"string iterator not incrementable" issue with the chromaprint_decode_fingerprint() function

[CyberSinh]

Hi Lukas,

I'm trying to use the chromaprint_decode_fingerprint function but I get the following error message at runtime:

Debug Assertion Failed!
Program: MSVCP140D.DLL
File: VC\include\xstring
Line: 106
Expression: string iterator not incrementable

Do you know why?

Thanks.

You will find below a sample repro:

uint32_t *fp;
int length, algorithm;

char *encoded = "AQABz9GSJEkkKYmS4Tp6xvjx-tBpXMfRpUP1w3yGHmUPcWTwhnhgiYNeeBcu5HhbxA2PZuEFnSd-9FECq-gJPbtQ_fiLfkf3wvnRl9AO__jxCj7-QjzyoFek4xcmPnA2-qjUDz9yTsR56PFRJp4GP8ePLj2qY-NRfkL2oXEx6cFThPCh7_iRVnzQbX9wHc0UT0I_5Duao1KVGOsPlpdQLcqFHxf5oqfRFVpySvjR_Ch7_NCO87h05ChL7Do65vDIFC2H8zhyKnhqXJ6GdsuLw4c276h-TGEcfAfjmWgeYzy6HT6u5UhvhCceZSp0PD5iZzka9Zh05NOEZmsgxZTx50ifa8hxpRv0E1vHKciFHk0cFY0moRKzabgbDb3gH_2RH8k3lGuEKc_x3_hRPehX5ODRfDX6JCtOIVyOMFyP-4XyHWkaF9fRt0VzD7sOJlUkHX2Q9Ed-9PnR8EpwijfCJJFi9PmhLySPhmOC-sIZiI8m_ML3INJ3pI6UknCNnkHzyNDEpchz400d9IN99PiSo9kyDf0xXTrS_HCC79D64Tx4o1YSIReeCKH84Q0ORT7CNMKPmQma62inD7xoodlEJNOJXEHzo3qCMEn4omWg_UPKqBN69EYz5kPyDrkeCb2OKd2i4RJ6PB3CQ5Wo5shTMUH7Hf6IHsd5NNcQnjFGo8oP__DJQz8OJk9s5BROotERSmSOjyaUv0LqsziV4zmaK5jIFLXAxEk0xIfeIcyFqiEVXL_hGLnQUOXRJ8SHSLnRr_jx5IU35CH0N0gfHtdQ_Wj0ZniT7ENZXPDRrijZIMxn7Dkqo0nIoG_QVDsO_mi6yOibDJqyHf6DSiX2fdAyVEyCXDyqhD2aRyf2H09EMJkchE-g60GYK3grNHHwHE9I9DrSMoJ2ZMd7_Ch7WEftI24DqTrCEteio9ePLxIVIj-uW1CjK6goVoYnhYZuuElwNDfyIT4e4lGWKWhEyUF5XKic47xQ0ZygO0XXhAgTMzP-FN_x4_lQiynCxBlxPgivIEyNL0e64zu-hCR-fMzBieLxIzy0MEZ-MNcc-Bqc53gYUfCPh0c6MmFI6DWaijk-K8g_PNXRhKjTD72UBSXzgT_-YIx27EsUJ6iThkJTZUd-aM_R03iaCk-CUwITPUcPVVfwLA8m0UbTrLgSHR3-Y8-DUsKVB6EkJWh-_HgPTv3AZs_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";

chromaprint_decode_fingerprint(encoded, strlen(encoded), &fp, &length, &algorithm, 1); // string iterator not incrementable       

[CyberSinh]

You will below an extract of the Visual Studio xstring header file.
I can define _ITERATOR_DEBUG_LEVEL=0 to workaround the issue in DEBUG mode and the program seems to run fine with that.
But perhaps the chromaprint source code could be changed to be more robust.

	_Myiter& operator++()
		{	// preincrement
 #if _ITERATOR_DEBUG_LEVEL == 2
		const auto _Mycont = static_cast<const _Mystr *>(this->_Getcont());
		if (_Mycont == 0
			|| _Ptr == nullptr_t{}
			|| _Mycont->_Myptr() + _Mycont->_Mysize <= _Unfancy(_Ptr))
			{	// report error
			_DEBUG_ERROR("string iterator not incrementable");
			_SCL_SECURE_OUT_OF_RANGE;
			}

 #elif _ITERATOR_DEBUG_LEVEL == 1
		_SCL_SECURE_VALIDATE(_Ptr != nullptr_t{});
		const auto _Mycont = static_cast<const _Mystr *>(this->_Getcont());
		_SCL_SECURE_VALIDATE(_Mycont != 0);
		_SCL_SECURE_VALIDATE_RANGE(_Unfancy(_Ptr) < _Mycont->_Myptr() + _Mycont->_Mysize);
 #endif /* _ITERATOR_DEBUG_LEVEL */

		++_Ptr;
		return (*this);
		}

[lalinsky]

I don't have access to a computer with Visual Studio. Can you help me pinpoint the code in Chromaprint that causes this? I don't see anything obviously wrong and Valgrind reports no illegal memory access.

[CyberSinh]

Hi Lukas,

You will find below a GIF screencast showing the stack trace:

Thanks.

[lalinsky]

That is very strange. The code is only iterating up to dest.end(), which should be fine. I guess I'll have to install Visual Studio somewhere to check what exactly is it complaining about.

[lalinsky]

Hm, actually no, there is something wrong. Thank for catching this. I'll have a fix soon.

[lalinsky]

It's a shame the C++ library included with GCC doesn't have this kind of iterator checks. Valgrind did not catch this, because std::string allocates one extra byte for the string.

[CyberSinh]

Yeah. Visual Studio is a very good IDE for development. And Visual Studio Community is free. You should try.
Thanks for the fix. It works now.