Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party

xz/src/liblzma/common/block_header_decoder.c

+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       block_header_decoder.c
+/// \brief      Decodes Block Header from .xz files
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "common.h"
+#include "check.h"
+
+
+static void
+free_properties(lzma_block *block, lzma_allocator *allocator)
+{
+        // Free allocated filter options. The last array member is not
+        // touched after the initialization in the beginning of
+        // lzma_block_header_decode(), so we don't need to touch that here.
+        for (size_t i = 0; i < LZMA_FILTERS_MAX; ++i) {
+                lzma_free(block->filters[i].options, allocator);
+                block->filters[i].id = LZMA_VLI_UNKNOWN;
+                block->filters[i].options = NULL;
+        }
+
+        return;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_block_header_decode(lzma_block *block,
+                lzma_allocator *allocator, const uint8_t *in)
+{
+        // NOTE: We consider the header to be corrupt not only when the
+        // CRC32 doesn't match, but also when variable-length integers
+        // are invalid or over 63 bits, or if the header is too small
+        // to contain the claimed information.
+
+        // Initialize the filter options array. This way the caller can
+        // safely free() the options even if an error occurs in this function.
+        for (size_t i = 0; i <= LZMA_FILTERS_MAX; ++i) {
+                block->filters[i].id = LZMA_VLI_UNKNOWN;
+                block->filters[i].options = NULL;
+        }
+
+        // Always zero for now.
+        block->version = 0;
+
+        // Validate Block Header Size and Check type. The caller must have
+        // already set these, so it is a programming error if this test fails.
+        if (lzma_block_header_size_decode(in[0]) != block->header_size
+                        || (unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
+                return LZMA_PROG_ERROR;
+
+        // Exclude the CRC32 field.
+        const size_t in_size = block->header_size - 4;
+
+        // Verify CRC32
+        if (lzma_crc32(in, in_size, 0) != unaligned_read32le(in + in_size))
+                return LZMA_DATA_ERROR;
+
+        // Check for unsupported flags.
+        if (in[1] & 0x3C)
+                return LZMA_OPTIONS_ERROR;
+
+        // Start after the Block Header Size and Block Flags fields.
+        size_t in_pos = 2;
+
+        // Compressed Size
+        if (in[1] & 0x40) {
+                return_if_error(lzma_vli_decode(&block->compressed_size,
+                                NULL, in, &in_pos, in_size));
+
+                // Validate Compressed Size. This checks that it isn't zero
+                // and that the total size of the Block is a valid VLI.
+                if (lzma_block_unpadded_size(block) == 0)
+                        return LZMA_DATA_ERROR;
+        } else {
+                block->compressed_size = LZMA_VLI_UNKNOWN;
+        }
+
+        // Uncompressed Size
+        if (in[1] & 0x80)
+                return_if_error(lzma_vli_decode(&block->uncompressed_size,
+                                NULL, in, &in_pos, in_size));
+        else
+                block->uncompressed_size = LZMA_VLI_UNKNOWN;
+
+        // Filter Flags
+        const size_t filter_count = (in[1] & 3) + 1;
+        for (size_t i = 0; i < filter_count; ++i) {
+                const lzma_ret ret = lzma_filter_flags_decode(
+                                &block->filters[i], allocator,
+                                in, &in_pos, in_size);
+                if (ret != LZMA_OK) {
+                        free_properties(block, allocator);
+                        return ret;
+                }
+        }
+
+        // Padding
+        while (in_pos < in_size) {
+                if (in[in_pos++] != 0x00) {
+                        free_properties(block, allocator);
+
+                        // Possibly some new field present so use
+                        // LZMA_OPTIONS_ERROR instead of LZMA_DATA_ERROR.
+                        return LZMA_OPTIONS_ERROR;
+                }
+        }
+
+        return LZMA_OK;
+}