Getting a mach-o plug-in bundle's path from within a dylib

Question

I'm trying to get the executable path of a plug-in bundle which is loaded by another process, when running a dylib module.

When running a non-plug-in bundle e.g. a regular application, it's easy enough to call [[NSBundle mainBundle] executablePath]. However, with a plug-in bundle this returns the path for the hosting app, not of the plug-in bundle.

In that case, the following tricky code can be used to get the executable's path:

#include <dlfcn.h>

const char* getExecutableFile()
{
    Dl_info exeInfo;
    dladdr((void*) getExecutableFile, &exeInfo);
    return exeInfo.dli_fname;
}

This returns the correct bundle executable's path, except when calling this function from within a function exported by a dylib, which returns the dylib's path.

Is there any way to get the bundle executable's path consistently even from within a call to a function in a different module?

Answer 1

You can do that if you use the dyld APIs directly. In fact, it's pretty easy. The following code dumps all the images, with their offsets (and ASLR value).

#include <mach-o/dyld.h>

// List all mach-o images in a process
uint32_t i;
uint32_t ic = _dyld_image_count();
printf ("Got %d images\n",ic); for (i = 0; i < ic; i++)
{
    printf ("%d: %p\t%s\t(slide: %p)\n", i, 
            _dyld_get_image_header(i),
           _dyld_get_image_name(i), 
            _dyld_get_image_slide(i));

}

So naturally, you can strstr() your bundle name in the char * returned by dyld_get_image_name(), and you'll get the full path of it.

Reference: "Mac OS X and iOS Internals" (Wiley, 2012), pg 123.