     {
 269       int result;
 270
 271 #ifdef F_GETFL
 272       /* Is there a reason this is being done twice?  It happens both
 273          places we use F_SETFL, so I'm inclined to think perhaps there
 274          is some reason, however perverse.  Perhaps not though...  */
 275       result = fcntl (0, F_SETFL, tinfo->tflags);
 276       result = fcntl (0, F_SETFL, tinfo->tflags);
 277       OOPSY ("fcntl F_SETFL");
 278 #endif
 279
 280       /* Because we were careful to not change in or out of raw mode in
 281          terminal_ours, we will not change in our out of raw mode with
 282          this call, so we don't flush any input.  */
 283       result = serial_set_tty_state (stdin_serial,
 284                                      tinfo->ttystate);
 285       OOPSY ("setting tty state");
 286
 287       if (!job_control)
 288         {
 289           sigint_ours = (void (*)()) signal (SIGINT, SIG_IGN);
 290 #ifdef SIGQUIT
 291           sigquit_ours = (void (*)()) signal (SIGQUIT, SIG_IGN);
 292 #endif
 293         }
 294
 295       /* If attach_flag is set, we don't know whether we are sharing a
 296          terminal with the inferior or not.  (attaching a process
 297          without a terminal is one case where we do not; attaching a
 298          process which we ran from the same shell as GDB via `&' is
 299          one case where we do, I think (but perhaps this is not
 300          `sharing' in the sense that we need to save and restore tty
 301          state)).  I don't know if there is any way to tell whether we
 302          are sharing a terminal.  So what we do is to go through all
 303          the saving and restoring of the tty state, but ignore errors
 304          setting the process group, which will happen if we are not
 305          sharing a terminal).  */
 306
 307       if (job_control)
 308         {
 309 #ifdef HAVE_TERMIOS
 310           result = tcsetpgrp (0, tinfo->process_group);
 311           if (!inf->attach_flag)
 312             OOPSY ("tcsetpgrp");
 313 #endif
 314
 315 #ifdef HAVE_SGTTY
 316           result = ioctl (0, TIOCSPGRP, &tinfo->process_group);
 317           if (!inf->attach_flag)
 318             OOPSY ("TIOCSPGRP");
 319 #endif
 320         }
 321
 322     }
 323   terminal_is_ours = 0;
 324 }
 325
 326 /* Put some of our terminal settings into effect,
 327    enough to get proper results from our output,
 328    but do not change into or out of RAW mode
 329    so that no input is discarded.
 330
 331    After doing this, either terminal_ours or terminal_inferior
 332    should be called to get back to a normal state of affairs.  */
 333
 334 void
 335 terminal_ours_for_output (void)
 336 {
 337   terminal_ours_1 (1);
 338 }
 339
 340 /* Put our terminal settings into effect.
 341    First record the inferior's terminal settings
 342    so they can be restored properly later.  */
 343
 344 void
 345 terminal_ours (void)
 346 {
 347   terminal_ours_1 (0);
 348 }
 349
 350 /* output_only is not used, and should not be used unless we introduce
 351    separate terminal_is_ours and terminal_is_ours_for_output
 352    flags.  */
 353
 354 static void
 355 terminal_ours_1 (int output_only)
 356 {
 357   struct inferior *inf;
 358   struct terminal_info *tinfo;
 359
 360   if (terminal_is_ours)
 361     return;
 362
 363   terminal_is_ours = 1;
 364
 365   /* Checking inferior->run_terminal is necessary so that
 366      if GDB is running in the background, it won't block trying
 367      to do the ioctl()'s below.  Checking gdb_has_a_terminal
 368      avoids attempting all the ioctl's when running in batch.  */
 369
 370   inf = current_inferior ();
 371   tinfo = get_inflow_inferior_data (inf);
 372
 373   if (tinfo->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 (tinfo->ttystate);
 390       tinfo->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         tinfo->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                                     tinfo->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       tinfo->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 /* Per-inferior data key.  */
 463 static const struct inferior_data *inflow_inferior_data;
 464
 465 static void
 466 inflow_inferior_data_cleanup (struct inferior *inf, void *arg)
 467 {
 468   struct terminal_info *info;
 469
 470   info = inferior_data (inf, inflow_inferior_data);
 471   if (info != NULL)
 472     {
 473       xfree (info->run_terminal);
 474       xfree (info);
 475     }
 476 }
 477
 478 /* Get the current svr4 data.  If none is found yet, add it now.  This
 479    function always returns a valid object.  */
 480
 481 static struct terminal_info *
 482 get_inflow_inferior_data (struct inferior *inf)
 483 {
 484   struct terminal_info *info;
 485
 486   info = inferior_data (inf, inflow_inferior_data);
 487   if (info == NULL)
 488     {
 489       info = XZALLOC (struct terminal_info);
 490       set_inferior_data (inf, inflow_inferior_data, info);
 491     }
 492
 493   return info;
 494 }
 495
 496 /* This is a "inferior_exit" observer.  Releases the TERMINAL_INFO member
 497    of the inferior structure.  This field is private to inflow.c, and
 498    its type is opaque to the rest of GDB.  PID is the target pid of
 499    the inferior that is about to be removed from the inferior
 500    list.  */
 501
 502 static void
 503 inflow_inferior_exit (int pid)
 504 {
 505   struct inferior *inf = find_inferior_pid (pid);
 506   struct terminal_info *info;
 507
 508   info = inferior_data (inf, inflow_inferior_data);
 509   if (info != NULL)
 510     {
 511       xfree (info->run_terminal);
 512       xfree (info);
 513       set_inferior_data (inf, inflow_inferior_data, NULL);
 514     }
 515 }
 516
 517 void
 518 copy_terminal_info (struct inferior *to, struct inferior *from)
 519 {
 520   struct terminal_info *tinfo_to, *tinfo_from;
 521
 522   tinfo_to = get_inflow_inferior_data (to);
 523   tinfo_from = get_inflow_inferior_data (from);
 524   *tinfo_to = *tinfo_from;
 525   if (tinfo_from->run_terminal)
 526     tinfo_to->run_terminal
 527       = xstrdup (tinfo_from->run_terminal);
 528 }
 529
 530 void
 531 term_info (char *arg, int from_tty)
 532 {
 533   target_terminal_info (arg, from_tty);
 534 }
 535
 536 void
 537 child_terminal_info (char *args, int from_tty)
 538 {
 539   struct inferior *inf;
 540   struct terminal_info *tinfo;
 541
 542   if (!gdb_has_a_terminal ())
 543     {
 544       printf_filtered (_("This GDB does not control a terminal.\n"));
 545       return;
 546     }
 547
 548   if (ptid_equal (inferior_ptid, null_ptid))
 549     return;
 550
 551   inf = current_inferior ();
 552   tinfo = get_inflow_inferior_data (inf);
 553
 554   printf_filtered (_("Inferior's terminal status (currently saved by GDB):\n"));
 555
 556   /* First the fcntl flags.  */
 557   {
 558     int flags;
 559
 560     flags = tinfo->tflags;
 561
 562     printf_filtered ("File descriptor flags = ");
 563
 564 #ifndef O_ACCMODE
 565 #define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
 566 #endif
 567     /* (O_ACCMODE) parens are to avoid Ultrix header file bug */
 568     switch (flags & (O_ACCMODE))
 569       {
 570       case O_RDONLY:
 571         printf_filtered ("O_RDONLY");
 572         break;
 573       case O_WRONLY:
 574         printf_filtered ("O_WRONLY");
 575         break;
 576       case O_RDWR:
 577         printf_filtered ("O_RDWR");
 578         break;
 579       }
 580     flags &= ~(O_ACCMODE);
 581
 582 #ifdef O_NONBLOCK
 583     if (flags & O_NONBLOCK)
 584       printf_filtered (" | O_NONBLOCK");
 585     flags &= ~O_NONBLOCK;
 586 #endif
 587
 588 #if defined (O_NDELAY)
 589     /* If O_NDELAY and O_NONBLOCK are defined to the same thing, we will
 590        print it as O_NONBLOCK, which is good cause that is what POSIX
 591        has, and the flag will already be cleared by the time we get here.  */
 592     if (flags & O_NDELAY)
 593       printf_filtered (" | O_NDELAY");
 594     flags &= ~O_NDELAY;
 595 #endif
 596
 597     if (flags & O_APPEND)
 598       printf_filtered (" | O_APPEND");
 599     flags &= ~O_APPEND;
 600
 601 #if defined (O_BINARY)
 602     if (flags & O_BINARY)
 603       printf_filtered (" | O_BINARY");
 604     flags &= ~O_BINARY;
 605 #endif
 606
 607     if (flags)
 608       printf_filtered (" | 0x%x", flags);
 609     printf_filtered ("\n");
 610   }
 611
 612 #ifdef PROCESS_GROUP_TYPE
 613   printf_filtered ("Process group = %d\n", (int) tinfo->process_group);
 614 #endif
 615
 616   serial_print_tty_state (stdin_serial, tinfo->ttystate, gdb_stdout);
 617 }
 618 \f
 619 /* NEW_TTY_PREFORK is called before forking a new child process,
 620    so we can record the state of ttys in the child to be formed.
 621    TTYNAME is null if we are to share the terminal with gdb;
 622    or points to a string containing the name of the desired tty.
 623
 624    NEW_TTY is called in new child processes under Unix, which will
 625    become debugger target processes.  This actually switches to
 626    the terminal specified in the NEW_TTY_PREFORK call.  */
 627
 628 void
 629 new_tty_prefork (const char *ttyname)
 630 {
 631   /* Save the name for later, for determining whether we and the child
 632      are sharing a tty.  */
 633   inferior_thisrun_terminal = ttyname;
 634 }
 635
 636 #if !defined(__GO32__) && !defined(_WIN32)
 637 /* If RESULT, assumed to be the return value from a system call, is
 638    negative, print the error message indicated by errno and exit.
 639    MSG should identify the operation that failed.  */
 640 static void
 641 check_syscall (const char *msg, int result)
 642 {
 643   if (result < 0)
 644     {
 645       print_sys_errmsg (msg, errno);
 646       _exit (1);
 647     }
 648 }
 649 #endif
 650
 651 void
 652 new_tty (void)
 653 {
 654   int tty;
 655
 656   if (inferior_thisrun_terminal == 0)
 657     return;
 658 #if !defined(__GO32__) && !defined(_WIN32)
 659 #ifdef TIOCNOTTY
 660   /* Disconnect the child process from our controlling terminal.  On some
 661      systems (SVR4 for example), this may cause a SIGTTOU, so temporarily
 662      ignore SIGTTOU. */
 663   tty = open ("/dev/tty", O_RDWR);
 664   if (tty > 0)
 665     {
 666       void (*osigttou) ();
 667
 668       osigttou = (void (*)()) signal (SIGTTOU, SIG_IGN);
 669       ioctl (tty, TIOCNOTTY, 0);
 670       close (tty);
 671       signal (SIGTTOU, osigttou);
 672     }
 673 #endif
 674
 675   /* Now open the specified new terminal.  */
 676   tty = open (inferior_thisrun_terminal, O_RDWR | O_NOCTTY);
 677   check_syscall (inferior_thisrun_terminal, tty);
 678
 679   /* Avoid use of dup2; doesn't exist on all systems.  */
 680   if (tty != 0)
 681     {
 682       close (0);
 683       check_syscall ("dup'ing tty into fd 0", dup (tty));
 684     }
 685   if (tty != 1)
 686     {
 687       close (1);
 688       check_syscall ("dup'ing tty into fd 1", dup (tty));
 689     }
 690   if (tty != 2)
 691     {
 692       close (2);
 693       check_syscall ("dup'ing tty into fd 2", dup (tty));
 694     }
 695
 696 #ifdef TIOCSCTTY
 697   /* Make tty our new controlling terminal.  */
 698   if (ioctl (tty, TIOCSCTTY, 0) == -1)
 699     /* Mention GDB in warning because it will appear in the inferior's
 700        terminal instead of GDB's.  */
 701     warning ("GDB: Failed to set controlling terminal: %s",
 702              safe_strerror (errno));
 703 #endif
 704
 705   if (tty > 2)
 706     close (tty);
 707 #endif /* !go32 && !win32 */
 708 }
 709
 710 /* NEW_TTY_POSTFORK is called after forking a new child process, and
 711    adding it to the inferior table, to store the TTYNAME being used by
 712    the child, or null if it sharing the terminal with gdb.  */
 713
 714 void
 715 new_tty_postfork (void)
 716 {
 717   /* Save the name for later, for determining whether we and the child
 718      are sharing a tty.  */
 719
 720   if (inferior_thisrun_terminal)
 721     {
 722       struct inferior *inf = current_inferior ();
 723       struct terminal_info *tinfo = get_inflow_inferior_data (inf);
 724
 725       tinfo->run_terminal = xstrdup (inferior_thisrun_terminal);
 726     }
 727
 728   inferior_thisrun_terminal = NULL;
 729 }
 730
 731 \f
 732 /* Call set_sigint_trap when you need to pass a signal on to an attached
 733    process when handling SIGINT */
 734
 735 static void
 736 pass_signal (int signo)
 737 {
 738 #ifndef _WIN32
 739   kill (PIDGET (inferior_ptid), SIGINT);
 740 #endif
 741 }
 742
 743 static void (*osig) ();
 744 static int osig_set;
 745
 746 void
 747 set_sigint_trap (void)
 748 {
 749   struct inferior *inf = current_inferior ();
 750   struct terminal_info *tinfo = get_inflow_inferior_data (inf);
 751
 752   if (inf->attach_flag || tinfo->run_terminal)
 753     {
 754       osig = (void (*)()) signal (SIGINT, pass_signal);
 755       osig_set = 1;
 756     }
 757   else
 758     osig_set = 0;
 759 }
 760
 761 void
 762 clear_sigint_trap (void)
 763 {
 764   if (osig_set)
 765     {
 766       signal (SIGINT, osig);
 767       osig_set = 0;
 768     }
 769 }
 770 \f
 771
 772 /* Create a new session if the inferior will run in a different tty.
 773    A session is UNIX's way of grouping processes that share a controlling
 774    terminal, so a new one is needed if the inferior terminal will be
 775    different from GDB's.
 776
 777    Returns the session id of the new session, 0 if no session was created
 778    or -1 if an error occurred.  */
 779 pid_t
 780 create_tty_session (void)
 781 {
 782 #ifdef HAVE_SETSID
 783   pid_t ret;
 784
 785   if (!job_control || inferior_thisrun_terminal == 0)
 786     return 0;
 787
 788   ret = setsid ();
 789   if (ret == -1)
 790     warning ("Failed to create new terminal session: setsid: %s",
 791              safe_strerror (errno));
 792
 793   return ret;
 794 #else
 795   return 0;
 796 #endif /* HAVE_SETSID */
 797 }
 798
 799 /* This is here because this is where we figure out whether we (probably)
 800    have job control.  Just using job_control only does part of it because
 801    setpgid or setpgrp might not exist on a system without job control.
 802    It might be considered misplaced (on the other hand, process groups and
 803    job control are closely related to ttys).
 804
 805    For a more clean implementation, in libiberty, put a setpgid which merely
 806    calls setpgrp and a setpgrp which does nothing (any system with job control
 807    will have one or the other).  */
 808 int
 809 gdb_setpgid (void)
 810 {
 811   int retval = 0;
 812
 813   if (job_control)
 814     {
 815 #if defined (HAVE_TERMIOS) || defined (TIOCGPGRP)
 816 #ifdef HAVE_SETPGID
 817       /* The call setpgid (0, 0) is supposed to work and mean the same
 818          thing as this, but on Ultrix 4.2A it fails with EPERM (and
 819          setpgid (getpid (), getpid ()) succeeds).  */
 820       retval = setpgid (getpid (), getpid ());
 821 #else
 822 #ifdef HAVE_SETPGRP
 823 #ifdef SETPGRP_VOID
 824       retval = setpgrp ();
 825 #else
 826       retval = setpgrp (getpid (), getpid ());
 827 #endif
 828 #endif /* HAVE_SETPGRP */
 829 #endif /* HAVE_SETPGID */
 830 #endif /* defined (HAVE_TERMIOS) || defined (TIOCGPGRP) */
 831     }
 832
 833   return retval;
 834 }
 835
 836 /* Get all the current tty settings (including whether we have a
 837    tty at all!).  We can't do this in _initialize_inflow because
 838    serial_fdopen() won't work until the serial_ops_list is
 839    initialized, but we don't want to do it lazily either, so
 840    that we can guarantee stdin_serial is opened if there is
 841    a terminal.  */
 842 void
 843 initialize_stdin_serial (void)
 844 {
 845   stdin_serial = serial_fdopen (0);
 846 }
 847
 848 void
 849 _initialize_inflow (void)
 850 {
 851   add_info ("terminal", term_info,
 852             _("Print inferior's saved terminal status."));
 853
 854   terminal_is_ours = 1;
 855
 856   /* OK, figure out whether we have job control.  If neither termios nor
 857      sgtty (i.e. termio or go32), leave job_control 0.  */
 858
 859 #if defined (HAVE_TERMIOS)
 860   /* Do all systems with termios have the POSIX way of identifying job
 861      control?  I hope so.  */
 862 #ifdef _POSIX_JOB_CONTROL
 863   job_control = 1;
 864 #else
 865 #ifdef _SC_JOB_CONTROL
 866   job_control = sysconf (_SC_JOB_CONTROL);
 867 #else
 868   job_control = 0;              /* have to assume the worst */
 869 #endif /* _SC_JOB_CONTROL */
 870 #endif /* _POSIX_JOB_CONTROL */
 871 #endif /* HAVE_TERMIOS */
 872
 873 #ifdef HAVE_SGTTY
 874 #ifdef TIOCGPGRP
 875   job_control = 1;
 876 #else
 877   job_control = 0;
 878 #endif /* TIOCGPGRP */
 879 #endif /* sgtty */
 880
 881   observer_attach_inferior_exit (inflow_inferior_exit);
 882
 883   inflow_inferior_data
 884     = register_inferior_data_with_cleanup (inflow_inferior_data_cleanup);
 885 }