Function kern_pipe

freebsd/kern/sys_pipe.c:443–492

* The pipe system call for the DTYPE_PIPE type of pipes. If we fail, let * the zone pick up the pieces via pipeclose(). */

 * the zone pick up the pieces via pipeclose().
 */
int
kern_pipe(struct thread *td, int fildes[2], int flags, struct filecaps *fcaps1,
    struct filecaps *fcaps2)
{
	struct file *rf, *wf;
	struct pipe *rpipe, *wpipe;
	struct pipepair *pp;
	int fd, fflags, error;

	error = pipe_paircreate(td, &pp);
	if (error != 0)
		return (error);
	rpipe = &pp->pp_rpipe;
	wpipe = &pp->pp_wpipe;
	error = falloc_caps(td, &rf, &fd, flags, fcaps1);
	if (error) {
		pipeclose(rpipe);
		pipeclose(wpipe);
		return (error);
	}
	/* An extra reference on `rf' has been held for us by falloc_caps(). */
	fildes[0] = fd;

	fflags = FREAD | FWRITE;
	if ((flags & O_NONBLOCK) != 0)
		fflags |= FNONBLOCK;

	/*
	 * Warning: once we've gotten past allocation of the fd for the
	 * read-side, we can only drop the read side via fdrop() in order
	 * to avoid races against processes which manage to dup() the read
	 * side while we are blocked trying to allocate the write side.
	 */
	finit(rf, fflags, DTYPE_PIPE, rpipe, &pipeops);
	error = falloc_caps(td, &wf, &fd, flags, fcaps2);
	if (error) {
		fdclose(td, rf, fildes[0]);
		fdrop(rf, td);
		/* rpipe has been closed by fdrop(). */
		pipeclose(wpipe);
		return (error);
	}
	/* An extra reference on `wf' has been held for us by falloc_caps(). */
	finit(wf, fflags, DTYPE_PIPE, wpipe, &pipeops);
	fdrop(wf, td);
	fildes[1] = fd;
	fdrop(rf, td);

	return (0);
}

#ifdef COMPAT_FREEBSD10
/* ARGSUSED */