[ot] python/qemu: ot.eflash.gen: fix a bug when storing an ELF file

When an ELF file is used to store an app in the flash image, and not
binary physical file exists, the binary data is automatically generated
but no match should be attempted between the ELF metadata and the
generated binary content.

Signed-off-by: Emmanuel Blot <eblot@rivosinc.com>

Author: rivos-eblot

python/qemu/ot/eflash/gen.py

@@ -301,7 +301,7 @@ def store_rom_ext(self, bank: int, dfp: BinaryIO,
         elif elfpath and not no_header:
             self._log.warning('Discarding ELF as input binary file is invalid')
             elfpath = None
-        if elfpath and not no_header:
+        if elfpath and isfile(dfp.name) and not no_header:
             elftime = stat(elfpath).st_mtime
             bintime = stat(dfp.name).st_mtime
             if bintime < elftime: