1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/os/linux/vm/jsig.c Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,227 @@
1.4 +/*
1.5 + * Copyright (c) 2001, 2013, 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 +
1.42 +#define bool int
1.43 +#define true 1
1.44 +#define false 0
1.45 +
1.46 +#define MAXSIGNUM 32
1.47 +#define MASK(sig) ((unsigned int)1 << sig)
1.48 +
1.49 +static struct sigaction sact[MAXSIGNUM]; /* saved signal handlers */
1.50 +static unsigned int jvmsigs = 0; /* signals used by jvm */
1.51 +
1.52 +/* used to synchronize the installation of signal handlers */
1.53 +static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
1.54 +static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
1.55 +static pthread_t tid = 0;
1.56 +
1.57 +typedef void (*sa_handler_t)(int);
1.58 +typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
1.59 +typedef sa_handler_t (*signal_t)(int, sa_handler_t);
1.60 +typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *);
1.61 +
1.62 +static signal_t os_signal = 0; /* os's version of signal()/sigset() */
1.63 +static sigaction_t os_sigaction = 0; /* os's version of sigaction() */
1.64 +
1.65 +static bool jvm_signal_installing = false;
1.66 +static bool jvm_signal_installed = false;
1.67 +
1.68 +static void signal_lock() {
1.69 + pthread_mutex_lock(&mutex);
1.70 + /* When the jvm is installing its set of signal handlers, threads
1.71 + * other than the jvm thread should wait */
1.72 + if (jvm_signal_installing) {
1.73 + if (tid != pthread_self()) {
1.74 + pthread_cond_wait(&cond, &mutex);
1.75 + }
1.76 + }
1.77 +}
1.78 +
1.79 +static void signal_unlock() {
1.80 + pthread_mutex_unlock(&mutex);
1.81 +}
1.82 +
1.83 +static sa_handler_t call_os_signal(int sig, sa_handler_t disp,
1.84 + bool is_sigset) {
1.85 + if (os_signal == NULL) {
1.86 + if (!is_sigset) {
1.87 + os_signal = (signal_t)dlsym(RTLD_NEXT, "signal");
1.88 + } else {
1.89 + os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset");
1.90 + }
1.91 + if (os_signal == NULL) {
1.92 + printf("%s\n", dlerror());
1.93 + exit(0);
1.94 + }
1.95 + }
1.96 + return (*os_signal)(sig, disp);
1.97 +}
1.98 +
1.99 +static void save_signal_handler(int sig, sa_handler_t disp) {
1.100 + sigset_t set;
1.101 + sact[sig].sa_handler = disp;
1.102 + sigemptyset(&set);
1.103 + sact[sig].sa_mask = set;
1.104 + sact[sig].sa_flags = 0;
1.105 +}
1.106 +
1.107 +static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) {
1.108 + sa_handler_t oldhandler;
1.109 + bool sigused;
1.110 +
1.111 + signal_lock();
1.112 +
1.113 + sigused = (sig < MAXSIGNUM) && ((MASK(sig) & jvmsigs) != 0);
1.114 + if (jvm_signal_installed && sigused) {
1.115 + /* jvm has installed its signal handler for this signal. */
1.116 + /* Save the handler. Don't really install it. */
1.117 + oldhandler = sact[sig].sa_handler;
1.118 + save_signal_handler(sig, disp);
1.119 +
1.120 + signal_unlock();
1.121 + return oldhandler;
1.122 + } else if (sig < MAXSIGNUM && jvm_signal_installing) {
1.123 + /* jvm is installing its signal handlers. Install the new
1.124 + * handlers and save the old ones. jvm uses sigaction().
1.125 + * Leave the piece here just in case. */
1.126 + oldhandler = call_os_signal(sig, disp, is_sigset);
1.127 + save_signal_handler(sig, oldhandler);
1.128 +
1.129 + /* Record the signals used by jvm */
1.130 + jvmsigs |= MASK(sig);
1.131 +
1.132 + signal_unlock();
1.133 + return oldhandler;
1.134 + } else {
1.135 + /* jvm has no relation with this signal (yet). Install the
1.136 + * the handler. */
1.137 + oldhandler = call_os_signal(sig, disp, is_sigset);
1.138 +
1.139 + signal_unlock();
1.140 + return oldhandler;
1.141 + }
1.142 +}
1.143 +
1.144 +sa_handler_t signal(int sig, sa_handler_t disp) {
1.145 + return set_signal(sig, disp, false);
1.146 +}
1.147 +
1.148 +sa_handler_t sigset(int sig, sa_handler_t disp) {
1.149 + return set_signal(sig, disp, true);
1.150 + }
1.151 +
1.152 +static int call_os_sigaction(int sig, const struct sigaction *act,
1.153 + struct sigaction *oact) {
1.154 + if (os_sigaction == NULL) {
1.155 + os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction");
1.156 + if (os_sigaction == NULL) {
1.157 + printf("%s\n", dlerror());
1.158 + exit(0);
1.159 + }
1.160 + }
1.161 + return (*os_sigaction)(sig, act, oact);
1.162 +}
1.163 +
1.164 +int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) {
1.165 + int res;
1.166 + bool sigused;
1.167 + struct sigaction oldAct;
1.168 +
1.169 + signal_lock();
1.170 +
1.171 + sigused = (sig < MAXSIGNUM) && ((MASK(sig) & jvmsigs) != 0);
1.172 + if (jvm_signal_installed && sigused) {
1.173 + /* jvm has installed its signal handler for this signal. */
1.174 + /* Save the handler. Don't really install it. */
1.175 + if (oact != NULL) {
1.176 + *oact = sact[sig];
1.177 + }
1.178 + if (act != NULL) {
1.179 + sact[sig] = *act;
1.180 + }
1.181 +
1.182 + signal_unlock();
1.183 + return 0;
1.184 + } else if (sig < MAXSIGNUM && jvm_signal_installing) {
1.185 + /* jvm is installing its signal handlers. Install the new
1.186 + * handlers and save the old ones. */
1.187 + res = call_os_sigaction(sig, act, &oldAct);
1.188 + sact[sig] = oldAct;
1.189 + if (oact != NULL) {
1.190 + *oact = oldAct;
1.191 + }
1.192 +
1.193 + /* Record the signals used by jvm */
1.194 + jvmsigs |= MASK(sig);
1.195 +
1.196 + signal_unlock();
1.197 + return res;
1.198 + } else {
1.199 + /* jvm has no relation with this signal (yet). Install the
1.200 + * the handler. */
1.201 + res = call_os_sigaction(sig, act, oact);
1.202 +
1.203 + signal_unlock();
1.204 + return res;
1.205 + }
1.206 +}
1.207 +
1.208 +/* The three functions for the jvm to call into */
1.209 +void JVM_begin_signal_setting() {
1.210 + signal_lock();
1.211 + jvm_signal_installing = true;
1.212 + tid = pthread_self();
1.213 + signal_unlock();
1.214 +}
1.215 +
1.216 +void JVM_end_signal_setting() {
1.217 + signal_lock();
1.218 + jvm_signal_installed = true;
1.219 + jvm_signal_installing = false;
1.220 + pthread_cond_broadcast(&cond);
1.221 + signal_unlock();
1.222 +}
1.223 +
1.224 +struct sigaction *JVM_get_signal_action(int sig) {
1.225 + /* Does race condition make sense here? */
1.226 + if ((MASK(sig) & jvmsigs) != 0) {
1.227 + return &sact[sig];
1.228 + }
1.229 + return NULL;
1.230 +}
