int pipecommon_unlink(FAR struct inode *inode)
{
FAR struct pipe_dev_s *dev;
DEBUGASSERT(inode && inode->i_private);
dev = (FAR struct pipe_dev_s *)inode->i_private;
/* Mark the pipe unlinked */
PIPE_UNLINK(dev->d_flags);
/* Are the any open references to the driver? */
if (dev->d_refs == 0)
{
/* No.. free the buffer (if there is one) */
if (dev->d_buffer)
{
kmm_free(dev->d_buffer);
}
/* And free the device structure. */
pipecommon_freedev(dev);
}
return OK;
}
int mkfifo(FAR const char *pathname, mode_t mode)
{
struct pipe_dev_s *dev;
int ret;
/* Allocate and initialize a new device structure instance */
dev = pipecommon_allocdev();
if (!dev)
{
return -ENOMEM;
}
ret = register_driver(pathname, &fifo_fops, mode, (void*)dev);
if (ret != 0)
{
pipecommon_freedev(dev);
}
return ret;
}
int pipecommon_close(FAR struct file *filep)
{
struct inode *inode = filep->f_inode;
struct pipe_dev_s *dev = inode->i_private;
int sval;
DEBUGASSERT(dev && dev->d_refs > 0);
/* Make sure that we have exclusive access to the device structure.
* NOTE: close() is supposed to return EINTR if interrupted, however
* I've never seen anyone check that.
*/
pipecommon_semtake(&dev->d_bfsem);
/* Decrement the number of references on the pipe. Check if there are
* still outstanding references to the pipe.
*/
/* Check if the decremented reference count would go to zero */
if (--dev->d_refs > 0)
{
/* No more references.. If opened for writing, decrement the count of
* writers on the pipe instance.
*/
if ((filep->f_oflags & O_WROK) != 0)
{
/* If there are no longer any writers on the pipe, then notify all of the
* waiting readers that they must return end-of-file.
*/
if (--dev->d_nwriters <= 0)
{
while (sem_getvalue(&dev->d_rdsem, &sval) == 0 && sval < 0)
{
sem_post(&dev->d_rdsem);
}
/* Inform poll readers that other end closed. */
pipecommon_pollnotify(dev, POLLHUP);
}
}
/* If opened for reading, decrement the count of readers on the pipe
* instance.
*/
if ((filep->f_oflags & O_RDOK) != 0)
{
if (--dev->d_nreaders <= 0)
{
if (PIPE_IS_POLICY_0(dev->d_flags))
{
/* Inform poll writers that other end closed. */
pipecommon_pollnotify(dev, POLLERR);
}
}
}
}
/* What is the buffer management policy? Do we free the buffe when the
* last client closes the pipe policy 0, or when the buffer becomes empty.
* In the latter case, the buffer data will remain valid and can be
* obtained when the pipe is re-opened.
*/
else if (PIPE_IS_POLICY_0(dev->d_flags) || dev->d_wrndx == dev->d_rdndx)
{
/* Policy 0 or the buffer is empty ... deallocate the buffer now. */
kmm_free(dev->d_buffer);
dev->d_buffer = NULL;
/* And reset all counts and indices */
dev->d_wrndx = 0;
dev->d_rdndx = 0;
dev->d_refs = 0;
dev->d_nwriters = 0;
dev->d_nreaders = 0;
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
/* If, in addition, we have been unlinked, then also need to free the
* device structure as well to prevent a memory leak.
*/
if (PIPE_IS_UNLINKED(dev->d_flags))
{
pipecommon_freedev(dev);
return OK;
}
#endif
}
sem_post(&dev->d_bfsem);
return OK;
}
int pipe(int fd[2])
{
FAR struct pipe_dev_s *dev = NULL;
char devname[16];
int pipeno;
int err;
int ret;
/* Get exclusive access to the pipe allocation data */
ret = sem_wait(&g_pipesem);
if (ret < 0)
{
/* sem_wait() will have already set errno */
return ERROR;
}
/* Allocate a minor number for the pipe device */
pipeno = pipe_allocate();
if (pipeno < 0)
{
(void)sem_post(&g_pipesem);
err = -pipeno;
goto errout;
}
/* Create a pathname to the pipe device */
sprintf(devname, "/dev/pipe%d", pipeno);
/* Check if the pipe device has already been created */
if ((g_pipecreated & (1 << pipeno)) == 0)
{
/* No.. Allocate and initialize a new device structure instance */
dev = pipecommon_allocdev();
if (!dev)
{
(void)sem_post(&g_pipesem);
err = ENOMEM;
goto errout_with_pipe;
}
dev->d_pipeno = pipeno;
/* Register the pipe device */
ret = register_driver(devname, &pipe_fops, 0666, (FAR void *)dev);
if (ret != 0)
{
(void)sem_post(&g_pipesem);
err = -ret;
goto errout_with_dev;
}
/* Remember that we created this device */
g_pipecreated |= (1 << pipeno);
}
(void)sem_post(&g_pipesem);
/* Get a write file descriptor */
fd[1] = open(devname, O_WRONLY);
if (fd[1] < 0)
{
err = -fd[1];
goto errout_with_driver;
}
/* Get a read file descriptor */
fd[0] = open(devname, O_RDONLY);
if (fd[0] < 0)
{
err = -fd[0];
goto errout_with_wrfd;
}
return OK;
errout_with_wrfd:
close(fd[1]);
errout_with_driver:
unregister_driver(devname);
errout_with_dev:
if (dev)
{
pipecommon_freedev(dev);
}
errout_with_pipe:
pipe_free(pipeno);
errout:
set_errno(err);
return ERROR;
}
