getFilename() -Error
DuanZhaobing opened this issue · 9 comments
SQLite::Database dbs("hello.db3", SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE);
auto db_name = dbs.getFilename().c_str();
When I use the above code to create and get the database file name, the compiler prompts an error and cannot get the relevant value.
SQLiteCpp/include/SQLiteCpp/Database.h
Line 465 in 164a606
Error reading characters of string.
please provide the following information:
- compiler name
- compiler version
- OS
- build system: cmake, meson, etc.
Hello,
I don't see anything wrong with how you use SQLiteCpp, only minor improvements that could be made to your code.
I can imagine that the issue is with the rest of the program; I would bet for garbage memory (eg if CenterWidget object is already destroyed when the function is called).
I copy pasted and slightly adapted your code to run in the example1/main.cpp, it's working as expected.
#include <vector>
void SaveToDatabase(
const std::string database_name,
const std::string table_name,
const std::vector<uint8_t>& receive_data,
std::uint32_t length)
{
try
{
// Open a database file in create/write mode
SQLite::Database database((database_name + ".db3").c_str(), SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE); // Error reading characters string
std::cout << "SQLite database file '" << database.getFilename().c_str() << "' opened successfully\n";
}
catch (std::exception& e)
{
std::cout << "SQLite exception: " << e.what() << std::endl;
}
}
void ReceiveCANData(const std::vector<uint8_t>& receive_data, uint32_t length)
{
std::string database_name("C:\\UnitySrc\\SQLiteCpp\\examples\\example1\\example");
std::string table_name = "table_name";
SaveToDatabase(database_name, table_name, receive_data, length);
}
int main()
{
const std::vector<uint8_t> receive_data = { 0x01, 0x02, 0x03, 0x04 };
ReceiveCANData(receive_data, receive_data.size());
The output starts with the expected log:
SQLite database file 'C:\UnitySrc\SQLiteCpp\examples\example1\example.db3' opened successfully
Hello sir.
I used the same code in Visual Studio to create a new C++ Console App and a Qt Empty App, but with different results.
In the C++ Console App, everything works. But in the Qt Empty App, the exception unable to open database file is thrown.
I don't have enough experience to look further into the cause. And I don't know if it's a problem with my usage or something else.
Sincerely look forward to your reply.
// In the Qt Empty App, no exception is thrown(when i use .data() or .c_str() function), but the database file name cannot be obtained(Unable to read memory).
SQLite::Database new_db(s.data(), SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE);
#define SQLITECPP_COMPILE_DLL
#include <string>
#include <iostream>
#include <SQLiteCpp/SQLiteCpp.h>
#include <SQLiteCpp/VariadicBind.h>
int main()
{
std::string s = "d.db3";
try {
// In the C++ Console App, everything works. But in the Qt Empty App, the exception unable to open database file is thrown.
SQLite::Database new_db(s, SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE);
// SQLite::Database new_db(s.data(), SQLite::OPEN_READWRITE | SQLite::OPEN_CREATE); // In the Qt Empty App, no exception is thrown, but the database file name cannot be obtained(Unable to read memory).
}
catch (std::exception& e) {
std::cout << "SQLite exception: " << e.what() << std::endl;
return EXIT_FAILURE; // unexpected error : exit the example program
}
return 0;
}
can you upload a sample repo with the code that throws the error?
as for the error seems that there is a use after free somewhere, probably related to the string used to initialize the database
Hello Sir.
The attachment is a simple sample code.Please check.
Here is the git repository address. https://github.com/DuanZhaobing/SQLiteCpp_getFilename-test
SQLiteCpp_getFilename-test.zip
seems that it could be caused for the following reasons:
- somewhere in your code the string is modified and you try to use the c_str after it, if you have a
std::stringis preferred to use it directly - the string is not utf8 encoded, the most easy solution in c++17 would be to use
std::filesystemthe constructor should convert it to utf8 automatically for you
for the example repo is recommended that you also show the example of your QT app, or at least a minimal failing example that we can debug
Sorry to have kept you waiting, Sir.
The project files of the Qt app have been uploaded to the git repository.
https://github.com/DuanZhaobing/SQLiteCpp_getFilename-test/tree/main/SQLiteCppTest_Qt