open() has been extended. You can now open block drivers and access them just as you can character drivers. For example, you can hexdump a block device.

ChangeLog

@@ -11132,4 +11132,9 @@
 	* drivers/timers/pcf85263.c and include/nuttx/times/pcf85263.h:  Add
 	  a driver for the NXP PCF85263 I2C RTC.  Untested on initial commit
 	  (2015-11-20).
-
+	* fs/driver/fs_blockproxy.c: Add logic to create a temporary char driver
+	  using drivers/bch to mediate character oriented accessed to a block
+	  driver (2015-11-21).
+	* fs/vfs/open.c: If the use attempts to open a block driver, use
+	  block_proxy() to insert a character driver conversion layer in front
+	  of the block driver (2015-11-21).

fs/driver/driver.h

@@ -91,8 +91,43 @@ extern "C"
  *
  ****************************************************************************/
 
+#ifndef CONFIG_DISABLE_MOUNTPOINT
 int find_blockdriver(FAR const char *pathname, int mountflags,
                      FAR struct inode **ppinode);
+#endif
+
+/* fs/drivers/fs_blockproxy.c ***********************************************/
+/****************************************************************************
+ * Name: block_proxy
+ *
+ * Description:
+ *   Create a temporary char driver using drivers/bch to mediate character
+ *   oriented accessed to the block driver.
+ *
+ * Input parameters:
+ *   blkdev - The path to the block driver
+ *   oflags - Character driver open flags
+ *
+ * Returned Value:
+ *   If positive, non-zero file descriptor is returned on success.  This
+ *   is the file descriptor of the nameless character driver that mediates
+ *   accesses to the block driver.
+ *
+ *   Errors that may be returned:
+ *
+ *     ENOMEM - Failed to create a temporay path name.
+ *
+ *   Plus:
+ *
+ *     - Errors reported from bchdev_register()
+ *     - Errors reported from open() or unlink()
+ *
+ ****************************************************************************/
+
+#if !defined(CONFIG_DISABLE_PSEUDOFS_OPERATIONS) && \
+    !defined(CONFIG_DISABLE_MOUNTPOINT)
+int block_proxy(FAR const char *blkdev, int oflags);
+#endif
 
 #undef EXTERN
 #if defined(__cplusplus)

fs/driver/fs_blockproxy.c

@@ -148,12 +148,12 @@ static FAR char *unique_chardev(void)
  * Name: block_proxy
  *
  * Description:
- *   Create a temporary char driver using drivers/bch that mediate character
+ *   Create a temporary char driver using drivers/bch to mediate character
  *   oriented accessed to the block driver.
  *
  * Input parameters:
  *   blkdev - The path to the block driver
- *   mode   - Character driver access priviledges
+ *   oflags - Character driver open flags
  *
  * Returned Value:
  *   If positive, non-zero file descriptor is returned on success.  This
@@ -171,7 +171,7 @@ static FAR char *unique_chardev(void)
  *
  ****************************************************************************/
 
-int block_proxy(FAR const char *blkdev, mode_t mode)
+int block_proxy(FAR const char *blkdev, int oflags)
 {
   FAR char *chardev;
   bool readonly;
@@ -179,7 +179,7 @@ int block_proxy(FAR const char *blkdev, mode_t mode)
   int fd;
 
   DEBUGASSERT(blkdev);
-  DEBUGASSERT((mode & (O_CREAT | O_EXCL | O_APPEND | O_TRUNC)) == 0);
+  DEBUGASSERT((oflags & (O_CREAT | O_EXCL | O_APPEND | O_TRUNC)) == 0);
 
   /* Create a unique temporary file name for the character device */
 
@@ -192,7 +192,7 @@ int block_proxy(FAR const char *blkdev, mode_t mode)
 
   /* Should this character driver be read-only? */
 
-  readonly = ((mode & O_WROK) == 0);
+  readonly = ((oflags & O_WROK) == 0);
 
   /* Wrap the block driver with an instance of the BCH driver */
 
@@ -207,8 +207,8 @@ int block_proxy(FAR const char *blkdev, mode_t mode)
 
   /* Open the newly created character driver */
 
-  mode &= ~(O_CREAT | O_EXCL | O_APPEND | O_TRUNC);
-  fd = open(chardev, mode);
+  oflags &= ~(O_CREAT | O_EXCL | O_APPEND | O_TRUNC);
+  fd = open(chardev, oflags);
   if (fd < 0)
     {
       ret = -errno;

fs/vfs/fs_open.c

@@ -130,9 +130,42 @@ int open(const char *path, int oflags, ...)
       goto errout;
     }
 
-  /* Verify that the inode is valid and either a "normal" character driver or a
-   * mountpoint.  We specifically exclude block drivers and and "special"
-   * inodes (semaphores, message queues, shared memory).
+#if !defined(CONFIG_DISABLE_PSEUDOFS_OPERATIONS) && \
+    !defined(CONFIG_DISABLE_MOUNTPOINT)
+   /* If the inode is block driver, then we may return a character driver
+    * proxy for the block driver.  block_proxy() will instantiate a BCH
+    * character driver wrapper around the block driver, open(), then
+    * unlink() the character driver.  On success, block_proxy() will
+    * return the file descriptor of the opened character driver.
+    *
+    * NOTE: This will recurse to open the character driver proxy.
+    */
+
+   if (INODE_IS_BLOCK(inode))
+     {
+       /* Release the inode reference */
+
+       inode_release(inode);
+
+       /* Get the file descriptor of the opened character driver proxy */
+
+       fd = block_proxy(path, oflags);
+       if (fd < 0)
+         {
+           ret = fd;
+           goto errout;
+         }
+
+       /* Return the file descriptor */
+
+       return fd;
+     }
+   else
+#endif
+
+  /* Verify that the inode is either a "normal" character driver or a
+   * mountpoint.  We specifically "special" inodes (semaphores, message
+   * queues, shared memory).
    */
 
 #ifndef CONFIG_DISABLE_MOUNTPOINT