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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME COMPONENTS --
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4 -- --
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5 -- A D A . E X C E P T I O N S --
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6 -- --
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7 -- S p e c --
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8 -- --
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145
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9 -- Copyright (C) 1992-2019, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- This specification is derived from the Ada Reference Manual for use with --
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12 -- GNAT. The copyright notice above, and the license provisions that follow --
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13 -- apply solely to the contents of the part following the private keyword. --
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14 -- --
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15 -- GNAT is free software; you can redistribute it and/or modify it under --
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16 -- terms of the GNU General Public License as published by the Free Soft- --
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17 -- ware Foundation; either version 3, or (at your option) any later ver- --
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18 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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19 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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20 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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21 -- --
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22 -- As a special exception under Section 7 of GPL version 3, you are granted --
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23 -- additional permissions described in the GCC Runtime Library Exception, --
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24 -- version 3.1, as published by the Free Software Foundation. --
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25 -- --
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26 -- You should have received a copy of the GNU General Public License and --
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27 -- a copy of the GCC Runtime Library Exception along with this program; --
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28 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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29 -- <http://www.gnu.org/licenses/>. --
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30 -- --
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31 -- GNAT was originally developed by the GNAT team at New York University. --
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32 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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33 -- --
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34 ------------------------------------------------------------------------------
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35
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145
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36 -- This is the default version of this package. We also have cert and zfp
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37 -- versions.
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38
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39 pragma Polling (Off);
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40 -- We must turn polling off for this unit, because otherwise we get
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41 -- elaboration circularities with ourself.
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42
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43 with System;
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44 with System.Parameters;
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45 with System.Standard_Library;
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46 with System.Traceback_Entries;
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47
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48 package Ada.Exceptions is
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49 pragma Preelaborate;
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50 -- In accordance with Ada 2005 AI-362.
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51
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52 type Exception_Id is private;
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53 pragma Preelaborable_Initialization (Exception_Id);
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54
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55 Null_Id : constant Exception_Id;
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56
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57 type Exception_Occurrence is limited private;
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58 pragma Preelaborable_Initialization (Exception_Occurrence);
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59
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60 type Exception_Occurrence_Access is access all Exception_Occurrence;
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61
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62 Null_Occurrence : constant Exception_Occurrence;
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63
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64 function Exception_Name (Id : Exception_Id) return String;
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65
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66 function Exception_Name (X : Exception_Occurrence) return String;
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67
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68 function Wide_Exception_Name
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69 (Id : Exception_Id) return Wide_String;
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70 pragma Ada_05 (Wide_Exception_Name);
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71
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72 function Wide_Exception_Name
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73 (X : Exception_Occurrence) return Wide_String;
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74 pragma Ada_05 (Wide_Exception_Name);
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75
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76 function Wide_Wide_Exception_Name
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77 (Id : Exception_Id) return Wide_Wide_String;
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78 pragma Ada_05 (Wide_Wide_Exception_Name);
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79
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80 function Wide_Wide_Exception_Name
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81 (X : Exception_Occurrence) return Wide_Wide_String;
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82 pragma Ada_05 (Wide_Wide_Exception_Name);
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83
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84 procedure Raise_Exception (E : Exception_Id; Message : String := "");
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85 pragma No_Return (Raise_Exception);
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86 -- Note: In accordance with AI-466, CE is raised if E = Null_Id
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87
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88 function Exception_Message (X : Exception_Occurrence) return String;
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89
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90 procedure Reraise_Occurrence (X : Exception_Occurrence);
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91 -- Note: it would be really nice to give a pragma No_Return for this
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92 -- procedure, but it would be wrong, since Reraise_Occurrence does return
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93 -- if the argument is the null exception occurrence. See also procedure
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94 -- Reraise_Occurrence_Always in the private part of this package.
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95
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96 function Exception_Identity (X : Exception_Occurrence) return Exception_Id;
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97
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98 function Exception_Information (X : Exception_Occurrence) return String;
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99 -- The format of the exception information is as follows:
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100 --
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101 -- exception name (as in Exception_Name)
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102 -- message (or a null line if no message)
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103 -- PID=nnnn
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104 -- 0xyyyyyyyy 0xyyyyyyyy ...
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105 --
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106 -- The lines are separated by a ASCII.LF character
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107 --
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108 -- The nnnn is the partition Id given as decimal digits
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109 --
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110 -- The 0x... line represents traceback program counter locations,
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111 -- in order with the first one being the exception location.
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112
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113 -- Note on ordering: the compiler uses the Save_Occurrence procedure, but
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114 -- not the function from Rtsfind, so it is important that the procedure
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115 -- come first, since Rtsfind finds the first matching entity.
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116
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117 procedure Save_Occurrence
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118 (Target : out Exception_Occurrence;
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119 Source : Exception_Occurrence);
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120
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121 function Save_Occurrence
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122 (Source : Exception_Occurrence)
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123 return Exception_Occurrence_Access;
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124
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125 -- Ada 2005 (AI-438): The language revision introduces the following
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126 -- subprograms and attribute definitions. We do not provide them
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127 -- explicitly. instead, the corresponding stream attributes are made
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128 -- available through a pragma Stream_Convert in the private part.
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129
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130 -- procedure Read_Exception_Occurrence
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131 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
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132 -- Item : out Exception_Occurrence);
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133
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134 -- procedure Write_Exception_Occurrence
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135 -- (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
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136 -- Item : Exception_Occurrence);
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137
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138 -- for Exception_Occurrence'Read use Read_Exception_Occurrence;
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139 -- for Exception_Occurrence'Write use Write_Exception_Occurrence;
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140
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141 private
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142 package SSL renames System.Standard_Library;
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143 package SP renames System.Parameters;
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144
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145 subtype EOA is Exception_Occurrence_Access;
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146
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147 Exception_Msg_Max_Length : constant := SP.Default_Exception_Msg_Max_Length;
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148
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149 ------------------
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150 -- Exception_Id --
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151 ------------------
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152
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153 subtype Code_Loc is System.Address;
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154 -- Code location used in building exception tables and for call addresses
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155 -- when propagating an exception. Values of this type are created by using
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156 -- Label'Address or extracted from machine states using Get_Code_Loc.
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157
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158 Null_Loc : constant Code_Loc := System.Null_Address;
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159 -- Null code location, used to flag outer level frame
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160
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161 type Exception_Id is new SSL.Exception_Data_Ptr;
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162
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163 function EId_To_String (X : Exception_Id) return String;
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164 function String_To_EId (S : String) return Exception_Id;
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165 pragma Stream_Convert (Exception_Id, String_To_EId, EId_To_String);
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166 -- Functions for implementing Exception_Id stream attributes
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167
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168 Null_Id : constant Exception_Id := null;
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169
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170 -------------------------
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171 -- Private Subprograms --
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172 -------------------------
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173
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174 function Exception_Name_Simple (X : Exception_Occurrence) return String;
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175 -- Like Exception_Name, but returns the simple non-qualified name of the
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176 -- exception. This is used to implement the Exception_Name function in
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177 -- Current_Exceptions (the DEC compatible unit). It is called from the
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178 -- compiler generated code (using Rtsfind, which does not respect the
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179 -- private barrier, so we can place this function in the private part
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180 -- where the compiler can find it, but the spec is unchanged.)
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181
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182 procedure Raise_Exception_Always (E : Exception_Id; Message : String := "");
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183 pragma No_Return (Raise_Exception_Always);
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184 pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception");
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185 -- This differs from Raise_Exception only in that the caller has determined
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186 -- that for sure the parameter E is not null, and that therefore no check
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187 -- for Null_Id is required. The expander converts Raise_Exception calls to
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188 -- Raise_Exception_Always if it can determine this is the case. The Export
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189 -- allows this routine to be accessed from Pure units.
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190
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191 procedure Raise_From_Signal_Handler
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192 (E : Exception_Id;
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193 M : System.Address);
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194 pragma Export
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195 (Ada, Raise_From_Signal_Handler,
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196 "ada__exceptions__raise_from_signal_handler");
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197 pragma No_Return (Raise_From_Signal_Handler);
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198 -- This routine is used to raise an exception from a signal handler. The
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199 -- signal handler has already stored the machine state (i.e. the state that
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200 -- corresponds to the location at which the signal was raised). E is the
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201 -- Exception_Id specifying what exception is being raised, and M is a
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202 -- pointer to a null-terminated string which is the message to be raised.
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203 -- Note that this routine never returns, so it is permissible to simply
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204 -- jump to this routine, rather than call it. This may be appropriate for
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205 -- systems where the right way to get out of signal handler is to alter the
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206 -- PC value in the machine state or in some other way ask the operating
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207 -- system to return here rather than to the original location.
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208
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209 procedure Raise_From_Controlled_Operation
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210 (X : Ada.Exceptions.Exception_Occurrence);
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211 pragma No_Return (Raise_From_Controlled_Operation);
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212 pragma Export
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213 (Ada, Raise_From_Controlled_Operation,
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214 "__gnat_raise_from_controlled_operation");
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215 -- Raise Program_Error, providing information about X (an exception raised
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216 -- during a controlled operation) in the exception message.
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217
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218 procedure Reraise_Library_Exception_If_Any;
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219 pragma Export
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220 (Ada, Reraise_Library_Exception_If_Any,
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221 "__gnat_reraise_library_exception_if_any");
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222 -- If there was an exception raised during library-level finalization,
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223 -- reraise the exception.
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224
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225 procedure Reraise_Occurrence_Always (X : Exception_Occurrence);
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226 pragma No_Return (Reraise_Occurrence_Always);
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227 -- This differs from Raise_Occurrence only in that the caller guarantees
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228 -- that for sure the parameter X is not the null occurrence, and that
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229 -- therefore this procedure cannot return. The expander uses this routine
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230 -- in the translation of a raise statement with no parameter (reraise).
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231
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232 procedure Reraise_Occurrence_No_Defer (X : Exception_Occurrence);
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233 pragma No_Return (Reraise_Occurrence_No_Defer);
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234 -- Exactly like Reraise_Occurrence, except that abort is not deferred
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235 -- before the call and the parameter X is known not to be the null
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236 -- occurrence. This is used in generated code when it is known that abort
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237 -- is already deferred.
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238
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239 function Triggered_By_Abort return Boolean;
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240 -- Determine whether the current exception (if it exists) is an instance of
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241 -- Standard'Abort_Signal.
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242
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243 -----------------------
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244 -- Polling Interface --
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245 -----------------------
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246
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247 -- The GNAT compiler has an option to generate polling calls to the Poll
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248 -- routine in this package. Specifying the -gnatP option for a compilation
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249 -- causes a call to Ada.Exceptions.Poll to be generated on every subprogram
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250 -- entry and on every iteration of a loop, thus avoiding the possibility of
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251 -- a case of unbounded time between calls.
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252
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253 -- This polling interface may be used for instrumentation or debugging
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254 -- purposes (e.g. implementing watchpoints in software or in the debugger).
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255
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256 -- In the GNAT technology itself, this interface is used to implement
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257 -- immediate asynchronous transfer of control and immediate abort on
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258 -- targets which do not provide for one thread interrupting another.
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259
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260 -- Note: this used to be in a separate unit called System.Poll, but that
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261 -- caused horrible circular elaboration problems between System.Poll and
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262 -- Ada.Exceptions.
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263
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264 procedure Poll;
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265 -- Check for asynchronous abort. Note that we do not inline the body.
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266 -- This makes the interface more useful for debugging purposes.
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267
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268 --------------------------
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269 -- Exception_Occurrence --
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270 --------------------------
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271
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272 package TBE renames System.Traceback_Entries;
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273
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274 Max_Tracebacks : constant := 50;
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275 -- Maximum number of trace backs stored in exception occurrence
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276
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277 subtype Tracebacks_Array is TBE.Tracebacks_Array (1 .. Max_Tracebacks);
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278 -- Traceback array stored in exception occurrence
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279
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280 type Exception_Occurrence is record
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281 Id : Exception_Id := Null_Id;
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111
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282 -- Exception_Identity for this exception occurrence
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283
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284 Machine_Occurrence : System.Address;
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285 -- The underlying machine occurrence. For GCC, this corresponds to the
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286 -- _Unwind_Exception structure address.
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287
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288 Msg_Length : Natural := 0;
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289 -- Length of message (zero = no message)
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290
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291 Msg : String (1 .. Exception_Msg_Max_Length);
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292 -- Characters of message
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293
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294 Exception_Raised : Boolean := False;
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295 -- Set to true to indicate that this exception occurrence has actually
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296 -- been raised. When an exception occurrence is first created, this is
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297 -- set to False, then when it is processed by Raise_Current_Exception,
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298 -- it is set to True. If Raise_Current_Exception is used to raise an
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299 -- exception for which this flag is already True, then it knows that
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300 -- it is dealing with the reraise case (which is useful to distinguish
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301 -- for exception tracing purposes).
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302
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303 Pid : Natural := 0;
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304 -- Partition_Id for partition raising exception
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305
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306 Num_Tracebacks : Natural range 0 .. Max_Tracebacks := 0;
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307 -- Number of traceback entries stored
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308
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309 Tracebacks : Tracebacks_Array;
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310 -- Stored tracebacks (in Tracebacks (1 .. Num_Tracebacks))
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311 end record;
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312
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313 function "=" (Left, Right : Exception_Occurrence) return Boolean
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314 is abstract;
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315 -- Don't allow comparison on exception occurrences, we should not need
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316 -- this, and it would not work right, because of the Msg and Tracebacks
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317 -- fields which have unused entries not copied by Save_Occurrence.
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318
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319 function Get_Exception_Machine_Occurrence
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320 (X : Exception_Occurrence) return System.Address;
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321 pragma Export (Ada, Get_Exception_Machine_Occurrence,
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322 "__gnat_get_exception_machine_occurrence");
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323 -- Get the machine occurrence corresponding to an exception occurrence.
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324 -- It is Null_Address if there is no machine occurrence (in runtimes that
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325 -- doesn't use GCC mechanism) or if it has been lost (Save_Occurrence
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326 -- doesn't save the machine occurrence).
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327
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328 function EO_To_String (X : Exception_Occurrence) return String;
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329 function String_To_EO (S : String) return Exception_Occurrence;
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330 pragma Stream_Convert (Exception_Occurrence, String_To_EO, EO_To_String);
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331 -- Functions for implementing Exception_Occurrence stream attributes
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332
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333 Null_Occurrence : constant Exception_Occurrence := (others => <>);
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111
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334
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335 end Ada.Exceptions;
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