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diff --git a/src/liblzma/api/lzma/index_hash.h b/src/liblzma/api/lzma/index_hash.h
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+/**
+ * \file        lzma/index_hash.h
+ * \brief       Validates Index by using a hash function
+ *
+ * Instead of constructing complete Index while decoding Blocks, Index hash
+ * calculates a hash of the Block sizes and Index, and then compares the
+ * hashes. This way memory usage is constant even with large number of
+ * Blocks and huge Index.
+ *
+ * \author      Copyright (C) 2008 Lasse Collin
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ */
+
+#ifndef LZMA_H_INTERNAL
+#	error Never include this file directly. Use <lzma.h> instead.
+#endif
+
+/**
+ * \brief       Opaque data type to hold the Index hash
+ */
+typedef struct lzma_index_hash_s lzma_index_hash;
+
+
+/**
+ * \brief       Allocate and initialize a new lzma_index_hash structure
+ *
+ * If index_hash is NULL, a new lzma_index_hash structure is allocated,
+ * initialized, and a pointer to it returned. If allocation fails, NULL
+ * is returned.
+ *
+ * If index_hash is non-NULL, it is reinitialized and the same pointer
+ * returned. In this case, return value cannot be NULL or a different
+ * pointer than the index_hash given as argument.
+ */
+extern lzma_index_hash *lzma_index_hash_init(
+		lzma_index_hash *index_hash, lzma_allocator *allocator);
+
+
+/**
+ * \brief       Deallocate the Index hash
+ */
+extern void lzma_index_hash_end(
+		lzma_index_hash *index_hash, lzma_allocator *allocator);
+
+
+/**
+ * \brief       Add a new Record to an Index hash
+ *
+ * \param       index             Pointer to a lzma_index_hash structure
+ * \param       total_size        Total Size of a Block
+ * \param       uncompressed_size Uncompressed Size of a Block
+ *
+ * \return      - LZMA_OK
+ *              - LZMA_DATA_ERROR: Compressed or uncompressed size of the
+ *                Stream or size of the Index field would grow too big.
+ *              - LZMA_PROG_ERROR: Invalid arguments or this function is being
+ *                used when lzma_index_hash_decode() has already been used.
+ */
+extern lzma_ret lzma_index_hash_append(lzma_index_hash *index_hash,
+		lzma_vli total_size, lzma_vli uncompressed_size);
+
+
+/**
+ * \brief       Decode the Index field
+ *
+ * \return      - LZMA_OK: So far good, but more input is needed.
+ *              - LZMA_STREAM_END: Index decoded successfully and it matches
+ *                the Records given with lzma_index_hash_append().
+ *              - LZMA_DATA_ERROR: Index is corrupt or doesn't match the
+ *                information given with lzma_index_hash_append().
+ *              - LZMA_PROG_ERROR
+ *
+ * \note        Once decoding of the Index field has been started, no more
+ *              Records can be added using lzma_index_hash_append().
+ */
+extern lzma_ret lzma_index_hash_decode(lzma_index_hash *index_hash,
+		const uint8_t *in, size_t *in_pos, size_t in_size);
+
+
+/**
+ * \brief       Get the size of the Index field as bytes
+ *
+ * This is needed to verify the Index Size field from the Stream Footer.
+ */
+extern lzma_vli lzma_index_hash_size(const lzma_index_hash *index_hash);