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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
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4 -- --
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5 -- S Y S T E M . I N T E R R U P T _ M A N A G E M E N T --
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6 -- --
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7 -- B o d y --
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8 -- --
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131
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9 -- Copyright (C) 2014-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNARL is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- In particular, you can freely distribute your programs built with the --
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23 -- GNAT Pro compiler, including any required library run-time units, using --
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24 -- any licensing terms of your choosing. See the AdaCore Software License --
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25 -- for full details. --
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26 -- --
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27 -- GNARL was developed by the GNARL team at Florida State University. --
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28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- This is the Android version of this package
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33
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34 -- Make a careful study of all signals available under the OS, to see which
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35 -- need to be reserved, kept always unmasked, or kept always unmasked. Be on
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36 -- the lookout for special signals that may be used by the thread library.
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37
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38 -- Since this is a multi target file, the signal <-> exception mapping
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39 -- is simple minded. If you need a more precise and target specific
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40 -- signal handling, create a new s-intman.adb that will fit your needs.
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41
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42 -- This file assumes that:
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43
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44 -- SIGFPE, SIGILL, SIGSEGV and SIGBUS exist. They are mapped as follows:
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45 -- SIGPFE => Constraint_Error
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46 -- SIGILL => Program_Error
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47 -- SIGSEGV => Storage_Error
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48 -- SIGBUS => Storage_Error
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49
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50 -- SIGINT exists and will be kept unmasked unless the pragma
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51 -- Unreserve_All_Interrupts is specified anywhere in the application.
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52
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53 -- System.OS_Interface contains the following:
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54 -- SIGADAABORT: the signal that will be used to abort tasks.
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55 -- Unmasked: the OS specific set of signals that should be unmasked in
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56 -- all the threads. SIGADAABORT is unmasked by
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57 -- default
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58 -- Reserved: the OS specific set of signals that are reserved.
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59
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60 with System.Task_Primitives;
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61
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62 package body System.Interrupt_Management is
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63
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64 use Interfaces.C;
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65 use System.OS_Interface;
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66
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67 type Interrupt_List is array (Interrupt_ID range <>) of Interrupt_ID;
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68 Exception_Interrupts : constant Interrupt_List :=
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69 (SIGFPE, SIGILL, SIGSEGV, SIGBUS);
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70
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71 Unreserve_All_Interrupts : Interfaces.C.int;
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72 pragma Import
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73 (C, Unreserve_All_Interrupts, "__gl_unreserve_all_interrupts");
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74
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75 -----------------------
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76 -- Local Subprograms --
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77 -----------------------
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78
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79 procedure Signal_Trampoline
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80 (signo : Signal;
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81 siginfo : System.Address;
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82 ucontext : System.Address;
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83 handler : System.Address);
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84 pragma Import (C, Signal_Trampoline, "__gnat_sigtramp");
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85 -- Pass the real handler to a speical function that handles unwinding by
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86 -- skipping over the kernel signal frame (which doesn't contain any unwind
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87 -- information).
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88
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89 function State (Int : Interrupt_ID) return Character;
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90 pragma Import (C, State, "__gnat_get_interrupt_state");
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91 -- Get interrupt state. Defined in init.c The input argument is the
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92 -- interrupt number, and the result is one of the following:
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93
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94 procedure Map_Signal
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95 (signo : Signal;
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96 siginfo : System.Address;
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97 ucontext : System.Address);
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98 -- This function identifies the Ada exception to be raised using the
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99 -- information when the system received a synchronous signal.
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100
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101 ----------------
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102 -- Map_Signal --
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103 ----------------
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104
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105 procedure Map_Signal
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106 (signo : Signal;
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107 siginfo : System.Address;
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108 ucontext : System.Address)
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109 is
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110 pragma Unreferenced (siginfo);
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111 pragma Unreferenced (ucontext);
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112
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113 begin
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114 -- Check that treatment of exception propagation here is consistent with
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115 -- treatment of the abort signal in System.Task_Primitives.Operations.
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116
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117 case signo is
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118 when SIGFPE => raise Constraint_Error;
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119 when SIGILL => raise Program_Error;
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120 when SIGSEGV => raise Storage_Error;
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121 when SIGBUS => raise Storage_Error;
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122 when others => null;
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123 end case;
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124 end Map_Signal;
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125
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126 ----------------------
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127 -- Notify_Exception --
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128 ----------------------
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129
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130 User : constant Character := 'u';
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131 Runtime : constant Character := 'r';
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132 Default : constant Character := 's';
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133 -- 'n' this interrupt not set by any Interrupt_State pragma
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134 -- 'u' Interrupt_State pragma set state to User
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135 -- 'r' Interrupt_State pragma set state to Runtime
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136 -- 's' Interrupt_State pragma set state to System (use "default"
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137 -- system handler)
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138
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139 procedure Notify_Exception
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140 (signo : Signal;
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141 siginfo : System.Address;
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142 ucontext : System.Address);
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143 -- This function is the signal handler and calls a trampoline subprogram
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144 -- that adjusts the unwind information so the ARM unwinder can find it's
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145 -- way back to the context of the originating subprogram. Compare with
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146 -- __gnat_error_handler for non-tasking programs.
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147
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148 ----------------------
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149 -- Notify_Exception --
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150 ----------------------
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151
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152 Signal_Mask : aliased sigset_t;
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153 -- The set of signals handled by Notify_Exception
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154
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155 procedure Notify_Exception
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156 (signo : Signal;
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157 siginfo : System.Address;
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158 ucontext : System.Address)
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159 is
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160 Result : Interfaces.C.int;
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161
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162 begin
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163 -- With the __builtin_longjmp, the signal mask is not restored, so we
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164 -- need to restore it explicitly. ??? We don't use __builtin_longjmp
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165 -- anymore, so do we still need this? */
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166
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167 Result := pthread_sigmask (SIG_UNBLOCK, Signal_Mask'Access, null);
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168 pragma Assert (Result = 0);
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169
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170 -- Perform the necessary context adjustments prior to calling the
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171 -- trampoline subprogram with the "real" signal handler.
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172
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173 Adjust_Context_For_Raise (signo, ucontext);
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174
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175 Signal_Trampoline (signo, siginfo, ucontext, Map_Signal'Address);
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176 end Notify_Exception;
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177
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178 ----------------
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179 -- Initialize --
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180 ----------------
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181
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182 Initialized : Boolean := False;
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183
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184 procedure Initialize is
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185 act : aliased struct_sigaction;
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186 old_act : aliased struct_sigaction;
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187 Result : System.OS_Interface.int;
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188
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189 Use_Alternate_Stack : constant Boolean :=
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190 System.Task_Primitives.Alternate_Stack_Size /= 0;
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191 -- Whether to use an alternate signal stack for stack overflows
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192
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193 begin
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194 if Initialized then
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195 return;
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196 end if;
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197
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198 Initialized := True;
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199
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200 -- Need to call pthread_init very early because it is doing signal
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201 -- initializations.
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202
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203 pthread_init;
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204
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205 Abort_Task_Interrupt := SIGADAABORT;
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206
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207 act.sa_handler := Notify_Exception'Address;
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208
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209 -- Setting SA_SIGINFO asks the kernel to pass more than just the signal
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210 -- number argument to the handler when it is called. The set of extra
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211 -- parameters includes a pointer to the interrupted context, which the
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212 -- ZCX propagation scheme needs.
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213
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214 -- Most man pages for sigaction mention that sa_sigaction should be set
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215 -- instead of sa_handler when SA_SIGINFO is on. In practice, the two
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216 -- fields are actually union'ed and located at the same offset.
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217
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218 -- On some targets, we set sa_flags to SA_NODEFER so that during the
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219 -- handler execution we do not change the Signal_Mask to be masked for
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220 -- the Signal.
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221
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222 -- This is a temporary fix to the problem that the Signal_Mask is not
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223 -- restored after the exception (longjmp) from the handler. The right
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224 -- fix should be made in sigsetjmp so that we save the Signal_Set and
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225 -- restore it after a longjmp.
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226
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227 -- We set SA_NODEFER to be compatible with what is done in
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228 -- __gnat_error_handler.
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229
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230 Result := sigemptyset (Signal_Mask'Access);
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231 pragma Assert (Result = 0);
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232
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233 -- Add signals that map to Ada exceptions to the mask
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234
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235 for J in Exception_Interrupts'Range loop
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236 if State (Exception_Interrupts (J)) /= Default then
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237 Result :=
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238 sigaddset
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239 (Signal_Mask'Access, Signal (Exception_Interrupts (J)));
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240 pragma Assert (Result = 0);
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241 end if;
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242 end loop;
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243
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244 act.sa_mask := Signal_Mask;
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245
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246 pragma Assert (Keep_Unmasked = (Interrupt_ID'Range => False));
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247 pragma Assert (Reserve = (Interrupt_ID'Range => False));
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248
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249 -- Process state of exception signals
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250
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251 for J in Exception_Interrupts'Range loop
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252 if State (Exception_Interrupts (J)) /= User then
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253 Keep_Unmasked (Exception_Interrupts (J)) := True;
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254 Reserve (Exception_Interrupts (J)) := True;
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255
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256 if State (Exception_Interrupts (J)) /= Default then
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257 act.sa_flags := SA_NODEFER + SA_RESTART + SA_SIGINFO;
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258
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259 if Use_Alternate_Stack
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260 and then Exception_Interrupts (J) = SIGSEGV
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261 then
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262 act.sa_flags := act.sa_flags + SA_ONSTACK;
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263 end if;
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264
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265 Result :=
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266 sigaction
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267 (Signal (Exception_Interrupts (J)), act'Unchecked_Access,
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268 old_act'Unchecked_Access);
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269 pragma Assert (Result = 0);
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270 end if;
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271 end if;
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272 end loop;
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273
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274 if State (Abort_Task_Interrupt) /= User then
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275 Keep_Unmasked (Abort_Task_Interrupt) := True;
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276 Reserve (Abort_Task_Interrupt) := True;
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277 end if;
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278
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279 -- Set SIGINT to unmasked state as long as it is not in "User" state.
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280 -- Check for Unreserve_All_Interrupts last.
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281
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282 if State (SIGINT) /= User then
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283 Keep_Unmasked (SIGINT) := True;
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284 Reserve (SIGINT) := True;
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285 end if;
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286
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287 -- Check all signals for state that requires keeping them unmasked and
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288 -- reserved.
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289
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290 for J in Interrupt_ID'Range loop
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291 if State (J) = Default or else State (J) = Runtime then
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292 Keep_Unmasked (J) := True;
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293 Reserve (J) := True;
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294 end if;
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295 end loop;
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296
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297 -- Add the set of signals that must always be unmasked for this target
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298
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299 for J in Unmasked'Range loop
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300 Keep_Unmasked (Interrupt_ID (Unmasked (J))) := True;
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301 Reserve (Interrupt_ID (Unmasked (J))) := True;
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302 end loop;
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303
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304 -- Add target-specific reserved signals
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305
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306 for J in Reserved'Range loop
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307 Reserve (Interrupt_ID (Reserved (J))) := True;
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308 end loop;
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309
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310 -- Process pragma Unreserve_All_Interrupts. This overrides any settings
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311 -- due to pragma Interrupt_State:
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312
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313 if Unreserve_All_Interrupts /= 0 then
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314 Keep_Unmasked (SIGINT) := False;
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315 Reserve (SIGINT) := False;
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316 end if;
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317
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318 -- We do not really have Signal 0. We just use this value to identify
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319 -- non-existent signals (see s-intnam.ads). Therefore, Signal should not
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320 -- be used in all signal related operations hence mark it as reserved.
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321
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322 Reserve (0) := True;
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323 end Initialize;
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324
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325 end System.Interrupt_Management;
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