1 | #include <stdio.h> |
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2 | #include <stdbool.h> |
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3 | |
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4 | // Proof of concept for resumption exception handling. |
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5 | // Names, checks promises and so on all would have to be improved. |
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6 | |
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7 | struct resume_group; |
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8 | |
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9 | // Stackwise information (global for single stack) |
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10 | struct code_stack_data { |
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11 | struct resume_group * top_resume; |
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12 | struct resume_group * current_resume; |
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13 | } stack = {NULL, NULL}; |
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14 | |
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15 | // private exception header begin ============================================ |
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16 | |
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17 | struct resume_group { |
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18 | struct resume_group * next; |
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19 | bool (*try_to_handle)(int); |
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20 | }; |
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21 | |
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22 | void __resume_group_dtor(struct resume_group * this) { |
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23 | stack.top_resume = this->next; |
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24 | } |
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25 | |
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26 | void __cfa_eh__throw_resume(int except) { |
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27 | struct resume_group * original_head = stack.current_resume; |
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28 | struct resume_group * current = |
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29 | (original_head) ? original_head->next : stack.top_resume; |
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30 | |
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31 | for ( ; current ; current = current->next) { |
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32 | stack.current_resume = current; |
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33 | if (current->try_to_handle(except)) { |
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34 | stack.current_resume = original_head; |
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35 | return; |
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36 | } |
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37 | } |
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38 | |
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39 | printf("Unhandled exception %d\n", except); |
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40 | } |
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41 | |
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42 | // private exception header end ============================================== |
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43 | |
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44 | // Set up of unwind checker type. |
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45 | struct type_raii_t { |
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46 | char * msg; |
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47 | }; |
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48 | |
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49 | void dtor( struct type_raii_t * this ) { |
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50 | printf("%s\n", this->msg); |
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51 | } |
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52 | |
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53 | #define raii_t __attribute__((cleanup(dtor))) struct type_raii_t |
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54 | |
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55 | void bar() { |
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56 | raii_t a = { "Bar dtor" }; |
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57 | |
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58 | __cfa_eh__throw_resume( 3 ); |
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59 | } |
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60 | |
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61 | void foo() { |
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62 | raii_t a = { "Foo dtor" }; |
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63 | |
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64 | { |
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65 | bool foo_catch_resume(int exception_id) { |
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66 | if (exception_id == 3) { |
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67 | printf("Exception caught\n"); |
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68 | return true; |
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69 | } |
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70 | return false; |
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71 | } |
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72 | struct resume_group __attribute__((cleanup(__resume_group_dtor))) |
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73 | foo_try_resume = {stack.top_resume, foo_catch_resume}; |
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74 | stack.top_resume = &foo_try_resume; |
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75 | { |
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76 | raii_t b = { "Foo try dtor" }; |
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77 | |
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78 | bar(); |
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79 | |
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80 | printf("Called bar successfully\n"); |
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81 | } |
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82 | } |
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83 | printf( "Foo exited normally\n" ); |
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84 | } |
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85 | |
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86 | // Not in main.cfa |
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87 | void foe() { |
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88 | raii_t a = { "Foe dtor" }; |
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89 | |
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90 | printf("Foe throws\n"); |
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91 | __cfa_eh__throw_resume( 4 ); |
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92 | |
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93 | printf("Foe exits normally\n"); |
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94 | } |
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95 | |
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96 | void fy() { |
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97 | raii_t a = { "Fy dtor" }; |
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98 | |
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99 | { |
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100 | bool fy_catch_resume(int exception_id) { |
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101 | if (4 == exception_id) { |
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102 | printf("Rethrow in fy\n"); |
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103 | __cfa_eh__throw_resume(exception_id); |
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104 | return true; |
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105 | } |
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106 | return false; |
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107 | } |
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108 | struct resume_group __attribute__((cleanup(__resume_group_dtor))) |
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109 | fy_try_resume = {stack.top_resume, fy_catch_resume}; |
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110 | stack.top_resume = &fy_try_resume; |
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111 | { |
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112 | raii_t b = { "Fy try dtor" }; |
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113 | foe(); |
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114 | } |
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115 | } |
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116 | |
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117 | printf("Fy exits normally\n"); |
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118 | } |
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119 | |
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120 | void fee() { |
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121 | raii_t a = { "Fee dtor" }; |
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122 | |
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123 | { |
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124 | bool fee_catch_resume(int exception_id) { |
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125 | if (4 == exception_id) { |
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126 | printf("fee caught exception\n"); |
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127 | return true; |
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128 | } |
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129 | return false; |
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130 | } |
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131 | struct resume_group __attribute__((cleanup(__resume_group_dtor))) |
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132 | fee_try_resume = {stack.top_resume, fee_catch_resume}; |
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133 | stack.top_resume = &fee_try_resume; |
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134 | { |
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135 | raii_t b = { "Fee try dtor" }; |
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136 | fy(); |
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137 | } |
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138 | } |
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139 | |
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140 | printf("Fee exits normally\n"); |
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141 | } |
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142 | // End not in main.cfa |
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143 | |
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144 | int main() { |
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145 | raii_t a = { "Main dtor" }; |
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146 | |
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147 | foo(); |
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148 | |
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149 | fee(); |
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150 | |
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151 | printf("End of program reached\n"); |
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152 | } |
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