fishhook would call the new function once when I just hook the old one?

[yehot]

#import "fishhook.h"

static void (*orig_NSLog)(NSString *format, ...);

void my_NSLog(NSString *format, ...) {
    va_list args;
    va_start(args, format);
    NSLogv(format, args);
    va_end(args);
    orig_NSLog(@"---do record log things---", nil);
}


int main(int argc, char * argv[]) {
    @autoreleasepool {
        
        struct rebinding reb_logs[1] = {
            {
                "NSLog",
                my_NSLog,
                (void *)&orig_NSLog
            }
        };
        rebind_symbols(reb_logs, 1);

        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

// console output:
2017-08-09 19:09:33.015 TestA[35807:551088] ---do record log things---

I use fishhook to hook the NSLog function, just use 'rebind_symbols', no any NSLog calling.
but my_NSLog been called once, and console output the log.
I wonder why fishhook do calling things when hook?
or, iOS system called NSLog ?

[kastiglione]

or, iOS system called NSLog?

I think it's probably this. You can set a breakpoint on my_NSLog and look at the stack trace to see which functions/classes/methods led to it being called.

[yehot]

Indeed, as you said, I look at the stack trace and found this:

It's being called by a symbolic breakpoint which added by myself to start a Reveal service:

expr (Class)NSClassFromString(@"IBARevealLoader") == nil ? (void *)dlopen("/Applications/Reveal.app/Contents/SharedSupport/iOS-Libraries/RevealServer.framework/RevealServer", 0x2) : ((void*)0)

After I disable the breakpoint, it's OK.
Thanks a lot !