3bf60b1367
The problem is that mime_decode_close() closes all files registered after mip->mi_pipe_end and this is getting set in mime_sendmessage() after a fflush(). When you print a large number of messages fflush() blocks and prevents mip->mi_pipe_end from getting set before the SIGPIPE comes in and jumps to the close block that calls mime_decode_close(). As a result, mime_decode_close() was closing all the registered files including obuf (mi_pipe_end was NULL).