>>191
仕様はend-of-fileに達した後はずーっとEOF

If the end-of-file indicator for the stream is set, or if the stream is at end-of-file,
the end-of-file indicator for the stream is set and fgetc returns EOF. Otherwise,
the fgetc function returns the next character from the input stream pointed to by stream. If a read error occurs, the error indicator for the stream is set and fgetc returns EOF.