When I try to run this little piece of code
#include <iostream>
#include <bsoncxx/builder/stream/document.hpp>
#include <bsoncxx/json.hpp>
#include <mongocxx/client.hpp>
#include <mongocxx/instance.hpp>
int main(int argc, char **argv)
{
mongocxx::client client{mongocxx::uri{}};
mongocxx::database db = client["xyz"];
std::cout << "Connected to xyz." << std::endl;
}
I always get this warning
Exception thrown at 0x00007FFF7815F1FD (libmongoc-1.0.dll) in Test.exe: 0xC0000005: Access violation writing location 0x0000000000000020.
Can someone help?
I fixed it by adding
mongocxx::instance instance{};
as the first line of code in the main function.
Related
I've started debbuging on some app, which hangs up in a loop based on readdir call.
Step by step I've cut everything but problem code, this is it:
So, in basic, it shows name of first entry and nothing more. It even does not exits, just waiting for something.
Also, I've found, that if don't lin it against libpocofoundation, it works.
But I have to do it because it used in the original app.
I'm a little bit confused, I don't use Poco in this example in any way, but it some way hangs it.
Please help me, I'm in panic :D
#include <iostream>
#include <sys/types.h>
#include <dirent.h>
#include <cstring>
#include <string>
#include <fcntl.h>
using namespace std;
int main(int argc, char *argv[])
{
const char TMP_DIR[] = "/opt";
DIR *dir = opendir(TMP_DIR);
std::cerr
<< readdir(dir)->d_name
<< readdir(dir)->d_name
<< std::endl;
return 0;
}
So... I don't know why it was happening. So I just dropped libpoco.
Here is a minimum example:
[joel#maison various] (master *)$ cat throw.cpp
#include <iostream>
int main(int argc, char* argv[])
{
throw("pouet pouet");
}
[joel#maison various] (master *)$ ./a.out
terminate called after throwing an instance of 'char const*'
Aborted (core dumped)
Reading the docs, it seems like the default terminate handler is abort(). I couldn't find anything about triggering a segfault in the abort man page.
Throwing an exception and not handling it calls abort() which raises SIGABRT.
You can verify it with the following
#include <iostream>
#include <stdexcept>
#include <signal.h>
extern "C" void handle_sigabrt(int)
{
std::cout << "Handling and then returning (exiting)" << std::endl;
}
int main()
{
signal(SIGABRT, &handle_sigabrt);
throw("pouet pouet");
}
Demo
i'm trying to write a C++ DLL which uses openSSL to secure a connection to a server.
I'm genuinly puzzled by the fact that this code
#include "stdafx.h"
#include <string.h>
#include <iostream>
//SSL stuff
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/x509.h>
#include <openssl/x509_vfy.h>
#include <openssl/ossl_typ.h>
#include <openssl/applink.c>
//Winsock stuf
#pragma comment(lib, "ws2_32.lib")
{... Create a method in which we set up the SSL connection ...}
char* tSend = "{\"reqtype\":\"keyexchange\"}";
int sendSize = strlen(tSend);
int net_tSend = htonl(sendSize);
SSL_write(ssl, &net_tSend, 4);
SSL_write(ssl, tSend, sendSize);
works fine in a Console application, but crashes in my DLL.
Here's my exception:
Exception thrown at 0x00007FF865207DA0 (libeay32.dll) in TestsForPKCSDLL.exe: 0xC0000005: Access violation reading location 0x0000000000000000.
Thanks a lot for your time.
After a bit of research, it looks like the problem comes from the htonl() function.
u_long mylong = 10L;
int net_tSend = htonl(mylong);
Exception thrown at 0x00007FF863807DA0 (libeay32.dll) in TestsForPKCSDLL.exe: 0xC0000005: Access violation reading location 0x0000000000000000.
Which apparently is not loaded properly. I think that, because my code is in a DLL, it crashes if the calling program doesn't reference SSL dlls. I'll try to link libeay32 and ssleay32 statically see if that works.
Well, I just wrote a simple logger program with log4cxx lib, It is working fine so far, but then I realized the exception handling doesnt work as I expected:
#include <iostream>
#include <log4cxx/logger.h>
#include <log4cxx/xml/domconfigurator.h>
#include <log4cxx/helpers/exception.h>
using namespace std;
using namespace log4cxx;
using namespace log4cxx::xml;
using namespace log4cxx::helpers;
int main(int argc, char *argv[])
{
/* some code here ... */
try
{
DOMConfigurator::configure("/path/to/logcfg.xml");
}
catch (Exception&)
{
cout << "error: problem in reading log config file" << endl;
/* here I want to free up some objects! */
exit(EXIT_FAILURE);
}
}
So, now lets say the logcfg.xml does not exist, the program will print out this message and exit:
log4cxx: Could not open file [/wrong/path/to/logcfg.xml].
Which seems to me, it never reached my exception handler, but raised and handled in library itself. Could you please tell me what is proper way to handle such case ?
Thanks
I am trying to derive key from password and want to generate randomly the salt(I dont know what size it should be for SHA-256 and does this matter like the IV in AES256, where it should be 128 bit,give a hint if someone know) with AutoSeededRandomPool but exception is cought
RandomNumberGenerator:GenerateBlock Not Implemented
I am using crypto++ 5.6.3rc5 with QT 5.5.1 and /MD release mode, this may be a bug, or unfinished work of someone.
#include <QCoreApplication>
#include <sha.h>
#include <base64.h>
#include <iostream>
#include <string>
#include <pwdbased.h>
#include <cstdio>
#include <iostream>
#include <osrng.h>
using CryptoPP::AutoSeededRandomPool;
#include <iostream>
using std::cout;
using std::cerr;
using std::endl;
#include <string>
using std::string;
#include <cstdlib>
using std::exit;
#include <cryptlib.h>
using CryptoPP::Exception;
#include <hex.h>
using CryptoPP::HexEncoder;
using CryptoPP::HexDecoder;
#include <filters.h>
using CryptoPP::StringSink;
//#include <stdlib.h>
#include <time.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
try
{
AutoSeededRandomPool rng;
byte salt[16*8];
rng.GenerateBlock(salt, 16*8);
byte password[] ="password";
size_t plen = strlen((const char*)password);
size_t slen = strlen((const char*)salt);
int c = 1;
byte derived[32];
CryptoPP::PKCS5_PBKDF2_HMAC<CryptoPP::SHA256> pbkdf2;
pbkdf2.DeriveKey(derived, sizeof(derived), 0, password, plen, salt, slen, c);
string result;
HexEncoder encoder(new StringSink(result));
encoder.Put(derived, sizeof(derived));
encoder.MessageEnd();
cout << "Derived: " << result << endl;
}
catch (const Exception& ex) {
cerr << ex.what() << endl;
}
return a.exec();
}
Crypto++ 5.6.3rc5 GenerateBlock Not Implemented
...
You can read the history on the change at Crash in RandomNumberGenerator::GenerateWord32 due to stack recursion. The change was eventually backed out.
It was fixed in RC6, but it has not been announced yet. There's a quasi-pre-RC6 at Crypto++ 5.6.3 Files. But as soon as it is announced, then its set in stone and will not be changed.
Right now, RC6 is undergoing minor changes due to Cygwin, MinGW and C++11 on Debian Unstable. The changes are not too bad, but testing them is painful. Some of the scripts take half a day to run under emulated platforms, like S/390x.
If you want to side step the issue and avoid the download of pre-RC6, then you can use one of the following generators. They call GenerateIntoBufferedTransformation:
AutoSeededX917RNG< AES >
X917RNG
RandomPool
Or, you can use OS_GenerateRandomBlock to draw directly from the OS's pool.
Or, you can remove the code that throws. Open cryptlib.h, find RandomNumberGenerator, remove the #if 0/#endif guarding the old code and delete the throw.
Also see RandomNumberGenerator on the Crypto++ wiki.