Im a trying to use pantheios logging framework from inside a c++ dll. I have successfully built the dll and it executes through my test application (C++ MFC Application).
I have used implicit linking with the following includes:
#include <pantheios/implicit_link/core.h>
#include <pantheios/implicit_link/fe.simple.h>
#include <pantheios/implicit_link/be.console.h>
My DllMain initializes pantheios with the following calls:
extern "C" const char PANTHEIOS_FE_PROCESS_IDENTITY[] = "FinishingLineController";
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
{
int panres = pantheios::pantheios_init();
if(panres < 0)
{
fprintf(stderr, "Failed to initialise the Pantheios libraries: %s\n",
pantheios::pantheios_getInitErrorString(panres));
return FALSE;
}
}
break;
case DLL_THREAD_ATTACH:
break;
case DLL_THREAD_DETACH:
break;
case DLL_PROCESS_DETACH:
pantheios::pantheios_uninit();
break;
}
return TRUE;
}
When I execute the following code I get an
Microsoft C++ exception: stlsoft::winstl_project::windows_exception at memory location 0x0013da84
pantheios::log_DEBUG("Test logging");
I have tried to use explicit linking instead without any result.
Some further tests showed that the logging from the dll works if I link it to a console application instead of a windows application. And if I change the backend to "file" instead of "console" the windows application do log correctly to the file. So the problem seem to be that the windows application doesn't have a "console".
The solution was to redirect standard output/input pipes to a new console. This has to be done for a win32 application since a console is not created by default.
void RedirectIOToConsole()
{
int hConHandle;
long lStdHandle;
CONSOLE_SCREEN_BUFFER_INFO coninfo;
FILE *fp;
// allocate a console for this app
AllocConsole();
// set the screen buffer to be big enough to let us scroll text
GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
coninfo.dwSize.Y = MAX_CONSOLE_LINES;
SetConsoleScreenBufferSize(GetStdHandle(STD_OUTPUT_HANDLE), coninfo.dwSize);
// redirect unbuffered STDOUT to the console
lStdHandle = (long)GetStdHandle(STD_OUTPUT_HANDLE);
hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
fp = _fdopen( hConHandle, "w" );
*stdout = *fp;
setvbuf( stdout, NULL, _IONBF, 0 );
// redirect unbuffered STDIN to the console
lStdHandle = (long)GetStdHandle(STD_INPUT_HANDLE);
hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
fp = _fdopen( hConHandle, "r" );
*stdin = *fp;
setvbuf( stdin, NULL, _IONBF, 0 );
// redirect unbuffered STDERR to the console
lStdHandle = (long)GetStdHandle(STD_ERROR_HANDLE);
hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
fp = _fdopen( hConHandle, "w" );
*stderr = *fp;
setvbuf( stderr, NULL, _IONBF, 0 );
// make cout, wcout, cin, wcin, wcerr, cerr, wclog and clog
// point to console as well
std::ios::sync_with_stdio();
}
And then call this function from DllMain.
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
{
RedirectIOToConsole();
int panres = pantheios::pantheios_init();
if(panres < 0)
{
fprintf(stderr, "Failed to initialise the Pantheios libraries: %s\n",
pantheios::pantheios_getInitErrorString(panres));
return FALSE;
}
// Set the file name for all back-ends.
//pantheios_be_file_setFilePath("output.log");
}
break;
case DLL_THREAD_ATTACH:
break;
case DLL_THREAD_DETACH:
break;
case DLL_PROCESS_DETACH:
pantheios::pantheios_uninit();
break;
}
return TRUE;
}