Debug Assertion Failed! Expression: __acrt_first_block == header - c++

I am trying to test the dll which I wrote with GoogleTest and when I call one of the tests It throws me this error:
I have come to the conclusion that the problem is in assigning memory to vectors but I don't know how to resolve this as I am fairly new to C++ programming. The code is as follows:
#ArraysCPP11.h
#ifdef ARRAYSCP11_EXPORTS
#define ARRAYSCP11_API __declspec(dllexport)
#else
#define ARRAYSCP11_API __declspec(dllimport)
#endif
__declspec(dllexport) void removeWhiteSpaces(std::vector<std::string> v, std::vector<std::string> &output);
#ArraysCPP11.cpp
void removeWhiteSpaces(std::vector<std::string> v, std::vector<std::string> &output) { //odstranjevanje presledkov iz vector-ja (vsak drugi element je bil presledek)
for (std::vector<std::string>::iterator it = v.begin(); it != v.end(); it++) {
std::string buffer = *it;
if (isdigit(buffer[0])){;
output.push_back(*it);
}
}
}
#TestTemp.h
template<class T>
class TestTemp
{
public:
TestTemp();
void SetValue(T obj_i);
T GetValue();
bool alwaysTrue();
bool TestTemp<T>::formattingTest(std::string input, std::vector<std::string> realVector, std::vector<std::string> formattedInput);
private:
T m_Obj;
};
template<class T>
inline bool TestTemp<T>::formattingTest(std::string input, std::vector<std::string> realVector, std::vector<std::string> formattedVector) {
std::string input2 = input;
// std::vector<std::string> fResult;
std::string first;
std::string second;
bool endResult = true;
std::vector<std::string> end;
//std::vector<std::string> result = split(input2, ' ');
removeWhiteSpaces(formattedVector,end);
std::vector<std::string>::iterator yt = realVector.begin();
for (std::vector<std::string>::iterator it = end.begin(); it != end.end(); it++, yt++) {
first = *it;
second = *yt;
if (first.compare(second) != 0) {
endResult = false;
break;
}
}
return endResult;
}
#ArraysCPP11-UnitTest.cpp
struct formattingTesting{
// formattingTesting* test;
std::string start;
std::vector<std::string> endResult;
formattingTesting() {
}
explicit formattingTesting(const std::string start, const std::vector<std::string> endResult)
: start{start}, endResult{endResult}
{
}
};
struct fTest : testing::Test {
formattingTesting* test;
fTest() {
test = new formattingTesting;
}
~fTest() {
delete test;
}
};
struct format {
std::string start;
std::vector<std::string> end;
};
struct formTest : fTest, testing::WithParamInterface<format> {
formTest() {
test->start = GetParam().start;
test->endResult = GetParam().end;
}
};
TEST_P(formTest, test1) {
bool endResult = true;
TestTemp<int> TempObj;
std::string first;
std::string second;
//std::string start ("1 2 3 4 5 6 7 8 9 10");
//std::vector<std::string> end = { "1","2","3","4","5","6","7","8","9","10" };
std::vector<std::string> start2 = { "1","","2","3","4","5","6","7","8","9","10" };
std::string start = GetParam().start;
std::vector<std::string> end = GetParam().end;
bool result = TempObj.formattingTest(start,end,start2);
EXPECT_TRUE(result);
}
INSTANTIATE_TEST_CASE_P(Default, formTest, testing::Values(
format{ "1", {"1"} },
format{ " ", {} },
format{ "1 2 3 4 5",{"1","2","3","4","5"} },
format{ "1 2 3 4 5 6", {"1","2","3","4","5","6"} }
));
int main(int argc, char** argv)
{
testing::InitGoogleTest(&argc, argv);
RUN_ALL_TESTS();
return 0;
}

As this is a DLL, the problem might lie in different heaps used for allocation and deallocation (try to build the library statically and check if that will work).
The problem is, that DLLs and templates do not agree together very well. In general, depending on the linkage of the MSVC runtime, it might be problem if the memory is allocated in the executable and deallocated in the DLL and vice versa (because they might have different heaps). And that can happen with templates very easily, for example: you push_back() to the vector inside the removeWhiteSpaces() in the DLL, so the vector memory is allocated inside the DLL. Then you use the output vector in the executable and once it gets out of scope, it is deallocated, but inside the executable whose heap doesn't know anything about the heap it has been allocated from. Bang, you're dead.
This can be worked-around if both DLL and the executable use the same heap. To ensure this, both the DLL and the executable must use the dynamic MSVC runtime - so make sure, that both link to the runtime dynamically, not statically. In particular, the exe should be compiled and linked with /MD[d] and the library with /LD[d] or /MD[d] as well, neither one with /MT[d]. Note that afterwards the computer which will be running the app will need the MSVC runtime library to run (for example, by installing "Visual C++ Redistributable" for the particular MSVC version).
You could get that work even with /MT, but that is more difficult - you would need to provide some interface which will allow the objects allocated in the DLL to be deallocated there as well. For example something like:
__declspec(dllexport) void deallocVector(std::vector<std::string> &x);
void deallocVector(std::vector<std::string> &x) {
std::vector<std::string> tmp;
v.swap(tmp);
}
(however this does not work very well in all cases, as this needs to be called explicitly so it will not be called e.g. in case of exception - to solve this properly, you would need to provide some interface from the DLL, which will cover the vector under the hood and will take care about the proper RAII)
EDIT: the final solution was actually was to have all of the projects (the exe, dll and the entire googleTest project) built in Multi-threaded Debug DLL (/MDd)
(the GoogleTest projects are built in Multi-threaded debug(/MTd) by default)

I had a similar problem and it turned out that my unittest project was set to a different code generation runtime library - so by setting it to the same as the DLL project, then no heap exception

That verification was implemented by Microsoft software developers a long time ago in 1992 - 1993 and it is No Longer valid since in case of Heterogeneous or MPI programming a new memory Could Be allocated Not from a Local Heap.
When an application gets a memory using OpenCL or CUDA APIs a GPU driver does all memory allocations and, of course, it doesn't use the Local Heap of the application. However, the application should release the memory before it exits. At that time Microsoft's Memory Leaks Detection API detects it and that assert is displayed.
Please take a look at a Video Technical Report regarding origins of that verification:
Origins of MS Visual Studio 2015 Assert __acrt_first_block == header ( VTR-010 )
https://www.youtube.com/watch?v=NJeA_YkLzxc
Note: A weblink to the youtube video updated since I've uploaded a video with some corrections.

I encountered the same error and I found a way to get more information about the cause of the problem: It is possible to set with visual studio a breakpoint condition on the line that raise this error (so that the debugger breaks before the error message).
It is necessary to open the corresponding file (debug_heap.cpp,somewhere in "C:\Program Files (x86)\Windows Kits\10\Source") and to write the following condition:
Then we can continue debugging and when the breakpoint is hit, we can observe the address of the block that raise the error (the "block" argument of the "free_dbg_nolock" function that contains the breakpoint).
From there you can observe the memory content of the block by copying the address into the memory window (Debug->Windows->Memory). If you are lucky it may be a string or an easily recognizable variable.
You can then identify the variable that causes the bug and try to fix it.
In my case it was a variable that was created in one dll and deleted in another. To correct it I replaced all my objects by pointers to these objects in one dll.

I had the same issue with Microsoft visual studio 2019, simply fixed by changing the "Runtime library" to " Multi-Threaded Debug DLL (/MDd)"
right click on solution on "Solution Explorer" -> "properties" -> "C/C++" -> "Code Generation" , and change "Runtime library" to " Multi-Threaded Debug DLL (/MDd)"

I was seeing this error too and in my case I had all the memory model settings lined up correctly. However having recently upgraded the projects from vs2013 to vs2015 I had stale references between the .exe and .dll, so in fact I was using the old DLL built with 2013. I had to remove the reference between the .exe and .dll and re-add it to update the name of the .lib that the exe was linking against. (Right click on the "References" child item of the .exe project and "Add", while confusingly also allows you to remove a reference).

Related

Qt3D custom mesh "Invalid address specified to RtlValidateHeap" runtime error

I made a custom mesh class inherited Qt3DRender::QGeometryRenderer to draw lines in Qt3D and use it in the same way as Qt3DExtras::QShpereMesh or others. Here the source( .h , .cpp )
And on test with single line creation everithing as i expected, line creates and destroy without an error. But if do test with std::vector<Qt3DCore::QEntity*> and put to it 100 Qt3DCore::QEntity* and add them line as a component i have heap error.(here test project)
Version of Qt:6.1.0.
In Visual Studio 2019 CE with DEBUG 64bit build the runtime error message is:
HEAP[QLineMesh_test.exe]: Invalid address specified to RtlValidateHeap( 0000013BF0630000, 0000013BF522D060 ) QLineMesh_test.exe has triggered a breakpoint.
and VS points to breakpoint line in file debug_heap.cpp:
// This function is provided for backwards compatibility only. It returns TRUE
// if the given block points to an allocation from the OS heap that underlies
// this CRT debug heap. Back when the CRT used its own OS heap (prior to Dev10),
// this function would thus also tell you whether the block was allocated by this
// debug heap. Now, it just tells you whether the block was allocated by some
// debug heap.
extern "C" int __cdecl _CrtIsValidHeapPointer(void const* const block)
{
if (!block)
return FALSE;
return HeapValidate(__acrt_heap, 0, header_from_block(block)); ///<-----breakpoint here on HeapValidate
}
In VS RELEASE 64bit build breakpoint is in qarraydata.h at QArrayData::reallocateUnaligned function call.
In QtCreator with MSVC2019 64bit and minGW64-bit builds program terminated after same behaviour but without such deep explanation.
May be the error happen in function which generate the vertex data of mesh and put it to QByteArray for later usage in Qt3DCore::QBuffer.The fragment code of function from here:
inline void QLineMesh::generateVertexData()
{
...
vertex_buf.clear();
vertex_buf.resize((3 + 3) * 6 * sizeof(float));
float* possitions = reinterpret_cast<float*>(vertex_buf.data());
int index = 0;
for (auto& v : vertices)
{
possitions[index++] = v.x();
possitions[index++] = v.y();
possitions[index++] = v.z();
}
};
I can`t imagene how the heap can be affected by this mesh creation class if it's just store pointers and logic to how to manage it.
UPDATE:
In Qt 5.15.2 everithing works as expected without errors. Source in question support both versions.

Access violation writing on platform toolset v140 DLL when call from v100

I have a DLL written in VS2015, with platform toolset: Visual Studio 2015 (v140).
this DLL include the following function:
std::string GetUserPoints(std::string ownerid);
I have created a win32 console application by visual studio 2010, and tried to call this "GetUserPoints" function!
I get a runtime access violation when GetUserPoints aim to return the string value.
I tried to change this GetUserPoints to:
int GetUserPoints(std::string ownerid, char*& output)
{
if (l_RestLowLevel != NULL) {
std::string str = utility::conversions::to_utf8string(l_RestLowLevel->GetUserCameraPoints(utility::conversions::to_string_t(ownerid)));
// Dynamically allocate memory for the returned string, +1 for terminating NULL
output = new char[str.length()+1];
// Copy source string in dynamically allocated string buffer
strncpy_s(output, str.length() + 1, str.c_str(), str.length());
return str.size();
}
return 0;
}
But I get a runtime "Access violation writing" exception on:
output = new char[str.length()+1];
All versions of Visual C++ have their own implementation of the strandard library ,which are not necesarilly the same ,in fact they're highly likely to be different.
Due to incompatibillities its recommended not to specify Standard library elements in your DLL interfaces.
Internally in your Programs and or Dll's you can use them without problems. but when interfacing with each other you have to agree on the implementation.

C++ DLL returning pointer to std::list<std::wstring>

I got a dll with the following prototype:
DLL_EXPORT std::list<std::wstring>* c_ExplodeWStringToList(std::wstring in_delimiter, std::wstring in_string, int in_limit);
The application uses this like that:
std::list<std::wstring>* exploded = mydllclass->c_ExplodeWStringToList(L" ", in_command.c_str(), 0);
This works great under XP 32, but when I try this at home with my Vista 64 my program just closes itself. No error and no warning?
Some days ago the DLL was returning the list directly - no pointer. But I switched to VC++ 2010 Express, and I could not compile my DLL without this modification.
Anything I am not seeing here?
Thank you :)
Update:
DLL_EXPORT std::list<std::wstring>* c_ExplodeWStringToList(std::wstring in_delimiter, std::wstring in_string, int in_limit)
{
std::list<std::wstring>* returnlist = new std::list<std::wstring>();
std::list<std::wstring>* stringlist = new std::list<std::wstring>();
UINT pos = 0;
while(true)
{
pos = in_string.find(in_delimiter, 0);
if(pos == std::string::npos)
{
stringlist->push_back(in_string.substr(0, pos));
break;
}
else
{
stringlist->push_back(in_string.substr(0, pos));
in_string = in_string.substr(pos + in_delimiter.length());
}
}
// ****
// Here is missing some code I've commented out while searching for the error.
// ****
returnlist = stringlist;
return returnlist;
}
T
I didn't dig into the code, but a conclusion I came to regarding working with DLLs is to not return anything but primitive types from DLL functions. This is because due to different compilers or different switches or project settings structs and classes are not aligned the same not have the same size in the DLL and in the code calling the DLL.
So returning a list from a DLL might be considered malformed in the caller application.
Same thing regards throwing exceptions from a DLL - the class thrown might be misinterpreted by the catching code.
So, best is export only C functions that return primitive types (to denote error codes).

Mutex assert in boost regex constructor

I'm using boost 1.47 for Arm, with the Code Sourcery C++ compiler (4.5.1), crosscompiling from Windows 7 targeting Ubuntu.
When we compile the debug version (i.e. asserts are enabled), there is an assert triggered:
pthread_mutex_lock.c:62: __pthread_mutex_lock: Assertion 'mutex->__data.__owner == 0' failed.
Compiling in release mode, the assert is not triggered and the program works fine (as far as we can tell).
This is happening under a Ubuntu 10.x Arm board.
So, it appears that the pthread_mutex_lock thinks the mutex was set by a different thread than the current one. At this point in my program, we're still single threaded, verified by printing out pthread_self in main and just before the regex constructor is called. That is, it should not have failed the assertion.
Below is the snippet of code that triggers the problem.
// Set connection server address and port from a URL
bool MyHttpsXmlClient::set_server_url(const std::string& server_url)
{
#ifdef BOOST_HAS_THREADS
cout <<"Boost has threads" << endl;
#else
cout <<"WARNING: boost does not support threads" << endl;
#endif
#ifdef PTHREAD_MUTEX_INITIALIZER
cout << "pthread mutex initializer" << endl;
#endif
{
pthread_t id = pthread_self();
printf("regex: Current threadid: %d\n",id);
}
const boost::regex e("^((http|https)://)?([^:]*)(:([0-9]*))?"); // 2: service, 3: host, 5: port // <-- dies in here
I've confirmed that BOOST_HAS_THREADS is set, as is PTHREAD_MUTEX_INITIALIZER.
I tried following the debugger though boost but it's templated code and it was rather difficult to follow the assembly, but we basically die in do_assign
(roughtly line 380 in basic_regex.hpp)
basic_regex& assign(const charT* p1,
const charT* p2,
flag_type f = regex_constants::normal)
{
return do_assign(p1, p2, f);
}
the templated code is:
// out of line members;
// these are the only members that mutate the basic_regex object,
// and are designed to provide the strong exception guarentee
// (in the event of a throw, the state of the object remains unchanged).
//
template <class charT, class traits>
basic_regex<charT, traits>& basic_regex<charT, traits>::do_assign(const charT* p1,
const charT* p2,
flag_type f)
{
shared_ptr<re_detail::basic_regex_implementation<charT, traits> > temp;
if(!m_pimpl.get())
{
temp = shared_ptr<re_detail::basic_regex_implementation<charT, traits> >(new re_detail::basic_regex_implementation<charT, traits>());
}
else
{
temp = shared_ptr<re_detail::basic_regex_implementation<charT, traits> >(new re_detail::basic_regex_implementation<charT, traits>(m_pimpl->m_ptraits));
}
temp->assign(p1, p2, f);
temp.swap(m_pimpl);
return *this;
}
I'm not sure what component is actually using the mutex--does anyone know?
In the debugger, I could retrieve the address for the variable mutex and then inspect (mutex->__data.__owner). I got the offsets from the compiler header file bits/pthreadtypes.h, which shows:
/* Data structures for mutex handling. The structure of the attribute
type is not exposed on purpose. */
typedef union
{
struct __pthread_mutex_s
{
int __lock;
unsigned int __count;
int __owner;
/* KIND must stay at this position in the structure to maintain
binary compatibility. */
int __kind;
unsigned int __nusers;
__extension__ union
{
int __spins;
__pthread_slist_t __list;
};
} __data;
char __size[__SIZEOF_PTHREAD_MUTEX_T];
long int __align;
I used these offsets to inspect the data in memory. The values did not make sense:
For instance, the __data.__lock field (an int) is 0xb086b580. The __count (an unsigned int) is 0x6078af00, and __owner (an int) is 0x6078af00.
This leads me to think that somehow initialization of this mutex was not performed. Either that or it was completely corrupted, but I'm leaning to missed initialization because when I linked with debug boost libraries, there was no assert.
Now, I'm assuming that whatever mutex that is being queried, is some global/static that is used to make regex threadsafe, and that somehow it was not initialized.
Has anyone encountered anything similar? Is there some extra step needed for Ubuntu to ensure mutex initialization?
Is my implementation assumption correct?
If it is correct, can someone point me to where this mutex is declared, and where it's initialization is occurring
any suggestions on further debugging steps? I'm thinking I might have to somehow download the source and rebuild with tracing in there (hoping StackOverflow can help me before I get to this point)
One of the first things to check when a really REALLY peculiar runtime crash appears in a well-known, well-tested library like boost is whether there's a header/library configuration mismatch. IMHO, putting _DEBUG or NDEBUG in headers, especially within the structures in a way that affects their binary layout, is an anti-pattern. Ideally we should be able to use the same .lib whether we define _DEBUG, DEBUG, Debug, Debug, NDEBUG, or whatever (so that we can select the .lib based on whether we want to have debug symbols or not, not whether it matches header defines). Unfortunately this isn't always the case.
I used these offsets to inspect the data in memory. The values did not make sense:
For instance, the __data.__lock field (an int) is 0xb086b580. The __count (an unsigned > int) is 0x6078af00, and __owner (an int) is 0x6078af00.
This sounds like different parts of your code have different views on how large various structures should be. Some things to check:
Is there any #define which enlarges a data structure, but is not consistently set throughout your code base? (On Windows, _SECURE_SCL is infamous for this kind of bugs)
Do you do any structure packing? If you set #pragma pack anywhere in a header and forget to unset it at the end of the header, any data structures included after that will have a different layout than elsewhere in your program.

Memory leaks after using typeinfo::name()

I have a program in which, partly for informational logging, I output the names of some classes as they are used (specifically I add an entry to a log saying along the lines of Messages::CSomeClass transmitted to 127.0.0.1). I do this with code similar to the following:
std::string getMessageName(void) const {
return std::string(typeid(*this).name());
}
And yes, before anyone points it out, I realise that the output of typeinfo::name is implementation-specific.
According to MSDN
The type_info::name member function returns a const char* to a null-terminated string representing the human-readable name of the type. The memory pointed to is cached and should never be directly deallocated.
However, when I exit my program in the debugger, any "new" use of typeinfo::name() shows up as a memory leak. If I output the information for 2 classes, I get 2 memory leaks, and so on. This hints that the cached data is never being freed.
While this is not a major issue, it looks messy, and after a long debugging session it could easily hide genuine memory leaks.
I have looked around and found some useful information (one SO answer gives some interesting information about how typeinfo may be implemented), but I'm wondering if this memory should normally be freed by the system, or if there is something i can do to "not notice" the leaks when debugging.
I do have a back-up plan, which is to code the getMessageName method myself and not rely on typeinfo::name, but I'd like to know anyway if there's something I've missed.
Another solution is to correct the underlying problem. This is not really a memory leak, just a false report. The memory blocks allocated to the tyepinfo() and the name() string are assigned the wrong block type. It is probably not a good idea to "free" this memory, since an attempt will be made by the CRT to free it again. The good news is this was finally fixed in VS2012 (_MSC_VER 1700+).
Since this only applies to _DEBUG builds, the following may be a safer solution. The function _FixTypeInfoBlockUse() should be called as mentioned above just before exiting the module entry point (main, WinMain, etc.).
#if defined(_DEBUG) && (_MSC_VER >= 1000 && _MSC_VER <= 1699)
//
// Debug memory block header:
// o Borrowed from the Microsoft CRT to fix the false "memory leak" report
// when using typeinfo 'name' accessor in a _DEBUG build of the library.
//
struct _CrtMemBlockHeader
{
struct _CrtMemBlockHeader * pBlockHeaderNext;
struct _CrtMemBlockHeader * pBlockHeaderPrev;
char * szFileName;
int nLine;
#ifdef _WIN64
int nBlockUse;
size_t nDataSize;
#else
size_t nDataSize;
int nBlockUse;
#endif
long lRequest;
unsigned char gap[4];
};
static void __cdecl _FixTypeInfoBlockUse(void)
{
__type_info_node* pNode = __type_info_root_node._Next;
while(pNode != NULL)
{
__type_info_node* pNext = pNode->_Next;
(((_CrtMemBlockHeader*)pNode) - 1)->nBlockUse = _CRT_BLOCK;
if (pNode->_MemPtr != NULL)
(((_CrtMemBlockHeader*)pNode->_MemPtr) - 1)->nBlockUse = _CRT_BLOCK;
pNode = pNext;
}
}
#endif//defined(_DEBUG) && (_MSC_VER >= 1000 && _MSC_VER <= 1699)
I've just stumbled upon this issue trying to clean the log of VLD. Yes, this is a known bug, which is fixed in VC11 only. It exists in previous versions of MSVC including 2010. This bug appears only if you use MFC. If you use MFC as DLL instead of static library, the memory leak will still exist, but won't be detected.
There is a global cache of type_info names and it is not cleared (the excerpt from <typeinfo>):
struct __type_info_node {
void *_MemPtr;
__type_info_node* _Next;
};
extern __type_info_node __type_info_root_node;
The idea is to clear this cache. This function works for me:
#include <typeinfo>
void clear_type_info_cache()
{
__type_info_node* & node = __type_info_root_node._Next;
while(node)
{
if (node->_MemPtr)
{
delete node->_MemPtr;
}
__type_info_node* tempNode = node;
node = node->_Next;
delete tempNode;
}
}
Call clear_type_info_cache() before exit. You can register it with atexit
#include <cstdlib>
int WinMain(...)
{
atexit(&clear_type_info_cache);
...
}
or call it immediately before leaving WinMain
struct dummy_scope_exit
{
typedef void (*Fun)();
dummy_scope_exit(Fun f) : m_f(f) {}
~dummy_scope_exit() { m_f(); }
Fun m_f;
};
int WinMain(...)
{
dummy_scope_exit cleaner = &clear_type_info_cache;
...
}
As pointed out by Chris Parton in the comments, this appears to be a known bug, at least with the version of compiler I am using - upgrading to VC11 would correct the issue, if I were able to upgrade.
Attempting to delete the output of typeinfo::name() partially works:
std::string getMessageName(void) const
{
std::string typeStr(typeid(*this).name());
delete (typeid(*this).name());
return typeStr;
}
However there are still some memory leaks - I just noticed that previously I appeared to be getting two leaks per call (perhaps due to the classes being inside a namespace?). Using the above version of code, this went down to one leak per call.
Another solution that appears to work is to link in the dynamic version of the MFC libraries (yes, I'm using MFC, don't judge me), rather than the static version.
VS stores type info in a singly-linked list. The header of this list is accessible by an opaque structure accessible by name __type_info_root_node. Actually it is a SLIST_HEADER structure.
Win32 API has a set of concurrency-safe function to work with such structures.
To fix memory leaks report In your case you need to delete all nodes of this list.
#include <Windows.h>
#include <typeinfo>
#include <vld.h>
void ClearTypeinfoCache()
{
#ifdef _DEBUG
while (auto entry = InterlockedPopEntrySList(reinterpret_cast<PSLIST_HEADER>(&__type_info_root_node)))
{
free(entry);
}
#endif
}
int main()
{
atexit(ClearTypeinfoCache);
return 0;
}
Updated: VLD 2.5.1 does not report memory leaks on type_info::name() in VS2015 Update 3.