gcc/ada/tracebak.c

   1 /****************************************************************************
   2  *                                                                          *
   3  *                         GNAT RUN-TIME COMPONENTS                         *
   4  *                                                                          *
   5  *                            T R A C E B A C K                             *
   6  *                                                                          *
   7  *                          C Implementation File                           *
   8  *                                                                          *
   9  *            Copyright (C) 2000-2016, Free Software Foundation, Inc.       *
  10  *                                                                          *
  11  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  12  * terms of the  GNU General Public License as published  by the Free Soft- *
  13  * ware  Foundation;  either version 3,  or (at your option) any later ver- *
  14  * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
  15  * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
  16  * or FITNESS FOR A PARTICULAR PURPOSE.                                     *
  17  *                                                                          *
  18  * As a special exception under Section 7 of GPL version 3, you are granted *
  19  * additional permissions described in the GCC Runtime Library Exception,   *
  20  * version 3.1, as published by the Free Software Foundation.               *
  21  *                                                                          *
  22  * You should have received a copy of the GNU General Public License and    *
  23  * a copy of the GCC Runtime Library Exception along with this program;     *
  24  * see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    *
  25  * <http://www.gnu.org/licenses/>.                                          *
  26  *                                                                          *
  27  * GNAT was originally developed  by the GNAT team at  New York University. *
  28  * Extensive contributions were provided by Ada Core Technologies Inc.      *
  29  *                                                                          *
  30  ****************************************************************************/
  31
  32 /* This file contains low level support for stack unwinding using GCC intrinsic
  33    functions.
  34    It has been tested on the following configurations:
  35    PowerPC/AiX
  36    PowerPC/Darwin
  37    PowerPC/VxWorks
  38    PowerPC/LynxOS-178
  39    SPARC/Solaris
  40    i386/GNU/Linux
  41    i386/Solaris
  42    i386/NT
  43    i386/OS2
  44    i386/LynxOS
  45    Alpha/VxWorks
  46    Alpha/VMS
  47 */
  48
  49 #ifdef __cplusplus
  50 extern "C" {
  51 #endif
  52
  53 #ifdef __alpha_vxworks
  54 #include "vxWorks.h"
  55 #endif
  56
  57 #ifdef IN_RTS
  58 #define POSIX
  59 #include "tconfig.h"
  60 #include "tsystem.h"
  61 #else
  62 #include "config.h"
  63 #include "system.h"
  64 /* We don't want fancy_abort here.  */
  65 #undef abort
  66 #endif
  67
  68 extern int __gnat_backtrace (void **, int, void *, void *, int);
  69
  70 /* The point is to provide an implementation of the __gnat_backtrace function
  71    above, called by the default implementation of the System.Traceback package.
  72
  73    We first have a series of target specific implementations, each included
  74    from a separate C file for readability purposes.
  75
  76    Then come two flavors of a generic implementation: one relying on static
  77    assumptions about the frame layout, and the other one using the GCC EH
  78    infrastructure.  The former uses a whole set of macros and structures which
  79    may be tailored on a per target basis, and is activated as soon as
  80    USE_GENERIC_UNWINDER is defined.  The latter uses a small subset of the
  81    macro definitions and is activated when USE_GCC_UNWINDER is defined. It is
  82    only available post GCC 3.3.
  83
  84    Finally, there is a default dummy implementation, necessary to make the
  85    linker happy on platforms where the feature is not supported, but where the
  86    function is still referenced by the default System.Traceback.  */
  87
  88 #define Lock_Task system__soft_links__lock_task
  89 extern void (*Lock_Task) (void);
  90
  91 #define Unlock_Task system__soft_links__unlock_task
  92 extern void (*Unlock_Task) (void);
  93
  94 /*-------------------------------------*
  95  *-- Target specific implementations --*
  96  *-------------------------------------*/
  97
  98 #if defined (_WIN64) && defined (__SEH__)
  99
 100 #include <windows.h>
 101
 102 #define IS_BAD_PTR(ptr) (IsBadCodePtr((FARPROC)ptr))
 103
 104 int
 105 __gnat_backtrace (void **array,
 106                   int size,
 107                   void *exclude_min,
 108                   void *exclude_max,
 109                   int skip_frames)
 110 {
 111   CONTEXT context;
 112   UNWIND_HISTORY_TABLE history;
 113   int i;
 114
 115   /* Get the context.  */
 116   RtlCaptureContext (&context);
 117
 118   /* Setup unwind history table (a cached to speed-up unwinding).  */
 119   memset (&history, 0, sizeof (history));
 120
 121   i = 0;
 122   while (1)
 123     {
 124       PRUNTIME_FUNCTION RuntimeFunction;
 125       KNONVOLATILE_CONTEXT_POINTERS NvContext;
 126       ULONG64 ImageBase;
 127       VOID *HandlerData;
 128       ULONG64 EstablisherFrame;
 129
 130       /* Get function metadata.  */
 131       RuntimeFunction = RtlLookupFunctionEntry
 132         (context.Rip, &ImageBase, &history);
 133
 134       if (!RuntimeFunction)
 135         {
 136           /* In case of failure, assume this is a leaf function.  */
 137           context.Rip = *(ULONG64 *) context.Rsp;
 138           context.Rsp += 8;
 139         }
 140       else
 141         {
 142           /* If the last unwinding step failed somehow, stop here.  */
 143           if (IS_BAD_PTR(context.Rip))
 144             break;
 145
 146           /* Unwind.  */
 147           memset (&NvContext, 0, sizeof (KNONVOLATILE_CONTEXT_POINTERS));
 148           RtlVirtualUnwind (0, ImageBase, context.Rip, RuntimeFunction,
 149                             &context, &HandlerData, &EstablisherFrame,
 150                             &NvContext);
 151         }
 152
 153       /* 0 means bottom of the stack.  */
 154       if (context.Rip == 0)
 155         break;
 156
 157       /* Skip frames.  */
 158       if (skip_frames > 1)
 159         {
 160           skip_frames--;
 161           continue;
 162         }
 163       /* Excluded frames.  */
 164       if ((void *)context.Rip >= exclude_min
 165           && (void *)context.Rip <= exclude_max)
 166         continue;
 167
 168       array[i++] = (void *)(context.Rip - 2);
 169       if (i >= size)
 170         break;
 171     }
 172   return i;
 173 }
 174 #else
 175
 176 /* No target specific implementation.  */
 177
 178 /*----------------------------------------------------------------*
 179  *-- Target specific definitions for the generic implementation --*
 180  *----------------------------------------------------------------*/
 181
 182 /* The stack layout is specified by the target ABI. The "generic" scheme is
 183    based on the following assumption:
 184
 185      The stack layout from some frame pointer is such that the information
 186      required to compute the backtrace is available at static offsets.
 187
 188    For a given frame, the information we are interested in is the saved return
 189    address (somewhere after the call instruction in the caller) and a pointer
 190    to the caller's frame. The former is the base of the call chain information
 191    we store in the tracebacks array. The latter allows us to loop over the
 192    successive frames in the chain.
 193
 194    To initiate the process, we retrieve an initial frame address using the
 195    appropriate GCC builtin (__builtin_frame_address).
 196
 197    This scheme is unfortunately not applicable on every target because the
 198    stack layout is not necessarily regular (static) enough. On targets where
 199    this scheme applies, the implementation relies on the following items:
 200
 201    o struct layout, describing the expected stack data layout relevant to the
 202      information we are interested in,
 203
 204    o FRAME_OFFSET, the offset, from a given frame address or frame pointer
 205      value, at which this layout will be found,
 206
 207    o FRAME_LEVEL, controls how many frames up we get at to start with,
 208      from the initial frame pointer we compute by way of the GCC builtin,
 209
 210      0 is most often the appropriate value. 1 may be necessary on targets
 211      where return addresses are saved by a function in it's caller's frame
 212      (e.g. PPC).
 213
 214    o PC_ADJUST, to account for the difference between a call point (address
 215      of a call instruction), which is what we want in the output array, and
 216      the associated return address, which is what we retrieve from the stack.
 217
 218    o STOP_FRAME, to decide whether we reached the top of the call chain, and
 219      thus if the process shall stop.
 220
 221            :
 222            :                   stack
 223            |             +----------------+
 224            |   +-------->|       :        |
 225            |   |         | (FRAME_OFFSET) |
 226            |   |         |       :        |  (PC_ADJUST)
 227            |   |  layout:| return_address ----------------+
 228            |   |         |     ....       |               |
 229            +---------------  next_frame   |               |
 230                |         |     ....       |               |
 231                |         |                |               |
 232                |         +----------------+               |  +-----+
 233                |         |       :        |<- Base fp     |  |  :  |
 234                |         | (FRAME_OFFSET) | (FRAME_LEVEL) |  |  :  |
 235                |         |       :        |               +--->    | [1]
 236                |  layout:| return_address -------------------->    | [0]
 237                |         |       ...      |  (PC_ADJUST)     +-----+
 238                +----------   next_frame   |                 traceback[]
 239                          |       ...      |
 240                          |                |
 241                          +----------------+
 242
 243    o BASE_SKIP,
 244
 245    Since we inherently deal with return addresses, there is an implicit shift
 246    by at least one for the initial point we are able to observe in the chain.
 247
 248    On some targets (e.g. sparc-solaris), the first return address we can
 249    easily get without special code is even our caller's return address, so
 250    there is a initial shift of two.
 251
 252    BASE_SKIP represents this initial shift, which is the minimal "skip_frames"
 253    value we support. We could add special code for the skip_frames < BASE_SKIP
 254    cases. This is not done currently because there is virtually no situation
 255    in which this would be useful.
 256
 257    Finally, to account for some ABI specificities, a target may (but does
 258    not have to) define:
 259
 260    o FORCE_CALL, to force a call to a dummy function at the very beginning
 261      of the computation. See the PPC AIX target for an example where this
 262      is useful.
 263
 264    o FETCH_UP_FRAME, to force an invocation of __builtin_frame_address with a
 265      positive argument right after a possibly forced call even if FRAME_LEVEL
 266      is 0. See the SPARC Solaris case for an example where this is useful.
 267
 268   */
 269
 270 /*------------------- Darwin 8 (OSX 10.4) or newer ----------------------*/
 271 #if defined (__APPLE__) \
 272     && defined (__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) \
 273     && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1040
 274
 275 #define USE_GCC_UNWINDER
 276
 277 #if defined (__i386__) || defined (__x86_64__)
 278 #define PC_ADJUST -2
 279 #elif defined (__ppc__) || defined (__ppc64__)
 280 #define PC_ADJUST -4
 281 #elif defined (__arm__)
 282 #define PC_ADJUST -2
 283 #elif defined (__arm64__)
 284 #define PC_ADJUST -4
 285 #else
 286 #error Unhandled darwin architecture.
 287 #endif
 288
 289 /*---------------------------- x86 *BSD --------------------------------*/
 290
 291 #elif defined (__i386__) &&   \
 292     ( defined (__NetBSD__) || defined (__FreeBSD__) || defined (__OpenBSD__) )
 293
 294 #define USE_GCC_UNWINDER
 295 /* The generic unwinder is not used for this target because the default
 296    implementation doesn't unwind on the BSD platforms.  AMD64 targets use the
 297    gcc unwinder for all platforms, so let's keep i386 consistent with that.
 298 */
 299
 300 #define PC_ADJUST -2
 301 /* The minimum size of call instructions on this architecture is 2 bytes */
 302
 303 /*---------------------- PPC AIX/PPC Lynx 178/Older Darwin ------------------*/
 304 #elif ((defined (_POWER) && defined (_AIX)) || \
 305        (defined (__powerpc__) && defined (__Lynx__) && !defined(__ELF__)) || \
 306        (defined (__ppc__) && defined (__APPLE__)))
 307
 308 #define USE_GENERIC_UNWINDER
 309
 310 struct layout
 311 {
 312   struct layout *next;
 313   void *pad;
 314   void *return_address;
 315 };
 316
 317 #define FRAME_OFFSET(FP) 0
 318 #define PC_ADJUST -4
 319
 320 /* Eventhough the base PPC ABI states that a toplevel frame entry
 321    should to feature a null backchain, AIX might expose a null return
 322    address instead.  */
 323
 324 /* Then LynxOS-178 features yet another variation, with return_address
 325    == &<entrypoint>, with two possible entry points (one for the main
 326    process and one for threads). Beware that &bla returns the address
 327    of a descriptor when "bla" is a function.  Getting the code address
 328    requires an extra dereference.  */
 329
 330 #if defined (__Lynx__)
 331 extern void __start();  /* process entry point.  */
 332 extern void __runnit(); /* thread entry point.  */
 333 #define EXTRA_STOP_CONDITION(CURRENT)                 \
 334   ((CURRENT)->return_address == *(void**)&__start     \
 335    || (CURRENT)->return_address == *(void**)&__runnit)
 336 #else
 337 #define EXTRA_STOP_CONDITION(CURRENT) (0)
 338 #endif
 339
 340 #define STOP_FRAME(CURRENT, TOP_STACK) \
 341   (((void *) (CURRENT) < (TOP_STACK)) \
 342    || (CURRENT)->return_address == NULL \
 343    || EXTRA_STOP_CONDITION(CURRENT))
 344
 345 /* The PPC ABI has an interesting specificity: the return address saved by a
 346    function is located in it's caller's frame, and the save operation only
 347    takes place if the function performs a call.
 348
 349    To have __gnat_backtrace retrieve its own return address, we then
 350    define ... */
 351
 352 #define FORCE_CALL 1
 353 #define FRAME_LEVEL 1
 354
 355 #define BASE_SKIP 1
 356
 357 /*----------- PPC ELF (GNU/Linux & VxWorks & Lynx178e) -------------------*/
 358
 359 #elif (defined (_ARCH_PPC) && defined (__vxworks)) ||  \
 360   (defined (__powerpc__) && defined (__Lynx__) && defined(__ELF__)) || \
 361   (defined (__linux__) && defined (__powerpc__))
 362
 363 #define USE_GENERIC_UNWINDER
 364
 365 struct layout
 366 {
 367   struct layout *next;
 368   void *return_address;
 369 };
 370
 371 #define FORCE_CALL 1
 372 #define FRAME_LEVEL 1
 373 /* See the PPC AIX case for an explanation of these values.  */
 374
 375 #define FRAME_OFFSET(FP) 0
 376 #define PC_ADJUST -4
 377
 378 /* According to the base PPC ABI, a toplevel frame entry should feature
 379    a null backchain.  What happens at signal handler frontiers isn't so
 380    well specified, so we add a safety guard on top.  */
 381
 382 #define STOP_FRAME(CURRENT, TOP_STACK) \
 383  ((CURRENT)->next == 0 || ((long)(CURRENT)->next % __alignof__(void*)) != 0)
 384
 385 #define BASE_SKIP 1
 386
 387 /*-------------------------- SPARC Solaris -----------------------------*/
 388
 389 #elif defined (__sun__) && defined (__sparc__)
 390
 391 #define USE_GENERIC_UNWINDER
 392
 393 /* These definitions are inspired from the Appendix D (Software
 394    Considerations) of the SPARC V8 architecture manual.  */
 395
 396 struct layout
 397 {
 398   struct layout *next;
 399   void *return_address;
 400 };
 401
 402 #ifdef __arch64__
 403 #define STACK_BIAS 2047 /* V9 ABI */
 404 #else
 405 #define STACK_BIAS 0    /* V8 ABI */
 406 #endif
 407
 408 #define FRAME_LEVEL 0
 409 #define FRAME_OFFSET(FP) (14 * sizeof (void*) + (FP ? STACK_BIAS : 0))
 410 #define PC_ADJUST 0
 411 #define STOP_FRAME(CURRENT, TOP_STACK) \
 412   ((CURRENT)->return_address == 0|| (CURRENT)->next == 0 \
 413    || (void *) (CURRENT) < (TOP_STACK))
 414
 415 /* The SPARC register windows need to be flushed before we may access them
 416    from the stack. This is achieved by way of builtin_frame_address only
 417    when the "count" argument is positive, so force at least one such call.  */
 418 #define FETCH_UP_FRAME_ADDRESS
 419
 420 #define BASE_SKIP 2
 421 /* From the frame pointer of frame N, we are accessing the flushed register
 422    window of frame N-1 (positive offset from fp), in which we retrieve the
 423    saved return address. We then end up with our caller's return address.  */
 424
 425 /*---------------------------- x86 & x86_64 ---------------------------------*/
 426
 427 #elif defined (__i386__) || defined (__x86_64__)
 428
 429 #if defined (__WIN32)
 430 #include <windows.h>
 431 #define IS_BAD_PTR(ptr) (IsBadCodePtr((FARPROC)ptr))
 432 #elif defined (__sun__)
 433 #define IS_BAD_PTR(ptr) ((unsigned long)ptr == -1UL)
 434 #else
 435 #define IS_BAD_PTR(ptr) 0
 436 #endif
 437
 438 /* Use the dwarf2 unwinder when we expect to have dwarf2 tables at
 439    hand. Backtraces will reliably stop on frames missing such tables,
 440    but our only alternative is the generic unwinder which requires
 441    compilation forcing a frame pointer to be reliable.  */
 442
 443 #if (defined (__x86_64__) || defined (__linux__)) && !defined (__USING_SJLJ_EXCEPTIONS__)
 444 #define USE_GCC_UNWINDER
 445 #else
 446 #define USE_GENERIC_UNWINDER
 447 #endif
 448
 449 struct layout
 450 {
 451   struct layout *next;
 452   void *return_address;
 453 };
 454
 455 #define FRAME_LEVEL 1
 456 /* builtin_frame_address (1) is expected to work on this family of targets,
 457    and (0) might return the soft stack pointer, which does not designate a
 458    location where a backchain and a return address might be found.  */
 459
 460 #define FRAME_OFFSET(FP) 0
 461 #define PC_ADJUST -2
 462 #define STOP_FRAME(CURRENT, TOP_STACK) \
 463   (IS_BAD_PTR((long)(CURRENT)) \
 464    || IS_BAD_PTR((long)(CURRENT)->return_address) \
 465    || (CURRENT)->return_address == 0 \
 466    || (void *) ((CURRENT)->next) < (TOP_STACK)  \
 467    || (void *) (CURRENT) < (TOP_STACK))
 468
 469 #define BASE_SKIP (1+FRAME_LEVEL)
 470
 471 /* On i386 architecture we check that at the call point we really have a call
 472    insn. Possible call instructions are:
 473
 474    call  addr16        E8 xx xx xx xx
 475    call  reg           FF Dx
 476    call  off(reg)      FF xx xx
 477    lcall addr seg      9A xx xx xx xx xx xx
 478
 479    This check will not catch all cases but it will increase the backtrace
 480    reliability on this architecture.
 481 */
 482
 483 #define VALID_STACK_FRAME(ptr) \
 484    (!IS_BAD_PTR(ptr) \
 485     && (((*((ptr) - 3) & 0xff) == 0xe8) \
 486         || ((*((ptr) - 5) & 0xff) == 0x9a) \
 487         || ((*((ptr) - 1) & 0xff) == 0xff) \
 488         || (((*(ptr) & 0xd0ff) == 0xd0ff))))
 489
 490 /*----------------------------- ia64 ---------------------------------*/
 491
 492 #elif defined (__ia64__) && (defined (__linux__) || defined (__hpux__))
 493
 494 #define USE_GCC_UNWINDER
 495 /* Use _Unwind_Backtrace driven exceptions on ia64 HP-UX and ia64
 496    GNU/Linux, where _Unwind_Backtrace is provided by the system unwind
 497    library. On HP-UX 11.23 this requires patch PHSS_33352, which adds
 498    _Unwind_Backtrace to the system unwind library. */
 499
 500 #define PC_ADJUST -4
 501
 502
 503 #endif
 504
 505 /*---------------------------------------------------------------------*
 506  *--      The post GCC 3.3 infrastructure based implementation       --*
 507  *---------------------------------------------------------------------*/
 508
 509 #if defined (USE_GCC_UNWINDER) && (__GNUC__ * 10 + __GNUC_MINOR__ > 33)
 510
 511 /* Conditioning the inclusion on the GCC version is useful to avoid bootstrap
 512    path problems, since the included file refers to post 3.3 functions in
 513    libgcc, and the stage1 compiler is unlikely to be linked against a post 3.3
 514    library.  It actually disables the support for backtraces in this compiler
 515    for targets defining USE_GCC_UNWINDER, which is OK since we don't use the
 516    traceback capability in the compiler anyway.
 517
 518    The condition is expressed the way above because we cannot reliably rely on
 519    any other macro from the base compiler when compiling stage1.  */
 520
 521 #include "tb-gcc.c"
 522
 523 /*------------------------------------------------------------------*
 524  *-- The generic implementation based on frame layout assumptions --*
 525  *------------------------------------------------------------------*/
 526
 527 #elif defined (USE_GENERIC_UNWINDER)
 528
 529 #ifndef CURRENT_STACK_FRAME
 530 # define CURRENT_STACK_FRAME  ({ char __csf; &__csf; })
 531 #endif
 532
 533 #ifndef VALID_STACK_FRAME
 534 #define VALID_STACK_FRAME(ptr) 1
 535 #endif
 536
 537 #ifndef MAX
 538 #define MAX(x,y) ((x) > (y) ? (x) : (y))
 539 #endif
 540
 541 #ifndef FORCE_CALL
 542 #define FORCE_CALL 0
 543 #endif
 544
 545 /* Make sure the function is not inlined.  */
 546 static void forced_callee (void) __attribute__ ((noinline));
 547
 548 static void forced_callee (void)
 549 {
 550   /* Make sure the function is not pure.  */
 551   volatile int i __attribute__ ((unused)) = 0;
 552 }
 553
 554 int
 555 __gnat_backtrace (void **array,
 556                   int size,
 557                   void *exclude_min,
 558                   void *exclude_max,
 559                   int skip_frames)
 560 {
 561   struct layout *current;
 562   void *top_frame;
 563   void *top_stack ATTRIBUTE_UNUSED;
 564   int cnt = 0;
 565
 566   if (FORCE_CALL)
 567     forced_callee ();
 568
 569   /* Force a call to builtin_frame_address with a positive argument
 570      if required. This is necessary e.g. on SPARC to have the register
 571      windows flushed before we attempt to access them on the stack.  */
 572 #if defined (FETCH_UP_FRAME_ADDRESS) && (FRAME_LEVEL == 0)
 573   __builtin_frame_address (1);
 574 #endif
 575
 576   top_frame = __builtin_frame_address (FRAME_LEVEL);
 577   top_stack = CURRENT_STACK_FRAME;
 578   current = (struct layout *) ((size_t) top_frame + FRAME_OFFSET (0));
 579
 580   /* Skip the number of calls we have been requested to skip, accounting for
 581      the BASE_SKIP parameter.
 582
 583      FRAME_LEVEL is meaningless for the count adjustment. It impacts where we
 584      start retrieving data from, but how many frames "up" we start at is in
 585      BASE_SKIP by definition.  */
 586
 587   skip_frames = MAX (0, skip_frames - BASE_SKIP);
 588
 589   while (cnt < skip_frames)
 590     {
 591       current = (struct layout *) ((size_t) current->next + FRAME_OFFSET (1));
 592       cnt++;
 593     }
 594
 595   cnt = 0;
 596   while (cnt < size)
 597     {
 598       if (STOP_FRAME (current, top_stack) ||
 599           !VALID_STACK_FRAME(((char *) current->return_address) + PC_ADJUST))
 600         break;
 601
 602       if (current->return_address < exclude_min
 603           || current->return_address > exclude_max)
 604         array[cnt++] = ((char *) current->return_address) + PC_ADJUST;
 605
 606       current = (struct layout *) ((size_t) current->next + FRAME_OFFSET (1));
 607     }
 608
 609   return cnt;
 610 }
 611
 612 #else
 613
 614 /* No target specific implementation and neither USE_GCC_UNWINDER nor
 615    USE_GENERIC_UNWINDER defined.  */
 616
 617 /*------------------------------*
 618  *-- The dummy implementation --*
 619  *------------------------------*/
 620
 621 int
 622 __gnat_backtrace (void **array ATTRIBUTE_UNUSED,
 623                   int size ATTRIBUTE_UNUSED,
 624                   void *exclude_min ATTRIBUTE_UNUSED,
 625                   void *exclude_max ATTRIBUTE_UNUSED,
 626                   int skip_frames ATTRIBUTE_UNUSED)
 627 {
 628   return 0;
 629 }
 630
 631 #endif
 632
 633 #endif
 634
 635 #ifdef __cplusplus
 636 }
 637 #endif