boost::interprocess::message_queue constructor failing when processes are run under different users.
To be more concrete. I'm creating message_queue in proc1. and trying to open the same message_queue from proc2 (another user).
Is it possible to make it working? Or I should find another way to synchronize my processes?
boost-1.52
OS: Windows 7 x86
Compiler: MSVC 2010
P.S. The code is trivial. And completely working if both processes was started from the same user.
P.P.S. This is a message box I've got. I could not call LastWindowError()...
---------------------------
Error
---------------------------
Runtime Error (at 18:421):
External exception E06D7363.
---------------------------
ОК
---------------------------
My code (of the Process2):
void ipcMsg1(HWND hWnd) {
util::MsgBox mb(hWnd, L"Sending Message1");
try {
mb.info(L"create mq");
bipc::message_queue mq(bipc::open_or_create, plmqproto::g_mqName, plmqproto::g_mqSize, sizeof(int));
mb.info(L"created");
const int msg = plmqproto::g_mqMessage1;
mq.send(&msg, sizeof(msg), 0);
bipc::message_queue::remove(plmqproto::g_mqName);
} catch(const bipc::interprocess_exception &ex) {
mb.error(plcore::stringToWString(ex.what()));
std::wstringstream ss;
const unsigned long we = GetLastError();
ss << L">1. GetLastError: " << we << std::endl;
ss << L" " << plcore::GetWindowsErrorMessage(we);
mb.error(ss.str());
} catch(const std::exception &ex) {
mb.error(plcore::stringToWString(ex.what()));
std::wstringstream ss;
const unsigned long we = GetLastError();
ss << L">2. GetLastError: " << we << std::endl;
ss << L" " << plcore::GetWindowsErrorMessage(we);
mb.error(ss.str());
} catch(...) {
std::wstringstream ss;
const unsigned long we = GetLastError();
ss << L">3. GetLastError: " << we << std::endl;
ss << L" " << plcore::GetWindowsErrorMessage(we);
mb.error(ss.str());
}
}
So. I'm getting only "create mq" message box. and fail after that.
Boost upgrade did not helped.
Related
I have two processes. One writes to a file, one has to read from it (At the same time..). So there's two fstreams open at a given time for the file (Although they may be in different processes).
I wrote a simple test function to crudely implement the sort of functionality I need:
void test_file_access()
{
try {
std::string file_name = "/Users/xxxx/temp_test_folder/test_file.dat";
std::ofstream out(file_name,
std::ios_base::out | std::ios_base::app | std::ios_base::binary);
out.write("Hello\n", 7);
std::this_thread::sleep_for(std::chrono::seconds(1));
std::array<char, 4096> read_buf;
std::ifstream in(file_name,
std::ios_base::in | std::ios_base::binary);
if (in.fail()) {
std::cout << "Error reading file" << std::endl;
return;
}
in.exceptions(std::ifstream::failbit | std::ifstream::badbit);
//Exception at the below line.
in.read(read_buf.data(), read_buf.size());
auto last_read_size = in.gcount();
auto offset = in.tellg();
std::cout << "Read [" << read_buf.data() << "] from file. read_size = " << last_read_size
<< ", offset = " << offset << std::endl;
out.write("World\n", 7);
std::this_thread::sleep_for(std::chrono::seconds(1));
//Do this so I can continue from the position I was before?
//in.clear();
in.read(read_buf.data(), read_buf.size());
last_read_size = in.gcount();
offset = in.tellg();
std::cout << "Read [" << read_buf.data() << "] from file. read_size = " << last_read_size
<< ", offset = " << offset << std::endl;
//Remove if you don't have boost.
boost::filesystem::remove(file_name);
}
catch(std::ios_base::failure const & ex)
{
std::cout << "Error : " << ex.what() << std::endl;
std::cout << "System error : " << strerror(errno) << std::endl;
}
}
int main()
{
test_file_access();
}
Run, and the output is like this:
Error : ios_base::clear: unspecified iostream_category error
System error : Operation timed out
So two questions,
What is going wrong here? Why do I get an Operation timed out error?
Is this an incorrect attempt to do what I need to get done? If so, what are the problems here?
You write into this file 7 bytes, but then try to read 4096 bytes. So in stream will read only 7 bytes and throw an exception as requested. Note that if you catch this exception the rest of the code will be executed correctly, e.g. last_read_size will be 7 and you can access those 7 bytes in buffer.
I have written a program using C++/C, the MySQL C++ connector and ncurses/CDK. It compiles just fine, and runs fine as well on an x86/64 architecture. It crashes, however, when run on a Raspberry Pi B+ (ArchLinux).
I realize this is a pretty hard question to answer, but maybe someone more experienced can help.
Here's the (hopefully) relevant Code:
//Open Connection to the Database
nrpeout::MYSQL_CON localhost("127.0.0.1", 3306, "root", "toor");
//localhost.write_attributes_to_console();
con = localhost.open_database_connection();
//Create a new object of type nrpeoutputquery
nrpeout::Nrpeoutputquery current_query("SELECT * FROM nrpeout", con);
//Execute query
res = current_query.execute_query();
//Close Database Connection
localhost.close_database_connection(con);
} catch (sql::SQLException &e) {
//Handle SQL-Exceptions
std::cout << "# ERR: SQLException in " << __FILE__;
std::cout << "(" << __FUNCTION__ << ") on line "
<< __LINE__ << std::endl;
std::cout << "# ERR: " << e.what();
std::cout << " (MySQL error code: " << e.getErrorCode();
std::cout << ", SQLState: " << e.getSQLState() << " )" << std::endl;
} catch(...) {
//Handle Standard Exceptions
std::cout << "Unknown Exception raised. Please contact your Administrator" << std::endl;
}
nrpeout::NrpeResultSet* currentResults = new nrpeout::NrpeResultSet(res);
Using Valgrind and GDB, I have tried to narrow the error down to the line where I create the object "currentResults".
Here's the member function that saves the query results:
nrpeout::NrpeResultSet::NrpeResultSet(sql::ResultSet* res)
{
for (unsigned int i = 0; i < res->rowsCount(); ++i)
{
res->next();
std::string command = res->getString("command");
//Shorten the String
size_t posCommand = command.find("_");
std::string shortened_command = command.substr(posCommand+1);
int ret = res->getInt("ret");
std::string text = res->getString("text");
//Shorten the Text
size_t posText = text.find("|");
std::string shortened_text = text.substr(0, posText-1);
std::string last_updated = res->getString("last_updated");
this->results.push_back(Row(shortened_command, ret, shortened_text, last_updated));
}
Well, you are not catching an exception, which you may want to handle. InvalidInstanceException is thrown when using closed databse connections, statements or resultsets.
My suggestion is to run your code with a gdb and catch exceptions:
gdb ./some-program
$ catch throw
$ r
This will break after each exception being thrown. (But also includes handled exceptions, so there may be quite a few breaks, depending on how long it takes you to get to the important part.)
I'm writing program using Boost::Asio, I want to implement simple chat. Currently I'm struggling with problem that when I put some code inline of class function it's working, but when same code is provided by another class object is not. I think it could be connected to Boost::Asio, but I'm not sure:
void Connection::session(socket_ptr sock)
{
try{
for(;;) {
char mesg[1024];
boost::system::error_code error;
size_t length = sock->read_some(boost::asio::buffer(mesg), error);
if (error == boost::asio::error::eof){
disconnected(sock);
break;
}
else if (error)
throw boost::system::system_error(error);
message msg(mesg,length);
char *data;
data = msg.getData();
std::cout << "In session " << strlen(data) << " " << data;
/*This is working
string s_msg,s_data;
s_msg = mesg;
s_data = s_msg.substr(2,length);
std::vector<char> writable(s_data.size() + 1);
std::copy(s_data.begin(), s_data.end(), writable.begin());
std::cout << "In session " << strlen(&writable[0]) << " " << &writable[0];
send_all(sock,&writable[0],strlen(&writable[0]));
*/
send_all(sock,data,strlen(data));
}
}
catch (std::exception& e){
std::cerr << "Exception in thread: " << e.what() << "\n";
}
}
Class message that is only parsing data
message::message(char *c_msg, size_t length)
{
msg = c_msg;
id = msg.at(0);
data = msg.substr(2,length);
}
char* message::getData()
{
std::vector<char> writable(data.size() + 1);
std::copy(data.begin(), data.end(), writable.begin());
std::cout << data;
std::cout << &writable[0];
return &writable[0];
}
So when using class message this line:
std::cout << "In session " << strlen(data) << " " << data;
I get:
st String //this is cout from message getData
st String //this is cout from message getData
In session 0
With inline version:
In session 11 st String
So, in session function string is empty although message cout shows something opposite.
I don't know if it's important, but this function is invoked as new thread from main.
Regards,
Piotr
You're returning the address of a temporary:
char* message::getData()
{
std::vector<char> writable(data.size() + 1);
//...
return &writable[0];
}
This is undefined behaviour.
I'm assuming that data is just a std::string. You could do this instead:
const char* message::getData() const
{
return data.c_str();
}
I have a problem where I try to compress a file's data. Everything works up to the compression call, but it isn't the compression call itself, as the segfault is thrown before it. Showing my code will make it much clearer:
std::cout << "FILENAME: ";
std::cin >> filename;
if(!fileExists(filename))
{
std::cout << "ERR: FILE NOT FOUND." << std::endl;
continue;
}
std::cout << "Compressing file data...";
writeFile(filename, zlib_compress(readFile(filename)));
std::cout << " Done." << std::endl;
At the function zlib_compress...
std::string zlib_compress(const std::string& str)
{
std::cout << "DEBUG" << std::endl;
z_stream zs; // z_stream is zlib's control structure
memset(&zs, 0, sizeof(zs));
if (deflateInit(&zs, 9) != Z_OK)
std::cout << "deflateInit failed while compressing." << std::endl;
zs.next_in = (Bytef*)str.data();
zs.avail_in = str.size(); // set the z_stream's input
int ret;
char outbuffer[1073741824];
std::string outstring;
// retrieve the compressed bytes blockwise
do
{
zs.next_out = reinterpret_cast<Bytef*>(outbuffer);
zs.avail_out = sizeof(outbuffer);
ret = deflate(&zs, Z_FINISH);
if (outstring.size() < zs.total_out)
{
// append the block to the output string
outstring.append(outbuffer, zs.total_out - outstring.size());
}
} while(ret == Z_OK);
deflateEnd(&zs);
if(ret != Z_STREAM_END) // an error occurred that was not EOF
{
std::ostringstream oss;
oss << "Exception during zlib compression: (" << ret << ") " << zs.msg;
std::cout << oss.str();
}
return outstring;
}
I know, I know, that function needs work, I just C&P'd from somewhere to try it out.
But the thing is this:
std::cout << "DEBUG" << std::endl; is never called. The compiler says that the seg fault is coming from here:
std::string zlib_compress(const std::string& str)
> {
But why...? It was working earlier. I just don't know what went wrong!
Edit: Debugger output.
#0 00000000 0x00402cbb in __chkstk_ms() (??:??)
#1 004013BE zlib_compress(str=...) (C:\Users\***\Documents\Work\Programming\Compressor\z.cpp:5)
#2 00401DDA _fu15___ZSt4cout() (C:\Users\***\Documents\Work\Programming\Compressor\main.cpp:80)
char outbuffer[1073741824];
That's too large to put on the stack
You are taking a constant reference to a string as a parameter in your zlib_compress - you need to make sure that memory is available (whatever is returned from your readfile) in your zlib_compress. It would be good if you can share the prototype of your readFile function too.
Windows 7 64 SP1
MongoDB 2.2.0
C++ driver
MSVS 2010
According to:
http://api.mongodb.org/cplusplus/2.2.0/classmongo_1_1_b_s_o_n_element.html#a692f3eecb505eae2181eb938b7680fbe
Double() (and like functions) should "throw a UserException if the element is not of the required type."
My code:
BSONObj a_document = BSON("a_string"<<"A string");
try
{
a_document["a_string"].Double();
}
catch(mongo::UserException ue)
{
cout << ue.toString() << endl;
}
But it doesn't get caught. Intead it asserts:
Sun Dec 09 16:04:28 Assertion: 13111:wrong type for field (a_string) 2 != 1
Sun Dec 09 16:04:28 dev: lastError==0 won't report:wrong type for field (a_string) 2 != 1
What am I doing wrong? I want to catch and handle the data type exceptions myself.
Thanks!
My feeling from looking through the cocumentation and headers is that the documentation is inaccurate at this point, or that some option was used that disables exceptions from MongoDB.
Try the following code:
BSONObj a_document = BSON("a_string"<<"A string");
try
{
a_document["a_string"].Double();
}
catch(mongo::UserException& ue)
{
cout << "UserException: " << ue.toString() << endl;
}
catch(mongo::MsgAssertionException& ex)
{
cout << "MsgAssertionException: " << ex.toString() << endl;
}
catch(mongo::DBException& ex)
{
cout << "DBException: " << ex.toString() << endl;
}
catch(std::exception& ex)
{
cout << "std::exception: " << ex.what() << endl;
}
to see which exception gets actually thrown (if any).