gdbsupport/signals-state-save-restore.cc

   1 /* Copyright (C) 2016-2020 Free Software Foundation, Inc.
   2
   3    This file is part of GDB.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include "common-defs.h"
  19 #include "signals-state-save-restore.h"
  20 #include "gdbsupport/gdb-sigmask.h"
  21
  22 #include <signal.h>
  23
  24 /* The original signal actions and mask.  */
  25
  26 #ifdef HAVE_SIGACTION
  27 static struct sigaction original_signal_actions[NSIG];
  28
  29 static sigset_t original_signal_mask;
  30 #endif
  31
  32 /* See signals-state-save-restore.h.   */
  33
  34 void
  35 save_original_signals_state (bool quiet)
  36 {
  37 #ifdef HAVE_SIGACTION
  38   int i;
  39   int res;
  40
  41   res = gdb_sigmask (0,  NULL, &original_signal_mask);
  42   if (res == -1)
  43     perror_with_name (("sigprocmask"));
  44
  45   bool found_preinstalled = false;
  46
  47   for (i = 1; i < NSIG; i++)
  48     {
  49       struct sigaction *oldact = &original_signal_actions[i];
  50
  51       res = sigaction (i, NULL, oldact);
  52       if (res == -1 && errno == EINVAL)
  53         {
  54           /* Some signal numbers in the range are invalid.  */
  55           continue;
  56         }
  57       else if (res == -1)
  58         perror_with_name (("sigaction"));
  59
  60       /* If we find a custom signal handler already installed, then
  61          this function was called too late.  This is a warning instead
  62          of an internal error because this can also happen if you
  63          LD_PRELOAD a library that installs a signal handler early via
  64          __attribute__((constructor)), like libSegFault.so.  */
  65       if (!quiet
  66           && oldact->sa_handler != SIG_DFL
  67           && oldact->sa_handler != SIG_IGN)
  68         {
  69           found_preinstalled = true;
  70
  71           /* Use raw fprintf here because we're being called in early
  72              startup, before GDB's filtered streams are created.  */
  73           fprintf (stderr,
  74                    _("warning: Found custom handler for signal "
  75                      "%d (%s) preinstalled.\n"), i,
  76                    strsignal (i));
  77         }
  78     }
  79
  80   if (found_preinstalled)
  81     {
  82       fprintf (stderr, _("\
  83 Some signal dispositions inherited from the environment (SIG_DFL/SIG_IGN)\n\
  84 won't be propagated to spawned programs.\n"));
  85     }
  86 #endif
  87 }
  88
  89 /* See signals-state-save-restore.h.   */
  90
  91 void
  92 restore_original_signals_state (void)
  93 {
  94 #ifdef HAVE_SIGACTION
  95   int i;
  96   int res;
  97
  98   for (i = 1; i < NSIG; i++)
  99     {
 100       res = sigaction (i, &original_signal_actions[i], NULL);
 101       if (res == -1 && errno == EINVAL)
 102         {
 103           /* Some signal numbers in the range are invalid.  */
 104           continue;
 105         }
 106       else if (res == -1)
 107         perror_with_name (("sigaction"));
 108     }
 109
 110   res = gdb_sigmask (SIG_SETMASK,  &original_signal_mask, NULL);
 111   if (res == -1)
 112     perror_with_name (("sigprocmask"));
 113 #endif
 114 }