C_SEEK
{ "oseek", f_seek, C_SEEK, C_SEEK },
{ "seek", f_seek, C_SEEK, C_SEEK },
if (!(ddflags & (C_SEEK | C_NOTRUNC)))
if ((ddflags & (C_OF | C_SEEK | C_NOTRUNC)) == (C_OF | C_SEEK) &&