1 //===-- IRMemoryMap.cpp -----------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "lldb/Core/DataBufferHeap.h"
11 #include "lldb/Core/DataExtractor.h"
12 #include "lldb/Core/Error.h"
13 #include "lldb/Core/Log.h"
14 #include "lldb/Core/Scalar.h"
15 #include "lldb/Expression/IRMemoryMap.h"
16 #include "lldb/Target/Process.h"
17 #include "lldb/Target/Target.h"
18 
19 using namespace lldb_private;
20 
21 IRMemoryMap::IRMemoryMap (lldb::TargetSP target_sp) :
22     m_target_wp(target_sp)
23 {
24     if (target_sp)
25         m_process_wp = target_sp->GetProcessSP();
26 }
27 
28 IRMemoryMap::~IRMemoryMap ()
29 {
30     lldb::ProcessSP process_sp = m_process_wp.lock();
31 
32     if (process_sp)
33     {
34         AllocationMap::iterator iter;
35 
36         Error err;
37 
38         while ((iter = m_allocations.begin()) != m_allocations.end())
39         {
40             err.Clear();
41             if (iter->second.m_leak)
42                 m_allocations.erase(iter);
43             else
44                 Free(iter->first, err);
45         }
46     }
47 }
48 
49 lldb::addr_t
50 IRMemoryMap::FindSpace (size_t size)
51 {
52     lldb::TargetSP target_sp = m_target_wp.lock();
53     lldb::ProcessSP process_sp = m_process_wp.lock();
54 
55     lldb::addr_t ret = LLDB_INVALID_ADDRESS;
56 
57     if (process_sp && process_sp->CanJIT() && process_sp->IsAlive())
58     {
59         Error alloc_error;
60 
61         ret = process_sp->AllocateMemory(size, lldb::ePermissionsReadable | lldb::ePermissionsWritable, alloc_error);
62 
63         if (!alloc_error.Success())
64             return LLDB_INVALID_ADDRESS;
65         else
66             return ret;
67     }
68 
69     for (int iterations = 0; iterations < 16; ++iterations)
70     {
71         lldb::addr_t candidate = LLDB_INVALID_ADDRESS;
72 
73         switch (target_sp->GetArchitecture().GetAddressByteSize())
74         {
75         case 4:
76             {
77                 uint32_t random_data = rand();
78                 candidate = random_data;
79                 candidate &= ~0xfffull;
80                 break;
81             }
82         case 8:
83             {
84                 uint32_t random_low = rand();
85                 uint32_t random_high = rand();
86                 candidate = random_high;
87                 candidate <<= 32ull;
88                 candidate |= random_low;
89                 candidate &= ~0xfffull;
90                 break;
91             }
92         }
93 
94         if (IntersectsAllocation(candidate, size))
95             continue;
96 
97         ret = candidate;
98 
99         return ret;
100     }
101 
102     return ret;
103 }
104 
105 IRMemoryMap::AllocationMap::iterator
106 IRMemoryMap::FindAllocation (lldb::addr_t addr, size_t size)
107 {
108     if (addr == LLDB_INVALID_ADDRESS)
109         return m_allocations.end();
110 
111     AllocationMap::iterator iter = m_allocations.lower_bound (addr);
112 
113     if (iter == m_allocations.end() ||
114         iter->first > addr)
115     {
116         if (iter == m_allocations.begin())
117             return m_allocations.end();
118         iter--;
119     }
120 
121     if (iter->first <= addr && iter->first + iter->second.m_size >= addr + size)
122         return iter;
123 
124     return m_allocations.end();
125 }
126 
127 bool
128 IRMemoryMap::IntersectsAllocation (lldb::addr_t addr, size_t size) const
129 {
130     if (addr == LLDB_INVALID_ADDRESS)
131         return false;
132 
133     AllocationMap::const_iterator iter = m_allocations.lower_bound (addr);
134 
135     // Since we only know that the returned interval begins at a location greater than or
136     // equal to where the given interval begins, it's possible that the given interval
137     // intersects either the returned interval or the previous interval.  Thus, we need to
138     // check both. Note that we only need to check these two intervals.  Since all intervals
139     // are disjoint it is not possible that an adjacent interval does not intersect, but a
140     // non-adjacent interval does intersect.
141     if (iter != m_allocations.end()) {
142         if (AllocationsIntersect(addr, size, iter->second.m_process_start, iter->second.m_size))
143             return true;
144     }
145 
146     if (iter != m_allocations.begin()) {
147         --iter;
148         if (AllocationsIntersect(addr, size, iter->second.m_process_start, iter->second.m_size))
149             return true;
150     }
151 
152     return false;
153 }
154 
155 bool
156 IRMemoryMap::AllocationsIntersect(lldb::addr_t addr1, size_t size1, lldb::addr_t addr2, size_t size2) {
157   // Given two half open intervals [A, B) and [X, Y), the only 6 permutations that satisfy
158   // A<B and X<Y are the following:
159   // A B X Y
160   // A X B Y  (intersects)
161   // A X Y B  (intersects)
162   // X A B Y  (intersects)
163   // X A Y B  (intersects)
164   // X Y A B
165   // The first is B <= X, and the last is Y <= A.
166   // So the condition is !(B <= X || Y <= A)), or (X < B && A < Y)
167   return (addr2 < (addr1 + size1)) && (addr1 < (addr2 + size2));
168 }
169 
170 lldb::ByteOrder
171 IRMemoryMap::GetByteOrder()
172 {
173     lldb::ProcessSP process_sp = m_process_wp.lock();
174 
175     if (process_sp)
176         return process_sp->GetByteOrder();
177 
178     lldb::TargetSP target_sp = m_target_wp.lock();
179 
180     if (target_sp)
181         return target_sp->GetArchitecture().GetByteOrder();
182 
183     return lldb::eByteOrderInvalid;
184 }
185 
186 uint32_t
187 IRMemoryMap::GetAddressByteSize()
188 {
189     lldb::ProcessSP process_sp = m_process_wp.lock();
190 
191     if (process_sp)
192         return process_sp->GetAddressByteSize();
193 
194     lldb::TargetSP target_sp = m_target_wp.lock();
195 
196     if (target_sp)
197         return target_sp->GetArchitecture().GetAddressByteSize();
198 
199     return UINT32_MAX;
200 }
201 
202 ExecutionContextScope *
203 IRMemoryMap::GetBestExecutionContextScope() const
204 {
205     lldb::ProcessSP process_sp = m_process_wp.lock();
206 
207     if (process_sp)
208         return process_sp.get();
209 
210     lldb::TargetSP target_sp = m_target_wp.lock();
211 
212     if (target_sp)
213         return target_sp.get();
214 
215     return NULL;
216 }
217 
218 IRMemoryMap::Allocation::Allocation (lldb::addr_t process_alloc,
219                                      lldb::addr_t process_start,
220                                      size_t size,
221                                      uint32_t permissions,
222                                      uint8_t alignment,
223                                      AllocationPolicy policy) :
224     m_process_alloc (process_alloc),
225     m_process_start (process_start),
226     m_size (size),
227     m_permissions (permissions),
228     m_alignment (alignment),
229     m_policy (policy),
230     m_leak (false)
231 {
232     switch (policy)
233     {
234         default:
235             assert (0 && "We cannot reach this!");
236         case eAllocationPolicyHostOnly:
237             m_data.SetByteSize(size);
238             memset(m_data.GetBytes(), 0, size);
239             break;
240         case eAllocationPolicyProcessOnly:
241             break;
242         case eAllocationPolicyMirror:
243             m_data.SetByteSize(size);
244             memset(m_data.GetBytes(), 0, size);
245             break;
246     }
247 }
248 
249 lldb::addr_t
250 IRMemoryMap::Malloc (size_t size, uint8_t alignment, uint32_t permissions, AllocationPolicy policy, Error &error)
251 {
252     lldb_private::Log *log (lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
253     error.Clear();
254 
255     lldb::ProcessSP process_sp;
256     lldb::addr_t    allocation_address  = LLDB_INVALID_ADDRESS;
257     lldb::addr_t    aligned_address     = LLDB_INVALID_ADDRESS;
258 
259     size_t          alignment_mask = alignment - 1;
260     size_t          allocation_size;
261 
262     if (size == 0)
263         allocation_size = alignment;
264     else
265         allocation_size = (size & alignment_mask) ? ((size + alignment) & (~alignment_mask)) : size;
266 
267     switch (policy)
268     {
269     default:
270         error.SetErrorToGenericError();
271         error.SetErrorString("Couldn't malloc: invalid allocation policy");
272         return LLDB_INVALID_ADDRESS;
273     case eAllocationPolicyHostOnly:
274         allocation_address = FindSpace(allocation_size);
275         if (allocation_address == LLDB_INVALID_ADDRESS)
276         {
277             error.SetErrorToGenericError();
278             error.SetErrorString("Couldn't malloc: address space is full");
279             return LLDB_INVALID_ADDRESS;
280         }
281         break;
282     case eAllocationPolicyMirror:
283         process_sp = m_process_wp.lock();
284         if (log)
285             log->Printf ("IRMemoryMap::%s process_sp=0x%" PRIx64 ", process_sp->CanJIT()=%s, process_sp->IsAlive()=%s", __FUNCTION__, (lldb::addr_t) process_sp.get (), process_sp && process_sp->CanJIT () ? "true" : "false", process_sp && process_sp->IsAlive () ? "true" : "false");
286         if (process_sp && process_sp->CanJIT() && process_sp->IsAlive())
287         {
288             allocation_address = process_sp->AllocateMemory(allocation_size, permissions, error);
289             if (!error.Success())
290                 return LLDB_INVALID_ADDRESS;
291         }
292         else
293         {
294             if (log)
295                 log->Printf ("IRMemoryMap::%s switching to eAllocationPolicyHostOnly due to failed condition (see previous expr log message)", __FUNCTION__);
296             policy = eAllocationPolicyHostOnly;
297             allocation_address = FindSpace(allocation_size);
298             if (allocation_address == LLDB_INVALID_ADDRESS)
299             {
300                 error.SetErrorToGenericError();
301                 error.SetErrorString("Couldn't malloc: address space is full");
302                 return LLDB_INVALID_ADDRESS;
303             }
304         }
305         break;
306     case eAllocationPolicyProcessOnly:
307         process_sp = m_process_wp.lock();
308         if (process_sp)
309         {
310             if (process_sp->CanJIT() && process_sp->IsAlive())
311             {
312                 allocation_address = process_sp->AllocateMemory(allocation_size, permissions, error);
313                 if (!error.Success())
314                     return LLDB_INVALID_ADDRESS;
315             }
316             else
317             {
318                 error.SetErrorToGenericError();
319                 error.SetErrorString("Couldn't malloc: process doesn't support allocating memory");
320                 return LLDB_INVALID_ADDRESS;
321             }
322         }
323         else
324         {
325             error.SetErrorToGenericError();
326             error.SetErrorString("Couldn't malloc: process doesn't exist, and this memory must be in the process");
327             return LLDB_INVALID_ADDRESS;
328         }
329         break;
330     }
331 
332 
333     lldb::addr_t mask = alignment - 1;
334     aligned_address = (allocation_address + mask) & (~mask);
335 
336     m_allocations[aligned_address] = Allocation(allocation_address,
337                                                 aligned_address,
338                                                 allocation_size,
339                                                 permissions,
340                                                 alignment,
341                                                 policy);
342 
343     if (log)
344     {
345         const char * policy_string;
346 
347         switch (policy)
348         {
349         default:
350             policy_string = "<invalid policy>";
351             break;
352         case eAllocationPolicyHostOnly:
353             policy_string = "eAllocationPolicyHostOnly";
354             break;
355         case eAllocationPolicyProcessOnly:
356             policy_string = "eAllocationPolicyProcessOnly";
357             break;
358         case eAllocationPolicyMirror:
359             policy_string = "eAllocationPolicyMirror";
360             break;
361         }
362 
363         log->Printf("IRMemoryMap::Malloc (%" PRIu64 ", 0x%" PRIx64 ", 0x%" PRIx64 ", %s) -> 0x%" PRIx64,
364                     (uint64_t)allocation_size,
365                     (uint64_t)alignment,
366                     (uint64_t)permissions,
367                     policy_string,
368                     aligned_address);
369     }
370 
371     return aligned_address;
372 }
373 
374 void
375 IRMemoryMap::Leak (lldb::addr_t process_address, Error &error)
376 {
377     error.Clear();
378 
379     AllocationMap::iterator iter = m_allocations.find(process_address);
380 
381     if (iter == m_allocations.end())
382     {
383         error.SetErrorToGenericError();
384         error.SetErrorString("Couldn't leak: allocation doesn't exist");
385         return;
386     }
387 
388     Allocation &allocation = iter->second;
389 
390     allocation.m_leak = true;
391 }
392 
393 void
394 IRMemoryMap::Free (lldb::addr_t process_address, Error &error)
395 {
396     error.Clear();
397 
398     AllocationMap::iterator iter = m_allocations.find(process_address);
399 
400     if (iter == m_allocations.end())
401     {
402         error.SetErrorToGenericError();
403         error.SetErrorString("Couldn't free: allocation doesn't exist");
404         return;
405     }
406 
407     Allocation &allocation = iter->second;
408 
409     switch (allocation.m_policy)
410     {
411     default:
412     case eAllocationPolicyHostOnly:
413         {
414             lldb::ProcessSP process_sp = m_process_wp.lock();
415             if (process_sp)
416             {
417                 if (process_sp->CanJIT() && process_sp->IsAlive())
418                     process_sp->DeallocateMemory(allocation.m_process_alloc); // FindSpace allocated this for real
419             }
420 
421             break;
422         }
423     case eAllocationPolicyMirror:
424     case eAllocationPolicyProcessOnly:
425         {
426             lldb::ProcessSP process_sp = m_process_wp.lock();
427             if (process_sp)
428                 process_sp->DeallocateMemory(allocation.m_process_alloc);
429         }
430     }
431 
432     if (lldb_private::Log *log = lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS))
433     {
434         log->Printf("IRMemoryMap::Free (0x%" PRIx64 ") freed [0x%" PRIx64 "..0x%" PRIx64 ")",
435                     (uint64_t)process_address,
436                     iter->second.m_process_start,
437                     iter->second.m_process_start + iter->second.m_size);
438     }
439 
440     m_allocations.erase(iter);
441 }
442 
443 void
444 IRMemoryMap::WriteMemory (lldb::addr_t process_address, const uint8_t *bytes, size_t size, Error &error)
445 {
446     error.Clear();
447 
448     AllocationMap::iterator iter = FindAllocation(process_address, size);
449 
450     if (iter == m_allocations.end())
451     {
452         lldb::ProcessSP process_sp = m_process_wp.lock();
453 
454         if (process_sp)
455         {
456             process_sp->WriteMemory(process_address, bytes, size, error);
457             return;
458         }
459 
460         error.SetErrorToGenericError();
461         error.SetErrorString("Couldn't write: no allocation contains the target range and the process doesn't exist");
462         return;
463     }
464 
465     Allocation &allocation = iter->second;
466 
467     uint64_t offset = process_address - allocation.m_process_start;
468 
469     lldb::ProcessSP process_sp;
470 
471     switch (allocation.m_policy)
472     {
473     default:
474         error.SetErrorToGenericError();
475         error.SetErrorString("Couldn't write: invalid allocation policy");
476         return;
477     case eAllocationPolicyHostOnly:
478         if (!allocation.m_data.GetByteSize())
479         {
480             error.SetErrorToGenericError();
481             error.SetErrorString("Couldn't write: data buffer is empty");
482             return;
483         }
484         ::memcpy (allocation.m_data.GetBytes() + offset, bytes, size);
485         break;
486     case eAllocationPolicyMirror:
487         if (!allocation.m_data.GetByteSize())
488         {
489             error.SetErrorToGenericError();
490             error.SetErrorString("Couldn't write: data buffer is empty");
491             return;
492         }
493         ::memcpy (allocation.m_data.GetBytes() + offset, bytes, size);
494         process_sp = m_process_wp.lock();
495         if (process_sp)
496         {
497             process_sp->WriteMemory(process_address, bytes, size, error);
498             if (!error.Success())
499                 return;
500         }
501         break;
502     case eAllocationPolicyProcessOnly:
503         process_sp = m_process_wp.lock();
504         if (process_sp)
505         {
506             process_sp->WriteMemory(process_address, bytes, size, error);
507             if (!error.Success())
508                 return;
509         }
510         break;
511     }
512 
513     if (lldb_private::Log *log = lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS))
514     {
515         log->Printf("IRMemoryMap::WriteMemory (0x%" PRIx64 ", 0x%" PRIx64 ", 0x%" PRId64 ") went to [0x%" PRIx64 "..0x%" PRIx64 ")",
516                     (uint64_t)process_address,
517                     (uint64_t)bytes,
518                     (uint64_t)size,
519                     (uint64_t)allocation.m_process_start,
520                     (uint64_t)allocation.m_process_start + (uint64_t)allocation.m_size);
521     }
522 }
523 
524 void
525 IRMemoryMap::WriteScalarToMemory (lldb::addr_t process_address, Scalar &scalar, size_t size, Error &error)
526 {
527     error.Clear();
528 
529     if (size == UINT32_MAX)
530         size = scalar.GetByteSize();
531 
532     if (size > 0)
533     {
534         uint8_t buf[32];
535         const size_t mem_size = scalar.GetAsMemoryData (buf, size, GetByteOrder(), error);
536         if (mem_size > 0)
537         {
538             return WriteMemory(process_address, buf, mem_size, error);
539         }
540         else
541         {
542             error.SetErrorToGenericError();
543             error.SetErrorString ("Couldn't write scalar: failed to get scalar as memory data");
544         }
545     }
546     else
547     {
548         error.SetErrorToGenericError();
549         error.SetErrorString ("Couldn't write scalar: its size was zero");
550     }
551     return;
552 }
553 
554 void
555 IRMemoryMap::WritePointerToMemory (lldb::addr_t process_address, lldb::addr_t address, Error &error)
556 {
557     error.Clear();
558 
559     Scalar scalar(address);
560 
561     WriteScalarToMemory(process_address, scalar, GetAddressByteSize(), error);
562 }
563 
564 void
565 IRMemoryMap::ReadMemory (uint8_t *bytes, lldb::addr_t process_address, size_t size, Error &error)
566 {
567     error.Clear();
568 
569     AllocationMap::iterator iter = FindAllocation(process_address, size);
570 
571     if (iter == m_allocations.end())
572     {
573         lldb::ProcessSP process_sp = m_process_wp.lock();
574 
575         if (process_sp)
576         {
577             process_sp->ReadMemory(process_address, bytes, size, error);
578             return;
579         }
580 
581         lldb::TargetSP target_sp = m_target_wp.lock();
582 
583         if (target_sp)
584         {
585             Address absolute_address(process_address);
586             target_sp->ReadMemory(absolute_address, false, bytes, size, error);
587             return;
588         }
589 
590         error.SetErrorToGenericError();
591         error.SetErrorString("Couldn't read: no allocation contains the target range, and neither the process nor the target exist");
592         return;
593     }
594 
595     Allocation &allocation = iter->second;
596 
597     uint64_t offset = process_address - allocation.m_process_start;
598 
599     if (offset > allocation.m_size)
600     {
601         error.SetErrorToGenericError();
602         error.SetErrorString("Couldn't read: data is not in the allocation");
603         return;
604     }
605 
606     lldb::ProcessSP process_sp;
607 
608     switch (allocation.m_policy)
609     {
610     default:
611         error.SetErrorToGenericError();
612         error.SetErrorString("Couldn't read: invalid allocation policy");
613         return;
614     case eAllocationPolicyHostOnly:
615         if (!allocation.m_data.GetByteSize())
616         {
617             error.SetErrorToGenericError();
618             error.SetErrorString("Couldn't read: data buffer is empty");
619             return;
620         }
621         if (allocation.m_data.GetByteSize() < offset + size)
622         {
623             error.SetErrorToGenericError();
624             error.SetErrorString("Couldn't read: not enough underlying data");
625             return;
626         }
627 
628         ::memcpy (bytes, allocation.m_data.GetBytes() + offset, size);
629         break;
630     case eAllocationPolicyMirror:
631         process_sp = m_process_wp.lock();
632         if (process_sp)
633         {
634             process_sp->ReadMemory(process_address, bytes, size, error);
635             if (!error.Success())
636                 return;
637         }
638         else
639         {
640             if (!allocation.m_data.GetByteSize())
641             {
642                 error.SetErrorToGenericError();
643                 error.SetErrorString("Couldn't read: data buffer is empty");
644                 return;
645             }
646             ::memcpy (bytes, allocation.m_data.GetBytes() + offset, size);
647         }
648         break;
649     case eAllocationPolicyProcessOnly:
650         process_sp = m_process_wp.lock();
651         if (process_sp)
652         {
653             process_sp->ReadMemory(process_address, bytes, size, error);
654             if (!error.Success())
655                 return;
656         }
657         break;
658     }
659 
660     if (lldb_private::Log *log = lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS))
661     {
662         log->Printf("IRMemoryMap::ReadMemory (0x%" PRIx64 ", 0x%" PRIx64 ", 0x%" PRId64 ") came from [0x%" PRIx64 "..0x%" PRIx64 ")",
663                     (uint64_t)process_address,
664                     (uint64_t)bytes,
665                     (uint64_t)size,
666                     (uint64_t)allocation.m_process_start,
667                     (uint64_t)allocation.m_process_start + (uint64_t)allocation.m_size);
668     }
669 }
670 
671 void
672 IRMemoryMap::ReadScalarFromMemory (Scalar &scalar, lldb::addr_t process_address, size_t size, Error &error)
673 {
674     error.Clear();
675 
676     if (size > 0)
677     {
678         DataBufferHeap buf(size, 0);
679         ReadMemory(buf.GetBytes(), process_address, size, error);
680 
681         if (!error.Success())
682             return;
683 
684         DataExtractor extractor(buf.GetBytes(), buf.GetByteSize(), GetByteOrder(), GetAddressByteSize());
685 
686         lldb::offset_t offset = 0;
687 
688         switch (size)
689         {
690         default:
691             error.SetErrorToGenericError();
692             error.SetErrorStringWithFormat("Couldn't read scalar: unsupported size %" PRIu64, (uint64_t)size);
693             return;
694         case 1: scalar = extractor.GetU8(&offset);  break;
695         case 2: scalar = extractor.GetU16(&offset); break;
696         case 4: scalar = extractor.GetU32(&offset); break;
697         case 8: scalar = extractor.GetU64(&offset); break;
698         }
699     }
700     else
701     {
702         error.SetErrorToGenericError();
703         error.SetErrorString ("Couldn't read scalar: its size was zero");
704     }
705     return;
706 }
707 
708 void
709 IRMemoryMap::ReadPointerFromMemory (lldb::addr_t *address, lldb::addr_t process_address, Error &error)
710 {
711     error.Clear();
712 
713     Scalar pointer_scalar;
714     ReadScalarFromMemory(pointer_scalar, process_address, GetAddressByteSize(), error);
715 
716     if (!error.Success())
717         return;
718 
719     *address = pointer_scalar.ULongLong();
720 
721     return;
722 }
723 
724 void
725 IRMemoryMap::GetMemoryData (DataExtractor &extractor, lldb::addr_t process_address, size_t size, Error &error)
726 {
727     error.Clear();
728 
729     if (size > 0)
730     {
731         AllocationMap::iterator iter = FindAllocation(process_address, size);
732 
733         if (iter == m_allocations.end())
734         {
735             error.SetErrorToGenericError();
736             error.SetErrorStringWithFormat("Couldn't find an allocation containing [0x%" PRIx64 "..0x%" PRIx64 ")", process_address, process_address + size);
737             return;
738         }
739 
740         Allocation &allocation = iter->second;
741 
742         switch (allocation.m_policy)
743         {
744         default:
745             error.SetErrorToGenericError();
746             error.SetErrorString("Couldn't get memory data: invalid allocation policy");
747             return;
748         case eAllocationPolicyProcessOnly:
749             error.SetErrorToGenericError();
750             error.SetErrorString("Couldn't get memory data: memory is only in the target");
751             return;
752         case eAllocationPolicyMirror:
753             {
754                 lldb::ProcessSP process_sp = m_process_wp.lock();
755 
756                 if (!allocation.m_data.GetByteSize())
757                 {
758                     error.SetErrorToGenericError();
759                     error.SetErrorString("Couldn't get memory data: data buffer is empty");
760                     return;
761                 }
762                 if (process_sp)
763                 {
764                     process_sp->ReadMemory(allocation.m_process_start, allocation.m_data.GetBytes(), allocation.m_data.GetByteSize(), error);
765                     if (!error.Success())
766                         return;
767                     uint64_t offset = process_address - allocation.m_process_start;
768                     extractor = DataExtractor(allocation.m_data.GetBytes() + offset, size, GetByteOrder(), GetAddressByteSize());
769                     return;
770                 }
771             }
772         case eAllocationPolicyHostOnly:
773             if (!allocation.m_data.GetByteSize())
774             {
775                 error.SetErrorToGenericError();
776                 error.SetErrorString("Couldn't get memory data: data buffer is empty");
777                 return;
778             }
779             uint64_t offset = process_address - allocation.m_process_start;
780             extractor = DataExtractor(allocation.m_data.GetBytes() + offset, size, GetByteOrder(), GetAddressByteSize());
781             return;
782         }
783     }
784     else
785     {
786         error.SetErrorToGenericError();
787         error.SetErrorString ("Couldn't get memory data: its size was zero");
788         return;
789     }
790 }
791 
792 
793