Add pipe()

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@779 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 257 insertions, 0 deletions

diff --git a/nuttx/drivers/pipe.c b/nuttx/drivers/pipe.c
new file mode 100644
index 000000000..fd5292cc1
--- /dev/null
+++ b/nuttx/drivers/pipe.c
@@ -0,0 +1,257 @@
+/****************************************************************************
+ * drivers/pipe.c
+ *
+ *   Copyright (C) 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Compilation Switches
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <nuttx/fs.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <semaphore.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "pipe-common.h"
+
+#if CONFIG_DEV_FIFO_SIZE > 0
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+#define MAX_PIPES 32
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int pipe_close(FAR struct file *filep);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static struct file_operations pipe_fops =
+{
+  pipecommon_open,   /* open */
+  pipe_close,        /* close */
+  pipecommon_read,   /* read */
+  pipecommon_write,  /* write */
+  0,                 /* seek */
+  0                  /* ioctl */
+};
+
+static sem_t  g_pipesem = { 1 };
+static uint32 g_pipeset = 0;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: pipe_allocate
+ ****************************************************************************/
+static inline int pipe_allocate(void)
+{
+  int pipeno;
+  int ret = sem_wait(&g_pipesem);
+  if (ret >= 0)
+    {
+      ret = -ENFILE;
+      for (pipeno = 0; pipeno < MAX_PIPES; pipeno++)
+        {
+          if ((g_pipeset & (1 << pipeno)) == 0)
+            {
+              g_pipeset |= (1 << pipeno);
+              ret = pipeno;
+              break;
+            }
+        }
+      (void)sem_post(&g_pipesem);
+    }
+  return ret;
+}
+
+/****************************************************************************
+ * Name: pipe_free
+ ****************************************************************************/
+static inline void pipe_free(int pipeno)
+{
+  int ret = sem_wait(&g_pipesem);
+  if (ret == 0)
+    {
+      g_pipeset &= ~(1 << pipeno);
+      (void)sem_post(&g_pipesem);
+    }
+}
+
+/****************************************************************************
+ * Name: pipe_close
+ ****************************************************************************/
+static int pipe_close(FAR struct file *filep)
+{
+  struct inode      *inode = filep->f_inode;
+  struct pipe_dev_s *dev   = inode->i_private;
+  ubyte              pipeno;
+  int                ret;
+
+  /* Some sanity checking */
+#if CONFIG_DEBUG
+  if (!dev)
+    {
+       return -EBADF;
+    }
+#endif
+  pipeno = dev->s.d_pipeno;
+
+  /* Perform common close operations */
+
+  ret =  pipecommon_close(filep);
+  if (ret == 0 && !inode->i_private)
+    {
+      char devname[16];
+      sprintf(devname, "/dev/pipe%d", pipeno);
+      unlink(devname);
+      pipe_free(pipeno);
+    }
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: pipe
+ *
+ * Description:
+ *   pipe() creates a pair of file descriptors, pointing to a pipe inode, and
+ *   places them in the array pointed to by 'filedes'. filedes[0] is for reading,
+ *   filedes[1] is for writing. 
+ *
+ * Inputs:
+ *   filedes[2] - The user provided array in which to catch the pipe file
+ *   descriptors
+ *
+ * Return:
+ *   0 is returned on success; otherwise, -1 is returned with errno set
+ *   appropriately.
+ *
+ ****************************************************************************/
+int pipe(int filedes[2])
+{
+  struct pipe_dev_s *dev;
+  char devname[16];
+  int pipeno;
+  int err;
+  int ret;
+
+  /* Allocate a minor number for the pipe device */
+
+  pipeno = pipe_allocate();
+  if (pipeno < 0)
+    {
+      err = -pipeno;
+      goto errout;
+    }
+
+  /* Allocate and initialize a new device structure instance */
+
+  dev = pipecommon_allocdev();
+  if (!dev)
+    {
+      pipe_free(pipeno);
+      err = ENOMEM;
+      goto errout;
+    }
+  dev->s.d_pipeno = pipeno;
+
+  /* Create a pathname to the pipe device */
+
+  sprintf(devname, "/dev/pipe%d", pipeno);
+
+  /* Register the pipe device */
+
+  ret = register_driver(devname, &pipe_fops, 0666, (void*)dev);
+  if (ret != 0)
+    {
+      err = -ret;
+      goto errout_with_dev;
+    }
+
+  /* Get a write file descriptor */
+
+  filedes[1] = open(devname, O_WRONLY);
+  if (filedes[1] < 0)
+    {
+      err = -filedes[1];
+      goto errout_with_driver;
+    }
+
+  /* Get a read file descriptor */
+
+  filedes[0] = open(devname, O_RDONLY);
+  if (filedes[0] < 0)
+    {
+      err = -filedes[0];
+      goto errout_with_wrfd;
+    }
+
+  return OK;
+
+errout_with_wrfd:
+  close(filedes[1]);
+errout_with_driver:
+  unregister_driver(devname);
+errout_with_dev:
+  pipecommon_freedev(dev);
+errout:
+  errno = err;
+  return ERROR;
+}
+
+#endif /* CONFIG_DEV_FIFO_SIZE > 0 */