diff options
Diffstat (limited to 'nuttx/drivers/pipes/pipe_common.c')
| -rw-r--r-- | nuttx/drivers/pipes/pipe_common.c | 107 |
1 files changed, 56 insertions, 51 deletions
diff --git a/nuttx/drivers/pipes/pipe_common.c b/nuttx/drivers/pipes/pipe_common.c index 2acaeab97..fe56f8d8a 100644 --- a/nuttx/drivers/pipes/pipe_common.c +++ b/nuttx/drivers/pipes/pipe_common.c @@ -1,7 +1,7 @@ /**************************************************************************** * drivers/pipes/pipe_common.c * - * Copyright (C) 2008-2009, 2011 Gregory Nutt. All rights reserved. + * Copyright (C) 2008-2009, 2011, 2015 Gregory Nutt. All rights reserved. * Author: Gregory Nutt <gnutt@nuttx.org> * * Redistribution and use in source and binary forms, with or without @@ -41,6 +41,7 @@ #include <sys/types.h> #include <sys/stat.h> +#include <sys/ioctl.h> #include <stdint.h> #include <stdbool.h> #include <stdlib.h> @@ -188,13 +189,7 @@ int pipecommon_open(FAR struct file *filep) int sval; int ret; - /* Some sanity checking */ -#if CONFIG_DEBUG - if (!dev) - { - return -EBADF; - } -#endif + DEBUGASSERT(dev); /* Make sure that we have exclusive access to the device structure. The * sem_wait() call should fail only if we are awakened by a signal. @@ -208,9 +203,12 @@ int pipecommon_open(FAR struct file *filep) return -get_errno(); } - /* If this the first reference on the device, then allocate the buffer */ + /* If this the first reference on the device, then allocate the buffer. In the + * case of d_policy == 1, the buffer already be present when the pipe is + * first opened. + */ - if (dev->d_refs == 0) + if (dev->d_refs == 0 && dev->d_buffer == NULL) { dev->d_buffer = (uint8_t*)kmm_malloc(CONFIG_DEV_PIPE_SIZE); if (!dev->d_buffer) @@ -243,11 +241,17 @@ int pipecommon_open(FAR struct file *filep) } } - /* If opened for read-only, then wait for at least one writer on the pipe */ + /* If opened for read-only, then wait for either (1) at least one writer + * on the pipe (policy == 0), or (2) until there is buffered data to be + * read (policy == 1). + */ sched_lock(); (void)sem_post(&dev->d_bfsem); - if ((filep->f_oflags & O_RDWR) == O_RDONLY && dev->d_nwriters < 1) + + if ((filep->f_oflags & O_RDWR) == O_RDONLY && /* Read-only */ + dev->d_nwriters < 1 && /* No writers on the pipe */ + dev->d_wrndx == dev->d_rdndx) /* Buffer is empty */ { /* NOTE: d_rdsem is normally used when the read logic waits for more * data to be written. But until the first writer has opened the @@ -289,13 +293,7 @@ int pipecommon_close(FAR struct file *filep) struct pipe_dev_s *dev = inode->i_private; int sval; - /* Some sanity checking */ -#if CONFIG_DEBUG - if (!dev) - { - return -EBADF; - } -#endif + 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 @@ -304,15 +302,17 @@ int pipecommon_close(FAR struct file *filep) pipecommon_semtake(&dev->d_bfsem); + /* Decrement the number of references on the pipe. Check if there are + * still oustanding references to the pipe. + */ + /* Check if the decremented reference count would go to zero */ - if (dev->d_refs > 1) + if (--dev->d_refs > 0) { - /* No.. then just decrement the reference count */ - - dev->d_refs--; - - /* If opened for writing, decrement the count of writers on on the pipe instance */ + /* No more references.. If opened for writing, decrement the count of + * writers on the pipe instance. + */ if ((filep->f_oflags & O_WROK) != 0) { @@ -329,9 +329,16 @@ int pipecommon_close(FAR struct file *filep) } } } - else + + /* What is the buffer management policy? Do we free the buffe when the + * last client closes the pipe (d_policy == 0), or when the buffer becomes + * empty (d_policy). In the latter case, the buffer data will remain + * valid and can be obtained when the pipe is re-opened. + */ + + else if (dev->d_policy == 0 || dev->d_wrndx == dev->d_rdndx) { - /* Yes... deallocate the buffer */ + /* Policy 0 or the buffer is empty ... deallocate the buffer now. */ kmm_free(dev->d_buffer); dev->d_buffer = NULL; @@ -363,13 +370,7 @@ ssize_t pipecommon_read(FAR struct file *filep, FAR char *buffer, size_t len) int sval; int ret; - /* Some sanity checking */ -#if CONFIG_DEBUG - if (!dev) - { - return -ENODEV; - } -#endif + DEBUGASSERT(dev); /* Make sure that we have exclusive access to the device structure */ @@ -453,15 +454,7 @@ ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer, size_t int nxtwrndx; int sval; - /* Some sanity checking */ - -#if CONFIG_DEBUG - if (!dev) - { - return -ENODEV; - } -#endif - + DEBUGASSERT(dev); pipe_dumpbuffer("To PIPE:", (uint8_t*)buffer, len); /* At present, this method cannot be called from interrupt handlers. That is @@ -581,14 +574,7 @@ int pipecommon_poll(FAR struct file *filep, FAR struct pollfd *fds, int ret = OK; int i; - /* Some sanity checking */ - -#if CONFIG_DEBUG - if (!dev || !fds) - { - return -ENODEV; - } -#endif + DEBUGASSERT(dev && fds); /* Are we setting up the poll? Or tearing it down? */ @@ -679,4 +665,23 @@ errout: } #endif +/**************************************************************************** + * Name: pipecommon_ioctl + ****************************************************************************/ + +int pipecommon_ioctl(FAR struct file *filep, int cmd, unsigned long arg) +{ + FAR struct inode *inode = filep->f_inode; + FAR struct pipe_dev_s *dev = inode->i_private; + + /* Only one command supported */ + + if (cmd == PIPEIOC_POLICY) + { + dev->d_policy = (arg != 0); + return OK; + } + + return -ENOTTY; +} #endif /* CONFIG_DEV_PIPE_SIZE > 0 */ |