+ * Calculate how many bytes of payload a block tree of the given
+ * depth MAY correspond to at most (this function ignores the fact that
+ * some blocks will only be present partially due to the total file
+ * size cutting some blocks off at the end).
+ *
+ * @param depth depth of the block. depth==0 is a DBLOCK.
+ * @return number of bytes of payload a subtree of this depth may correspond to
+ */
+uint64_t
+GNUNET_FS_tree_compute_tree_size (unsigned int depth)
+{
+ uint64_t rsize;
+ unsigned int i;
+
+ rsize = DBLOCK_SIZE;
+ for (i = 0; i < depth; i++)
+ rsize *= CHK_PER_INODE;
+ return rsize;
+}
+
+
+/**
+ * Compute the size of the current IBLOCK. The encoder is
+ * triggering the calculation of the size of an IBLOCK at the
+ * *end* (hence end_offset) of its construction. The IBLOCK
+ * maybe a full or a partial IBLOCK, and this function is to
+ * calculate how long it should be.
+ *
+ * @param depth depth of the IBlock in the tree, 0 would be a DBLOCK,
+ * must be > 0 (this function is for IBLOCKs only!)
+ * @param end_offset current offset in the payload (!) of the overall file,
+ * must be > 0 (since this function is called at the
+ * end of a block).
+ * @return size of the corresponding IBlock
+ */
+static uint16_t
+GNUNET_FS_tree_compute_iblock_size (unsigned int depth, uint64_t end_offset)
+{
+ unsigned int ret;
+ uint64_t mod;
+ uint64_t bds;
+
+ GNUNET_assert (depth > 0);
+ GNUNET_assert (end_offset > 0);
+ bds = GNUNET_FS_tree_compute_tree_size (depth);
+ mod = end_offset % bds;
+ if (0 == mod)
+ {
+ /* we were triggered at the end of a full block */
+ ret = CHK_PER_INODE;
+ }
+ else
+ {
+ /* we were triggered at the end of the file */
+ bds /= CHK_PER_INODE;
+ ret = mod / bds;
+ if (0 != mod % bds)
+ ret++;
+ }
+ return (uint16_t) (ret * sizeof (struct ContentHashKey));
+}
+
+
+/**
+ * Compute how many bytes of data should be stored in
+ * the specified block.
+ *
+ * @param fsize overall file size, must be > 0.
+ * @param offset offset in the original data corresponding
+ * to the beginning of the tree induced by the block;
+ * must be <= fsize
+ * @param depth depth of the node in the tree, 0 for DBLOCK
+ * @return number of bytes stored in this node
+ */
+size_t
+GNUNET_FS_tree_calculate_block_size (uint64_t fsize, uint64_t offset,
+ unsigned int depth)
+{
+ size_t ret;
+ uint64_t rsize;
+ uint64_t epos;
+ unsigned int chks;
+
+ GNUNET_assert (fsize > 0);
+ GNUNET_assert (offset <= fsize);
+ if (depth == 0)
+ {
+ ret = DBLOCK_SIZE;
+ if ((offset + ret > fsize) || (offset + ret < offset))
+ ret = (size_t) (fsize - offset);
+ return ret;
+ }
+
+ rsize = GNUNET_FS_tree_compute_tree_size (depth - 1);
+ epos = offset + rsize * CHK_PER_INODE;
+ if ((epos < offset) || (epos > fsize))
+ epos = fsize;
+ /* round up when computing #CHKs in our IBlock */
+ chks = (epos - offset + rsize - 1) / rsize;
+ GNUNET_assert (chks <= CHK_PER_INODE);
+ return chks * sizeof (struct ContentHashKey);
+}
+
+
+/**
+ * Initialize a tree encoder. This function will call @a proc and
projects / oweals / gnunet.git / blobdiff