open() has been extended. You can now open block drivers and access them just...

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