Fix issue with finding subcaches.

Author: arandomdev

bin/dyldex

@@ -78,7 +78,7 @@ def _getArguments():
 
 
 def _openSubCaches(
-	mainCachePath: str,
+	mainCachePath: pathlib.Path,
 	numSubCaches: int
 ) -> Tuple[List[DyldContext], List[BinaryIO]]:
 	"""Create DyldContext objects for each sub cache.
@@ -92,10 +92,10 @@ def _openSubCaches(
 	Returns:
 		A list of subcaches, and their file objects, which must be closed!
 	"""
-	subCaches = []
-	subCachesFiles = []
+	subCaches: List[DyldContext] = []
+	subCachesFiles: List[BinaryIO] = []
 
-	subCacheSuffixes = [i for i in range(1, numSubCaches + 1)]
+	subCacheSuffixes = [str(i) for i in range(1, numSubCaches + 1)]
 	subCacheSuffixes.append("symbols")
 	for cacheSuffix in subCacheSuffixes:
 		subCachePath = f"{mainCachePath}.{cacheSuffix}"

src/DyldExtractor/converter/linkedit_optimizer.py

@@ -251,6 +251,10 @@ def copyLocalSymbols(self, newLinkedit: bytearray) -> None:
 		self.statusBar.update(status="Copy Local Symbols")
 
 		symbolsCache = self.dyldCtx.getSymbolsCache()
+		if symbolsCache.header.localSymbolsOffset == 0:
+			self.logger.error("Symbols Cache doesn't contain local symbols.")
+			return
+
 		localSymbolsInfo = dyld_cache_local_symbols_info(
 			symbolsCache.file,
 			symbolsCache.header.localSymbolsOffset

src/DyldExtractor/dyld/dyld_context.py

@@ -97,12 +97,24 @@ def headerContainsField(self, field: str) -> bool:
 
 	def hasSubCaches(self) -> bool:
 		"""Check if the dyld cache has sub caches.
+
+		Returns:
+			If the cache has subcaches or not. The symbols cache is factored
+			into this calculation, but the symbols cache is not counted in
+			numSubCaches. It is implicitly included.
 		"""
 
 		if self.headerContainsField("numSubCaches") and self.header.numSubCaches:
 			return True
-		else:
-			return False
+
+		emptyUUID = b"\x00" * len(self.header.symbolSubCacheUUID)
+		if (
+			self.headerContainsField("symbolSubCacheUUID")
+			and bytes(self.header.symbolSubCacheUUID) != emptyUUID
+		):
+			return True
+
+		return False
 
 	def addSubCaches(self, subCacheCtxs: List["DyldContext"]) -> None:
 		for ctx in subCacheCtxs: