Function LoadLibraryImpl

loader_darwin.go:45–158

LoadLibraryImpl - loads a single library to memory, without trying to check or load required imports

(name string, image *[]byte)

// LoadLibraryImpl - loads a single library to memory, without trying to check or load required imports
func LoadLibraryImpl(name string, image *[]byte) (*Library, error) {
	// On MacOS Sierra and up, NSLinkModule is just a wrapper around
	// dlopen, pwrite and unlink. There's no "in-memory" only method using
	// dyld4 APIs, so there's no point in using NSCreateObjectFileImageFromMemory and NSLinkModule anymore.
	// We can just write our own version that:
	// - writes the binary image to a temporary file
	// - calls dlopen on the temporary file
	// - unlinks the temporary file
	// - uses dlsym to resolve all the symbols
	// See https://github.com/apple-oss-distributions/dyld/blob/main/dyld/DyldAPIs.cpp#L2785-L2847 for more details.
	if isSierra() {
		return LoadLibraryDlopen(name, image)
	}
	// force input image to be a bundle
	// this is not the most efficient method, but it does create the abililty to do more fixups down the road,
	// like if we added universal file support
	machoFile, err := macho.NewFile(bytes.NewReader(*image))
	if err != nil {
		return nil, err
	}
	machoFile.FileHeader.Type = macho.TypeBundle
	newImage, err := machoFile.Bytes()
	if err != nil {
		return nil, err
	}
	image = &newImage

	// Find dyld, loop through all the Mach-O images in memory until we find
	// one that exports NSCreateObjectFileImageFromMemory and NSLinkModule
	var execBase uintptr = uintptr(0x0000000001000000)
	ptr := execBase
	var createObjectAddr, linkModuleAddr uint64

	for i := 0; i < 10; i++ { // quit after the first ten images
		ptr, err = findMacho(ptr, 0x1000)
		if err != nil {
			return nil, err
		}
		fmt.Printf("Found image at 0x%08x\n", ptr)
		rawr := rawreader.New(ptr, MaxInt)
		machoFile, err := macho.NewFileFromMemory(rawr)
		if err != nil {
			return nil, err
		}
		exports := machoFile.Exports()

		foundCreateObj := false
		foundLinkModule := false
		for _, export := range exports {
			if export.Name == "_NSCreateObjectFileImageFromMemory" {
				fmt.Println("found NSCreateObjectFileImageFromMemory")
				createObjectAddr = export.VirtualAddress
				foundCreateObj = true
			}
			if export.Name == "_NSLinkModule" {
				fmt.Println("found NSLinkModule")
				linkModuleAddr = export.VirtualAddress
				foundLinkModule = true