disable file size sanity check when loading the wallet cache

contrib/epee/include/file_io_utils.h

@@ -128,7 +128,7 @@ namespace file_io_utils
 
 
 	inline
-		bool load_file_to_string(const std::string& path_to_file, std::string& target_str)
+		bool load_file_to_string(const std::string& path_to_file, std::string& target_str, size_t max_size = 1000000000)
 	{
 #ifdef WIN32
                 WCHAR wide_path[1000];
@@ -139,7 +139,7 @@ namespace file_io_utils
                 if (file_handle == INVALID_HANDLE_VALUE)
                     return false;
                 DWORD file_size = GetFileSize(file_handle, NULL);
-                if ((file_size == INVALID_FILE_SIZE) || (file_size > 1000000000)) {
+                if ((file_size == INVALID_FILE_SIZE) || (uint64_t)file_size > (uint64_t)max_size) {
                     CloseHandle(file_handle);
                     return false;
                 }
@@ -159,7 +159,7 @@ namespace file_io_utils
 
 			std::ifstream::pos_type file_size = fstream.tellg();
 			
-			if(file_size > 1000000000)
+			if((uint64_t)file_size > (uint64_t)max_size) // ensure a large domain for comparison, and negative -> too large
 				return false;//don't go crazy
 			size_t file_size_t = static_cast<size_t>(file_size);
 

src/wallet/wallet2.cpp

@@ -3772,7 +3772,7 @@ void wallet2::load(const std::string& wallet_, const epee::wipeable_string& pass
   {
     wallet2::cache_file_data cache_file_data;
     std::string buf;
-    bool r = epee::file_io_utils::load_file_to_string(m_wallet_file, buf);
+    bool r = epee::file_io_utils::load_file_to_string(m_wallet_file, buf, std::numeric_limits<size_t>::max());
     THROW_WALLET_EXCEPTION_IF(!r, error::file_read_error, m_wallet_file);
 
     // try to read it as an encrypted cache