Exemple #1
0
/*
 * initialize and allocate VM and memory for pipe
 */
int
pipe_create(struct pipe *cpipe)
{
	int error;

	/* so pipe_free_kmem() doesn't follow junk pointer */
	cpipe->pipe_buffer.buffer = NULL;
	/*
	 * protect so pipeclose() doesn't follow a junk pointer
	 * if pipespace() fails.
	 */
	bzero(&cpipe->pipe_sel, sizeof cpipe->pipe_sel);
	cpipe->pipe_state = 0;
	cpipe->pipe_peer = NULL;
	cpipe->pipe_busy = 0;

	error = pipespace(cpipe, PIPE_SIZE);
	if (error != 0)
		return (error);

	getnanotime(&cpipe->pipe_ctime);
	cpipe->pipe_atime = cpipe->pipe_ctime;
	cpipe->pipe_mtime = cpipe->pipe_ctime;
	cpipe->pipe_pgid = NO_PID;

	return (0);
}
Exemple #2
0
/*
 * expand the size of pipe while there is data to be read,
 * and then free the old buffer once the current buffered
 * data has been transferred to new storage.
 * Required: PIPE_LOCK and io lock to be held by caller.
 * returns 0 on success or no expansion possible
 */
static int 
expand_pipespace(struct pipe *p, int target_size)
{
	struct pipe tmp, oldpipe;
	int error;
	tmp.pipe_buffer.buffer = 0;
	
	if (p->pipe_buffer.size >= (unsigned) target_size) {
		return 0; /* the existing buffer is max size possible */
	}
	
	/* create enough space in the target */
	error = pipespace(&tmp, target_size);
	if (error != 0)
		return (error);

	oldpipe.pipe_buffer.buffer = p->pipe_buffer.buffer;
	oldpipe.pipe_buffer.size = p->pipe_buffer.size;
	
	memcpy(tmp.pipe_buffer.buffer, p->pipe_buffer.buffer, p->pipe_buffer.size);
	if (p->pipe_buffer.cnt > 0 && p->pipe_buffer.in <= p->pipe_buffer.out ){
		/* we are in State 3 and need extra copying for read to be consistent */
		memcpy(&tmp.pipe_buffer.buffer[p->pipe_buffer.size], p->pipe_buffer.buffer, p->pipe_buffer.size);
		p->pipe_buffer.in += p->pipe_buffer.size;
	}

	p->pipe_buffer.buffer = tmp.pipe_buffer.buffer;
	p->pipe_buffer.size = tmp.pipe_buffer.size;


	pipe_free_kmem(&oldpipe);
	return 0;
}
Exemple #3
0
int
pipe_write(struct file *fp, off_t *poff, struct uio *uio, struct ucred *cred)
{
	int error = 0;
	int orig_resid;

	struct pipe *wpipe, *rpipe;

	rpipe = (struct pipe *) fp->f_data;
	wpipe = rpipe->pipe_peer;

	/*
	 * detect loss of pipe read side, issue SIGPIPE if lost.
	 */
	if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
		return (EPIPE);
	}
	++wpipe->pipe_busy;

	/*
	 * If it is advantageous to resize the pipe buffer, do
	 * so.
	 */
	if ((uio->uio_resid > PIPE_SIZE) &&
	    (nbigpipe < LIMITBIGPIPES) &&
	    (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
	    (wpipe->pipe_buffer.cnt == 0)) {

		if ((error = pipelock(wpipe)) == 0) {
			if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
				nbigpipe++;
			pipeunlock(wpipe);
		}
	}

	/*
	 * If an early error occurred unbusy and return, waking up any pending
	 * readers.
	 */
	if (error) {
		--wpipe->pipe_busy;
		if ((wpipe->pipe_busy == 0) &&
		    (wpipe->pipe_state & PIPE_WANT)) {
			wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
			wakeup(wpipe);
		}
		return (error);
	}

	orig_resid = uio->uio_resid;

	while (uio->uio_resid) {
		int space;

retrywrite:
		if (wpipe->pipe_state & PIPE_EOF) {
			error = EPIPE;
			break;
		}

		space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;

		/* Writes of size <= PIPE_BUF must be atomic. */
		if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
			space = 0;

		if (space > 0) {
			if ((error = pipelock(wpipe)) == 0) {
				int size;	/* Transfer size */
				int segsize;	/* first segment to transfer */

				/*
				 * If a process blocked in uiomove, our
				 * value for space might be bad.
				 *
				 * XXX will we be ok if the reader has gone
				 * away here?
				 */
				if (space > wpipe->pipe_buffer.size -
				    wpipe->pipe_buffer.cnt) {
					pipeunlock(wpipe);
					goto retrywrite;
				}

				/*
				 * Transfer size is minimum of uio transfer
				 * and free space in pipe buffer.
				 */
				if (space > uio->uio_resid)
					size = uio->uio_resid;
				else
					size = space;
				/*
				 * First segment to transfer is minimum of
				 * transfer size and contiguous space in
				 * pipe buffer.  If first segment to transfer
				 * is less than the transfer size, we've got
				 * a wraparound in the buffer.
				 */
				segsize = wpipe->pipe_buffer.size -
					wpipe->pipe_buffer.in;
				if (segsize > size)
					segsize = size;

				/* Transfer first segment */

				error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 
						segsize, uio);

				if (error == 0 && segsize < size) {
					/*
					 * Transfer remaining part now, to
					 * support atomic writes.  Wraparound
					 * happened.
					 */
#ifdef DIAGNOSTIC
					if (wpipe->pipe_buffer.in + segsize !=
					    wpipe->pipe_buffer.size)
						panic("Expected pipe buffer wraparound disappeared");
#endif

					error = uiomove(&wpipe->pipe_buffer.buffer[0],
							size - segsize, uio);
				}
				if (error == 0) {
					wpipe->pipe_buffer.in += size;
					if (wpipe->pipe_buffer.in >=
					    wpipe->pipe_buffer.size) {
#ifdef DIAGNOSTIC
						if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
							panic("Expected wraparound bad");
#endif
						wpipe->pipe_buffer.in = size - segsize;
					}

					wpipe->pipe_buffer.cnt += size;
#ifdef DIAGNOSTIC
					if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
						panic("Pipe buffer overflow");
#endif
				}
				pipeunlock(wpipe);
			}
			if (error)
				break;
		} else {
			/*
			 * If the "read-side" has been blocked, wake it up now.
			 */
			if (wpipe->pipe_state & PIPE_WANTR) {
				wpipe->pipe_state &= ~PIPE_WANTR;
				wakeup(wpipe);
			}

			/*
			 * don't block on non-blocking I/O
			 */
			if (fp->f_flag & FNONBLOCK) {
				error = EAGAIN;
				break;
			}

			/*
			 * We have no more space and have something to offer,
			 * wake up select/poll.
			 */
			pipeselwakeup(wpipe);

			wpipe->pipe_state |= PIPE_WANTW;
			error = tsleep(wpipe, (PRIBIO + 1)|PCATCH,
			    "pipewr", 0);
			if (error)
				break;
			/*
			 * If read side wants to go away, we just issue a
			 * signal to ourselves.
			 */
			if (wpipe->pipe_state & PIPE_EOF) {
				error = EPIPE;
				break;
			}	
		}
	}

	--wpipe->pipe_busy;

	if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
		wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
		wakeup(wpipe);
	} else if (wpipe->pipe_buffer.cnt > 0) {
		/*
		 * If we have put any characters in the buffer, we wake up
		 * the reader.
		 */
		if (wpipe->pipe_state & PIPE_WANTR) {
			wpipe->pipe_state &= ~PIPE_WANTR;
			wakeup(wpipe);
		}
	}

	/*
	 * Don't return EPIPE if I/O was successful
	 */
	if ((wpipe->pipe_buffer.cnt == 0) &&
	    (uio->uio_resid == 0) &&
	    (error == EPIPE)) {
		error = 0;
	}

	if (error == 0)
		getnanotime(&wpipe->pipe_mtime);
	/*
	 * We have something to offer, wake up select/poll.
	 */
	if (wpipe->pipe_buffer.cnt)
		pipeselwakeup(wpipe);

	return (error);
}
Exemple #4
0
/* ARGSUSED */
int
pipe(proc_t p, __unused struct pipe_args *uap, int32_t *retval)
{
	struct fileproc *rf, *wf;
	struct pipe *rpipe, *wpipe;
	lck_mtx_t   *pmtx;
	int fd, error;

	if ((pmtx = lck_mtx_alloc_init(pipe_mtx_grp, pipe_mtx_attr)) == NULL)
	        return (ENOMEM);
	
	rpipe = wpipe = NULL;
	if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
	        error = ENFILE;
		goto freepipes;
	}
        /*
	 * allocate the space for the normal I/O direction up
	 * front... we'll delay the allocation for the other
	 * direction until a write actually occurs (most likely it won't)...
         */
	error = pipespace(rpipe, choose_pipespace(rpipe->pipe_buffer.size, 0));
        if (error)
	        goto freepipes;

	TAILQ_INIT(&rpipe->pipe_evlist);
	TAILQ_INIT(&wpipe->pipe_evlist);

	error = falloc(p, &rf, &fd, vfs_context_current());
	if (error) {
	        goto freepipes;
	}
	retval[0] = fd;

	/*
	 * for now we'll create half-duplex pipes(refer returns section above). 
	 * this is what we've always supported..
	 */
	rf->f_flag = FREAD;
	rf->f_data = (caddr_t)rpipe;
	rf->f_ops = &pipeops;

	error = falloc(p, &wf, &fd, vfs_context_current());
	if (error) {
		fp_free(p, retval[0], rf);
	        goto freepipes;
	}
	wf->f_flag = FWRITE;
	wf->f_data = (caddr_t)wpipe;
	wf->f_ops = &pipeops;

	rpipe->pipe_peer = wpipe;
	wpipe->pipe_peer = rpipe;
	/* both structures share the same mutex */
	rpipe->pipe_mtxp = wpipe->pipe_mtxp = pmtx; 

	retval[1] = fd;
#if CONFIG_MACF
	/*
	 * XXXXXXXX SHOULD NOT HOLD FILE_LOCK() XXXXXXXXXXXX
	 *
	 * struct pipe represents a pipe endpoint.  The MAC label is shared
	 * between the connected endpoints.  As a result mac_pipe_label_init() and
	 * mac_pipe_label_associate() should only be called on one of the endpoints
	 * after they have been connected.
	 */
	mac_pipe_label_init(rpipe);
	mac_pipe_label_associate(kauth_cred_get(), rpipe);
	wpipe->pipe_label = rpipe->pipe_label;
#endif
	proc_fdlock_spin(p);
	procfdtbl_releasefd(p, retval[0], NULL);
	procfdtbl_releasefd(p, retval[1], NULL);
	fp_drop(p, retval[0], rf, 1);
	fp_drop(p, retval[1], wf, 1);
	proc_fdunlock(p);


	return (0);

freepipes:
	pipeclose(rpipe); 
	pipeclose(wpipe); 
	lck_mtx_free(pmtx, pipe_mtx_grp);

	return (error);
}