/usr/include/d/ldc/eh/common.d is in libphobos2-ldc-dev 1:0.17.1-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 | /**
* This module contains functions and structures required for exception
* handling which are shared by platform-specific implementations.
*/
module ldc.eh.common;
// debug = EH_personality;
// debug = EH_personality_verbose;
import core.memory : GC;
import core.stdc.stdio;
import core.stdc.stdlib;
import core.stdc.stdarg;
import ldc.eh.fixedpool;
version (ARM)
{
version (iOS)
version = SjLj_Exceptions;
else
version = ARM_EABI_UNWINDER;
}
// D runtime function
extern(C) int _d_isbaseof(ClassInfo oc, ClassInfo c);
// error and exit
extern(C) void fatalerror(in char* format, ...)
{
va_list args;
va_start(args, format);
fprintf(stderr, "Fatal error in EH code: ");
vfprintf(stderr, format, args);
fprintf(stderr, "\n");
abort();
}
// ------------------------
// Reading DWARF data
// ------------------------
version (CRuntime_Microsoft) {} else
{
extern(C)
{
alias void* _Unwind_Context_Ptr;
ptrdiff_t _Unwind_GetRegionStart(_Unwind_Context_Ptr context);
ptrdiff_t _Unwind_GetTextRelBase(_Unwind_Context_Ptr context);
ptrdiff_t _Unwind_GetDataRelBase(_Unwind_Context_Ptr context);
}
}
enum _DW_EH_Format : int
{
DW_EH_PE_absptr = 0x00, // The Value is a literal pointer whose size is determined by the architecture.
DW_EH_PE_uleb128 = 0x01, // Unsigned value is encoded using the Little Endian Base 128 (LEB128)
DW_EH_PE_udata2 = 0x02, // A 2 bytes unsigned value.
DW_EH_PE_udata4 = 0x03, // A 4 bytes unsigned value.
DW_EH_PE_udata8 = 0x04, // An 8 bytes unsigned value.
DW_EH_PE_sleb128 = 0x09, // Signed value is encoded using the Little Endian Base 128 (LEB128)
DW_EH_PE_sdata2 = 0x0A, // A 2 bytes signed value.
DW_EH_PE_sdata4 = 0x0B, // A 4 bytes signed value.
DW_EH_PE_sdata8 = 0x0C, // An 8 bytes signed value.
DW_EH_PE_pcrel = 0x10, // Value is relative to the current program counter.
DW_EH_PE_textrel = 0x20, // Value is relative to the beginning of the .text section.
DW_EH_PE_datarel = 0x30, // Value is relative to the beginning of the .got or .eh_frame_hdr section.
DW_EH_PE_funcrel = 0x40, // Value is relative to the beginning of the function.
DW_EH_PE_aligned = 0x50, // Value is aligned to an address unit sized boundary.
DW_EH_PE_indirect = 0x80,
DW_EH_PE_omit = 0xff // Indicates that no value is present.
}
uint udata4_read(ref ubyte* addr)
{
// read udata4 from possibly unaligned `addr`
import core.stdc.string : memcpy;
uint udata4;
memcpy(&udata4, addr, udata4.sizeof);
addr += udata4.sizeof;
return udata4;
}
ubyte* get_uleb128(ubyte* addr, ref size_t res)
{
res = 0;
size_t bitsize = 0;
// read as long as high bit is set
while(*addr & 0x80)
{
res |= (*addr & 0x7f) << bitsize;
bitsize += 7;
addr += 1;
if (bitsize >= size_t.sizeof*8)
fatalerror("tried to read uleb128 that exceeded size of size_t");
}
// read last
if (bitsize != 0 && *addr >= 1L << size_t.sizeof*8 - bitsize)
fatalerror("tried to read uleb128 that exceeded size of size_t");
res |= (*addr) << bitsize;
return addr + 1;
}
ubyte* get_sleb128(ubyte* addr, ref ptrdiff_t res)
{
res = 0;
size_t bitsize = 0;
// read as long as high bit is set
while (*addr & 0x80)
{
res |= (*addr & 0x7f) << bitsize;
bitsize += 7;
addr += 1;
if (bitsize >= size_t.sizeof*8)
fatalerror("tried to read sleb128 that exceeded size of size_t");
}
// read last
if (bitsize != 0 && *addr >= 1L << size_t.sizeof*8 - bitsize)
fatalerror("tried to read sleb128 that exceeded size of size_t");
res |= (*addr) << bitsize;
// take care of sign
if (bitsize < size_t.sizeof*8 && ((*addr) & 0x40))
res |= cast(ptrdiff_t)(-1) ^ ((1 << (bitsize+7)) - 1);
return addr + 1;
}
size_t get_size_of_encoded_value(ubyte encoding)
{
if (encoding == _DW_EH_Format.DW_EH_PE_omit)
return 0;
switch (encoding & 0x07)
{
case _DW_EH_Format.DW_EH_PE_absptr:
return size_t.sizeof;
case _DW_EH_Format.DW_EH_PE_udata2:
return 2;
case _DW_EH_Format.DW_EH_PE_udata4:
return 4;
case _DW_EH_Format.DW_EH_PE_udata8:
return 8;
default:
fatalerror("Unsupported DWARF Exception Header value format: unknown encoding");
}
assert(0);
}
ubyte* get_encoded_value(ubyte* addr, ref size_t res, ubyte encoding, void* context)
{
ubyte *old_addr = addr;
if (encoding == _DW_EH_Format.DW_EH_PE_aligned)
goto Lerr;
switch (encoding & 0x0f)
{
case _DW_EH_Format.DW_EH_PE_absptr:
res = cast(size_t)*cast(ubyte**)addr;
addr += size_t.sizeof;
break;
case _DW_EH_Format.DW_EH_PE_uleb128:
addr = get_uleb128(addr, res);
break;
case _DW_EH_Format.DW_EH_PE_sleb128:
ptrdiff_t r;
addr = get_sleb128(addr, r);
r = cast(size_t)res;
break;
case _DW_EH_Format.DW_EH_PE_udata2:
res = *cast(ushort*)addr;
addr += 2;
break;
case _DW_EH_Format.DW_EH_PE_udata4:
res = *cast(uint*)addr;
addr += 4;
break;
case _DW_EH_Format.DW_EH_PE_udata8:
res = cast(size_t)*cast(ulong*)addr;
addr += 8;
break;
case _DW_EH_Format.DW_EH_PE_sdata2:
res = *cast(short*)addr;
addr += 2;
break;
case _DW_EH_Format.DW_EH_PE_sdata4:
res = *cast(int*)addr;
addr += 4;
break;
case _DW_EH_Format.DW_EH_PE_sdata8:
res = cast(size_t)*cast(long*)addr;
addr += 8;
break;
default:
goto Lerr;
}
switch (encoding & 0x70)
{
case _DW_EH_Format.DW_EH_PE_absptr:
break;
case _DW_EH_Format.DW_EH_PE_pcrel:
res += cast(size_t)old_addr;
break;
case _DW_EH_Format.DW_EH_PE_funcrel:
version(CRuntime_Microsoft) fatalerror("Not yet implemented."); else
res += cast(size_t)_Unwind_GetRegionStart(context);
break;
case _DW_EH_Format.DW_EH_PE_textrel:
version(CRuntime_Microsoft) fatalerror("Not yet implemented."); else
res += cast(size_t)_Unwind_GetTextRelBase(context);
break;
case _DW_EH_Format.DW_EH_PE_datarel:
version(CRuntime_Microsoft) fatalerror("Not yet implemented."); else
res += cast(size_t)_Unwind_GetDataRelBase(context);
break;
default:
goto Lerr;
}
if (encoding & _DW_EH_Format.DW_EH_PE_indirect)
res = cast(size_t)*cast(void**)res;
return addr;
Lerr:
fatalerror("Unsupported DWARF Exception Header value format");
return addr;
}
ptrdiff_t get_base_of_encoded_value(ubyte encoding, void* context)
{
if (encoding == _DW_EH_Format.DW_EH_PE_omit)
return 0;
with (_DW_EH_Format) switch (encoding & 0x70) {
case DW_EH_PE_absptr:
case DW_EH_PE_pcrel:
case DW_EH_PE_aligned:
return 0;
version(CRuntime_Microsoft) {} else
{
case DW_EH_PE_textrel:
return _Unwind_GetTextRelBase (context);
case DW_EH_PE_datarel:
return _Unwind_GetDataRelBase (context);
case DW_EH_PE_funcrel:
return _Unwind_GetRegionStart (context);
}
default:
fatalerror("Unsupported encoding type to get base from.");
assert(0);
}
}
void _d_getLanguageSpecificTables(ubyte* data, ref ubyte* callsite, ref ubyte* action, ref ubyte* classinfo_table, ref ubyte ciEncoding)
{
if (data is null)
{
debug(EH_personality) printf("language specific data was null\n");
callsite = null;
action = null;
classinfo_table = null;
return;
}
debug(EH_personality) printf(" - LSDA: %p\n", data);
//TODO: Do proper DWARF reading here
if (*data++ != _DW_EH_Format.DW_EH_PE_omit)
fatalerror("DWARF header has unexpected format 1");
ciEncoding = *data++;
if (ciEncoding == _DW_EH_Format.DW_EH_PE_omit)
{
// Used for simple cleanup actions (finally, dtors) that don't care
// about exception type
version (SjLj_Exceptions)
classinfo_table = null;
else
fatalerror("Language Specific Data does not contain Types Table");
}
else
{
// Note in libsupc++ eh_personality says it is necessary to override
// type encoding generated by older ARM EABI toolchains
// (_GLIBCXX_OVERRIDE_TTYPE_ENCODING)
version (ARM_EABI_UNWINDER) version (linux) {
with (_DW_EH_Format) {
ciEncoding = DW_EH_PE_pcrel | DW_EH_PE_indirect;
}
}
size_t cioffset;
data = get_uleb128(data, cioffset);
classinfo_table = data + cioffset;
}
if (*data++ != _DW_EH_Format.DW_EH_PE_udata4)
fatalerror("DWARF header has unexpected format 2");
size_t callsitelength;
data = get_uleb128(data, callsitelength);
action = data + callsitelength;
callsite = data;
debug(EH_personality) printf(" - callsite: %p, action: %p, classinfo_table: %p, ciEncoding: %d\n", callsite, action, classinfo_table, ciEncoding);
}
// -----------------------------
// Stack of finally blocks
// -----------------------------
struct ActiveCleanupBlock {
/// Link to the next active finally block.
ActiveCleanupBlock* outerBlock;
/// The exception that caused this cleanup block to be entered.
Object dObject;
/// The exception struct associated with the above exception. Currently only
/// used by libunwind; define destroyExceptionStruct in your implementation's
/// NativeContext code to handle this correctly.
void* exceptionStruct;
/// The CFA (stack address, roughly) when this cleanup block was entered, as
/// reported by libunwind.
///
/// Used to determine when this pad is reached again when unwinding from
/// somewhere within it. Note that this must somehow be related to the
/// stack, not the instruction pointer, to properly support recursive
/// chaining.
ptrdiff_t cfaAddr;
}
static FixedPool!(ActiveCleanupBlock, 8) ActiveCleanupBlockPool;
/// Stack of active finally blocks (i.e. cleanup landing pads) that were entered
/// because of exception unwinding. Used for exception chaining.
///
/// Note that sometimes a landing pad is both a catch and a cleanup. This
/// happens for example when there is a try/finally nested inside a try/catch
/// in the same function, or has been inlined into one. Whether a catch will
/// actually execute (which terminates this strand of unwinding) or not is
/// determined by the program code and cannot be known inside the personality
/// routine. Thus, we always push such a block even before entering a catch(),
/// and have the user code call _d_eh_enter_catch() once the (possible) cleanup
/// part is done so we can pop it again. In theory, this could be optimized a
/// bit, because we only need to do it for landing pads which have this double
/// function, which we could possibly figure out form the DWARF tables. However,
/// since this makes generating the code for popping it non-trivial, this is not
/// currently done.
ActiveCleanupBlock* innermostCleanupBlock = null;
/// innermostCleanupBlock is per-stack, not per-thread, and as such needs to be
/// swapped out on fiber context switches.
extern(C) void* _d_eh_swapContext(void* newContext) nothrow
{
auto old = innermostCleanupBlock;
innermostCleanupBlock = cast(ActiveCleanupBlock*)newContext;
return old;
}
/// During the search phase of unwinding, points to the currently active cleanup
/// block (i.e. somewhere in the innermostCleanupBlock linked list, but possibly
/// not at the beginning if the search for the catch block has already continued
/// past that).
///
/// Note that this and searchPhaseCurrentCleanupBlock can just be a single
/// variable because there can never be more than one search phase running per
/// thread.
ActiveCleanupBlock* searchPhaseCurrentCleanupBlock = null;
/// During the search phase, keeps track of the type of the dynamic type of the
/// currently thrown exception (might change according to exception chaining
/// rules).
ClassInfo searchPhaseClassInfo = null;
ActiveCleanupBlock* pushCleanupBlockRecord(ptrdiff_t cfaAddr, Object dObject)
{
auto acb = ActiveCleanupBlockPool.malloc();
if (!acb)
fatalerror("Could not allocate memory for exception chaining.");
acb.cfaAddr = cfaAddr;
acb.dObject = dObject;
acb.outerBlock = innermostCleanupBlock;
innermostCleanupBlock = acb;
// We need to be sure that an in-flight exception is kept alive while
// executing a finally block. This is not automatically the case if the
// finally block always throws, because the compiler then does not need to
// keep a reference to the object extracted from the landing pad around as
// there is no _d_eh_resume_unwind() call.
GC.addRoot(cast(void*)dObject);
return acb;
}
void popCleanupBlockRecord()
{
if (!innermostCleanupBlock)
{
fatalerror("No cleanup block record found, should have been pushed " ~
"before entering the finally block.");
}
// Remove the cleanup block we installed for this handler.
auto acb = innermostCleanupBlock;
GC.removeRoot(cast(void*)acb.dObject);
innermostCleanupBlock = acb.outerBlock;
ActiveCleanupBlockPool.free(acb);
}
/// This is the implementation of the personality function, which is called by
/// libunwind twice per frame (search phase, unwind phase).
///
/// It is responsible to figure out whether we need to stop unwinding because of
/// a catch block or if there is a finally block to execute by reading the DWARF
/// EH tables.
extern(C) auto eh_personality_common(NativeContext)(ref NativeContext nativeContext)
{
//
// First, we need to find the Language-Specific Data table for this frame
// and extract our information tables (the "language-specific" part is a bit
// of a misnomer, in reality this is generated by LLVM).
//
// The callsite and action tables do not contain static-length data and will
// be parsed as needed.
//
ubyte* callsite_table;
ubyte* action_table;
ubyte* classinfo_table; // points past the end of the table
ubyte classinfo_table_encoding;
ubyte* data = nativeContext.getLanguageSpecificData();
_d_getLanguageSpecificTables(data, callsite_table, action_table, classinfo_table, classinfo_table_encoding);
if (!callsite_table)
return nativeContext.continueUnwind();
//
// Now, we need to figure out if the address of the current instruction
// in this frame corresponds to a block which has an associated landing pad.
//
// The table entries are all relative to the start address of the region.
immutable ptrdiff_t region_start = nativeContext.getRegionStart();
// The address of the landing pad to jump to (null if no match).
ptrdiff_t landingPadAddr;
// The offset in the action table corresponding to the first action for this
// landing pad (will be zero if there are none).
size_t actionTableStartOffset;
version (SjLj_Exceptions)
{
// The instruction pointer (ip) will point to the next instruction after
// whatever made execution leave this frame, so substract 1 for the range
// comparison below.
ptrdiff_t ip = nativeContext.getIP() - 1;
if (ip < 0)
return nativeContext.continueUnwind();
// If ip is not present in the table, call terminate.
if (ip == 0)
fatalerror("Instruction pointer not found in table");
size_t cs_lp, cs_action;
ubyte* callsite_walker = callsite_table;
do
{
callsite_walker = get_uleb128(callsite_walker, cs_lp);
callsite_walker = get_uleb128(callsite_walker, cs_action);
debug(EH_personality_verbose)
printf("%x %x\n", cs_lp, cs_action);
}
while (--ip);
landingPadAddr = cs_lp + 1;
actionTableStartOffset = cs_action;
}
else // !SjLj_Exceptions
{
// The instruction pointer (ip) will point to the next instruction after
// whatever made execution leave this frame, so substract 1 for the range
// comparison below.
immutable ptrdiff_t ip = nativeContext.getIP() - 1;
ubyte* callsite_walker = callsite_table;
while (true)
{
// if we've gone through the list and found nothing...
if (callsite_walker >= action_table)
return nativeContext.continueUnwind();
immutable block_start_offset = udata4_read(callsite_walker);
immutable block_size = udata4_read(callsite_walker);
landingPadAddr = udata4_read(callsite_walker);
callsite_walker = get_uleb128(callsite_walker, actionTableStartOffset);
debug(EH_personality_verbose)
{
printf(" - ip=%p %u %u %tx\n", ip, block_start_offset,
block_size, landingPadAddr);
}
// since the list is sorted, as soon as we're past the ip
// there's no handler to be found
if (ip < region_start + block_start_offset)
return nativeContext.continueUnwind();
// if we've found our block, exit
if (ip < region_start + block_start_offset + block_size)
break;
}
} // !SjLj_Exceptions
debug(EH_personality)
{
printf(" - Found correct landing pad and actionTableStartOffset %d\n",
actionTableStartOffset);
}
// There is no landing pad for this part of the frame, continue with the next level.
if (!landingPadAddr)
return nativeContext.continueUnwind();
// We have a landing pad, adjust by region start address.
landingPadAddr += region_start;
immutable bool isSearchPhase = nativeContext.isSearchPhase();
//
// We have at least a finally landing pad in this scope. First, check if we
// have arrived at the scope a previous exception was thrown in. In this
// case, we need to chain exception_struct.exception_object to it or replace
// it with the former.
//
immutable ptrdiff_t currentCfaAddr = nativeContext.getCfaAddress();
ref ActiveCleanupBlock* acb()
{
return isSearchPhase ? searchPhaseCurrentCleanupBlock : innermostCleanupBlock;
}
while (acb)
{
debug(EH_personality)
{
printf(" - Current CFA: %p, Previous CFA: %p\n",
currentCfaAddr, acb.cfaAddr);
}
// If the next active cleanup block is somewhere further up the stack,
// there is nothing to do/check.
// Note: assumes the stack grows downwards.
if (currentCfaAddr < acb.cfaAddr)
break;
Object thrownDObject = nativeContext.getThrownObject();
auto currentClassInfo = isSearchPhase ? searchPhaseClassInfo : thrownDObject.classinfo;
if (_d_isbaseof(currentClassInfo, Error.classinfo) && !cast(Error)acb.dObject)
{
// The currently unwound Throwable is an Error but the previous one
// is not, so replace the latter with the former.
debug(EH_personality)
{
printf(" ++ Replacing %p (%s) by %p (%s)\n",
acb.dObject,
acb.dObject.classinfo.name.ptr,
thrownDObject,
thrownDObject.classinfo.name.ptr);
}
if (!isSearchPhase)
{
(cast(Error)thrownDObject).bypassedException =
cast(Throwable)acb.dObject;
}
}
else
{
// We are just unwinding an Exception or there was already an Error,
// so append this Throwable to the end of the previous chain.
if (isSearchPhase)
{
debug(EH_personality)
{
printf(" ++ Setting up classinfo to chain %s to %p (%s, classinfo at %p)\n",
searchPhaseClassInfo.name.ptr, acb.dObject,
acb.dObject.classinfo.name.ptr, acb.dObject.classinfo);
}
searchPhaseClassInfo = acb.dObject.classinfo;
}
else
{
auto lastChainElem = cast(Throwable)acb.dObject;
while (lastChainElem.next)
{
lastChainElem = lastChainElem.next;
}
auto thisThrowable = cast(Throwable)thrownDObject;
if (lastChainElem is thisThrowable)
{
// We would need to chain an exception to itself. This can
// happen if somebody throws the same exception object twice.
// It is questionable whether this is supposed to work in the
// first place, but core.demangle does it when generating the
// backtrace for its internal exceptions during demangling a
// symbol as part of the default trace handler (it uses the
// .init value for the exception class instead of allocating
// new instances).
debug(EH_personality)
{
printf(" ++ Not chaining %p (%s) to itself\n",
thisThrowable, thisThrowable.classinfo.name.ptr);
}
}
else
{
debug(EH_personality)
{
printf(" ++ Chaining %p (%s) to %p (%s)\n",
thisThrowable, thisThrowable.classinfo.name.ptr,
lastChainElem, lastChainElem.classinfo.name.ptr);
}
lastChainElem.next = thisThrowable;
}
nativeContext.overrideThrownObject(acb.dObject);
}
}
// In both cases, we've executed one level of chaining.
auto outer = acb.outerBlock;
if (!isSearchPhase)
{
// Destroy the exception struct associated with the previous level.
// This is necessary as the libunwind implementation allocates new
// exception structs for each throw; if we're chaining an exception,
// we need to destroy the previous exception struct.
nativeContext.destroyExceptionStruct(acb.exceptionStruct);
GC.removeRoot(cast(void*)acb.dObject);
ActiveCleanupBlockPool.free(acb);
}
acb = outer;
}
//
// Exception chaining is now done. Let's figure out what we have to do in
// this frame.
//
// If there are no actions, this is a cleanup landing pad.
if (!actionTableStartOffset)
{
return nativeContext.installFinallyContext(landingPadAddr);
}
// We have at least some attached actions. Figure out whether any of them
// match the type of the current exception.
immutable ci_size = get_size_of_encoded_value(classinfo_table_encoding);
debug(EH_personality) printf(" - ci_size: %td, ci_encoding: %d\n", ci_size, classinfo_table_encoding);
ubyte* action_walker = action_table + actionTableStartOffset - 1;
while (true)
{
ptrdiff_t ti_offset;
action_walker = get_sleb128(action_walker, ti_offset);
debug(EH_personality) printf(" - ti_offset: %tx\n", ti_offset);
// it is intentional that we not modify action_walker here
// next_action_offset is from current action_walker position
ptrdiff_t next_action_offset;
get_sleb128(action_walker, next_action_offset);
// negative are 'filters' which we don't use
if (!(ti_offset >= 0))
fatalerror("Filter actions are unsupported");
// zero means cleanup, which we require to be the last action
if (ti_offset == 0)
{
if (!(next_action_offset == 0))
fatalerror("Cleanup action must be last in chain");
return nativeContext.installFinallyContext(landingPadAddr);
}
if (!nativeContext.skipCatchComparison())
{
ClassInfo catchClassInfo = nativeContext.getCatchClassInfo(
classinfo_table - ti_offset * ci_size, classinfo_table_encoding);
ClassInfo exceptionClassInfo = isSearchPhase ?
searchPhaseClassInfo : nativeContext.getThrownObject().classinfo;
debug(EH_personality)
{
printf(" - Comparing catch %s to exception %s\n",
catchClassInfo.name.ptr, exceptionClassInfo.name.ptr);
}
if (_d_isbaseof(exceptionClassInfo, catchClassInfo))
{
return nativeContext.installCatchContext(ti_offset, landingPadAddr);
}
}
debug(EH_personality) printf(" - Type mismatch, next action offset: %tx\n", next_action_offset);
if (next_action_offset == 0)
return nativeContext.continueUnwind();
action_walker += next_action_offset;
}
}
|