A small utility that observes any changes of a search field of a given application

spotlight-ax.m

/* Cocoa accessibility framework for intercepting Spotlight user input. */
#import <Cocoa/Cocoa.h>
#import <AppKit/NSAccessibility.h>


static CFStringRef kSpotlightBundleIdentifier = CFSTR("com.apple.spotlight");


static void SpotlightCallback(AXObserverRef observer,
                              AXUIElementRef element,
                              CFStringRef notification,
                              void *data) {
  CFTypeRef subrole;
  
  if (AXUIElementCopyAttributeValue(element, kAXSubroleAttribute, &subrole) == kAXErrorSuccess && 
        CFGetTypeID(subrole) == CFStringGetTypeID() && 
        CFStringCompare(kAXSearchFieldSubrole, (CFStringRef) subrole, 0) == kCFCompareEqualTo) {
    CFTypeRef query;
      
    if (AXUIElementCopyAttributeValue(element, kAXValueAttribute, &query) == kAXErrorSuccess &&
          CFGetTypeID(query) == CFStringGetTypeID()) {
      NSLog(@"> %s", CFStringGetCStringPtr(query, CFStringGetSystemEncoding()));
      CFRelease(query);
    }
  }
}

// Figure out the PID for a bundle identifier
static OSStatus FindProcessIDForBundleIdentifier(CFStringRef identifier, pid_t *pid) {
  ProcessSerialNumber psn = {0, kNoProcess};
  OSStatus status;
  
  while ((status = GetNextProcess(&psn)) == noErr) {
    CFDictionaryRef info = ProcessInformationCopyDictionary(
        &psn, kProcessDictionaryIncludeAllInformationMask);
    CFStringRef bundle;
      
    if (CFDictionaryGetValueIfPresent(info, kCFBundleIdentifierKey, (const void **) &bundle) && 
          CFStringCompare(bundle, identifier, 0) == kCFCompareEqualTo) {
      return GetProcessPID(&psn, pid);
    }
  }
  
  return status;
}


int main(int argc, char *argv[])
{
  if (!AXAPIEnabled()) {
    NSLog(@"AXAPIEnabled == FALSE. Poop!");
    return 1;
  }
  
  pid_t spotlight;
  OSStatus status = FindProcessIDForBundleIdentifier(kSpotlightBundleIdentifier, &spotlight);
  
  if (status != noErr) {
    NSLog(@"Could not find PID for Spotlight");
    return status;
  }
  
  AXObserverRef observer;
  AXError err = AXObserverCreate(spotlight, SpotlightCallback, &observer);
  
  if (err != kAXErrorSuccess) {
    NSLog(@"Failed to create observer");
    return err;
  }
  
  // Sign up for notification's when Spotlight's "value" changes
  AXUIElementRef element = AXUIElementCreateApplication(spotlight);
  err = AXObserverAddNotification(observer, element, kAXValueChangedNotification, NULL);
  CFRelease(element);
  
  if (err != kAXErrorSuccess) {
    NSLog(@"Failed adding observer");
    return err;
  }
  
  CFRunLoopAddSource(CFRunLoopGetMain(),
                     AXObserverGetRunLoopSource(observer),
                     kCFRunLoopCommonModes);
  
  
  return NSApplicationMain(argc,  (const char **) argv);
}