long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, size_t len, unsigned int flags) { struct pipe_inode_info *pipe; long ret, bytes; loff_t out_off; umode_t i_mode; int i; /* * We require the input being a regular file, as we don't want to * randomly drop data for eg socket -> socket splicing. Use the * piped splicing for that! */ i_mode = in->f_dentry->d_inode->i_mode; if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) return -EINVAL; /* * neither in nor out is a pipe, setup an internal pipe attached to * 'out' and transfer the wanted data from 'in' to 'out' through that */ pipe = current->splice_pipe; if (unlikely(!pipe)) { pipe = alloc_pipe_info(NULL); if (!pipe) return -ENOMEM; /* * We don't have an immediate reader, but we'll read the stuff * out of the pipe right after the splice_to_pipe(). So set * PIPE_READERS appropriately. */ pipe->readers = 1; current->splice_pipe = pipe; } /* * Do the splice. */ ret = 0; bytes = 0; out_off = 0; while (len) { size_t read_len, max_read_len; /* * Do at most PIPE_BUFFERS pages worth of transfer: */ max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE)); ret = do_splice_to(in, ppos, pipe, max_read_len, flags); if (unlikely(ret < 0)) goto out_release; read_len = ret; /* * NOTE: nonblocking mode only applies to the input. We * must not do the output in nonblocking mode as then we * could get stuck data in the internal pipe: */ ret = do_splice_from(pipe, out, &out_off, read_len, flags & ~SPLICE_F_NONBLOCK); if (unlikely(ret < 0)) goto out_release; bytes += ret; len -= ret; /* * In nonblocking mode, if we got back a short read then * that was due to either an IO error or due to the * pagecache entry not being there. In the IO error case * the _next_ splice attempt will produce a clean IO error * return value (not a short read), so in both cases it's * correct to break out of the loop here: */ if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len)) break; } pipe->nrbufs = pipe->curbuf = 0; return bytes; out_release: /* * If we did an incomplete transfer we must release * the pipe buffers in question: */ for (i = 0; i < PIPE_BUFFERS; i++) { struct pipe_buffer *buf = pipe->bufs + i; if (buf->ops) { buf->ops->release(pipe, buf); buf->ops = NULL; } } pipe->nrbufs = pipe->curbuf = 0; /* * If we transferred some data, return the number of bytes: */ if (bytes > 0) return bytes; return ret; }
static int fifo_open(struct inode *inode, struct file *filp) { struct pipe_inode_info *pipe; int ret; mutex_lock(&inode->i_mutex); pipe = inode->i_pipe; if (!pipe) { ret = -ENOMEM; pipe = alloc_pipe_info(inode); if (!pipe) goto err_nocleanup; inode->i_pipe = pipe; } filp->f_version = 0; /* We can only do regular read/write on fifos */ filp->f_mode &= (FMODE_READ | FMODE_WRITE); switch (filp->f_mode) { case FMODE_READ: /* * O_RDONLY * POSIX.1 says that O_NONBLOCK means return with the FIFO * opened, even when there is no process writing the FIFO. */ filp->f_op = &read_pipefifo_fops; pipe->r_counter++; if (atomic_inc_return(&pipe->readers) == 1) wake_up_partner(inode); if (!atomic_read(&pipe->writers)) { if ((filp->f_flags & O_NONBLOCK)) { /* suppress POLLHUP until we have * seen a writer */ filp->f_version = pipe->w_counter; } else { if (wait_for_partner(inode, &pipe->w_counter)) goto err_rd; } } break; case FMODE_WRITE: /* * O_WRONLY * POSIX.1 says that O_NONBLOCK means return -1 with * errno=ENXIO when there is no process reading the FIFO. */ ret = -ENXIO; if ((filp->f_flags & O_NONBLOCK) && !atomic_read(&pipe->readers)) goto err; filp->f_op = &write_pipefifo_fops; pipe->w_counter++; if (atomic_inc_return(&pipe->writers) == 1) wake_up_partner(inode); if (!atomic_read(&pipe->readers)) { if (wait_for_partner(inode, &pipe->r_counter)) goto err_wr; } break; case FMODE_READ | FMODE_WRITE: /* * O_RDWR * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set. * This implementation will NEVER block on a O_RDWR open, since * the process can at least talk to itself. */ filp->f_op = &rdwr_pipefifo_fops; atomic_inc(&pipe->readers); atomic_inc(&pipe->writers); pipe->r_counter++; pipe->w_counter++; if (atomic_read(&pipe->readers) == 1 || atomic_read(&pipe->writers) == 1) wake_up_partner(inode); break; default: ret = -EINVAL; goto err; } /* Ok! */ mutex_unlock(&inode->i_mutex); return 0; err_rd: if (atomic_dec_and_test(&pipe->readers)) wake_up_interruptible(&pipe->wait); ret = -ERESTARTSYS; goto err; err_wr: if (atomic_dec_and_test(&pipe->writers)) wake_up_interruptible(&pipe->wait); ret = -ERESTARTSYS; goto err; err: if (!atomic_read(&pipe->readers) && !atomic_read(&pipe->writers)) free_pipe_info(inode); err_nocleanup: mutex_unlock(&inode->i_mutex); return ret; }
static int fifo_open(struct inode *inode, struct file *filp) { struct pipe_inode_info *pipe; int ret; mutex_lock(&inode->i_mutex); pipe = inode->i_pipe; if (!pipe) { ret = -ENOMEM; pipe = alloc_pipe_info(inode); if (!pipe) goto err_nocleanup; inode->i_pipe = pipe; } filp->f_version = 0; /* */ filp->f_mode &= (FMODE_READ | FMODE_WRITE); switch (filp->f_mode) { case FMODE_READ: /* */ filp->f_op = &read_pipefifo_fops; pipe->r_counter++; if (pipe->readers++ == 0) wake_up_partner(inode); if (!pipe->writers) { if ((filp->f_flags & O_NONBLOCK)) { /* */ filp->f_version = pipe->w_counter; } else { wait_for_partner(inode, &pipe->w_counter); if(signal_pending(current)) goto err_rd; } } break; case FMODE_WRITE: /* */ ret = -ENXIO; if ((filp->f_flags & O_NONBLOCK) && !pipe->readers) goto err; filp->f_op = &write_pipefifo_fops; pipe->w_counter++; if (!pipe->writers++) wake_up_partner(inode); if (!pipe->readers) { wait_for_partner(inode, &pipe->r_counter); if (signal_pending(current)) goto err_wr; } break; case FMODE_READ | FMODE_WRITE: /* */ filp->f_op = &rdwr_pipefifo_fops; pipe->readers++; pipe->writers++; pipe->r_counter++; pipe->w_counter++; if (pipe->readers == 1 || pipe->writers == 1) wake_up_partner(inode); break; default: ret = -EINVAL; goto err; } /* */ mutex_unlock(&inode->i_mutex); return 0; err_rd: if (!--pipe->readers) wake_up_interruptible(&pipe->wait); ret = -ERESTARTSYS; goto err; err_wr: if (!--pipe->writers) wake_up_interruptible(&pipe->wait); ret = -ERESTARTSYS; goto err; err: if (!pipe->readers && !pipe->writers) free_pipe_info(inode); err_nocleanup: mutex_unlock(&inode->i_mutex); return ret; }