Python and C interaction - callback function

Question

I am trying to make a key logger for Mac OS for one of my research projects. I have C code that will capture keystrokes and write them to a text file. (The following code I extracted some not important things)

Now I need to do like PyHook, instead of writing data to a text file, pass the Python callback function to C code and make it pass the input key to Python, so I can do the necessary analysis using Python.

I'm looking for how to do this, but to be honest, I have no idea how to approach this, since I'm not used to programming in C or Python extensions. Any help would be greatly appreciated.

#include <Carbon/Carbon.h> #include <ApplicationServices/ApplicationServices.h> #include <unistd.h> #include <stdio.h> #include <sys/time.h> #define NUM_RECORDING_EVENT_TYPES 5 #define RECORD 0 #define MOUSEACTION 0 #define KEYSTROKE 1 // maximum expected line length, for fgets #define LINE_LENGTH 80 #define kShowMouse TRUE OSStatus RUIRecordingEventOccurred(EventHandlerCallRef nextHandler, EventRef theEvent, void *userData); void prepareToRecord(); // install the event handler, wait for record signal // note that keyboard character codes are found in Figure C2 of the document // Inside Macintosh: Text available from http://developer.apple.com char * keyStringForKeyCode(int keyCode); // get the representation of the Mac keycode // Global Variables int dieNow = 0; // should the program terminate int ifexit = 0; // Exit state char *filename = NULL; // Log file name FILE *fd = NULL; // Log file descriptor int typecount = 0; // count keystroke to periodically save to a txt file struct timeval thetime; // for gettimeofday long currenttime; // the current time in milliseconds int main() { filename = "test.txt"; fd = fopen(filename, "a"); // Get RUI ready to record or play, based off of mode prepareToRecord(); return EXIT_SUCCESS; } // event handler for RUI recorder OSStatus RUIRecordingEventOccurred(EventHandlerCallRef nextHandler, EventRef theEvent, void *userData) { // Determine class and kind of event int eventClass = GetEventClass(theEvent); int eventKind = GetEventKind(theEvent); /* Handle Keyboard Events */ if((eventClass == kEventClassKeyboard) && (eventKind == kEventRawKeyDown)) /* key release implied */ { int keyCode, modifiers; // what did the user press? any modifier keys down? // gather keystroke information GetEventParameter(theEvent, kEventParamKeyCode, typeInteger, NULL, sizeof(keyCode), NULL, &keyCode); GetEventParameter(theEvent, kEventParamKeyModifiers, typeInteger, NULL, sizeof(modifiers), NULL, &modifiers); // What time is it? gettimeofday(&thetime, NULL); currenttime =(((thetime.tv_sec*1000000) + (thetime.tv_usec))); fprintf(fd, "%s\n", keyStringForKeyCode(keyCode)); } return EXIT_SUCCESS; } void prepareToRecord() { EventRecord event; // holds an event for examination // Types of events to listen for EventTypeSpec eventTypes[NUM_RECORDING_EVENT_TYPES] = {{kEventClassKeyboard, kEventRawKeyDown}}; // Install the event handler InstallEventHandler(GetEventMonitorTarget(), NewEventHandlerUPP(RUIRecordingEventOccurred), NUM_RECORDING_EVENT_TYPES, eventTypes, nil, nil); // event loop - get events until die command do { WaitNextEvent((everyEvent),&event,GetCaretTime(),nil); } while (dieNow == 0); } char * keyStringForKeyCode(int keyCode) { // return key char switch (keyCode) { case 0: return("a"); default: return("Empty"); // Unknown key, Return "Empty" } } 

Answer 1

It's easy - just follow the instructions - Call Python functions from C.

Alternatively, if you are trying to call C / C ++ functions from Python, you can use SWIG or one of the Python CTypes modules