signal/sigvec.c

   1 /* ABI compatibility for obsolete sigvec function from 4.2BSD.
   2    Copyright (C) 1991-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <shlib-compat.h>
  20
  21 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_21)
  22
  23 # include <signal.h>
  24 # include <errno.h>
  25 # include <stddef.h>
  26
  27
  28 /* These are the struct sigvec and SV_* bit definitions that
  29    used to be in <signal.h>.  The whole interface now exists
  30    solely for ABI compatibility, so it can just be here.  */
  31 struct sigvec
  32   {
  33     __sighandler_t sv_handler;  /* Signal handler.  */
  34     int sv_mask;                /* Mask of signals to be blocked.  */
  35
  36     int sv_flags;               /* Flags (see below).  */
  37   };
  38 # define SV_ONSTACK     (1 << 0)/* Take the signal on the signal stack.  */
  39 # define SV_INTERRUPT   (1 << 1)/* Do not restart system calls.  */
  40 # define SV_RESETHAND   (1 << 2)/* Reset handler to SIG_DFL on receipt.  */
  41
  42
  43 /* Include macros to convert between `sigset_t' and old-style mask. */
  44 # include <sigset-cvt-mask.h>
  45
  46 # ifndef SA_RESETHAND
  47 /* When sigaction lacks the extension bit for it,
  48    we use a wrapper handler to support SV_RESETHAND.  */
  49 struct sigvec_wrapper_data
  50 {
  51   __sighandler_t sw_handler;
  52   unsigned int sw_mask;
  53 };
  54
  55 static void sigvec_wrapper_handler (int sig) __THROW;
  56
  57 static struct sigvec_wrapper_data sigvec_wrapper_data[NSIG];
  58 # endif
  59
  60
  61 /* If VEC is non-NULL, set the handler for SIG to the `sv_handler' member
  62    of VEC.  The signals in `sv_mask' will be blocked while the handler runs.
  63    If the SV_RESETHAND bit is set in `sv_flags', the handler for SIG will be
  64    reset to SIG_DFL before `sv_handler' is entered.  If OVEC is non-NULL,
  65    it is filled in with the old information for SIG.  */
  66 int
  67 __sigvec (int sig,
  68           const struct sigvec *vec,
  69           struct sigvec *ovec)
  70 {
  71   struct sigaction old;
  72
  73 # ifndef SA_RESETHAND
  74   if (vec == NULL || !(vec->sv_flags & SV_RESETHAND))
  75 # endif
  76     {
  77       struct sigaction new, *n;
  78
  79       if (vec == NULL)
  80         n = NULL;
  81       else
  82         {
  83           __sighandler_t handler;
  84           unsigned int mask;
  85           unsigned int sv_flags;
  86           unsigned int sa_flags;
  87
  88           handler = vec->sv_handler;
  89           mask = vec->sv_mask;
  90           sv_flags = vec->sv_flags;
  91           sa_flags = 0;
  92           if (sv_flags & SV_ONSTACK)
  93             {
  94 # ifdef SA_ONSTACK
  95               sa_flags |= SA_ONSTACK;
  96 # else
  97               __set_errno (ENOSYS);
  98               return -1;
  99 # endif
 100             }
 101 # ifdef SA_RESTART
 102           if (!(sv_flags & SV_INTERRUPT))
 103             sa_flags |= SA_RESTART;
 104 # endif
 105 # ifdef SA_RESETHAND
 106           if (sv_flags & SV_RESETHAND)
 107             sa_flags |= SA_RESETHAND;
 108 # endif
 109           n = &new;
 110           new.sa_handler = handler;
 111           if (sigset_set_old_mask (&new.sa_mask, mask) < 0)
 112             return -1;
 113           new.sa_flags = sa_flags;
 114         }
 115
 116       if (__sigaction (sig, n, &old) < 0)
 117         return -1;
 118     }
 119 # ifndef SA_RESETHAND
 120   else
 121     {
 122       __sighandler_t handler;
 123       unsigned int mask;
 124       struct sigvec_wrapper_data *data;
 125       struct sigaction wrapper;
 126
 127       handler = vec->sv_handler;
 128       mask = (unsigned int)vec->sv_mask;
 129       data = &sigvec_wrapper_data[sig];
 130       wrapper.sa_handler = sigvec_wrapper_handler;
 131       /* FIXME: should we set wrapper.sa_mask, wrapper.sa_flags??  */
 132       data->sw_handler = handler;
 133       data->sw_mask = mask;
 134
 135       if (__sigaction (sig, &wrapper, &old) < 0)
 136         return -1;
 137     }
 138 # endif
 139
 140   if (ovec != NULL)
 141     {
 142       __sighandler_t handler;
 143       unsigned int sv_flags;
 144       unsigned int sa_flags;
 145       unsigned int mask;
 146
 147       handler = old.sa_handler;
 148       sv_flags = 0;
 149       sa_flags = old.sa_flags;
 150 # ifndef SA_RESETHAND
 151       if (handler == sigvec_wrapper_handler)
 152         {
 153           handler = sigvec_wrapper_data[sig].sw_handler;
 154           /* should we use data->sw_mask?? */
 155           sv_flags |= SV_RESETHAND;
 156         }
 157 # else
 158      if (sa_flags & SA_RESETHAND)
 159         sv_flags |= SV_RESETHAND;
 160 # endif
 161       mask = sigset_get_old_mask (&old.sa_mask);
 162 # ifdef SA_ONSTACK
 163      if (sa_flags & SA_ONSTACK)
 164         sv_flags |= SV_ONSTACK;
 165 # endif
 166 # ifdef SA_RESTART
 167      if (!(sa_flags & SA_RESTART))
 168 # endif
 169         sv_flags |= SV_INTERRUPT;
 170       ovec->sv_handler = handler;
 171       ovec->sv_mask = (int)mask;
 172       ovec->sv_flags = (int)sv_flags;
 173     }
 174
 175   return 0;
 176 }
 177
 178 compat_symbol (libc, __sigvec, sigvec, GLIBC_2_0);
 179
 180 # ifndef SA_RESETHAND
 181 static void
 182 sigvec_wrapper_handler (int sig)
 183 {
 184   struct sigvec_wrapper_data *data;
 185   struct sigaction act;
 186   int save;
 187   __sighandler_t handler;
 188
 189   data = &sigvec_wrapper_data[sig];
 190   act.sa_handler = SIG_DFL;
 191   act.sa_flags = 0;
 192   sigset_set_old_mask (&act.sa_mask, data->sw_mask);
 193   handler = data->sw_handler;
 194   save = errno;
 195   (void) __sigaction (sig, &act, (struct sigaction *) NULL);
 196   __set_errno (save);
 197
 198   (*handler) (sig);
 199 }
 200 # endif  /* No SA_RESETHAND.  */
 201
 202 #endif  /* SHLIB_COMPAT */