/* * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012, 2015 SAP SE. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ /* CopyrightVersion 1.2 */ /* This is a special library that should be loaded before libc & * libthread to interpose the signal handler installation functions: * sigaction(), signal(), sigset(). * Used for signal-chaining. See RFE 4381843. */ #include #include #include #include #include #include #define bool int #define true 1 #define false 0 static struct sigaction sact[NSIG]; /* saved signal handlers */ static sigset_t jvmsigs; /* Signals used by jvm. */ /* Used to synchronize the installation of signal handlers. */ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; static pthread_cond_t cond = PTHREAD_COND_INITIALIZER; static pthread_t tid = 0; typedef void (*sa_handler_t)(int); typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); // signal_t is already defined on AIX. typedef sa_handler_t (*signal_like_function_t)(int, sa_handler_t); typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *); static signal_like_function_t os_signal = 0; /* os's version of signal()/sigset() */ static sigaction_t os_sigaction = 0; /* os's version of sigaction() */ static bool jvm_signal_installing = false; static bool jvm_signal_installed = false; static void signal_lock() { pthread_mutex_lock(&mutex); /* When the jvm is installing its set of signal handlers, threads * other than the jvm thread should wait. */ if (jvm_signal_installing) { if (tid != pthread_self()) { pthread_cond_wait(&cond, &mutex); } } } static void signal_unlock() { pthread_mutex_unlock(&mutex); } static sa_handler_t call_os_signal(int sig, sa_handler_t disp, bool is_sigset) { if (os_signal == NULL) { if (!is_sigset) { // Aix: call functions directly instead of dlsym'ing them. os_signal = signal; } else { // Aix: call functions directly instead of dlsym'ing them. os_signal = sigset; } if (os_signal == NULL) { printf("%s\n", dlerror()); exit(0); } } return (*os_signal)(sig, disp); } static void save_signal_handler(int sig, sa_handler_t disp) { sigset_t set; sact[sig].sa_handler = disp; sigemptyset(&set); sact[sig].sa_mask = set; sact[sig].sa_flags = 0; } static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) { sa_handler_t oldhandler; bool sigused; signal_lock(); sigused = sigismember(&jvmsigs, sig); if (jvm_signal_installed && sigused) { /* jvm has installed its signal handler for this signal. */ /* Save the handler. Don't really install it. */ oldhandler = sact[sig].sa_handler; save_signal_handler(sig, disp); signal_unlock(); return oldhandler; } else if (jvm_signal_installing) { /* jvm is installing its signal handlers. Install the new * handlers and save the old ones. jvm uses sigaction(). * Leave the piece here just in case. */ oldhandler = call_os_signal(sig, disp, is_sigset); save_signal_handler(sig, oldhandler); /* Record the signals used by jvm */ sigaddset(&jvmsigs, sig); signal_unlock(); return oldhandler; } else { /* jvm has no relation with this signal (yet). Install the * the handler. */ oldhandler = call_os_signal(sig, disp, is_sigset); signal_unlock(); return oldhandler; } } sa_handler_t signal(int sig, sa_handler_t disp) { return set_signal(sig, disp, false); } sa_handler_t sigset(int sig, sa_handler_t disp) { return set_signal(sig, disp, true); } static int call_os_sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { if (os_sigaction == NULL) { // Aix: call functions directly instead of dlsym'ing them. os_sigaction = sigaction; if (os_sigaction == NULL) { printf("%s\n", dlerror()); exit(0); } } return (*os_sigaction)(sig, act, oact); } int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { int res; bool sigused; struct sigaction oldAct; signal_lock(); sigused = sigismember(&jvmsigs, sig); if (jvm_signal_installed && sigused) { /* jvm has installed its signal handler for this signal. */ /* Save the handler. Don't really install it. */ if (oact != NULL) { *oact = sact[sig]; } if (act != NULL) { sact[sig] = *act; } signal_unlock(); return 0; } else if (jvm_signal_installing) { /* jvm is installing its signal handlers. Install the new * handlers and save the old ones. */ res = call_os_sigaction(sig, act, &oldAct); sact[sig] = oldAct; if (oact != NULL) { *oact = oldAct; } /* Record the signals used by jvm. */ sigaddset(&jvmsigs, sig); signal_unlock(); return res; } else { /* jvm has no relation with this signal (yet). Install the * the handler. */ res = call_os_sigaction(sig, act, oact); signal_unlock(); return res; } } /* The three functions for the jvm to call into. */ void JVM_begin_signal_setting() { signal_lock(); sigemptyset(&jvmsigs); jvm_signal_installing = true; tid = pthread_self(); signal_unlock(); } void JVM_end_signal_setting() { signal_lock(); jvm_signal_installed = true; jvm_signal_installing = false; pthread_cond_broadcast(&cond); signal_unlock(); } struct sigaction *JVM_get_signal_action(int sig) { /* Does race condition make sense here? */ if (sigismember(&jvmsigs, sig)) { return &sact[sig]; } return NULL; }