gdb/gdbsupport/signals-state-save-restore.c

   1 /* Copyright (C) 2016-2019 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
  21 #include <signal.h>
  22
  23 /* The original signal actions and mask.  */
  24
  25 #ifdef HAVE_SIGACTION
  26 static struct sigaction original_signal_actions[NSIG];
  27
  28 /* Note that we use sigprocmask without worrying about threads because
  29    the save/restore functions are called either from main, or after a
  30    fork.  In both cases, we know the calling process is single
  31    threaded.  */
  32 static sigset_t original_signal_mask;
  33 #endif
  34
  35 /* See signals-state-save-restore.h.   */
  36
  37 void
  38 save_original_signals_state (bool quiet)
  39 {
  40 #ifdef HAVE_SIGACTION
  41   int i;
  42   int res;
  43
  44   res = sigprocmask (0,  NULL, &original_signal_mask);
  45   if (res == -1)
  46     perror_with_name (("sigprocmask"));
  47
  48   bool found_preinstalled = false;
  49
  50   for (i = 1; i < NSIG; i++)
  51     {
  52       struct sigaction *oldact = &original_signal_actions[i];
  53
  54       res = sigaction (i, NULL, oldact);
  55       if (res == -1 && errno == EINVAL)
  56         {
  57           /* Some signal numbers in the range are invalid.  */
  58           continue;
  59         }
  60       else if (res == -1)
  61         perror_with_name (("sigaction"));
  62
  63       /* If we find a custom signal handler already installed, then
  64          this function was called too late.  This is a warning instead
  65          of an internal error because this can also happen if you
  66          LD_PRELOAD a library that installs a signal handler early via
  67          __attribute__((constructor)), like libSegFault.so.  */
  68       if (!quiet
  69           && oldact->sa_handler != SIG_DFL
  70           && oldact->sa_handler != SIG_IGN)
  71         {
  72           found_preinstalled = true;
  73
  74           /* Use raw fprintf here because we're being called in early
  75              startup, before GDB's filtered streams are created.  */
  76           fprintf (stderr,
  77                    _("warning: Found custom handler for signal "
  78                      "%d (%s) preinstalled.\n"), i,
  79                    strsignal (i));
  80         }
  81     }
  82
  83   if (found_preinstalled)
  84     {
  85       fprintf (stderr, _("\
  86 Some signal dispositions inherited from the environment (SIG_DFL/SIG_IGN)\n\
  87 won't be propagated to spawned programs.\n"));
  88     }
  89 #endif
  90 }
  91
  92 /* See signals-state-save-restore.h.   */
  93
  94 void
  95 restore_original_signals_state (void)
  96 {
  97 #ifdef HAVE_SIGACTION
  98   int i;
  99   int res;
 100
 101   for (i = 1; i < NSIG; i++)
 102     {
 103       res = sigaction (i, &original_signal_actions[i], NULL);
 104       if (res == -1 && errno == EINVAL)
 105         {
 106           /* Some signal numbers in the range are invalid.  */
 107           continue;
 108         }
 109       else if (res == -1)
 110         perror_with_name (("sigaction"));
 111     }
 112
 113   res = sigprocmask (SIG_SETMASK,  &original_signal_mask, NULL);
 114   if (res == -1)
 115     perror_with_name (("sigprocmask"));
 116 #endif
 117 }