1 /* |
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2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. |
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3 * Copyright (c) 2012, 2015 SAP SE. All rights reserved. |
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4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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5 * |
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6 * This code is free software; you can redistribute it and/or modify it |
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7 * under the terms of the GNU General Public License version 2 only, as |
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8 * published by the Free Software Foundation. |
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9 * |
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10 * This code is distributed in the hope that it will be useful, but WITHOUT |
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11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 * version 2 for more details (a copy is included in the LICENSE file that |
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14 * accompanied this code). |
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15 * |
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16 * You should have received a copy of the GNU General Public License version |
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17 * 2 along with this work; if not, write to the Free Software Foundation, |
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18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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19 * |
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20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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21 * or visit www.oracle.com if you need additional information or have any |
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22 * questions. |
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23 * |
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24 */ |
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25 |
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26 /* CopyrightVersion 1.2 */ |
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27 |
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28 /* This is a special library that should be loaded before libc & |
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29 * libthread to interpose the signal handler installation functions: |
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30 * sigaction(), signal(), sigset(). |
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31 * Used for signal-chaining. See RFE 4381843. |
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32 */ |
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33 |
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34 #include <signal.h> |
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35 #include <dlfcn.h> |
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36 #include <pthread.h> |
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37 #include <stdio.h> |
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38 #include <stdlib.h> |
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39 #include <stdint.h> |
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40 #include "jni.h" |
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41 |
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42 #define bool int |
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43 #define true 1 |
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44 #define false 0 |
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45 |
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46 static struct sigaction sact[NSIG]; /* saved signal handlers */ |
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47 static sigset_t jvmsigs; /* Signals used by jvm. */ |
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48 |
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49 /* Used to synchronize the installation of signal handlers. */ |
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50 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; |
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51 static pthread_cond_t cond = PTHREAD_COND_INITIALIZER; |
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52 static pthread_t tid = 0; |
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53 |
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54 typedef void (*sa_handler_t)(int); |
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55 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); |
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56 // signal_t is already defined on AIX. |
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57 typedef sa_handler_t (*signal_like_function_t)(int, sa_handler_t); |
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58 typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *); |
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59 |
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60 static signal_like_function_t os_signal = 0; /* os's version of signal()/sigset() */ |
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61 static sigaction_t os_sigaction = 0; /* os's version of sigaction() */ |
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62 |
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63 static bool jvm_signal_installing = false; |
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64 static bool jvm_signal_installed = false; |
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65 |
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66 static void signal_lock() { |
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67 pthread_mutex_lock(&mutex); |
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68 /* When the jvm is installing its set of signal handlers, threads |
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69 * other than the jvm thread should wait. */ |
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70 if (jvm_signal_installing) { |
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71 if (tid != pthread_self()) { |
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72 pthread_cond_wait(&cond, &mutex); |
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73 } |
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74 } |
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75 } |
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76 |
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77 static void signal_unlock() { |
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78 pthread_mutex_unlock(&mutex); |
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79 } |
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80 |
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81 static sa_handler_t call_os_signal(int sig, sa_handler_t disp, |
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82 bool is_sigset) { |
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83 if (os_signal == NULL) { |
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84 if (!is_sigset) { |
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85 // Aix: call functions directly instead of dlsym'ing them. |
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86 os_signal = signal; |
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87 } else { |
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88 // Aix: call functions directly instead of dlsym'ing them. |
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89 os_signal = sigset; |
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90 } |
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91 if (os_signal == NULL) { |
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92 printf("%s\n", dlerror()); |
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93 exit(0); |
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94 } |
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95 } |
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96 return (*os_signal)(sig, disp); |
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97 } |
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98 |
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99 static void save_signal_handler(int sig, sa_handler_t disp) { |
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100 sigset_t set; |
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101 sact[sig].sa_handler = disp; |
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102 sigemptyset(&set); |
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103 sact[sig].sa_mask = set; |
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104 sact[sig].sa_flags = 0; |
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105 } |
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106 |
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107 static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) { |
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108 sa_handler_t oldhandler; |
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109 bool sigused; |
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110 |
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111 signal_lock(); |
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112 |
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113 sigused = sigismember(&jvmsigs, sig); |
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114 if (jvm_signal_installed && sigused) { |
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115 /* jvm has installed its signal handler for this signal. */ |
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116 /* Save the handler. Don't really install it. */ |
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117 oldhandler = sact[sig].sa_handler; |
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118 save_signal_handler(sig, disp); |
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119 |
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120 signal_unlock(); |
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121 return oldhandler; |
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122 } else if (jvm_signal_installing) { |
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123 /* jvm is installing its signal handlers. Install the new |
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124 * handlers and save the old ones. jvm uses sigaction(). |
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125 * Leave the piece here just in case. */ |
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126 oldhandler = call_os_signal(sig, disp, is_sigset); |
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127 save_signal_handler(sig, oldhandler); |
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128 |
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129 /* Record the signals used by jvm */ |
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130 sigaddset(&jvmsigs, sig); |
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131 |
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132 signal_unlock(); |
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133 return oldhandler; |
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134 } else { |
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135 /* jvm has no relation with this signal (yet). Install the |
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136 * the handler. */ |
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137 oldhandler = call_os_signal(sig, disp, is_sigset); |
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138 |
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139 signal_unlock(); |
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140 return oldhandler; |
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141 } |
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142 } |
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143 |
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144 JNIEXPORT sa_handler_t JNICALL |
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145 signal(int sig, sa_handler_t disp) { |
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146 return set_signal(sig, disp, false); |
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147 } |
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148 |
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149 JNIEXPORT sa_handler_t JNICALL |
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150 sigset(int sig, sa_handler_t disp) { |
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151 return set_signal(sig, disp, true); |
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152 } |
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153 |
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154 static int call_os_sigaction(int sig, const struct sigaction *act, |
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155 struct sigaction *oact) { |
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156 if (os_sigaction == NULL) { |
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157 // Aix: call functions directly instead of dlsym'ing them. |
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158 os_sigaction = sigaction; |
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159 if (os_sigaction == NULL) { |
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160 printf("%s\n", dlerror()); |
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161 exit(0); |
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162 } |
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163 } |
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164 return (*os_sigaction)(sig, act, oact); |
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165 } |
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166 |
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167 JNIEXPORT int JNICALL |
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168 sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { |
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169 int res; |
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170 bool sigused; |
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171 struct sigaction oldAct; |
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172 |
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173 signal_lock(); |
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174 |
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175 sigused = sigismember(&jvmsigs, sig); |
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176 if (jvm_signal_installed && sigused) { |
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177 /* jvm has installed its signal handler for this signal. */ |
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178 /* Save the handler. Don't really install it. */ |
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179 if (oact != NULL) { |
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180 *oact = sact[sig]; |
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181 } |
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182 if (act != NULL) { |
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183 sact[sig] = *act; |
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184 } |
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185 |
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186 signal_unlock(); |
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187 return 0; |
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188 } else if (jvm_signal_installing) { |
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189 /* jvm is installing its signal handlers. Install the new |
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190 * handlers and save the old ones. */ |
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191 res = call_os_sigaction(sig, act, &oldAct); |
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192 sact[sig] = oldAct; |
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193 if (oact != NULL) { |
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194 *oact = oldAct; |
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195 } |
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196 |
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197 /* Record the signals used by jvm. */ |
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198 sigaddset(&jvmsigs, sig); |
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199 |
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200 signal_unlock(); |
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201 return res; |
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202 } else { |
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203 /* jvm has no relation with this signal (yet). Install the |
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204 * the handler. */ |
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205 res = call_os_sigaction(sig, act, oact); |
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206 |
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207 signal_unlock(); |
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208 return res; |
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209 } |
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210 } |
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211 |
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212 /* The three functions for the jvm to call into. */ |
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213 JNIEXPORT void JNICALL |
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214 JVM_begin_signal_setting() { |
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215 signal_lock(); |
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216 sigemptyset(&jvmsigs); |
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217 jvm_signal_installing = true; |
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218 tid = pthread_self(); |
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219 signal_unlock(); |
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220 } |
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221 |
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222 JNIEXPORT void JNICALL |
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223 JVM_end_signal_setting() { |
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224 signal_lock(); |
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225 jvm_signal_installed = true; |
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226 jvm_signal_installing = false; |
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227 pthread_cond_broadcast(&cond); |
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228 signal_unlock(); |
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229 } |
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230 |
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231 JNIEXPORT struct sigaction * JNICALL |
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232 JVM_get_signal_action(int sig) { |
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233 /* Does race condition make sense here? */ |
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234 if (sigismember(&jvmsigs, sig)) { |
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235 return &sact[sig]; |
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236 } |
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237 return NULL; |
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238 } |
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