1  ///////////////////////////////////////////////////////////////////////////////
       2  //
       3  /// \file       stream_buffer_encoder.c
       4  /// \brief      Single-call .xz Stream encoder
       5  //
       6  //  Author:     Lasse Collin
       7  //
       8  //  This file has been put into the public domain.
       9  //  You can do whatever you want with this file.
      10  //
      11  ///////////////////////////////////////////////////////////////////////////////
      12  
      13  #include "common.h"
      14  #include "index.h"
      15  
      16  
      17  /// Maximum size of Index that has exactly one Record.
      18  /// Index Indicator + Number of Records + Record + CRC32 rounded up to
      19  /// the next multiple of four.
      20  #define INDEX_BOUND ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 4 + 3) & ~3)
      21  
      22  /// Stream Header, Stream Footer, and Index
      23  #define HEADERS_BOUND (2 * LZMA_STREAM_HEADER_SIZE + INDEX_BOUND)
      24  
      25  
      26  extern LZMA_API(size_t)
      27  lzma_stream_buffer_bound(size_t uncompressed_size)
      28  {
      29  	// Get the maximum possible size of a Block.
      30  	const size_t block_bound = lzma_block_buffer_bound(uncompressed_size);
      31  	if (block_bound == 0)
      32  		return 0;
      33  
      34  	// Catch the possible integer overflow and also prevent the size of
      35  	// the Stream exceeding LZMA_VLI_MAX (theoretically possible on
      36  	// 64-bit systems).
      37  	if (my_min(SIZE_MAX, LZMA_VLI_MAX) - block_bound < HEADERS_BOUND)
      38  		return 0;
      39  
      40  	return block_bound + HEADERS_BOUND;
      41  }
      42  
      43  
      44  extern LZMA_API(lzma_ret)
      45  lzma_stream_buffer_encode(lzma_filter *filters, lzma_check check,
      46  		const lzma_allocator *allocator,
      47  		const uint8_t *in, size_t in_size,
      48  		uint8_t *out, size_t *out_pos_ptr, size_t out_size)
      49  {
      50  	// Sanity checks
      51  	if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX
      52  			|| (in == NULL && in_size != 0) || out == NULL
      53  			|| out_pos_ptr == NULL || *out_pos_ptr > out_size)
      54  		return LZMA_PROG_ERROR;
      55  
      56  	if (!lzma_check_is_supported(check))
      57  		return LZMA_UNSUPPORTED_CHECK;
      58  
      59  	// Note for the paranoids: Index encoder prevents the Stream from
      60  	// getting too big and still being accepted with LZMA_OK, and Block
      61  	// encoder catches if the input is too big. So we don't need to
      62  	// separately check if the buffers are too big.
      63  
      64  	// Use a local copy. We update *out_pos_ptr only if everything
      65  	// succeeds.
      66  	size_t out_pos = *out_pos_ptr;
      67  
      68  	// Check that there's enough space for both Stream Header and
      69  	// Stream Footer.
      70  	if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)
      71  		return LZMA_BUF_ERROR;
      72  
      73  	// Reserve space for Stream Footer so we don't need to check for
      74  	// available space again before encoding Stream Footer.
      75  	out_size -= LZMA_STREAM_HEADER_SIZE;
      76  
      77  	// Encode the Stream Header.
      78  	lzma_stream_flags stream_flags = {
      79  		.version = 0,
      80  		.check = check,
      81  	};
      82  
      83  	if (lzma_stream_header_encode(&stream_flags, out + out_pos)
      84  			!= LZMA_OK)
      85  		return LZMA_PROG_ERROR;
      86  
      87  	out_pos += LZMA_STREAM_HEADER_SIZE;
      88  
      89  	// Encode a Block but only if there is at least one byte of input.
      90  	lzma_block block = {
      91  		.version = 0,
      92  		.check = check,
      93  		.filters = filters,
      94  	};
      95  
      96  	if (in_size > 0)
      97  		return_if_error(lzma_block_buffer_encode(&block, allocator,
      98  				in, in_size, out, &out_pos, out_size));
      99  
     100  	// Index
     101  	{
     102  		// Create an Index. It will have one Record if there was
     103  		// at least one byte of input to encode. Otherwise the
     104  		// Index will be empty.
     105  		lzma_index *i = lzma_index_init(allocator);
     106  		if (i == NULL)
     107  			return LZMA_MEM_ERROR;
     108  
     109  		lzma_ret ret = LZMA_OK;
     110  
     111  		if (in_size > 0)
     112  			ret = lzma_index_append(i, allocator,
     113  					lzma_block_unpadded_size(&block),
     114  					block.uncompressed_size);
     115  
     116  		// If adding the Record was successful, encode the Index
     117  		// and get its size which will be stored into Stream Footer.
     118  		if (ret == LZMA_OK) {
     119  			ret = lzma_index_buffer_encode(
     120  					i, out, &out_pos, out_size);
     121  
     122  			stream_flags.backward_size = lzma_index_size(i);
     123  		}
     124  
     125  		lzma_index_end(i, allocator);
     126  
     127  		if (ret != LZMA_OK)
     128  			return ret;
     129  	}
     130  
     131  	// Stream Footer. We have already reserved space for this.
     132  	if (lzma_stream_footer_encode(&stream_flags, out + out_pos)
     133  			!= LZMA_OK)
     134  		return LZMA_PROG_ERROR;
     135  
     136  	out_pos += LZMA_STREAM_HEADER_SIZE;
     137  
     138  	// Everything went fine, make the new output position available
     139  	// to the application.
     140  	*out_pos_ptr = out_pos;
     141  	return LZMA_OK;
     142  }