5261 //--------------------------------------------------------------------------------------------------

  5262 // Non-product code

  5263 

  5264 static int mallocDebugIntervalCounter = 0;

  5265 static int mallocDebugCounter = 0;

  5266 

  5267 // For debugging possible bugs inside HeapWalk (a ring buffer)

  5268 #define SAVE_COUNT 8

  5269 static PROCESS_HEAP_ENTRY saved_heap_entries[SAVE_COUNT];

  5270 static int saved_heap_entry_index;

  5271 

  5272 bool os::check_heap(bool force) {

  5273   if (++mallocDebugCounter < MallocVerifyStart && !force) return true;

  5274   if (++mallocDebugIntervalCounter >= MallocVerifyInterval || force) {

  5275     // Note: HeapValidate executes two hardware breakpoints when it finds something

  5276     // wrong; at these points, eax contains the address of the offending block (I think).

  5277     // To get to the exlicit error message(s) below, just continue twice.

  5278     //

  5279     // Note:  we want to check the CRT heap, which is not necessarily located in the

  5280     // process default heap.

  5281     HANDLE heap = (HANDLE) _get_heap_handle();

  5282     if (!heap) {

  5283       return true;

  5284     }

  5285 

  5286     // If we fail to lock the heap, then gflags.exe has been used

  5287     // or some other special heap flag has been set that prevents

  5288     // locking. We don't try to walk a heap we can't lock.

  5289     if (HeapLock(heap) != 0) {

  5290       PROCESS_HEAP_ENTRY phe;

  5291       phe.lpData = NULL;

  5292       memset(saved_heap_entries, 0, sizeof(saved_heap_entries));

  5293       saved_heap_entry_index = 0;

  5294       int count = 0;

  5295 

  5296       while (HeapWalk(heap, &phe) != 0) {

  5297         count ++;

  5298         if ((phe.wFlags & PROCESS_HEAP_ENTRY_BUSY) &&

  5299             !HeapValidate(heap, 0, phe.lpData)) {

  5300           tty->print_cr("C heap has been corrupted (time: %d allocations)", mallocDebugCounter);

  5301           tty->print_cr("corrupted block near address %#x, length %d, count %d", phe.lpData, phe.cbData, count);

  5302           HeapUnlock(heap);

  5303           fatal("corrupted C heap");

  5304         } else {

  5305           // Save previous seen entries in a ring buffer. We have seen strange

  5306           // heap corruption fatal errors that produced mdmp files, but when we load

  5307           // these mdmp files in WinDBG, "!heap -triage" shows no error.

  5308           // We can examine the saved_heap_entries[] array in the mdmp file to

  5309           // diagnose such seemingly spurious errors reported by HeapWalk.

  5310           saved_heap_entries[saved_heap_entry_index++] = phe;

  5311           if (saved_heap_entry_index >= SAVE_COUNT) {

  5312             saved_heap_entry_index = 0;

  5313           }

  5314         }

  5315       }

  5316       DWORD err = GetLastError();

  5317       if (err != ERROR_NO_MORE_ITEMS && err != ERROR_CALL_NOT_IMPLEMENTED &&

  5318          (err == ERROR_INVALID_FUNCTION && phe.lpData != NULL)) {

  5319         HeapUnlock(heap);

  5320         fatal("heap walk aborted with error %d", err);

  5321       }

  5322       HeapUnlock(heap);

  5323     }

  5324     mallocDebugIntervalCounter = 0;

  5325   }

  5326   return true;

  5327 }

  5328 

  5329