iOS Daemon app will not start (Jailbreak) - how to debug?

Question

I\'m building a daemon app for a jailbroken iPhone and followed the guidelines as described in several questions and answers here on stackoverflow and ofcourse Chris Alvares\' w

Answer 1

As I said in my comment, first try to make sure your daemon executable is runnable:

1. login to your device as root, via ssh
2. execute the command /Applications/NoUIDameon.app/NoUIDaemon at the command line
3. check to see if it's running with ps -Aef | grep NoUIDaemon

If it's not running, I would check to make sure that your build process is fake code-signing the NoUIDaemon executable. Jailbroken phones don't require a valid signature, but they still do require a signature. Also, if it doesn't run (or stay running), it might help for you to post the code from your daemon's main program (e.g. main.m):

int main(int argc, char *argv[]) {
   // what's in here?
}

If that does work, and it runs when you start it manually (but not automatically), then check:

1. is the plist file above named dmn.NoUIDaemon.plist?
2. I think this is actually an error in Chris's blog, but the Label value in your plist should be dmn.NoUIDaemon, not dmn.NoUIDaemon.plist. I don't think this would prevent your daemon from running, I think it's just being consistent with the naming convention of system launch daemons.
3. I don't think just installing the plist file in /System/Library/LaunchDaemons is enough to start the daemon. You probably need to either reboot the phone, or manually launch the daemon with launchctl load -w /System/Library/LaunchDaemons/dmn.NoUIDaemon.plist
4. check to make sure the file permissions and ownership of your dmn.NoUIDaemon.plist are the same as the other launch daemon plists in /System/Library/LaunchDaemons.
5. I'm not sure if this is necessary, but I think the name of the daemon (the Label and the name of the plist file) are supposed to match the bundle ID specified in your NoUIDaemon-Info.plist file. So, the Info.plist should have:

    CFBundleExecutable
    NoUIDaemon
    CFBundleIdentifier
    dmn.${PRODUCT_NAME:rfc1034identifier}

or

    CFBundleExecutable
    NoUIDaemon
    CFBundleIdentifier
    dmn.NoUIDaemon

Update:

Also, I don't think your daemon's main program should have a call to UIApplicationMain. It's not supposed to be a UIApplication. It's supposed to be a background process, right? If you look on Page 1 of Chris's blog, it shows an example. Here's an example from one of mine:

int main(int argc, char *argv[]) {
   @autoreleasepool {
      SignalMonitor* daemon = [[SignalMonitor alloc] init];

      // start a timer so that the process does not exit.
      NSTimer* timer = [[NSTimer alloc] initWithFireDate: [NSDate date]
                                                interval: 1.0
                                                  target: daemon
                                                selector: @selector(setup:)
                                                userInfo: nil
                                                 repeats: NO];

      NSRunLoop* runLoop = [NSRunLoop currentRunLoop];
      [runLoop addTimer: timer forMode: NSDefaultRunLoopMode];
      [runLoop run];
   }

   return 0;
}

Also, here's a copy of my daemon's plist file (Info.plist), with your daemon name in it:

        CFBundleDevelopmentRegion
        English
        CFBundleExecutable
        NoUIDaemon
        CFBundleIdentifier
        dmn.NoUIDaemon
        CFBundleInfoDictionaryVersion
        6.0
        CFBundleName
        ${PRODUCT_NAME}
        CFBundlePackageType
        APPL
        CFBundleShortVersionString
        1.0
        CFBundleSignature
        ????
        CFBundleVersion
        1.0-0
        LSRequiresIPhoneOS
        
        LSApplicationCategoryType