1 /* 2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 /* CopyrightVersion 1.2 */ 26 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 */ 32 33 #include <signal.h> 34 #include <dlfcn.h> 35 #include <pthread.h> 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <stdint.h> 39 40 #define bool int 41 #define true 1 42 #define false 0 43 44 #define MASK(sig) ((uint64_t)1 << (sig-1)) // 0 is not a signal. 45 // Check whether all signals fit into jvmsigs. -1 as MASK shifts by -1. 46 #if (64 < NSIG-1) 47 #error "Not all signals can be encoded in jvmsigs. Adapt its type!" 48 #endif 49 static struct sigaction sact[NSIG]; /* saved signal handlers */ 50 static uint64_t jvmsigs = 0; /* signals used by jvm */ 51 52 /* used to synchronize the installation of signal handlers */ 53 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; 54 static pthread_cond_t cond = PTHREAD_COND_INITIALIZER; 55 static pthread_t tid = 0; 56 57 typedef void (*sa_handler_t)(int); 58 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 59 typedef sa_handler_t (*signal_t)(int, sa_handler_t); 60 typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *); 61 62 static signal_t os_signal = 0; /* os's version of signal()/sigset() */ 63 static sigaction_t os_sigaction = 0; /* os's version of sigaction() */ 64 65 static bool jvm_signal_installing = false; 66 static bool jvm_signal_installed = false; 67 68 static void signal_lock() { 69 pthread_mutex_lock(&mutex); 70 /* When the jvm is installing its set of signal handlers, threads 71 * other than the jvm thread should wait */ 72 if (jvm_signal_installing) { 73 if (tid != pthread_self()) { 74 pthread_cond_wait(&cond, &mutex); 75 } 76 } 77 } 78 79 static void signal_unlock() { 80 pthread_mutex_unlock(&mutex); 81 } 82 83 static sa_handler_t call_os_signal(int sig, sa_handler_t disp, 84 bool is_sigset) { 85 if (os_signal == NULL) { 86 if (!is_sigset) { 87 os_signal = (signal_t)dlsym(RTLD_NEXT, "signal"); 88 } else { 89 os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset"); 90 } 91 if (os_signal == NULL) { 92 printf("%s\n", dlerror()); 93 exit(0); 94 } 95 } 96 return (*os_signal)(sig, disp); 97 } 98 99 static void save_signal_handler(int sig, sa_handler_t disp) { 100 sigset_t set; 101 sact[sig].sa_handler = disp; 102 sigemptyset(&set); 103 sact[sig].sa_mask = set; 104 sact[sig].sa_flags = 0; 105 } 106 107 static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) { 108 sa_handler_t oldhandler; 109 bool sigused; 110 111 signal_lock(); 112 113 sigused = (sig < NSIG) && ((MASK(sig) & jvmsigs) != 0); 114 if (jvm_signal_installed && sigused) { 115 /* jvm has installed its signal handler for this signal. */ 116 /* Save the handler. Don't really install it. */ 117 oldhandler = sact[sig].sa_handler; 118 save_signal_handler(sig, disp); 119 120 signal_unlock(); 121 return oldhandler; 122 } else if (sig < NSIG && jvm_signal_installing) { 123 /* jvm is installing its signal handlers. Install the new 124 * handlers and save the old ones. jvm uses sigaction(). 125 * Leave the piece here just in case. */ 126 oldhandler = call_os_signal(sig, disp, is_sigset); 127 save_signal_handler(sig, oldhandler); 128 129 /* Record the signals used by jvm */ 130 jvmsigs |= MASK(sig); 131 132 signal_unlock(); 133 return oldhandler; 134 } else { 135 /* jvm has no relation with this signal (yet). Install the 136 * the handler. */ 137 oldhandler = call_os_signal(sig, disp, is_sigset); 138 139 signal_unlock(); 140 return oldhandler; 141 } 142 } 143 144 sa_handler_t signal(int sig, sa_handler_t disp) { 145 return set_signal(sig, disp, false); 146 } 147 148 sa_handler_t sigset(int sig, sa_handler_t disp) { 149 return set_signal(sig, disp, true); 150 } 151 152 static int call_os_sigaction(int sig, const struct sigaction *act, 153 struct sigaction *oact) { 154 if (os_sigaction == NULL) { 155 os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction"); 156 if (os_sigaction == NULL) { 157 printf("%s\n", dlerror()); 158 exit(0); 159 } 160 } 161 return (*os_sigaction)(sig, act, oact); 162 } 163 164 int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { 165 int res; 166 bool sigused; 167 struct sigaction oldAct; 168 169 signal_lock(); 170 171 sigused = (sig < NSIG) && ((MASK(sig) & jvmsigs) != 0); 172 if (jvm_signal_installed && sigused) { 173 /* jvm has installed its signal handler for this signal. */ 174 /* Save the handler. Don't really install it. */ 175 if (oact != NULL) { 176 *oact = sact[sig]; 177 } 178 if (act != NULL) { 179 sact[sig] = *act; 180 } 181 182 signal_unlock(); 183 return 0; 184 } else if (sig < NSIG && jvm_signal_installing) { 185 /* jvm is installing its signal handlers. Install the new 186 * handlers and save the old ones. */ 187 res = call_os_sigaction(sig, act, &oldAct); 188 sact[sig] = oldAct; 189 if (oact != NULL) { 190 *oact = oldAct; 191 } 192 193 /* Record the signals used by jvm */ 194 jvmsigs |= MASK(sig); 195 196 signal_unlock(); 197 return res; 198 } else { 199 /* jvm has no relation with this signal (yet). Install the 200 * the handler. */ 201 res = call_os_sigaction(sig, act, oact); 202 203 signal_unlock(); 204 return res; 205 } 206 } 207 208 /* The three functions for the jvm to call into */ 209 void JVM_begin_signal_setting() { 210 signal_lock(); 211 jvm_signal_installing = true; 212 tid = pthread_self(); 213 signal_unlock(); 214 } 215 216 void JVM_end_signal_setting() { 217 signal_lock(); 218 jvm_signal_installed = true; 219 jvm_signal_installing = false; 220 pthread_cond_broadcast(&cond); 221 signal_unlock(); 222 } 223 224 struct sigaction *JVM_get_signal_action(int sig) { 225 /* Does race condition make sense here? */ 226 if ((MASK(sig) & jvmsigs) != 0) { 227 return &sact[sig]; 228 } 229 return NULL; 230 } | 1 /* 2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2012, 2015 SAP SE. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 /* This is a special library that should be loaded before libc & 27 * libthread to interpose the signal handler installation functions: 28 * sigaction(), signal(), sigset(). 29 * Used for signal-chaining. See RFE 4381843. 30 */ 31 32 #include <dlfcn.h> 33 #include <signal.h> 34 #include <stdio.h> 35 #include <stdlib.h> 36 37 #ifdef SOLARIS 38 #include <synch.h> 39 #include <thread.h> 40 #else 41 #include <pthread.h> 42 #endif 43 44 #if (__STDC_VERSION__ >= 199901L) 45 #include <stdbool.h> 46 #else 47 #define bool int 48 #define true 1 49 #define false 0 50 #endif 51 52 #ifndef NSIG 53 #define NSIG SIGRTMAX 54 #endif 55 56 static struct sigaction sact[NSIG]; /* saved signal handlers */ 57 static sigset_t jvmsigs; /* Signals used by jvm. */ 58 static __thread bool reentry = false; /* prevent reentry deadlock (per-thread) */ 59 60 /* Used to synchronize the installation of signal handlers. */ 61 #ifdef SOLARIS 62 static mutex_t mutex = DEFAULTMUTEX; 63 static cond_t cond = DEFAULTCV; 64 static thread_t tid = 0; 65 #else 66 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; 67 static pthread_cond_t cond = PTHREAD_COND_INITIALIZER; 68 static pthread_t tid = 0; 69 #endif 70 71 typedef void (*sa_handler_t)(int); 72 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); 73 typedef sa_handler_t (*signal_function_t)(int, sa_handler_t); 74 typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *); 75 76 static signal_function_t os_signal = 0; /* os's version of signal()/sigset() */ 77 static sigaction_t os_sigaction = 0; /* os's version of sigaction() */ 78 79 static bool jvm_signal_installing = false; 80 static bool jvm_signal_installed = false; 81 82 static void signal_lock() { 83 #ifdef SOLARIS 84 mutex_lock(&mutex); 85 #else 86 pthread_mutex_lock(&mutex); 87 #endif 88 /* When the jvm is installing its set of signal handlers, threads 89 * other than the jvm thread should wait. */ 90 if (jvm_signal_installing) { 91 #ifdef SOLARIS 92 if (tid != thr_self()) { 93 cond_wait(&cond, &mutex); 94 } 95 #else 96 if (tid != pthread_self()) { 97 pthread_cond_wait(&cond, &mutex); 98 } 99 #endif 100 } 101 } 102 103 static void signal_unlock() { 104 #ifdef SOLARIS 105 mutex_unlock(&mutex); 106 #else 107 pthread_mutex_unlock(&mutex); 108 #endif 109 } 110 111 static sa_handler_t call_os_signal(int sig, sa_handler_t disp, 112 bool is_sigset) { 113 sa_handler_t res; 114 115 if (os_signal == NULL) { 116 if (!is_sigset) { 117 #ifdef AIX 118 os_signal = signal; 119 #else 120 os_signal = (signal_function_t)dlsym(RTLD_NEXT, "signal"); 121 #endif 122 } else { 123 #ifdef AIX 124 os_signal = sigset; 125 #else 126 os_signal = (signal_function_t)dlsym(RTLD_NEXT, "sigset"); 127 #endif 128 } 129 if (os_signal == NULL) { 130 printf("%s\n", dlerror()); 131 exit(0); 132 } 133 } 134 /* On some OSes like macosx, the OS implementation of signal calls sigaction. 135 * Make sure we do not deadlock with ourself. (See JDK-8072147). */ 136 reentry = true; 137 res = (*os_signal)(sig, disp); 138 reentry = false; 139 return res; 140 } 141 142 static void save_signal_handler(int sig, sa_handler_t disp, bool is_sigset) { 143 sigset_t set; 144 sact[sig].sa_handler = disp; 145 sigemptyset(&set); 146 sact[sig].sa_mask = set; 147 if (!is_sigset) { 148 #ifdef SOLARIS 149 sact[sig].sa_flags = SA_NODEFER; 150 if (sig != SIGILL && sig != SIGTRAP && sig != SIGPWR) { 151 sact[sig].sa_flags |= SA_RESETHAND; 152 } 153 #else 154 sact[sig].sa_flags = 0; 155 #endif 156 } else { 157 sact[sig].sa_flags = 0; 158 } 159 } 160 161 static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) { 162 sa_handler_t oldhandler; 163 bool sigused; 164 bool sigblocked; 165 166 signal_lock(); 167 168 sigused = sigismember(&jvmsigs, sig); 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 (is_sigset) { 173 sigblocked = sigismember(&(sact[sig].sa_mask), sig); 174 } 175 oldhandler = sact[sig].sa_handler; 176 save_signal_handler(sig, disp, is_sigset); 177 178 #ifdef SOLARIS 179 if (is_sigset && sigblocked) { 180 /* We won't honor the SIG_HOLD request to change the signal mask */ 181 oldhandler = SIG_HOLD; 182 } 183 #endif 184 185 signal_unlock(); 186 return oldhandler; 187 } else if (jvm_signal_installing) { 188 /* jvm is installing its signal handlers. Install the new 189 * handlers and save the old ones. jvm uses sigaction(). 190 * Leave the piece here just in case. */ 191 oldhandler = call_os_signal(sig, disp, is_sigset); 192 save_signal_handler(sig, oldhandler, is_sigset); 193 194 /* Record the signals used by jvm */ 195 sigaddset(&jvmsigs, sig); 196 197 signal_unlock(); 198 return oldhandler; 199 } else { 200 /* jvm has no relation with this signal (yet). Install the 201 * the handler. */ 202 oldhandler = call_os_signal(sig, disp, is_sigset); 203 204 signal_unlock(); 205 return oldhandler; 206 } 207 } 208 209 sa_handler_t signal(int sig, sa_handler_t disp) { 210 return set_signal(sig, disp, false); 211 } 212 213 sa_handler_t sigset(int sig, sa_handler_t disp) { 214 #ifdef _ALLBSD_SOURCE 215 printf("sigset() is not supported by BSD"); 216 exit(0); 217 #else 218 return set_signal(sig, disp, true); 219 #endif 220 } 221 222 static int call_os_sigaction(int sig, const struct sigaction *act, 223 struct sigaction *oact) { 224 if (os_sigaction == NULL) { 225 #ifdef AIX 226 os_sigaction = sigaction; 227 #else 228 os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction"); 229 #endif 230 if (os_sigaction == NULL) { 231 printf("%s\n", dlerror()); 232 exit(0); 233 } 234 } 235 return (*os_sigaction)(sig, act, oact); 236 } 237 238 int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { 239 int res; 240 bool sigused; 241 struct sigaction oldAct; 242 243 if (reentry) { 244 return call_os_sigaction(sig, act, oact); 245 } 246 247 signal_lock(); 248 249 sigused = sigismember(&jvmsigs, sig); 250 if (jvm_signal_installed && sigused) { 251 /* jvm has installed its signal handler for this signal. */ 252 /* Save the handler. Don't really install it. */ 253 if (oact != NULL) { 254 *oact = sact[sig]; 255 } 256 if (act != NULL) { 257 sact[sig] = *act; 258 } 259 260 signal_unlock(); 261 return 0; 262 } else if (jvm_signal_installing) { 263 /* jvm is installing its signal handlers. Install the new 264 * handlers and save the old ones. */ 265 res = call_os_sigaction(sig, act, &oldAct); 266 sact[sig] = oldAct; 267 if (oact != NULL) { 268 *oact = oldAct; 269 } 270 271 /* Record the signals used by jvm. */ 272 sigaddset(&jvmsigs, sig); 273 274 signal_unlock(); 275 return res; 276 } else { 277 /* jvm has no relation with this signal (yet). Install the 278 * the handler. */ 279 res = call_os_sigaction(sig, act, oact); 280 281 signal_unlock(); 282 return res; 283 } 284 } 285 286 /* The three functions for the jvm to call into. */ 287 void JVM_begin_signal_setting() { 288 signal_lock(); 289 sigemptyset(&jvmsigs); 290 jvm_signal_installing = true; 291 #ifdef SOLARIS 292 tid = thr_self(); 293 #else 294 tid = pthread_self(); 295 #endif 296 signal_unlock(); 297 } 298 299 void JVM_end_signal_setting() { 300 signal_lock(); 301 jvm_signal_installed = true; 302 jvm_signal_installing = false; 303 #ifdef SOLARIS 304 cond_broadcast(&cond); 305 #else 306 pthread_cond_broadcast(&cond); 307 #endif 308 signal_unlock(); 309 } 310 311 struct sigaction *JVM_get_signal_action(int sig) { 312 /* Does race condition make sense here? */ 313 if (sigismember(&jvmsigs, sig)) { 314 return &sact[sig]; 315 } 316 return NULL; 317 } |