gdbsupport/job-control.cc

   1 /* Job control and terminal related functions, for GDB and gdbserver
   2    when running under Unix.
   3
   4    Copyright (C) 1986-2020 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 "common-defs.h"
  22 #include "job-control.h"
  23 #ifdef HAVE_TERMIOS_H
  24 #include <termios.h>
  25 #endif
  26 #include <unistd.h>
  27
  28 /* Nonzero if we have job control.  */
  29 int job_control;
  30
  31 /* Set the process group ID of the inferior.
  32
  33    Just using job_control only does part of it because setpgid or
  34    setpgrp might not exist on a system without job control.
  35
  36    For a more clean implementation, in libiberty, put a setpgid which merely
  37    calls setpgrp and a setpgrp which does nothing (any system with job control
  38    will have one or the other).  */
  39
  40 int
  41 gdb_setpgid ()
  42 {
  43   int retval = 0;
  44
  45   if (job_control)
  46     {
  47 #ifdef HAVE_SETPGID
  48       /* The call setpgid (0, 0) is supposed to work and mean the same
  49          thing as this, but on Ultrix 4.2A it fails with EPERM (and
  50          setpgid (getpid (), getpid ()) succeeds).  */
  51       retval = setpgid (getpid (), getpid ());
  52 #else
  53 #ifdef HAVE_SETPGRP
  54 #ifdef SETPGRP_VOID
  55       retval = setpgrp ();
  56 #else
  57       retval = setpgrp (getpid (), getpid ());
  58 #endif
  59 #endif /* HAVE_SETPGRP */
  60 #endif /* HAVE_SETPGID */
  61     }
  62
  63   return retval;
  64 }
  65
  66 /* See gdbsupport/common-terminal.h.  */
  67
  68 void
  69 have_job_control ()
  70 {
  71   /* OK, figure out whether we have job control.  If termios is not
  72      available, leave job_control 0.  */
  73 #if defined (HAVE_TERMIOS_H)
  74   /* Do all systems with termios have the POSIX way of identifying job
  75      control?  I hope so.  */
  76 #ifdef _POSIX_JOB_CONTROL
  77   job_control = 1;
  78 #else
  79 #ifdef _SC_JOB_CONTROL
  80   job_control = sysconf (_SC_JOB_CONTROL);
  81 #else
  82   job_control = 0;              /* Have to assume the worst.  */
  83 #endif /* _SC_JOB_CONTROL */
  84 #endif /* _POSIX_JOB_CONTROL */
  85 #endif /* HAVE_TERMIOS_H */
  86 }