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src/java.base/linux/native/libjsig/jsig.c
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@@ -1,7 +1,8 @@
/*
- * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2018, 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.
@@ -20,57 +21,57 @@
* 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 <signal.h>
#include <dlfcn.h>
#include <pthread.h>
+#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
-#include <stdint.h>
-#define bool int
-#define true 1
-#define false 0
-
-#define MASK(sig) ((uint64_t)1 << (sig-1)) // 0 is not a signal.
-// Check whether all signals fit into jvmsigs. -1 as MASK shifts by -1.
-#if (64 < NSIG-1)
-#error "Not all signals can be encoded in jvmsigs. Adapt its type!"
+#if (__STDC_VERSION__ >= 199901L)
+ #include <stdbool.h>
+#else
+ #define bool int
+ #define true 1
+ #define false 0
#endif
+
static struct sigaction sact[NSIG]; /* saved signal handlers */
-static uint64_t jvmsigs = 0; /* signals used by jvm */
+static sigset_t jvmsigs; /* Signals used by jvm. */
-/* used to synchronize the installation of signal handlers */
+#ifdef MACOSX
+static __thread bool reentry = false; /* prevent reentry deadlock (per-thread) */
+#endif
+
+/* 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 *);
-typedef sa_handler_t (*signal_t)(int, sa_handler_t);
+typedef sa_handler_t (*signal_function_t)(int, sa_handler_t);
typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *);
-static signal_t os_signal = 0; /* os's version of signal()/sigset() */
+static signal_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 */
+ * other than the jvm thread should wait. */
if (jvm_signal_installing) {
if (tid != pthread_self()) {
pthread_cond_wait(&cond, &mutex);
}
}
@@ -80,56 +81,93 @@
pthread_mutex_unlock(&mutex);
}
static sa_handler_t call_os_signal(int sig, sa_handler_t disp,
bool is_sigset) {
+ sa_handler_t res;
+
if (os_signal == NULL) {
if (!is_sigset) {
- os_signal = (signal_t)dlsym(RTLD_NEXT, "signal");
+ os_signal = (signal_function_t)dlsym(RTLD_NEXT, "signal");
} else {
- os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset");
+ os_signal = (signal_function_t)dlsym(RTLD_NEXT, "sigset");
}
if (os_signal == NULL) {
printf("%s\n", dlerror());
exit(0);
}
}
- return (*os_signal)(sig, disp);
+
+#ifdef MACOSX
+ /* On macosx, the OS implementation of signal calls sigaction.
+ * Make sure we do not deadlock with ourself. (See JDK-8072147). */
+ reentry = true;
+#endif
+
+ res = (*os_signal)(sig, disp);
+
+#ifdef MACOSX
+ reentry = false;
+#endif
+
+ return res;
}
-static void save_signal_handler(int sig, sa_handler_t disp) {
+static void save_signal_handler(int sig, sa_handler_t disp, bool is_sigset) {
sigset_t set;
sact[sig].sa_handler = disp;
sigemptyset(&set);
sact[sig].sa_mask = set;
+ if (!is_sigset) {
+#ifdef SOLARIS
+ sact[sig].sa_flags = SA_NODEFER;
+ if (sig != SIGILL && sig != SIGTRAP && sig != SIGPWR) {
+ sact[sig].sa_flags |= SA_RESETHAND;
+ }
+#else
sact[sig].sa_flags = 0;
+#endif
+ } else {
+ 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;
+ bool sigblocked;
signal_lock();
- sigused = (sig < NSIG) && ((MASK(sig) & jvmsigs) != 0);
+ 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 (is_sigset) {
+ sigblocked = sigismember(&(sact[sig].sa_mask), sig);
+ }
oldhandler = sact[sig].sa_handler;
- save_signal_handler(sig, disp);
+ save_signal_handler(sig, disp, is_sigset);
+
+#ifdef SOLARIS
+ if (is_sigset && sigblocked) {
+ /* We won't honor the SIG_HOLD request to change the signal mask */
+ oldhandler = SIG_HOLD;
+ }
+#endif
signal_unlock();
return oldhandler;
- } else if (sig < NSIG && jvm_signal_installing) {
+ } 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);
+ save_signal_handler(sig, oldhandler, is_sigset);
/* Record the signals used by jvm */
- jvmsigs |= MASK(sig);
+ sigaddset(&jvmsigs, sig);
signal_unlock();
return oldhandler;
} else {
/* jvm has no relation with this signal (yet). Install the
@@ -144,12 +182,17 @@
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) {
+#ifdef _ALLBSD_SOURCE
+ printf("sigset() is not supported by BSD");
+ exit(0);
+#else
return set_signal(sig, disp, true);
- }
+#endif
+}
static int call_os_sigaction(int sig, const struct sigaction *act,
struct sigaction *oact) {
if (os_sigaction == NULL) {
os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction");
@@ -164,13 +207,19 @@
int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) {
int res;
bool sigused;
struct sigaction oldAct;
+#ifdef MACOSX
+ if (reentry) {
+ return call_os_sigaction(sig, act, oact);
+ }
+#endif
+
signal_lock();
- sigused = (sig < NSIG) && ((MASK(sig) & jvmsigs) != 0);
+ 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];
@@ -179,21 +228,21 @@
sact[sig] = *act;
}
signal_unlock();
return 0;
- } else if (sig < NSIG && jvm_signal_installing) {
+ } 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 */
- jvmsigs |= MASK(sig);
+ /* Record the signals used by jvm. */
+ sigaddset(&jvmsigs, sig);
signal_unlock();
return res;
} else {
/* jvm has no relation with this signal (yet). Install the
@@ -203,13 +252,14 @@
signal_unlock();
return res;
}
}
-/* The three functions for the jvm to call into */
+/* 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();
}
@@ -221,10 +271,10 @@
signal_unlock();
}
struct sigaction *JVM_get_signal_action(int sig) {
/* Does race condition make sense here? */
- if ((MASK(sig) & jvmsigs) != 0) {
+ if (sigismember(&jvmsigs, sig)) {
return &sact[sig];
}
return NULL;
}
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