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@@ -1144,6 +1144,144 @@ SYSCALL_DEFINE1(pipe, int __user *, fildes)
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return sys_pipe2(fildes, 0);
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return sys_pipe2(fildes, 0);
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}
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}
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+static int wait_for_partner(struct inode* inode, unsigned int *cnt)
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+{
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+ int cur = *cnt;
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+
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+ while (cur == *cnt) {
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+ pipe_wait(inode->i_pipe);
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+ if (signal_pending(current))
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+ break;
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+ }
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+ return cur == *cnt ? -ERESTARTSYS : 0;
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+}
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+
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+static void wake_up_partner(struct inode* inode)
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+{
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+ wake_up_interruptible(&inode->i_pipe->wait);
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+}
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+
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+static int fifo_open(struct inode *inode, struct file *filp)
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+{
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+ struct pipe_inode_info *pipe;
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+ int ret;
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+
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+ mutex_lock(&inode->i_mutex);
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+ pipe = inode->i_pipe;
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+ if (!pipe) {
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+ ret = -ENOMEM;
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+ pipe = alloc_pipe_info(inode);
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+ if (!pipe)
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+ goto err_nocleanup;
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+ inode->i_pipe = pipe;
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+ }
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+ filp->f_version = 0;
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+
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+ /* We can only do regular read/write on fifos */
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+ filp->f_mode &= (FMODE_READ | FMODE_WRITE);
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+
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+ switch (filp->f_mode) {
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+ case FMODE_READ:
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+ /*
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+ * O_RDONLY
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+ * POSIX.1 says that O_NONBLOCK means return with the FIFO
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+ * opened, even when there is no process writing the FIFO.
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+ */
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+ filp->f_op = &read_pipefifo_fops;
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+ pipe->r_counter++;
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+ if (pipe->readers++ == 0)
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+ wake_up_partner(inode);
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+
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+ if (!pipe->writers) {
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+ if ((filp->f_flags & O_NONBLOCK)) {
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+ /* suppress POLLHUP until we have
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+ * seen a writer */
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+ filp->f_version = pipe->w_counter;
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+ } else {
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+ if (wait_for_partner(inode, &pipe->w_counter))
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+ goto err_rd;
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+ }
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+ }
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+ break;
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+
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+ case FMODE_WRITE:
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+ /*
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+ * O_WRONLY
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+ * POSIX.1 says that O_NONBLOCK means return -1 with
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+ * errno=ENXIO when there is no process reading the FIFO.
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+ */
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+ ret = -ENXIO;
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+ if ((filp->f_flags & O_NONBLOCK) && !pipe->readers)
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+ goto err;
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+
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+ filp->f_op = &write_pipefifo_fops;
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+ pipe->w_counter++;
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+ if (!pipe->writers++)
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+ wake_up_partner(inode);
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+
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+ if (!pipe->readers) {
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+ if (wait_for_partner(inode, &pipe->r_counter))
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+ goto err_wr;
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+ }
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+ break;
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+
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+ case FMODE_READ | FMODE_WRITE:
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+ /*
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+ * O_RDWR
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+ * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
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+ * This implementation will NEVER block on a O_RDWR open, since
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+ * the process can at least talk to itself.
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+ */
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+ filp->f_op = &rdwr_pipefifo_fops;
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+
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+ pipe->readers++;
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+ pipe->writers++;
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+ pipe->r_counter++;
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+ pipe->w_counter++;
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+ if (pipe->readers == 1 || pipe->writers == 1)
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+ wake_up_partner(inode);
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+ break;
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+
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+ default:
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+ ret = -EINVAL;
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+ goto err;
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+ }
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+
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+ /* Ok! */
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+ mutex_unlock(&inode->i_mutex);
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+ return 0;
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+
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+err_rd:
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+ if (!--pipe->readers)
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+ wake_up_interruptible(&pipe->wait);
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+ ret = -ERESTARTSYS;
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+ goto err;
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+
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+err_wr:
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+ if (!--pipe->writers)
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+ wake_up_interruptible(&pipe->wait);
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+ ret = -ERESTARTSYS;
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+ goto err;
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+
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+err:
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+ if (!pipe->readers && !pipe->writers)
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+ free_pipe_info(inode);
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+
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+err_nocleanup:
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+ mutex_unlock(&inode->i_mutex);
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+ return ret;
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+}
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+
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+/*
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+ * Dummy default file-operations: the only thing this does
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+ * is contain the open that then fills in the correct operations
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+ * depending on the access mode of the file...
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+ */
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+const struct file_operations def_fifo_fops = {
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+ .open = fifo_open, /* will set read_ or write_pipefifo_fops */
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+ .llseek = noop_llseek,
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+};
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+
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/*
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/*
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* Allocate a new array of pipe buffers and copy the info over. Returns the
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* Allocate a new array of pipe buffers and copy the info over. Returns the
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* pipe size if successful, or return -ERROR on error.
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* pipe size if successful, or return -ERROR on error.
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