fold fifo.c into pipe.c

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 138 insertions, 0 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index 2234f3f61f8d..aed80c25cd40 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1144,6 +1144,144 @@ SYSCALL_DEFINE1(pipe, int __user *, fildes)
         return sys_pipe2(fildes, 0);
 }
 
+static int wait_for_partner(struct inode* inode, unsigned int *cnt)
+{
+        int cur = *cnt; 
+
+        while (cur == *cnt) {
+                pipe_wait(inode->i_pipe);
+                if (signal_pending(current))
+                        break;
+        }
+        return cur == *cnt ? -ERESTARTSYS : 0;
+}
+
+static void wake_up_partner(struct inode* inode)
+{
+        wake_up_interruptible(&inode->i_pipe->wait);
+}
+
+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 (pipe->readers++ == 0)
+                        wake_up_partner(inode);
+
+                if (!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) && !pipe->readers)
+                        goto err;
+
+                filp->f_op = &write_pipefifo_fops;
+                pipe->w_counter++;
+                if (!pipe->writers++)
+                        wake_up_partner(inode);
+
+                if (!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;
+
+                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;
+        }
+
+        /* Ok! */
+        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;
+}
+
+/*
+ * Dummy default file-operations: the only thing this does
+ * is contain the open that then fills in the correct operations
+ * depending on the access mode of the file...
+ */
+const struct file_operations def_fifo_fops = {
+        .open           = fifo_open,    /* will set read_ or write_pipefifo_fops */
+        .llseek         = noop_llseek,
+};
+
 /*
  * Allocate a new array of pipe buffers and copy the info over. Returns the
  * pipe size if successful, or return -ERROR on error.