[SharedCache] Fix overzealous alert about missing shared cache entries

Following the conversation in #6631 we are going to make the edited alerts warnings and then also fix the warning showing on certain shared caches even when all entries are present.

Author: emesare

view/sharedcache/core/SharedCache.cpp

@@ -59,12 +59,10 @@ CacheEntry CacheEntry::FromFile(const std::string& filePath, const std::string&
 
 	// Read the header, this _should_ be compatible with all known DSC formats.
 	// Mason: the above is not true! https://github.com/Vector35/binaryninja-api/issues/6073
+	// The mappingOffset should point right after the header. We use this to constrain the read size so unsupported fields are zeroed.
+	auto headerSize = file->ReadUInt32(0x10);
 	dyld_cache_header header = {};
-	file->Read(&header, 0, sizeof(header));
-
-	// Adjust the array count to actually be the "real" number for comparisons with what we load.
-	// This is required so we can check if we loaded the required number of caches, in view init.
-	header.subCacheArrayCount += header.cacheSubType;
+	file->Read(&header, 0, headerSize);
 
 	// Read the mappings using the headers `mappingCount` and `mappingOffset`.
 	dyld_cache_mapping_info currentMapping = {};

view/sharedcache/core/SharedCacheView.cpp

@@ -861,16 +861,23 @@ bool SharedCacheView::InitController()
 			LogSecondaryFileName(entry.GetFileName());
 			// Set the number of sub-caches so we can verify it later.
 			if (entry.GetType() == CacheEntryType::Primary)
-				expectedFileCount += entry.GetHeader().subCacheArrayCount;
+			{
+				const auto& entryHeader = entry.GetHeader();
+				// TODO: Some caches seem to have less sub caches than what we report having.
+				expectedFileCount += entryHeader.subCacheArrayCount;
+				// On older caches we don't have any sub-caches, so we want to skip alerting the user to that fact.
+				if (entryHeader.subCacheArrayOffset == 0)
+					expectedFileCount = 0;
+			}
 		}
 		for (const auto& missingFileName: missingCacheEntries)
 			m_logger->LogErrorF("Secondary cache file '{}' is missing!", missingFileName);
 
 		// Verify that we have the required amount of sub-caches, if not alert the user.
 		if (expectedFileCount == 1)
-			m_logger->LogAlertF("Primary cache file '{}' has no sub-caches! You are likely opening a secondary cache file instead of a primary one.", m_primaryFileName);
+			m_logger->LogWarnF("Primary cache file '{}' has no sub-caches! You are likely opening a secondary cache file instead of a primary one.", m_primaryFileName);
 		else if (totalEntries < expectedFileCount)
-			m_logger->LogAlertF("Insufficient cache files in dyld header ({}/{}), loading as partial shared cache...", totalEntries, expectedFileCount);
+			m_logger->LogWarnF("Insufficient cache files in dyld header ({}/{}), loading as partial shared cache...", totalEntries, expectedFileCount);
 	}
 
 	auto sharedCache = sharedCacheBuilder.Finalize();