http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30162
--- Comment #47 from tkoenig at netcologne dot de <tkoenig at netcologne dot de> 2013-02-18 21:24:31 UTC --- Am 18.02.2013 21:16, schrieb jb at gcc dot gnu.org: >> Look at this piece of code: >> > >> > /* Seek to the head and overwrite the bogus length with the real >> > length. */ >> > >> > if (unlikely (sseek (dtp->u.p.current_unit->s, - m - 2 * record_marker, >> > SEEK_CUR) < 0)) >> > goto io_error; >> > >> >This works if it happens within a buffer, but you cannot rely on that. >> > >> >I would therefore suggest to resolve this PR by issuing a well-defined >> >error if we encounter a pipe on opening. >> > >> >I'll prepare a patch. > As I explained in comment #23, this is already handled. When opening a file, > we > stat() the fd, and use the buffered I/O functions only if it's a regular file, > otherwise the unbuffered raw I/O functions are used. This is part of the precipitate, not part of the solution ;-) For unformatted sequential, we first write a dummy record marker, write the data and the final record marker, then seek to the first marker and re-write that. Of course, this fails for an unbuffered fifo. If we want this to work, we should make sure we always use _buffered_ I/O for unformatted sequential, setting a maximum record length on open that we can handle with our buffer.
