jdk8-mips64-public/hotspot: src/os/linux/vm/jsig.c@9c2ecc2ffb12

     1 /*

     2  * Copyright 2001-2006 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    25 /* CopyrightVersion 1.2 */

    27 /* This is a special library that should be loaded before libc &

    28  * libthread to interpose the signal handler installation functions:

    29  * sigaction(), signal(), sigset().

    30  * Used for signal-chaining. See RFE 4381843.

    31  */

    33 #include <signal.h>

    34 #include <dlfcn.h>

    35 #include <pthread.h>

    36 #include <stdio.h>

    37 #include <stdlib.h>

    39 #define bool int

    40 #define true 1

    41 #define false 0

    43 #define MAXSIGNUM 32

    44 #define MASK(sig) ((unsigned int)1 << sig)

    46 static struct sigaction sact[MAXSIGNUM]; /* saved signal handlers */

    47 static unsigned int jvmsigs = 0; /* signals used by jvm */

    49 /* used to synchronize the installation of signal handlers */

    50 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

    51 static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

    52 static pthread_t tid = 0;

    54 typedef void (*sa_handler_t)(int);

    55 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);

    56 typedef sa_handler_t (*signal_t)(int, sa_handler_t);

    57 typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *);

    59 static signal_t os_signal = 0; /* os's version of signal()/sigset() */

    60 static sigaction_t os_sigaction = 0; /* os's version of sigaction() */

    62 static bool jvm_signal_installing = false;

    63 static bool jvm_signal_installed = false;

    65 static void signal_lock() {

    66   pthread_mutex_lock(&mutex);

    67   /* When the jvm is installing its set of signal handlers, threads

    68    * other than the jvm thread should wait */

    69   if (jvm_signal_installing) {

    70     if (tid != pthread_self()) {

    71       pthread_cond_wait(&cond, &mutex);

    72     }

    73   }

    74 }

    76 static void signal_unlock() {

    77   pthread_mutex_unlock(&mutex);

    78 }

    80 static sa_handler_t call_os_signal(int sig, sa_handler_t disp,

    81                                    bool is_sigset) {

    82   if (os_signal == NULL) {

    83     if (!is_sigset) {

    84       os_signal = (signal_t)dlsym(RTLD_NEXT, "signal");

    85     } else {

    86       os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset");

    87     }

    88     if (os_signal == NULL) {

    89       printf("%s\n", dlerror());

    90       exit(0);

    91     }

    92   }

    93   return (*os_signal)(sig, disp);

    94 }

    96 static void save_signal_handler(int sig, sa_handler_t disp) {

    97   sigset_t set;

    98   sact[sig].sa_handler = disp;

    99   sigemptyset(&set);

   100   sact[sig].sa_mask = set;

   101   sact[sig].sa_flags = 0;

   102 }

   104 static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) {

   105   sa_handler_t oldhandler;

   106   bool sigused;

   108   signal_lock();

   110   sigused = (MASK(sig) & jvmsigs) != 0;

   111   if (jvm_signal_installed && sigused) {

   112     /* jvm has installed its signal handler for this signal. */

   113     /* Save the handler. Don't really install it. */

   114     oldhandler = sact[sig].sa_handler;

   115     save_signal_handler(sig, disp);

   117     signal_unlock();

   118     return oldhandler;

   119   } else if (jvm_signal_installing) {

   120     /* jvm is installing its signal handlers. Install the new

   121      * handlers and save the old ones. jvm uses sigaction().

   122      * Leave the piece here just in case. */

   123     oldhandler = call_os_signal(sig, disp, is_sigset);

   124     save_signal_handler(sig, oldhandler);

   126     /* Record the signals used by jvm */

   127     jvmsigs |= MASK(sig);

   129     signal_unlock();

   130     return oldhandler;

   131   } else {

   132     /* jvm has no relation with this signal (yet). Install the

   133      * the handler. */

   134     oldhandler = call_os_signal(sig, disp, is_sigset);

   136     signal_unlock();

   137     return oldhandler;

   138   }

   139 }

   141 sa_handler_t signal(int sig, sa_handler_t disp) {

   142   return set_signal(sig, disp, false);

   143 }

   145 sa_handler_t sigset(int sig, sa_handler_t disp) {

   146   return set_signal(sig, disp, true);

   147  }

   149 static int call_os_sigaction(int sig, const struct sigaction  *act,

   150                              struct sigaction *oact) {

   151   if (os_sigaction == NULL) {

   152     os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction");

   153     if (os_sigaction == NULL) {

   154       printf("%s\n", dlerror());

   155       exit(0);

   156     }

   157   }

   158   return (*os_sigaction)(sig, act, oact);

   159 }

   161 int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) {

   162   int res;

   163   bool sigused;

   164   struct sigaction oldAct;

   166   signal_lock();

   168   sigused = (MASK(sig) & jvmsigs) != 0;

   169   if (jvm_signal_installed && sigused) {

   170     /* jvm has installed its signal handler for this signal. */

   171     /* Save the handler. Don't really install it. */

   172     if (oact != NULL) {

   173       *oact = sact[sig];

   174     }

   175     if (act != NULL) {

   176       sact[sig] = *act;

   177     }

   179     signal_unlock();

   180     return 0;

   181   } else if (jvm_signal_installing) {

   182     /* jvm is installing its signal handlers. Install the new

   183      * handlers and save the old ones. */

   184     res = call_os_sigaction(sig, act, &oldAct);

   185     sact[sig] = oldAct;

   186     if (oact != NULL) {

   187       *oact = oldAct;

   188     }

   190     /* Record the signals used by jvm */

   191     jvmsigs |= MASK(sig);

   193     signal_unlock();

   194     return res;

   195   } else {

   196     /* jvm has no relation with this signal (yet). Install the

   197      * the handler. */

   198     res = call_os_sigaction(sig, act, oact);

   200     signal_unlock();

   201     return res;

   202   }

   203 }

   205 /* The three functions for the jvm to call into */

   206 void JVM_begin_signal_setting() {

   207   signal_lock();

   208   jvm_signal_installing = true;

   209   tid = pthread_self();

   210   signal_unlock();

   211 }

   213 void JVM_end_signal_setting() {

   214   signal_lock();

   215   jvm_signal_installed = true;

   216   jvm_signal_installing = false;

   217   pthread_cond_broadcast(&cond);

   218   signal_unlock();

   219 }

   221 struct sigaction *JVM_get_signal_action(int sig) {

   222   /* Does race condition make sense here? */

   223   if ((MASK(sig) & jvmsigs) != 0) {

   224     return &sact[sig];

   225   }

   226   return NULL;

   227 }

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