known_sizes.c

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//
//
//  Author:     Lasse Collin
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
 
#include "sysdefs.h"
#include "lzma.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/unistd.h>
#include <stdio.h>
 
 
// Support file sizes up to 1 MiB. We use this for output space too, so files
// close to 1 MiB had better compress at least a little or we have a buffer
// overflow.
#define BUFFER_SIZE (1U << 20)
 
 
int
main(void)
{
    // Allocate the buffers.
    uint8_t *in = malloc(BUFFER_SIZE);
    uint8_t *out = malloc(BUFFER_SIZE);
    if (in == NULL || out == NULL)
        return 1;
 
    // Fill the input buffer.
    const size_t in_size = fread(in, 1, BUFFER_SIZE, stdin);
 
    // Filter setup
    lzma_options_lzma opt_lzma;
    if (lzma_lzma_preset(&opt_lzma, 1))
        return 1;
 
    lzma_filter filters[] = {
        {
            .id = LZMA_FILTER_LZMA2,
            .options = &opt_lzma
        },
        {
            .id = LZMA_VLI_UNKNOWN
        }
    };
 
    lzma_block block = {
        .check = LZMA_CHECK_CRC32,
        .compressed_size = BUFFER_SIZE, // Worst case reserve
        .uncompressed_size = in_size,
        .filters = filters,
    };
 
    lzma_stream strm = LZMA_STREAM_INIT;
    if (lzma_block_encoder(&strm, &block) != LZMA_OK)
        return 1;
 
    // Reserve space for Stream Header and Block Header. We need to
    // calculate the size of the Block Header first.
    if (lzma_block_header_size(&block) != LZMA_OK)
        return 1;
 
    size_t out_size = LZMA_STREAM_HEADER_SIZE + block.header_size;
 
    strm.next_in = in;
    strm.avail_in = in_size;
    strm.next_out = out + out_size;
    strm.avail_out = BUFFER_SIZE - out_size;
 
    if (lzma_code(&strm, LZMA_FINISH) != LZMA_STREAM_END)
        return 1;
 
    out_size += strm.total_out;
 
    if (lzma_block_header_encode(&block, out + LZMA_STREAM_HEADER_SIZE)
            != LZMA_OK)
        return 1;
 
    lzma_index *idx = lzma_index_init(NULL);
    if (idx == NULL)
        return 1;
 
    if (lzma_index_append(idx, NULL, block.header_size + strm.total_out,
            strm.total_in) != LZMA_OK)
        return 1;
 
    if (lzma_index_encoder(&strm, idx) != LZMA_OK)
        return 1;
 
    if (lzma_code(&strm, LZMA_RUN) != LZMA_STREAM_END)
        return 1;
 
    out_size += strm.total_out;
 
    lzma_end(&strm);
 
    lzma_index_end(idx, NULL);
 
    // Encode the Stream Header and Stream Footer. backwards_size is
    // needed only for the Stream Footer.
    lzma_stream_flags sf = {
        .backward_size = strm.total_out,
        .check = block.check,
    };
 
    if (lzma_stream_header_encode(&sf, out) != LZMA_OK)
        return 1;
 
    if (lzma_stream_footer_encode(&sf, out + out_size) != LZMA_OK)
        return 1;
 
    out_size += LZMA_STREAM_HEADER_SIZE;
 
    // Write out the file.
    fwrite(out, 1, out_size, stdout);
 
    return 0;
}