| 1 | /* Exception (throw catch) mechanism, for GDB, the GNU debugger. |
| 2 | |
| 3 | Copyright (C) 1986-2020 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include "common-defs.h" |
| 21 | #include "common-exceptions.h" |
| 22 | #include <forward_list> |
| 23 | |
| 24 | /* Possible catcher states. */ |
| 25 | enum catcher_state { |
| 26 | /* Initial state, a new catcher has just been created. */ |
| 27 | CATCHER_CREATED, |
| 28 | /* The catch code is running. */ |
| 29 | CATCHER_RUNNING, |
| 30 | CATCHER_RUNNING_1, |
| 31 | /* The catch code threw an exception. */ |
| 32 | CATCHER_ABORTING |
| 33 | }; |
| 34 | |
| 35 | /* Possible catcher actions. */ |
| 36 | enum catcher_action { |
| 37 | CATCH_ITER, |
| 38 | CATCH_ITER_1, |
| 39 | CATCH_THROWING |
| 40 | }; |
| 41 | |
| 42 | struct catcher |
| 43 | { |
| 44 | enum catcher_state state = CATCHER_CREATED; |
| 45 | /* Jump buffer pointing back at the exception handler. */ |
| 46 | jmp_buf buf; |
| 47 | /* Status buffer belonging to the exception handler. */ |
| 48 | struct gdb_exception exception; |
| 49 | }; |
| 50 | |
| 51 | /* Where to go for throw_exception(). */ |
| 52 | static std::forward_list<struct catcher> catchers; |
| 53 | |
| 54 | jmp_buf * |
| 55 | exceptions_state_mc_init () |
| 56 | { |
| 57 | catchers.emplace_front (); |
| 58 | return &catchers.front ().buf; |
| 59 | } |
| 60 | |
| 61 | /* Catcher state machine. Returns non-zero if the m/c should be run |
| 62 | again, zero if it should abort. */ |
| 63 | |
| 64 | static int |
| 65 | exceptions_state_mc (enum catcher_action action) |
| 66 | { |
| 67 | switch (catchers.front ().state) |
| 68 | { |
| 69 | case CATCHER_CREATED: |
| 70 | switch (action) |
| 71 | { |
| 72 | case CATCH_ITER: |
| 73 | /* Allow the code to run the catcher. */ |
| 74 | catchers.front ().state = CATCHER_RUNNING; |
| 75 | return 1; |
| 76 | default: |
| 77 | internal_error (__FILE__, __LINE__, _("bad state")); |
| 78 | } |
| 79 | case CATCHER_RUNNING: |
| 80 | switch (action) |
| 81 | { |
| 82 | case CATCH_ITER: |
| 83 | /* No error/quit has occured. */ |
| 84 | return 0; |
| 85 | case CATCH_ITER_1: |
| 86 | catchers.front ().state = CATCHER_RUNNING_1; |
| 87 | return 1; |
| 88 | case CATCH_THROWING: |
| 89 | catchers.front ().state = CATCHER_ABORTING; |
| 90 | /* See also throw_exception. */ |
| 91 | return 1; |
| 92 | default: |
| 93 | internal_error (__FILE__, __LINE__, _("bad switch")); |
| 94 | } |
| 95 | case CATCHER_RUNNING_1: |
| 96 | switch (action) |
| 97 | { |
| 98 | case CATCH_ITER: |
| 99 | /* The did a "break" from the inner while loop. */ |
| 100 | return 0; |
| 101 | case CATCH_ITER_1: |
| 102 | catchers.front ().state = CATCHER_RUNNING; |
| 103 | return 0; |
| 104 | case CATCH_THROWING: |
| 105 | catchers.front ().state = CATCHER_ABORTING; |
| 106 | /* See also throw_exception. */ |
| 107 | return 1; |
| 108 | default: |
| 109 | internal_error (__FILE__, __LINE__, _("bad switch")); |
| 110 | } |
| 111 | case CATCHER_ABORTING: |
| 112 | switch (action) |
| 113 | { |
| 114 | case CATCH_ITER: |
| 115 | { |
| 116 | /* Exit normally if this catcher can handle this |
| 117 | exception. The caller analyses the func return |
| 118 | values. */ |
| 119 | return 0; |
| 120 | } |
| 121 | default: |
| 122 | internal_error (__FILE__, __LINE__, _("bad state")); |
| 123 | } |
| 124 | default: |
| 125 | internal_error (__FILE__, __LINE__, _("bad switch")); |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | int |
| 130 | exceptions_state_mc_catch (struct gdb_exception *exception, |
| 131 | int mask) |
| 132 | { |
| 133 | *exception = std::move (catchers.front ().exception); |
| 134 | catchers.pop_front (); |
| 135 | |
| 136 | if (exception->reason < 0) |
| 137 | { |
| 138 | if (mask & RETURN_MASK (exception->reason)) |
| 139 | { |
| 140 | /* Exit normally and let the caller handle the |
| 141 | exception. */ |
| 142 | return 1; |
| 143 | } |
| 144 | |
| 145 | /* The caller didn't request that the event be caught, relay the |
| 146 | event to the next exception_catch/CATCH_SJLJ. */ |
| 147 | throw_exception_sjlj (*exception); |
| 148 | } |
| 149 | |
| 150 | /* No exception was thrown. */ |
| 151 | return 0; |
| 152 | } |
| 153 | |
| 154 | int |
| 155 | exceptions_state_mc_action_iter (void) |
| 156 | { |
| 157 | return exceptions_state_mc (CATCH_ITER); |
| 158 | } |
| 159 | |
| 160 | int |
| 161 | exceptions_state_mc_action_iter_1 (void) |
| 162 | { |
| 163 | return exceptions_state_mc (CATCH_ITER_1); |
| 164 | } |
| 165 | |
| 166 | /* Return EXCEPTION to the nearest containing CATCH_SJLJ block. */ |
| 167 | |
| 168 | void |
| 169 | throw_exception_sjlj (const struct gdb_exception &exception) |
| 170 | { |
| 171 | /* Jump to the nearest CATCH_SJLJ block, communicating REASON to |
| 172 | that call via setjmp's return value. Note that REASON can't be |
| 173 | zero, by definition in common-exceptions.h. */ |
| 174 | exceptions_state_mc (CATCH_THROWING); |
| 175 | enum return_reason reason = exception.reason; |
| 176 | catchers.front ().exception = exception; |
| 177 | longjmp (catchers.front ().buf, reason); |
| 178 | } |
| 179 | |
| 180 | /* Implementation of throw_exception that uses C++ try/catch. */ |
| 181 | |
| 182 | void |
| 183 | throw_exception (gdb_exception &&exception) |
| 184 | { |
| 185 | if (exception.reason == RETURN_QUIT) |
| 186 | throw gdb_exception_quit (std::move (exception)); |
| 187 | else if (exception.reason == RETURN_ERROR) |
| 188 | throw gdb_exception_error (std::move (exception)); |
| 189 | else |
| 190 | gdb_assert_not_reached ("invalid return reason"); |
| 191 | } |
| 192 | |
| 193 | static void ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (3, 0) |
| 194 | throw_it (enum return_reason reason, enum errors error, const char *fmt, |
| 195 | va_list ap) |
| 196 | { |
| 197 | if (reason == RETURN_QUIT) |
| 198 | throw gdb_exception_quit (fmt, ap); |
| 199 | else if (reason == RETURN_ERROR) |
| 200 | throw gdb_exception_error (error, fmt, ap); |
| 201 | else |
| 202 | gdb_assert_not_reached ("invalid return reason"); |
| 203 | } |
| 204 | |
| 205 | void |
| 206 | throw_verror (enum errors error, const char *fmt, va_list ap) |
| 207 | { |
| 208 | throw_it (RETURN_ERROR, error, fmt, ap); |
| 209 | } |
| 210 | |
| 211 | void |
| 212 | throw_vquit (const char *fmt, va_list ap) |
| 213 | { |
| 214 | throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap); |
| 215 | } |
| 216 | |
| 217 | void |
| 218 | throw_error (enum errors error, const char *fmt, ...) |
| 219 | { |
| 220 | va_list args; |
| 221 | |
| 222 | va_start (args, fmt); |
| 223 | throw_verror (error, fmt, args); |
| 224 | va_end (args); |
| 225 | } |
| 226 | |
| 227 | void |
| 228 | throw_quit (const char *fmt, ...) |
| 229 | { |
| 230 | va_list args; |
| 231 | |
| 232 | va_start (args, fmt); |
| 233 | throw_vquit (fmt, args); |
| 234 | va_end (args); |
| 235 | } |