return EISDIR in case ql_file object has a directory path and a read syscall is attempted on it

Author: rliebig

qiling/os/posix/syscall/unistd.py

@@ -415,6 +415,8 @@ def ql_syscall_read(ql: Qiling, fd: int, buf: int, length: int):
 
     try:
         data = f.read(length)
+    except IsADirectoryError:
+        return -EISDIR
     except ConnectionError:
         ql.log.debug('read failed due to a connection error')
         return -EIO