usr/src/lib/libc/port/sys/signal.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #pragma weak _signal = signal
  30 #pragma weak _sighold = sighold
  31 #pragma weak _sigrelse = sigrelse
  32 #pragma weak _sigignore = sigignore
  33 #pragma weak _sigset = sigset
  34
  35 #include "lint.h"
  36 #include <sys/types.h>
  37 #include <unistd.h>
  38 #include <errno.h>
  39 #include <signal.h>
  40 #include <wait.h>
  41
  42 /*
  43  * Check for valid signal number as per SVID.
  44  */
  45 #define CHECK_SIG(s, code) \
  46         if ((s) <= 0 || (s) >= NSIG || (s) == SIGKILL || (s) == SIGSTOP) { \
  47                 errno = EINVAL; \
  48                 return (code); \
  49         }
  50
  51 /*
  52  * Equivalent to stopdefault set in the kernel implementation (sig.c).
  53  */
  54 #define STOPDEFAULT(s) \
  55         ((s) == SIGSTOP || (s) == SIGTSTP || (s) == SIGTTOU || (s) == SIGTTIN)
  56
  57
  58 /*
  59  * SVr3.x signal compatibility routines. They are now
  60  * implemented as library routines instead of system
  61  * calls.
  62  */
  63
  64 void(*
  65 signal(int sig, void(*func)(int)))(int)
  66 {
  67         struct sigaction nact;
  68         struct sigaction oact;
  69
  70         CHECK_SIG(sig, SIG_ERR);
  71
  72         nact.sa_handler = func;
  73         nact.sa_flags = SA_RESETHAND|SA_NODEFER;
  74         (void) sigemptyset(&nact.sa_mask);
  75
  76         /*
  77          * Pay special attention if sig is SIGCHLD and
  78          * the disposition is SIG_IGN, per sysV signal man page.
  79          */
  80         if (sig == SIGCHLD) {
  81                 nact.sa_flags |= SA_NOCLDSTOP;
  82                 if (func == SIG_IGN)
  83                         nact.sa_flags |= SA_NOCLDWAIT;
  84         }
  85
  86         if (STOPDEFAULT(sig))
  87                 nact.sa_flags |= SA_RESTART;
  88
  89         if (sigaction(sig, &nact, &oact) < 0)
  90                 return (SIG_ERR);
  91
  92         return (oact.sa_handler);
  93 }
  94
  95 int
  96 sighold(int sig)
  97 {
  98         sigset_t set;
  99
 100         CHECK_SIG(sig, -1);
 101
 102         /*
 103          * errno set on failure by either sigaddset or sigprocmask.
 104          */
 105         (void) sigemptyset(&set);
 106         if (sigaddset(&set, sig) < 0)
 107                 return (-1);
 108         return (sigprocmask(SIG_BLOCK, &set, (sigset_t *)0));
 109 }
 110
 111 int
 112 sigrelse(int sig)
 113 {
 114         sigset_t set;
 115
 116         CHECK_SIG(sig, -1);
 117
 118         /*
 119          * errno set on failure by either sigaddset or sigprocmask.
 120          */
 121         (void) sigemptyset(&set);
 122         if (sigaddset(&set, sig) < 0)
 123                 return (-1);
 124         return (sigprocmask(SIG_UNBLOCK, &set, (sigset_t *)0));
 125 }
 126
 127 int
 128 sigignore(int sig)
 129 {
 130         struct sigaction act;
 131         sigset_t set;
 132
 133         CHECK_SIG(sig, -1);
 134
 135         act.sa_handler = SIG_IGN;
 136         act.sa_flags = 0;
 137         (void) sigemptyset(&act.sa_mask);
 138
 139         /*
 140          * Pay special attention if sig is SIGCHLD and
 141          * the disposition is SIG_IGN, per sysV signal man page.
 142          */
 143         if (sig == SIGCHLD) {
 144                 act.sa_flags |= SA_NOCLDSTOP;
 145                 act.sa_flags |= SA_NOCLDWAIT;
 146         }
 147
 148         if (STOPDEFAULT(sig))
 149                 act.sa_flags |= SA_RESTART;
 150
 151         if (sigaction(sig, &act, NULL) < 0)
 152                 return (-1);
 153
 154         (void) sigemptyset(&set);
 155         if (sigaddset(&set, sig) < 0)
 156                 return (-1);
 157         return (sigprocmask(SIG_UNBLOCK, &set, (sigset_t *)0));
 158 }
 159
 160 int
 161 __sigpause(int sig)
 162 {
 163         sigset_t set;
 164         int rval;
 165
 166         CHECK_SIG(sig, -1);
 167
 168         /*
 169          * sigpause() is defined to unblock the signal
 170          * and not block it again on return.
 171          * sigsuspend() restores the original signal set,
 172          * so we have to unblock sig overtly.
 173          */
 174         (void) sigprocmask(0, (sigset_t *)0, &set);
 175         if (sigdelset(&set, sig) < 0)
 176                 return (-1);
 177         rval = sigsuspend(&set);
 178         (void) sigrelse(sig);
 179         return (rval);
 180 }
 181
 182 void(*
 183 sigset(int sig, void(*func)(int)))(int)
 184 {
 185         struct sigaction nact;
 186         struct sigaction oact;
 187         sigset_t nset;
 188         sigset_t oset;
 189         int code;
 190
 191         CHECK_SIG(sig, SIG_ERR);
 192
 193         (void) sigemptyset(&nset);
 194         if (sigaddset(&nset, sig) < 0)
 195                 return (SIG_ERR);
 196
 197         if (func == SIG_HOLD) {
 198                 if (sigprocmask(SIG_BLOCK, &nset, &oset) < 0)
 199                         return (SIG_ERR);
 200                 if (sigaction(sig, NULL, &oact) < 0)
 201                         return (SIG_ERR);
 202         } else {
 203                 nact.sa_handler = func;
 204                 nact.sa_flags = 0;
 205                 (void) sigemptyset(&nact.sa_mask);
 206                 /*
 207                  * Pay special attention if sig is SIGCHLD and
 208                  * the disposition is SIG_IGN, per sysV signal man page.
 209                  */
 210                 if (sig == SIGCHLD) {
 211                         nact.sa_flags |= SA_NOCLDSTOP;
 212                         if (func == SIG_IGN)
 213                                 nact.sa_flags |= SA_NOCLDWAIT;
 214                 }
 215
 216                 if (STOPDEFAULT(sig))
 217                         nact.sa_flags |= SA_RESTART;
 218
 219                 if (sigaction(sig, &nact, &oact) < 0)
 220                         return (SIG_ERR);
 221
 222                 if (sigprocmask(SIG_UNBLOCK, &nset, &oset) < 0)
 223                         return (SIG_ERR);
 224         }
 225
 226         if ((code = sigismember(&oset, sig)) < 0)
 227                 return (SIG_ERR);
 228         else if (code == 1)
 229                 return (SIG_HOLD);
 230
 231         return (oact.sa_handler);
 232 }