Clear stream errors in FileStore::MaxRetrievable (GH #968)

1 files changed, 9 insertions, 0 deletions

diff --git a/files.cpp b/files.cpp
index 2d05e03f..22af7097 100644
--- a/files.cpp
+++ b/files.cpp
@@ -65,10 +65,19 @@ lword FileStore::MaxRetrievable() const
 	if (!m_stream)

 		return 0;

 

+	// Clear error bits due to seekg(). Also see

+	// https://github.com/weidai11/cryptopp/pull/968

 	std::streampos current = m_stream->tellg();

 	std::streampos end = m_stream->seekg(0, std::ios::end).tellg();

 	m_stream->clear();

 	m_stream->seekg(current);

+	m_stream->clear();

+

+	// Return max for a non-seekable stream

+	// https://www.cplusplus.com/reference/istream/istream/tellg/

+	if (end == static_cast<std::streampos>(-1))

+		return LWORD_MAX;

+

 	return end-current;

 }