Add support for a union file system that can be used to overlay and merge the content of two mounted file systems.

Documentation/README.html

@@ -8,7 +8,7 @@
   <tr align="center" bgcolor="#e4e4e4">
     <td>
       <h1><big><font color="#3c34ec"><i>NuttX README Files</i></font></big></h1>
-      <p>Last Updated:  May 7, 2015</p>
+      <p>Last Updated:  June 5, 2015</p>
     </td>
   </tr>
 </table>
@@ -299,8 +299,10 @@
  |   |   |   `- <a href="http://sourceforge.net/p/nuttx/git/ci/master/tree/nuttx/fs/nxffs/README.txt"><b><i>README.txt</i></b></a>
  |   |   |- smartfs/
  |   |   |   `- <a href="http://sourceforge.net/p/nuttx/git/ci/master/tree/nuttx/fs/smartfs/README.txt"><b><i>README.txt</i></b></a>
- |   |   `- procfs/
+ |   |   |- procfs/
- |   |       `- <a href="http://sourceforge.net/p/nuttx/git/ci/master/tree/nuttx/fs/procfs/README.txt"><b><i>README.txt</i></b></a>
+ |   |   |   `- <a href="http://sourceforge.net/p/nuttx/git/ci/master/tree/nuttx/fs/procfs/README.txt"><b><i>README.txt</i></b></a>
+ |   |   `- unionfs/
+ |   |       `- <a href="http://sourceforge.net/p/nuttx/git/ci/master/tree/nuttx/fs/unionfs/README.txt"><b><i>README.txt</i></b></a>
  |   |- graphics/
  |   |   `- <a href="http://sourceforge.net/p/nuttx/git/ci/master/tree/nuttx/graphics/README.txt"><b><i>README.txt</i></b></a>
  |   |- lib/

README.txt

@@ -1358,7 +1358,9 @@ nuttx
  |   |   `- README.txt
  |   |- smartfs/
  |   |   `- README.txt
- |   `- procfs/
+ |   |- procfs/
+ |   |   `- README.txt
+ |   `- unionfs/
  |       `- README.txt
  |- graphics/
  |   `- README.txt

configs/olimex-lpc1766stk/README.txt

@@ -1131,8 +1131,10 @@ Configuration Sub-Directories
 
   STATUS:
     2015-06-02.  This configuration was added in an attempt to replace
-      thttpd-nxflat (see below).  It concurrent does not run properly.
+      thttpd-nxflat (see below).  I concurrently get out-of-memory errors
-      It looks like I get out-of-memory errors during execution of CGI.
+      during execution of CGI.  The 32KiB SRAM may be insufficient for
+      this configuration; this might be fixed with some carefult tuning
+      of stack usage.
 
   thttpd-nxflat:
     This builds the THTTPD web server example using the THTTPD and

fs/Kconfig

@@ -60,6 +60,7 @@ source fs/romfs/Kconfig
 source fs/smartfs/Kconfig
 source fs/binfs/Kconfig
 source fs/procfs/Kconfig
+source fs/unionfs/Kconfig
 
 comment "System Logging"
 

fs/Makefile

@@ -69,6 +69,7 @@ include nfs/Make.defs
 include smartfs/Make.defs
 include binfs/Make.defs
 include procfs/Make.defs
+include unionfs/Make.defs
 
 endif
 endif
@@ -80,8 +81,6 @@ OBJS = $(AOBJS) $(COBJS)
 
 BIN = libfs$(LIBEXT)
 
-SUBDIRS = mmap fat romfs nxffs nfs binfs procfs
-
 all: $(BIN)
 
 $(AOBJS): %$(OBJEXT): %.S

fs/unionfs/Kconfig

@@ -0,0 +1,28 @@
+#
+# For a description of the syntax of this configuration file,
+# see misc/tools/kconfig-language.txt.
+#
+
+config FS_UNIONFS
+	bool "Union File System"
+	default n
+	---help---
+		The Union file system is provides a mechanism to overlay two
+		different, mounted file systems so that they appear as one.  In
+		general this works like this:
+
+			1) Mount file system 1 at some location, say /mnt/file1
+			2) Mount file system 2 at some location, say /mnt/file2
+			3) Call unionfs_mount() to combine and overly /mnt/file1 and
+			mnt/file2 as a new mount point, say /mnt/unionfs.
+
+		/mnt/file1 and /mnt/file2 will disappear and be replaced by the
+		single mountpoint /mnut/unionfs.  The previous contents under
+		/mnt/file1 and /mnt/file2 will appear merged under /mnt/unionfs.
+		Files at the same relative path in file system1 will take presence.
+		If another file of the same name and same relative location exists
+		in file system 2, it will not be visible because it will be occluded
+		by the file in file system1.
+
+		See include/nutts/unionfs.h for additional information.
+

fs/unionfs/Make.defs

@@ -0,0 +1,47 @@
+############################################################################
+# fs/unionfs/Make.defs
+#
+#   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+# 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.
+#
+############################################################################
+
+ifeq ($(CONFIG_FS_UNIONFS),y)
+# Files required for Union file system support
+
+ASRCS +=
+CSRCS += fs_unionfs.c
+
+# Include Union File System build support
+
+DEPPATH += --dep-path unionfs
+VPATH += :unionfs
+
+endif

fs/unionfs/README.txt

@@ -0,0 +1,39 @@
+fs/unionfs/README.txt
+=====================
+
+  This directory contains the NuttX Union File System.  The Union file
+  system is provides a mechanism to overlay two different, mounted file
+  systems so that they appear as one.  In general this works like this:
+
+  1) Mount file system 1 at some location, say /mnt/file1
+  2) Mount file system 2 at some location, say /mnt/file2
+  3) Call unionfs_mount() to combine and overly /mnt/file1 and mnt/file2
+     as a new mount point, say /mnt/unionfs.
+
+  /mnt/file1 and /mnt/file2 will disappear and be replaced by the single
+  mountpoint /mnut/unionfs.  The previous contents under /mnt/file1 and
+  /mnt/file2 will appear merged under /mnt/unionfs. Files at the same
+  relative path in file system1 will take presence. If another file of the
+  same name and same relative location exists 	in file system 2, it will
+  not be visible because it will be occluded by the file in file system1.
+
+  See include/nutts/unionfs.h for additional information.
+
+  The Union File Sysem is enabled by selecting the CONFIG_FS_UNIONFS option
+  in the NuttX configruation file.
+
+  The original motivation for this file was for the use of the built-in
+  function file system (BINFS) with a web server.  In that case, the built
+  in functions provide CGI programs.  But the BINFS file system cannot hold
+  content.  Fixed content would need to be retained in a more standard file
+  system such as ROMFS.  With this Union File System, you can overly the
+  BINFS mountpoint on the the ROMFS mountpoint, providing a single directory
+  that appears to contain the executables from the BINFS file system along
+  with the web content from the ROMFS file system.
+
+  Another possible use for the Union File System could be to augment or
+  replace files in a FLASH file system.  For example, suppose that you have
+  a product that ships with content in a ROMFS file system provided by the
+  on-board FLASH.  Later, you overlay that ROMFS file system with additional
+  files from an SD card by using the Union File System to overlay, and
+  perhaps replace, the ROMFS files.

include/nuttx/fs/dirent.h

@@ -1,7 +1,7 @@
 /****************************************************************************
  * include/nuttx/fs/dirent.h
  *
- *   Copyright (C) 2007, 2009, 2011-2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011-2013, 2015 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -144,7 +144,20 @@ struct fs_smartfsdir_s
 {
   uint16_t fs_firstsector;                    /* First sector of directory list */
   uint16_t fs_currsector;                     /* Current sector of directory list */
-  uint16_t fs_curroffset;                     /* Current offset withing current sector */
+  uint16_t fs_curroffset;                     /* Current offset within current sector */
+};
+#endif
+
+#ifdef CONFIG_FS_UNIONFS
+/* The Union File System can be used to merge to different mountpoints so
+ * that they appear as a single merged directory.
+ */
+
+struct fs_dirent_s;                           /* Forward reference */
+struct fs_unionfsdir_s
+{
+  uint8_t fu_ndx;                             /* Index of file system being enumerated */
+  FAR struct fs_dirent_s *fu_lower[2];        /* dirent struct used by contained file system */
 };
 #endif
 
@@ -208,6 +221,9 @@ struct fs_dirent_s
 #ifdef CONFIG_FS_SMARTFS
       struct fs_smartfsdir_s smartfs;
 #endif
+#ifdef CONFIG_FS_UNIONFS
+      struct fs_unionfsdir_s unionfs;
+#endif
 #endif /* !CONFIG_DISABLE_MOUNTPOINT */
    } u;
 

include/nuttx/fs/unionfs.h

@@ -0,0 +1,103 @@
+/****************************************************************************
+ * include/nuttx/fs/unionfs.h
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_NUTTX_FS_UNIONFS_H
+#define __INCLUDE_NUTTX_FS_UNIONFS_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#ifdef CONFIG_FS_UNIONFS
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Type Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: unionfs_mount
+ *
+ * Description:
+ *   Create and mount a union file system
+ *
+ * Input Parameters:
+ *   fspath1 - The full path to the first file system mountpoint
+ *   prefix1 - An optiona prefix that may be applied to make the first
+ *             file system appear a some path below the unionfs mountpoint,
+ *   fspath2 - The full path to the second file system mountpoint
+ *   prefix2 - An optiona prefix that may be applied to make the first
+ *             file system appear a some path below the unionfs mountpoint,
+ *   mountpt - The full path to the mountpoint for the union file system
+ *
+ * Returned value:
+ *   Zero (OK) is returned if the union file system was correctly created and
+ *   mounted.  On any failure, a negated error value will be returned to
+ *   indicate the nature of the failure.
+ *
+ ****************************************************************************/
+
+int unionfs_mount(FAR const char *fspath1, FAR const char *prefix1,
+                  FAR const char *fspath2, FAR const char *prefix2,
+                  FAR const char *mountpt);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CONFIG_FS_UNIONFS */
+#endif /* __INCLUDE_NUTTX_FS_UNIONFS_H */

include/sys/statfs.h

@@ -102,6 +102,7 @@
 #define PROCFS_MAGIC          0x434f5250
 #define NXFFS_MAGIC           0x4747
 #define SMARTFS_MAGIC         0x54524D53
+#define UNIONFS_MAGIC         0x53464e55
 
 /****************************************************************************
  * Type Definitions