1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/os/bsd/vm/jsig.c Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,225 @@
1.4 +/*
1.5 + * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +/* CopyrightVersion 1.2 */
1.29 +
1.30 +/* This is a special library that should be loaded before libc &
1.31 + * libthread to interpose the signal handler installation functions:
1.32 + * sigaction(), signal(), sigset().
1.33 + * Used for signal-chaining. See RFE 4381843.
1.34 + */
1.35 +
1.36 +#include <signal.h>
1.37 +#include <dlfcn.h>
1.38 +#include <pthread.h>
1.39 +#include <stdio.h>
1.40 +#include <stdlib.h>
1.41 +#include <stdbool.h>
1.42 +
1.43 +#define MAXSIGNUM 32
1.44 +#define MASK(sig) ((unsigned int)1 << sig)
1.45 +
1.46 +static struct sigaction sact[MAXSIGNUM]; /* saved signal handlers */
1.47 +static unsigned int jvmsigs = 0; /* signals used by jvm */
1.48 +
1.49 +/* used to synchronize the installation of signal handlers */
1.50 +static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
1.51 +static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
1.52 +static pthread_t tid = 0;
1.53 +
1.54 +typedef void (*sa_handler_t)(int);
1.55 +typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
1.56 +typedef sa_handler_t (*signal_t)(int, sa_handler_t);
1.57 +typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *);
1.58 +
1.59 +static signal_t os_signal = 0; /* os's version of signal()/sigset() */
1.60 +static sigaction_t os_sigaction = 0; /* os's version of sigaction() */
1.61 +
1.62 +static bool jvm_signal_installing = false;
1.63 +static bool jvm_signal_installed = false;
1.64 +
1.65 +static void signal_lock() {
1.66 + pthread_mutex_lock(&mutex);
1.67 + /* When the jvm is installing its set of signal handlers, threads
1.68 + * other than the jvm thread should wait */
1.69 + if (jvm_signal_installing) {
1.70 + if (tid != pthread_self()) {
1.71 + pthread_cond_wait(&cond, &mutex);
1.72 + }
1.73 + }
1.74 +}
1.75 +
1.76 +static void signal_unlock() {
1.77 + pthread_mutex_unlock(&mutex);
1.78 +}
1.79 +
1.80 +static sa_handler_t call_os_signal(int sig, sa_handler_t disp,
1.81 + bool is_sigset) {
1.82 + if (os_signal == NULL) {
1.83 + if (!is_sigset) {
1.84 + os_signal = (signal_t)dlsym(RTLD_NEXT, "signal");
1.85 + } else {
1.86 + os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset");
1.87 + }
1.88 + if (os_signal == NULL) {
1.89 + printf("%s\n", dlerror());
1.90 + exit(0);
1.91 + }
1.92 + }
1.93 + return (*os_signal)(sig, disp);
1.94 +}
1.95 +
1.96 +static void save_signal_handler(int sig, sa_handler_t disp) {
1.97 + sigset_t set;
1.98 + sact[sig].sa_handler = disp;
1.99 + sigemptyset(&set);
1.100 + sact[sig].sa_mask = set;
1.101 + sact[sig].sa_flags = 0;
1.102 +}
1.103 +
1.104 +static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) {
1.105 + sa_handler_t oldhandler;
1.106 + bool sigused;
1.107 +
1.108 + signal_lock();
1.109 +
1.110 + sigused = (MASK(sig) & jvmsigs) != 0;
1.111 + if (jvm_signal_installed && sigused) {
1.112 + /* jvm has installed its signal handler for this signal. */
1.113 + /* Save the handler. Don't really install it. */
1.114 + oldhandler = sact[sig].sa_handler;
1.115 + save_signal_handler(sig, disp);
1.116 +
1.117 + signal_unlock();
1.118 + return oldhandler;
1.119 + } else if (jvm_signal_installing) {
1.120 + /* jvm is installing its signal handlers. Install the new
1.121 + * handlers and save the old ones. jvm uses sigaction().
1.122 + * Leave the piece here just in case. */
1.123 + oldhandler = call_os_signal(sig, disp, is_sigset);
1.124 + save_signal_handler(sig, oldhandler);
1.125 +
1.126 + /* Record the signals used by jvm */
1.127 + jvmsigs |= MASK(sig);
1.128 +
1.129 + signal_unlock();
1.130 + return oldhandler;
1.131 + } else {
1.132 + /* jvm has no relation with this signal (yet). Install the
1.133 + * the handler. */
1.134 + oldhandler = call_os_signal(sig, disp, is_sigset);
1.135 +
1.136 + signal_unlock();
1.137 + return oldhandler;
1.138 + }
1.139 +}
1.140 +
1.141 +sa_handler_t signal(int sig, sa_handler_t disp) {
1.142 + return set_signal(sig, disp, false);
1.143 +}
1.144 +
1.145 +sa_handler_t sigset(int sig, sa_handler_t disp) {
1.146 + printf("sigset() is not supported by BSD");
1.147 + exit(0);
1.148 + }
1.149 +
1.150 +static int call_os_sigaction(int sig, const struct sigaction *act,
1.151 + struct sigaction *oact) {
1.152 + if (os_sigaction == NULL) {
1.153 + os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction");
1.154 + if (os_sigaction == NULL) {
1.155 + printf("%s\n", dlerror());
1.156 + exit(0);
1.157 + }
1.158 + }
1.159 + return (*os_sigaction)(sig, act, oact);
1.160 +}
1.161 +
1.162 +int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) {
1.163 + int res;
1.164 + bool sigused;
1.165 + struct sigaction oldAct;
1.166 +
1.167 + signal_lock();
1.168 +
1.169 + sigused = (MASK(sig) & jvmsigs) != 0;
1.170 + if (jvm_signal_installed && sigused) {
1.171 + /* jvm has installed its signal handler for this signal. */
1.172 + /* Save the handler. Don't really install it. */
1.173 + if (oact != NULL) {
1.174 + *oact = sact[sig];
1.175 + }
1.176 + if (act != NULL) {
1.177 + sact[sig] = *act;
1.178 + }
1.179 +
1.180 + signal_unlock();
1.181 + return 0;
1.182 + } else if (jvm_signal_installing) {
1.183 + /* jvm is installing its signal handlers. Install the new
1.184 + * handlers and save the old ones. */
1.185 + res = call_os_sigaction(sig, act, &oldAct);
1.186 + sact[sig] = oldAct;
1.187 + if (oact != NULL) {
1.188 + *oact = oldAct;
1.189 + }
1.190 +
1.191 + /* Record the signals used by jvm */
1.192 + jvmsigs |= MASK(sig);
1.193 +
1.194 + signal_unlock();
1.195 + return res;
1.196 + } else {
1.197 + /* jvm has no relation with this signal (yet). Install the
1.198 + * the handler. */
1.199 + res = call_os_sigaction(sig, act, oact);
1.200 +
1.201 + signal_unlock();
1.202 + return res;
1.203 + }
1.204 +}
1.205 +
1.206 +/* The three functions for the jvm to call into */
1.207 +void JVM_begin_signal_setting() {
1.208 + signal_lock();
1.209 + jvm_signal_installing = true;
1.210 + tid = pthread_self();
1.211 + signal_unlock();
1.212 +}
1.213 +
1.214 +void JVM_end_signal_setting() {
1.215 + signal_lock();
1.216 + jvm_signal_installed = true;
1.217 + jvm_signal_installing = false;
1.218 + pthread_cond_broadcast(&cond);
1.219 + signal_unlock();
1.220 +}
1.221 +
1.222 +struct sigaction *JVM_get_signal_action(int sig) {
1.223 + /* Does race condition make sense here? */
1.224 + if ((MASK(sig) & jvmsigs) != 0) {
1.225 + return &sact[sig];
1.226 + }
1.227 + return NULL;
1.228 +}
