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src/os/linux/vm/jsig.c@bbfbe9b06038 (annotated)

src/os/linux/vm/jsig.c

Thu, 13 Mar 2014 14:57:01 -0700

author

kvn

date

Thu, 13 Mar 2014 14:57:01 -0700

changeset 6513

bbfbe9b06038

parent 5420

732af649bc3a

child 6876

710a3c8b516e

permissions

-rw-r--r--

Merge

duke@435	1	/*
ccheung@5420	2	* Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	/* CopyrightVersion 1.2 */
duke@435	26
duke@435	27	/* This is a special library that should be loaded before libc &
duke@435	28	* libthread to interpose the signal handler installation functions:
duke@435	29	* sigaction(), signal(), sigset().
duke@435	30	* Used for signal-chaining. See RFE 4381843.
duke@435	31	*/
duke@435	32
duke@435	33	#include <signal.h>
duke@435	34	#include <dlfcn.h>
duke@435	35	#include <pthread.h>
duke@435	36	#include <stdio.h>
duke@435	37	#include <stdlib.h>
duke@435	38
duke@435	39	#define bool int
duke@435	40	#define true 1
duke@435	41	#define false 0
duke@435	42
duke@435	43	#define MAXSIGNUM 32
duke@435	44	#define MASK(sig) ((unsigned int)1 << sig)
duke@435	45
duke@435	46	static struct sigaction sact[MAXSIGNUM]; /* saved signal handlers */
duke@435	47	static unsigned int jvmsigs = 0; /* signals used by jvm */
duke@435	48
duke@435	49	/* used to synchronize the installation of signal handlers */
duke@435	50	static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
duke@435	51	static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
duke@435	52	static pthread_t tid = 0;
duke@435	53
duke@435	54	typedef void (*sa_handler_t)(int);
duke@435	55	typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
duke@435	56	typedef sa_handler_t (*signal_t)(int, sa_handler_t);
duke@435	57	typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *);
duke@435	58
duke@435	59	static signal_t os_signal = 0; /* os's version of signal()/sigset() */
duke@435	60	static sigaction_t os_sigaction = 0; /* os's version of sigaction() */
duke@435	61
duke@435	62	static bool jvm_signal_installing = false;
duke@435	63	static bool jvm_signal_installed = false;
duke@435	64
duke@435	65	static void signal_lock() {
duke@435	66	pthread_mutex_lock(&mutex);
duke@435	67	/* When the jvm is installing its set of signal handlers, threads
duke@435	68	* other than the jvm thread should wait */
duke@435	69	if (jvm_signal_installing) {
duke@435	70	if (tid != pthread_self()) {
duke@435	71	pthread_cond_wait(&cond, &mutex);
duke@435	72	}
duke@435	73	}
duke@435	74	}
duke@435	75
duke@435	76	static void signal_unlock() {
duke@435	77	pthread_mutex_unlock(&mutex);
duke@435	78	}
duke@435	79
duke@435	80	static sa_handler_t call_os_signal(int sig, sa_handler_t disp,
duke@435	81	bool is_sigset) {
duke@435	82	if (os_signal == NULL) {
duke@435	83	if (!is_sigset) {
duke@435	84	os_signal = (signal_t)dlsym(RTLD_NEXT, "signal");
duke@435	85	} else {
duke@435	86	os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset");
duke@435	87	}
duke@435	88	if (os_signal == NULL) {
duke@435	89	printf("%s\n", dlerror());
duke@435	90	exit(0);
duke@435	91	}
duke@435	92	}
duke@435	93	return (*os_signal)(sig, disp);
duke@435	94	}
duke@435	95
duke@435	96	static void save_signal_handler(int sig, sa_handler_t disp) {
duke@435	97	sigset_t set;
duke@435	98	sact[sig].sa_handler = disp;
duke@435	99	sigemptyset(&set);
duke@435	100	sact[sig].sa_mask = set;
duke@435	101	sact[sig].sa_flags = 0;
duke@435	102	}
duke@435	103
duke@435	104	static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) {
duke@435	105	sa_handler_t oldhandler;
duke@435	106	bool sigused;
duke@435	107
duke@435	108	signal_lock();
duke@435	109
ccheung@5420	110	sigused = (sig < MAXSIGNUM) && ((MASK(sig) & jvmsigs) != 0);
duke@435	111	if (jvm_signal_installed && sigused) {
duke@435	112	/* jvm has installed its signal handler for this signal. */
duke@435	113	/* Save the handler. Don't really install it. */
duke@435	114	oldhandler = sact[sig].sa_handler;
duke@435	115	save_signal_handler(sig, disp);
duke@435	116
duke@435	117	signal_unlock();
duke@435	118	return oldhandler;
ccheung@5420	119	} else if (sig < MAXSIGNUM && jvm_signal_installing) {
duke@435	120	/* jvm is installing its signal handlers. Install the new
duke@435	121	* handlers and save the old ones. jvm uses sigaction().
duke@435	122	* Leave the piece here just in case. */
duke@435	123	oldhandler = call_os_signal(sig, disp, is_sigset);
duke@435	124	save_signal_handler(sig, oldhandler);
duke@435	125
duke@435	126	/* Record the signals used by jvm */
duke@435	127	jvmsigs |= MASK(sig);
duke@435	128
duke@435	129	signal_unlock();
duke@435	130	return oldhandler;
duke@435	131	} else {
duke@435	132	/* jvm has no relation with this signal (yet). Install the
duke@435	133	* the handler. */
duke@435	134	oldhandler = call_os_signal(sig, disp, is_sigset);
duke@435	135
duke@435	136	signal_unlock();
duke@435	137	return oldhandler;
duke@435	138	}
duke@435	139	}
duke@435	140
duke@435	141	sa_handler_t signal(int sig, sa_handler_t disp) {
duke@435	142	return set_signal(sig, disp, false);
duke@435	143	}
duke@435	144
duke@435	145	sa_handler_t sigset(int sig, sa_handler_t disp) {
duke@435	146	return set_signal(sig, disp, true);
duke@435	147	}
duke@435	148
duke@435	149	static int call_os_sigaction(int sig, const struct sigaction *act,
duke@435	150	struct sigaction *oact) {
duke@435	151	if (os_sigaction == NULL) {
duke@435	152	os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction");
duke@435	153	if (os_sigaction == NULL) {
duke@435	154	printf("%s\n", dlerror());
duke@435	155	exit(0);
duke@435	156	}
duke@435	157	}
duke@435	158	return (*os_sigaction)(sig, act, oact);
duke@435	159	}
duke@435	160
duke@435	161	int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) {
duke@435	162	int res;
duke@435	163	bool sigused;
duke@435	164	struct sigaction oldAct;
duke@435	165
duke@435	166	signal_lock();
duke@435	167
ccheung@5420	168	sigused = (sig < MAXSIGNUM) && ((MASK(sig) & jvmsigs) != 0);
duke@435	169	if (jvm_signal_installed && sigused) {
duke@435	170	/* jvm has installed its signal handler for this signal. */
duke@435	171	/* Save the handler. Don't really install it. */
duke@435	172	if (oact != NULL) {
duke@435	173	*oact = sact[sig];
duke@435	174	}
duke@435	175	if (act != NULL) {
duke@435	176	sact[sig] = *act;
duke@435	177	}
duke@435	178
duke@435	179	signal_unlock();
duke@435	180	return 0;
ccheung@5420	181	} else if (sig < MAXSIGNUM && jvm_signal_installing) {
duke@435	182	/* jvm is installing its signal handlers. Install the new
duke@435	183	* handlers and save the old ones. */
duke@435	184	res = call_os_sigaction(sig, act, &oldAct);
duke@435	185	sact[sig] = oldAct;
duke@435	186	if (oact != NULL) {
duke@435	187	*oact = oldAct;
duke@435	188	}
duke@435	189
duke@435	190	/* Record the signals used by jvm */
duke@435	191	jvmsigs |= MASK(sig);
duke@435	192
duke@435	193	signal_unlock();
duke@435	194	return res;
duke@435	195	} else {
duke@435	196	/* jvm has no relation with this signal (yet). Install the
duke@435	197	* the handler. */
duke@435	198	res = call_os_sigaction(sig, act, oact);
duke@435	199
duke@435	200	signal_unlock();
duke@435	201	return res;
duke@435	202	}
duke@435	203	}
duke@435	204
duke@435	205	/* The three functions for the jvm to call into */
duke@435	206	void JVM_begin_signal_setting() {
duke@435	207	signal_lock();
duke@435	208	jvm_signal_installing = true;
duke@435	209	tid = pthread_self();
duke@435	210	signal_unlock();
duke@435	211	}
duke@435	212
duke@435	213	void JVM_end_signal_setting() {
duke@435	214	signal_lock();
duke@435	215	jvm_signal_installed = true;
duke@435	216	jvm_signal_installing = false;
duke@435	217	pthread_cond_broadcast(&cond);
duke@435	218	signal_unlock();
duke@435	219	}
duke@435	220
duke@435	221	struct sigaction *JVM_get_signal_action(int sig) {
duke@435	222	/* Does race condition make sense here? */
duke@435	223	if ((MASK(sig) & jvmsigs) != 0) {
duke@435	224	return &sact[sig];
duke@435	225	}
duke@435	226	return NULL;
duke@435	227	}