CODEWITHSUNDEEP
iosc++11objective-c++mach-o
Brandon
Brandon

Reputation: 23500

Detect if code is in a Framework vs. App vs. Bundle

Is there a way to detect if the code being compiled is in a Framework, a Bundle, or a Dynamic Library?

The reason is because of a crash reporter library that needs to know if a struct variable exists before taking the address of it..

IE:

#ifdef MH_EXECUTE_SYM
return (uint8_t*)&_mh_execute_header;
#else
return (uint8_t*)&_mh_dylib_header;
#endif

The problem is that MH_EXECUTE_SYM, MH_BUNDLE_SYM, MH_DYLIB_SYM is always defined for every kind of executable, bundle, framework..

So I need a way of determining which struct variable to take the address of.. Any ideas?

Upvotes: 3

Views: 328

Answers (1)

rob mayoff
rob mayoff

Reputation: 385500

It looks like you really just want to get a pointer to the appropriate mach_header_64 (or mach_header on 32-bit systems).

If you have a pointer, you can use the dladdr function to find out which (if any) mach-o it was loaded from. That function fills in a Dl_info structure which includes, amongst other things, a pointer to the mach_header_64 for the mach-o.

// For TARGET_RT_64_BIT:
#import <TargetConditionals.h>

// For dladdr:
#import <dlfcn.h>

// For mach_header and mach_header_64:
#import <mach-o/loader.h>

#ifdef TARGET_RT_64_BIT

struct mach_header_64 *mach_header_for_address(const void *address) {
    Dl_info info;
    if (dladdr(address, &info) == 0) {
        // address doesn't point into a mach-o.
        return 0;
    }
    struct mach_header_64 *header = (struct mach_header_64 *)info.dli_fbase;
    if (header->magic != MH_MAGIC_64) {
        // Something went wrong...
        return 0;
    }

    return header;
}

#else

struct mach_header mach_header_for_address(const void *address) {
    Dl_info info;
    if (dladdr(address, &info) == 0) {
        // address doesn't point into a mach-o.
        return 0;
    }
    struct mach_header *header = (struct mach_header *)info.dli_fbase;
    if (header->magic != MH_MAGIC) {
        // Something went wrong...
        return 0;
    }

    return header;
}

#endif

Upvotes: 3

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