1 /*
   2  * Copyright (c) 1999, 2011, 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 #include "precompiled.hpp"
  26 #include "prims/jvm.h"
  27 #include "runtime/interfaceSupport.hpp"
  28 #include "runtime/osThread.hpp"
  29 
  30 #include <signal.h>
  31 
  32 
  33 // sun.misc.Signal ///////////////////////////////////////////////////////////
  34 // Signal code is mostly copied from classic vm, signals_md.c   1.4 98/08/23
  35 /*
  36  * This function is included primarily as a debugging aid. If Java is
  37  * running in a console window, then pressing <CTRL-\\> will cause
  38  * the current state of all active threads and monitors to be written
  39  * to the console window.
  40  */
  41 
  42 JVM_ENTRY_NO_ENV(void*, JVM_RegisterSignal(jint sig, void* handler))
  43   // Copied from classic vm
  44   // signals_md.c       1.4 98/08/23
  45   void* newHandler = handler == (void *)2
  46                    ? os::user_handler()
  47                    : handler;
  48   switch (sig) {
  49     /* The following are already used by the VM. */
  50     case INTERRUPT_SIGNAL:
  51     case SIGFPE:
  52     case SIGILL:
  53     case SIGSEGV:
  54 
  55     /* The following signal is used by the VM to dump thread stacks unless
  56        ReduceSignalUsage is set, in which case the user is allowed to set
  57        his own _native_ handler for this signal; thus, in either case,
  58        we do not allow JVM_RegisterSignal to change the handler. */
  59     case BREAK_SIGNAL:
  60       return (void *)-1;
  61 
  62     /* The following signals are used for Shutdown Hooks support. However, if
  63        ReduceSignalUsage (-Xrs) is set, Shutdown Hooks must be invoked via
  64        System.exit(), Java is not allowed to use these signals, and the the
  65        user is allowed to set his own _native_ handler for these signals and
  66        invoke System.exit() as needed. Terminator.setup() is avoiding
  67        registration of these signals when -Xrs is present.
  68        - If the HUP signal is ignored (from the nohup) command, then Java
  69          is not allowed to use this signal.
  70      */
  71 
  72     case SHUTDOWN1_SIGNAL:
  73     case SHUTDOWN2_SIGNAL:
  74     case SHUTDOWN3_SIGNAL:
  75       if (ReduceSignalUsage) return (void*)-1;
  76       if (os::Bsd::is_sig_ignored(sig)) return (void*)1;
  77   }
  78 
  79   void* oldHandler = os::signal(sig, newHandler);
  80   if (oldHandler == os::user_handler()) {
  81       return (void *)2;
  82   } else {
  83       return oldHandler;
  84   }
  85 JVM_END
  86 
  87 
  88 JVM_ENTRY_NO_ENV(jboolean, JVM_RaiseSignal(jint sig))
  89   if (ReduceSignalUsage) {
  90     // do not allow SHUTDOWN1_SIGNAL,SHUTDOWN2_SIGNAL,SHUTDOWN3_SIGNAL,
  91     // BREAK_SIGNAL to be raised when ReduceSignalUsage is set, since
  92     // no handler for them is actually registered in JVM or via
  93     // JVM_RegisterSignal.
  94     if (sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
  95         sig == SHUTDOWN3_SIGNAL || sig == BREAK_SIGNAL) {
  96       return JNI_FALSE;
  97     }
  98   }
  99   else if ((sig == SHUTDOWN1_SIGNAL || sig == SHUTDOWN2_SIGNAL ||
 100             sig == SHUTDOWN3_SIGNAL) && os::Bsd::is_sig_ignored(sig)) {
 101     // do not allow SHUTDOWN1_SIGNAL to be raised when SHUTDOWN1_SIGNAL
 102     // is ignored, since no handler for them is actually registered in JVM
 103     // or via JVM_RegisterSignal.
 104     // This also applies for SHUTDOWN2_SIGNAL and SHUTDOWN3_SIGNAL
 105     return JNI_FALSE;
 106   }
 107 
 108   os::signal_raise(sig);
 109   return JNI_TRUE;
 110 JVM_END
 111 
 112 /*
 113   All the defined signal names for Bsd.
 114 
 115   NOTE that not all of these names are accepted by our Java implementation
 116 
 117   Via an existing claim by the VM, sigaction restrictions, or
 118   the "rules of Unix" some of these names will be rejected at runtime.
 119   For example the VM sets up to handle USR1, sigaction returns EINVAL for
 120   STOP, and Bsd simply doesn't allow catching of KILL.
 121 
 122   Here are the names currently accepted by a user of sun.misc.Signal with
 123   1.4.1 (ignoring potential interaction with use of chaining, etc):
 124 
 125     HUP, INT, TRAP, ABRT, IOT, BUS, USR2, PIPE, ALRM, TERM, STKFLT,
 126     CLD, CHLD, CONT, TSTP, TTIN, TTOU, URG, XCPU, XFSZ, VTALRM, PROF,
 127     WINCH, POLL, IO, PWR, SYS
 128 
 129 */
 130 
 131 struct siglabel {
 132   const char *name;
 133   int   number;
 134 };
 135 
 136 struct siglabel siglabels[] = {
 137   /* derived from /usr/include/bits/signum.h on RH7.2 */
 138    "HUP",       SIGHUP,         /* Hangup (POSIX).  */
 139   "INT",        SIGINT,         /* Interrupt (ANSI).  */
 140   "QUIT",       SIGQUIT,        /* Quit (POSIX).  */
 141   "ILL",        SIGILL,         /* Illegal instruction (ANSI).  */
 142   "TRAP",       SIGTRAP,        /* Trace trap (POSIX).  */
 143   "ABRT",       SIGABRT,        /* Abort (ANSI).  */
 144   "EMT",        SIGEMT,         /* EMT trap  */
 145   "FPE",        SIGFPE,         /* Floating-point exception (ANSI).  */
 146   "KILL",       SIGKILL,        /* Kill, unblockable (POSIX).  */
 147   "BUS",        SIGBUS,         /* BUS error (4.2 BSD).  */
 148   "SEGV",       SIGSEGV,        /* Segmentation violation (ANSI).  */
 149   "SYS",        SIGSYS,         /* Bad system call. Only on some Bsden! */
 150   "PIPE",       SIGPIPE,        /* Broken pipe (POSIX).  */
 151   "ALRM",       SIGALRM,        /* Alarm clock (POSIX).  */
 152   "TERM",       SIGTERM,        /* Termination (ANSI).  */
 153   "URG",        SIGURG,         /* Urgent condition on socket (4.2 BSD).  */
 154   "STOP",       SIGSTOP,        /* Stop, unblockable (POSIX).  */
 155   "TSTP",       SIGTSTP,        /* Keyboard stop (POSIX).  */
 156   "CONT",       SIGCONT,        /* Continue (POSIX).  */
 157   "CHLD",       SIGCHLD,        /* Child status has changed (POSIX).  */
 158   "TTIN",       SIGTTIN,        /* Background read from tty (POSIX).  */
 159   "TTOU",       SIGTTOU,        /* Background write to tty (POSIX).  */
 160   "IO",         SIGIO,          /* I/O now possible (4.2 BSD).  */
 161   "XCPU",       SIGXCPU,        /* CPU limit exceeded (4.2 BSD).  */
 162   "XFSZ",       SIGXFSZ,        /* File size limit exceeded (4.2 BSD).  */
 163   "VTALRM",     SIGVTALRM,      /* Virtual alarm clock (4.2 BSD).  */
 164   "PROF",       SIGPROF,        /* Profiling alarm clock (4.2 BSD).  */
 165   "WINCH",      SIGWINCH,       /* Window size change (4.3 BSD, Sun).  */
 166   "INFO",       SIGINFO,        /* Information request.  */
 167   "USR1",       SIGUSR1,        /* User-defined signal 1 (POSIX).  */
 168   "USR2",       SIGUSR2         /* User-defined signal 2 (POSIX).  */
 169   };
 170 
 171 JVM_ENTRY_NO_ENV(jint, JVM_FindSignal(const char *name))
 172 
 173   /* find and return the named signal's number */
 174 
 175   for(uint i=0; i<ARRAY_SIZE(siglabels); i++)
 176     if(!strcmp(name, siglabels[i].name))
 177       return siglabels[i].number;
 178 
 179   return -1;
 180 
 181 JVM_END
 182 
 183 // used by os::exception_name()
 184 extern bool signal_name(int signo, char* buf, size_t len) {
 185   for(uint i = 0; i < ARRAY_SIZE(siglabels); i++) {
 186     if (signo == siglabels[i].number) {
 187       jio_snprintf(buf, len, "SIG%s", siglabels[i].name);
 188       return true;
 189     }
 190   }
 191   return false;
 192 }