inket/dsc_extractor

How to use dsc_extractor to extract the dyld_shared_cache

dsc_extractor

How to use dsc_extractor to extract the dyld_shared_cache

from https://opensource.apple.com/source/dyld/:

// extractor.c

#include <stdio.h>
#include <stddef.h>
#include <dlfcn.h>

typedef int (*extractor_proc)(const char* shared_cache_file_path, const char* extraction_root_path,
													void (^progress)(unsigned current, unsigned total));
int main(int argc, const char* argv[])
{
	if ( argc != 3 ) {
		fprintf(stderr, "usage: dsc_extractor <path-to-cache-file> <path-to-device-dir>\n");
		return 1;
	}
	
	//void* handle = dlopen("/Volumes/my/src/dyld/build/Debug/dsc_extractor.bundle", RTLD_LAZY);
	void* handle = dlopen("/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/usr/lib/dsc_extractor.bundle", RTLD_LAZY);
	if ( handle == NULL ) {
		fprintf(stderr, "dsc_extractor.bundle could not be loaded\n");
		return 1;
	}
	
	extractor_proc proc = (extractor_proc)dlsym(handle, "dyld_shared_cache_extract_dylibs_progress");
	if ( proc == NULL ) {
		fprintf(stderr, "dsc_extractor.bundle did not have dyld_shared_cache_extract_dylibs_progress symbol\n");
		return 1;
	}
	
	int result = (*proc)(argv[1], argv[2], ^(unsigned c, unsigned total) { printf("%d/%d\n", c, total); } );
	fprintf(stderr, "dyld_shared_cache_extract_dylibs_progress() => %d\n", result);
	return 0;
}

then

clang++ -o dsc_extractor extractor.c

./dsc_extractor
# usage: dsc_extractor <path-to-cache-file> <path-to-device-dir>

# for extracting M1 macOS dyld shared cache
./dsc_extractor /System/Library/dyld/dyld_shared_cache_arm64e ./