57 lines
1.5 KiB
C++
57 lines
1.5 KiB
C++
#include "gzip.h"
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#define ZLIB_CONST
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#include <zlib.h>
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#include <math.h>
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#include <memory>
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#include "byte_utils.h"
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std::vector<ubyte> gzip::compress(const ubyte* src, size_t size) {
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size_t buffer_size = 23+size*1.01;
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std::vector<ubyte> buffer;
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buffer.resize(buffer_size);
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// zlib struct
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z_stream defstream {};
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defstream.zalloc = Z_NULL;
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defstream.zfree = Z_NULL;
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defstream.opaque = Z_NULL;
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defstream.avail_in = size;
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defstream.next_in = src;
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defstream.avail_out = buffer_size;
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defstream.next_out = buffer.data();
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// compression
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deflateInit2(&defstream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
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16 + MAX_WBITS, 8, Z_DEFAULT_STRATEGY);
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deflate(&defstream, Z_FINISH);
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deflateEnd(&defstream);
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size_t compressed_size = defstream.next_out - buffer.data();
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buffer.resize(compressed_size);
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return buffer;
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}
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std::vector<ubyte> gzip::decompress(const ubyte* src, size_t size) {
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// getting uncompressed data length from gzip footer
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size_t decompressed_size = *(uint32_t*)(src+size-4);
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std::vector<ubyte> buffer;
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buffer.resize(decompressed_size);
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// zlib struct
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z_stream infstream;
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infstream.zalloc = Z_NULL;
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infstream.zfree = Z_NULL;
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infstream.opaque = Z_NULL;
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infstream.avail_in = size;
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infstream.next_in = src;
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infstream.avail_out = decompressed_size;
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infstream.next_out = buffer.data();
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inflateInit2(&infstream, 16+MAX_WBITS);
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inflate(&infstream, Z_NO_FLUSH);
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inflateEnd(&infstream);
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return buffer;
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}
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