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+/****************************************************************************
+ * fs/nxffs/nxffs_block.c
+ *
+ * Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ * Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * References: Linux/Documentation/filesystems/romfs.txt
+ *
+ * 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/mtd.h>
+
+#include "nxffs.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxffs_verifyblock
+ *
+ * Description:
+ * Assure the the provided (logical) block number is in the block cache
+ * and that it has a valid block header (i.e., proper magic and
+ * marked good)
+ *
+ * Input Parameters:
+ * volume - Describes the NXFFS volume
+ * block - The (logical) block number to load and verify.
+ *
+ * Returned Values:
+ * Zero is returned on success. Otherwise, a negated errno value is
+ * returned indicating the nature of the failure. -ENOENT is returned
+ * if the block is a bad block.
+ *
+ ****************************************************************************/
+
+int nxffs_verifyblock(FAR struct nxffs_volume_s *volume, off_t block)
+{
+ FAR struct nxffs_block_s *blkhdr;
+ int ret;
+
+ /* Make sure the the block is in the cache */
+
+ ret = nxffs_rdcache(volume, block);
+ if (ret < 0)
+ {
+ /* Perhaps we are at the end of the media */
+
+ fvdbg("Failed to read data into cache: %d\n", ret);
+ return ret;
+ }
+
+ /* Check if the block has a magic number (meaning that it is not
+ * erased) and that it is valid (meaning that it is not marked
+ * for deletion)
+ */
+
+ blkhdr = (FAR struct nxffs_block_s *)volume->cache;
+ if (memcmp(blkhdr->magic, g_blockmagic, NXFFS_MAGICSIZE) == 0)
+ {
+ /* This does appear to be a block */
+
+ if (blkhdr->state == BLOCK_STATE_GOOD)
+ {
+ /* The block is valid */
+
+ return OK;
+ }
+ else if (blkhdr->state == BLOCK_STATE_BAD)
+ {
+ /* -ENOENT is a special indication that this is a properly marked
+ * bad block
+ */
+
+ return -ENOENT;
+ }
+ }
+
+ /* Whatever is here where a block header should be is invalid */
+
+ return -EINVAL;
+}
+
+/****************************************************************************
+ * Name: nxffs_validblock
+ *
+ * Description:
+ * Find the next valid (logical) block in the volume.
+ *
+ * Input Parameters:
+ * volume - Describes the NXFFS volume
+ * block - On entry, this provides the starting block number. If the
+ * function is succesfful, then this memory location will hold the
+ * block number of the next valid block on return.
+ *
+ * Returned Value:
+ * Zero on success otherwise a negated errno value indicating the nature
+ * of the failure.
+ *
+ ****************************************************************************/
+
+int nxffs_validblock(struct nxffs_volume_s *volume, off_t *block)
+{
+ off_t i;
+ int ret;
+
+ DEBUGASSERT(volume && block);
+
+ /* Loop for each possible block or until a valid block is found */
+
+ for (i = *block; i < volume->nblocks; i++)
+ {
+ /* Loop until we find a valid block */
+
+ ret = nxffs_verifyblock(volume, i);
+ if (ret == OK)
+ {
+ /* We found it, return the block number */
+
+ *block = i;
+ return OK;
+ }
+ }
+
+ /* ENOSPC is special return value that means that there is no further,
+ * valid blocks left in the volume.
+ */
+
+ fdbg("No valid block found\n");
+ return -ENOSPC;
+}