Add basic NXFFS read logic

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3546 42af7a65-404d-4744-a932-0658087f49c3

fs/nxffs/nxffs.h

@@ -496,19 +496,15 @@ extern int nxffs_rdcache(FAR struct nxffs_volume_s *volume, off_t block,
  *
  * Input Parameters:
  *   volume - Describes the current volume
- *   block  - The first logical block to write
- *   nblocks - The number of logical blocks to be write.
  *
  * Returned Value:
  *   Negated errnos are returned only in the case of MTD reported failures.
- *   Nothing in the volume data itself will generate errors.
  *
  * Defined in nxffs_cache.c
  *
  ****************************************************************************/
 
-extern int nxffs_wrcache(FAR struct nxffs_volume_s *volume, off_t block,
+extern int nxffs_wrcache(FAR struct nxffs_volume_s *volume);
-                         uint8_t nblocks);
 
 /****************************************************************************
  * Name: nxffs_ioseek
@@ -594,29 +590,6 @@ extern int nxffs_getc(FAR struct nxffs_volume_s *volume);
 extern ssize_t nxffs_rddata(FAR struct nxffs_volume_s *volume,
                             FAR uint8_t *buffer, size_t buflen);
 
-/****************************************************************************
- * Name: nxffs_wrdata
- *
- * Description:
- *   Write a sequence of data bytes into volume cache memory.  Nothing is
- *   actually written to FLASH!  This function allows the data in the formatted
- *   FLASH blocks to be read as a continuous byte stream, skipping over bad 
- *   blocks and block headers as necessary.
- *
- * Input Parameters:
- *   volume - Describes the NXFFS volume.
- *   buffer - A pointer to memory to containing the data to write to FLASH.
- *   buflen - The maximum number of bytes to write to FLASH.
- *
- * Returned Value:
- *   The number of bytes written is returned on success.  Otherwise, a negated
- *   errno indicating the nature of the failure.
- *
- ****************************************************************************/
-
-extern ssize_t nxffs_wrdata(FAR struct nxffs_volume_s *volume,
-                            FAR const uint8_t *buffer, size_t buflen);
-
 /****************************************************************************
  * Name: nxffs_freeentry
  *

fs/nxffs/nxffs_cache.c

@@ -103,7 +103,7 @@ int nxffs_rdcache(FAR struct nxffs_volume_s *volume, off_t block,
       if (nxfrd != nblocks)
         {
           fdbg("Read block %d-%d failed: %d\n",
-                block, block + nblocks -1, nxfrd);
+               block, block + nblocks - 1, nxfrd);
           return -EIO;
         }
 
@@ -123,22 +123,41 @@ int nxffs_rdcache(FAR struct nxffs_volume_s *volume, off_t block,
  *
  * Input Parameters:
  *   volume - Describes the current volume
- *   block  - The first logical block to write
- *   nblocks - The number of logical blocks to be write.
  *
  * Returned Value:
  *   Negated errnos are returned only in the case of MTD reported failures.
- *   Nothing in the volume data itself will generate errors.
- *
- * Defined in nxffs_cache.c
  *
  ****************************************************************************/
 
-int nxffs_wrcache(FAR struct nxffs_volume_s *volume, off_t block,
+int nxffs_wrcache(FAR struct nxffs_volume_s *volume)
-                  uint8_t nblocks)
 {
-#warning "Missing logic"
+  size_t nxfrd;
+
+  /* Check if there are blocks in the cache */
+
+  if (volume->ncached > 0)
+    {
+      /* Read the specified blocks into cache */
+
+      nxfrd = MTD_BWRITE(volume->mtd, volume->cblock, volume->ncached,
+                         volume->cache);
+      if (nxfrd != volume->ncached)
+        {
+          fdbg("Write block %d-%d failed: %d\n",
+               volume->cblock, volume->cblock + volume->ncached - 1, nxfrd);
+          return -EIO;
+        }
+
+      /* Write was successful */
+
       return OK;
+    }
+
+  /* Probably won't get here because there is almost always something in
+   * the cache
+   */
+
+  return -EINVAL;
 }
 
 /****************************************************************************
@@ -287,30 +306,3 @@ ssize_t nxffs_rddata(FAR struct nxffs_volume_s *volume,
 
   return buflen;
 }
-
-/****************************************************************************
- * Name: nxffs_wrdata
- *
- * Description:
- *   Write a sequence of data bytes into volume cache memory.  Nothing is
- *   actually written to FLASH!  This function allows the data in the formatted
- *   FLASH blocks to be read as a continuous byte stream, skipping over bad 
- *   blocks and block headers as necessary.
- *
- * Input Parameters:
- *   volume - Describes the NXFFS volume.
- *   buffer - A pointer to memory to containing the data to write to FLASH.
- *   buflen - The maximum number of bytes to write to FLASH.
- *
- * Returned Value:
- *   The number of bytes written is returned on success.  Otherwise, a negated
- *   errno indicating the nature of the failure.
- *
- ****************************************************************************/
-
-ssize_t nxffs_wrdata(FAR struct nxffs_volume_s *volume,
-                     FAR const uint8_t *buffer, size_t buflen)
-{
-#warning "Missing Logic"
-  return -ENOSYS;
-}

fs/nxffs/nxffs_open.c

@@ -820,7 +820,7 @@ static int nxffs_wrclose(FAR struct nxffs_volume_s *volume,
     {
       /* Write the block with the inode header */
 
-      ret = nxffs_wrcache(volume, volume->ioblock, 1);
+      ret = nxffs_wrcache(volume);
       if (ret < 0)
         {
           fdbg("Failed to write inode header block %d: %d\n", volume->ioblock, -ret);
@@ -842,7 +842,7 @@ static int nxffs_wrclose(FAR struct nxffs_volume_s *volume,
   /* Finally, copy the inode name to the cache and write the inode name block */
 
   memcpy(&volume->cache[namoffset], wrfile->ofile.entry.name, namlen);
-  ret = nxffs_wrcache(volume, volume->ioblock, 1);
+  ret = nxffs_wrcache(volume);
   if (ret < 0)
     {
       fdbg("Failed to write inode header block %d: %d\n", volume->ioblock, -ret);

fs/nxffs/nxffs_read.c

@@ -43,6 +43,7 @@
 
 #include <string.h>
 #include <fcntl.h>
+#include <crc32.h>
 #include <assert.h>
 #include <errno.h>
 #include <debug.h>
@@ -68,6 +69,178 @@
  * Private Functions
  ****************************************************************************/
 
+/****************************************************************************
+ * Name: nxffs_rdblkhdr
+ *
+ * Description:
+ *   Read the dataa block header at this offset.  Called only from nxffs_nextblock().
+ *
+ * Input Parameters:
+ *   volume - Describes the current volume.
+ *   offset - The byte offset from the beginning of FLASH where the data block
+ *     header is expected.
+ *   datlen  - A memory location to return the data block length.
+ *
+ * Returned Value:
+ *   Zero on success.  Otherwise, a negater errno value is returned
+ *   indicating the nature of the failure.
+ *
+ ****************************************************************************/
+
+static int nxffs_rdblkhdr(FAR struct nxffs_volume_s *volume, off_t offset,
+                          FAR size_t *datlen)
+{
+  struct nxffs_data_s blkhdr;
+  uint32_t ecrc;
+  uint32_t crc;
+  uint16_t doffset;
+  uint16_t dlen;
+  int ret;
+
+  /* Read the header at the FLASH offset */
+
+  nxffs_ioseek(volume, offset);
+  ret = nxffs_rddata(volume, (FAR uint8_t *)&blkhdr, SIZEOF_NXFFS_DATA_HDR);
+  if (ret < 0)
+    {
+      fdbg("Failed to read data block header, offset %d: %d\n", offset, -ret);
+      return -EIO;
+    }
+  doffset = volume->iooffset;
+
+  /* Extract the data length */
+
+  dlen = nxffs_rdle16(blkhdr.datlen);
+  if ((uint32_t)doffset + (uint32_t)dlen > (uint32_t)volume->geo.blocksize)
+    {
+      fdbg("Data length=%d is unreasonable at offset=%d\n", dlen, doffset);
+      return -EIO;
+    }
+ 
+  /* Extract the expected CRC and calculate the CRC of the data block */
+
+  ecrc = nxffs_rdle32(blkhdr.crc);
+
+  nxffs_wrle16(blkhdr.crc, 0);
+  crc = crc32((FAR const uint8_t *)&blkhdr, SIZEOF_NXFFS_DATA_HDR);
+  crc = crc32part(&volume->cache[doffset], dlen, crc);
+  if (crc != ecrc)
+    {
+      fdbg("CRC failure\n");
+      return -EIO;
+    }
+
+  /* Looks good! Return the data length and success */
+
+  *datlen = dlen;
+  return OK;
+}
+
+/****************************************************************************
+ * Name: nxffs_nextblock
+ *
+ * Description:
+ *   Search for the next valid data block starting at the provided FLASH offset.
+ *
+ * Input Parameters:
+ *   volume - Describes the NXFFS volume.
+ *   offset - The FLASH memory offset to begin searching.
+ *   datlen  - A memory location to return the data block length.
+ *  
+ * Returned Value:
+ *   Zero is returned on success. Otherwise, a negated errno is returned
+ *   that indicates the nature of the failure.
+ *
+ ****************************************************************************/
+
+int nxffs_nextblock(FAR struct nxffs_volume_s *volume, off_t offset,
+                    FAR size_t *datlen)
+{
+  int nmagic;
+  int ch;
+  int nerased;
+  int ret;
+
+  /* Seek to the first FLASH offset provided by the caller. */
+
+  nxffs_ioseek(volume, offset);
+
+  /* Then begin searching */
+  
+  nerased = 0;
+  nmagic  = 0;
+
+  for (;;)
+    {
+      /* Read the next character */
+
+      ch = nxffs_getc(volume);
+      if (ch < 0)
+        {
+          fvdbg("nxffs_getc failed: %d\n", -ch);
+          return ch;
+        }
+
+      /* Check for another erased byte */
+
+      else if (ch == CONFIG_NXFFS_ERASEDSTATE)
+        {
+          /* If we have encountered NXFFS_NERASED number of consecutive
+           * erased bytes, then presume we have reached the end of valid
+           * data.
+           */
+
+          if (++nerased >= NXFFS_NERASED)
+            {
+              fvdbg("No entry found\n");
+              return -ENOENT;
+            }
+        }
+      else
+        {
+          nerased = 0;
+
+          /* Check for the magic sequence indicating the start of an NXFFS
+           * data block or start of the next inode. There is the possibility
+           * of this magic sequnce occurring in FLASH data.  However, the
+           * data block CRC should distinguish between real NXFFS data blocks
+           * headers and such false alarms.
+           */
+
+          if (ch != g_datamagic[nmagic])
+            {
+              nmagic = 0;
+            }
+          else if (nmagic < NXFFS_MAGICSIZE - 1)
+            {
+              nmagic++;
+            }
+
+          /* We have found the magic sequence in the FLASH data that may
+           * indicate the beginning of an NXFFS data block.
+           */
+
+          else 
+            {
+              ret = nxffs_rdblkhdr(volume, offset, datlen);
+              if (ret == OK)
+                {
+                  fdbg("Found a valid fileheader\n");
+                  return OK;
+                }
+
+              /* False alarm.. keep looking */
+
+              nmagic = 0;
+            }
+        }
+    }
+
+  /* We won't get here, but to keep some compilers happy: */
+
+  return -ENOENT;
+}
+
 /****************************************************************************
  * Name: nxffs_rdseek
  *
@@ -88,8 +261,32 @@ static ssize_t nxffs_rdseek(FAR struct nxffs_volume_s *volume,
                             FAR struct nxffs_entry_s *entry,
                             off_t fpos)
 {
-#warning "Missing Logic"
+  size_t datlen = 0;
-  return 0;
+  size_t blklen = 0;
+  off_t offset = fpos;
+  int ret;
+
+  /* Loop until we read the data block containing the desired position */
+
+  do
+    {
+      /* Get the data offset at the start of the next data block */
+
+      datlen += blklen;
+
+      /* Get the length of the next data block */
+
+      ret = nxffs_nextblock(volume, offset, &blklen);
+      if (ret < 0)
+        {
+          fdbg("nxffs_nextblock failed: %d\n", -ret);
+          return ret;
+        }
+    }
+  while (datlen <= fpos && datlen + blklen > fpos);
+
+  volume->iooffset += (fpos - datlen);
+  return OK;
 }
 
 /****************************************************************************

fs/nxffs/nxffs_unlink.c

@@ -137,7 +137,7 @@ int nxffs_rminode(FAR struct nxffs_volume_s *volume, FAR const char *name)
 
   /* Then write the cached block back to FLASH */
 
-  ret = nxffs_wrcache(volume, volume->ioblock, 1);
+  ret = nxffs_wrcache(volume);
   if (ret < 0)
     {
       fdbg("Failed to read data into cache: %d\n", ret);

fs/nxffs/nxffs_write.c

@@ -403,7 +403,7 @@ static inline ssize_t nxffs_wrappend(FAR struct nxffs_volume_s *volume,
  
       if (nbytesleft > 0)
         {
-          ret = nxffs_wrcache(volume, volume->ioblock, 1);
+          ret = nxffs_wrcache(volume);
           if (ret < 0)
             {
               fdbg("nxffs_wrcache failed: %d\n", -ret);
@@ -811,7 +811,7 @@ int nxffs_wrblkhdr(FAR struct nxffs_volume_s *volume,
 
   /* And write the data block to FLASH */
 
-  ret = nxffs_wrcache(volume, volume->ioblock, 1);
+  ret = nxffs_wrcache(volume);
   if (ret < 0)
     {
       fdbg("nxffs_wrcache failed: %d\n", -ret);