mirror of https://git.tukaani.org/xz.git
90 lines
2.4 KiB
C
90 lines
2.4 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file stream_flags_encoder.c
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/// \brief Encodes Stream Header and Stream Footer for .lzma files
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//
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// Copyright (C) 2007 Lasse Collin
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "stream_flags_common.h"
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static bool
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stream_flags_encode(const lzma_stream_flags *options, uint8_t *out)
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{
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if ((unsigned int)(options->check) > LZMA_CHECK_ID_MAX)
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return true;
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out[0] = 0x00;
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out[1] = options->check;
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return false;
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}
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extern LZMA_API lzma_ret
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lzma_stream_header_encode(const lzma_stream_flags *options, uint8_t *out)
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{
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assert(sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE
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+ 4 == LZMA_STREAM_HEADER_SIZE);
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// Magic
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memcpy(out, lzma_header_magic, sizeof(lzma_header_magic));
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// Stream Flags
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if (stream_flags_encode(options, out + sizeof(lzma_header_magic)))
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return LZMA_PROG_ERROR;
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// CRC32 of the Stream Header
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const uint32_t crc = lzma_crc32(out + sizeof(lzma_header_magic),
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LZMA_STREAM_FLAGS_SIZE, 0);
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integer_write_32(out + sizeof(lzma_header_magic)
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+ LZMA_STREAM_FLAGS_SIZE, crc);
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return LZMA_OK;
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}
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extern LZMA_API lzma_ret
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lzma_stream_footer_encode(const lzma_stream_flags *options, uint8_t *out)
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{
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assert(2 * 4 + LZMA_STREAM_FLAGS_SIZE + sizeof(lzma_footer_magic)
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== LZMA_STREAM_HEADER_SIZE);
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// Backward Size
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if (options->backward_size < LZMA_BACKWARD_SIZE_MIN
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|| options->backward_size > LZMA_BACKWARD_SIZE_MAX
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|| (options->backward_size & 3))
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return LZMA_PROG_ERROR;
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integer_write_32(out + 4, options->backward_size / 4 - 1);
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// Stream Flags
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if (stream_flags_encode(options, out + 2 * 4))
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return LZMA_PROG_ERROR;
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// CRC32
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const uint32_t crc = lzma_crc32(
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out + 4, 4 + LZMA_STREAM_FLAGS_SIZE, 0);
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integer_write_32(out, crc);
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// Magic
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memcpy(out + 2 * 4 + LZMA_STREAM_FLAGS_SIZE,
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lzma_footer_magic, sizeof(lzma_footer_magic));
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return LZMA_OK;
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}
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