Disk ARchive: compressor_zstd.hpp Source File

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compressor_zstd.hpp
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1/*********************************************************************/
2// dar - disk archive - a backup/restoration program
3// Copyright (C) 2002-2025 Denis Corbin
4//
5// This program is free software; you can redistribute it and/or
6// modify it under the terms of the GNU General Public License
7// as published by the Free Software Foundation; either version 2
8// of the License, or (at your option) any later version.
9//
10// This program is distributed in the hope that it will be useful,
11// but WITHOUT ANY WARRANTY; without even the implied warranty of
12// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13// GNU General Public License for more details.
14//
15// You should have received a copy of the GNU General Public License
16// along with this program; if not, write to the Free Software
17// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18//
19// to contact the author, see the AUTHOR file
20/*********************************************************************/
21
25
26#ifndef COMPRESSOR_ZSTD_HPP
27#define COMPRESSOR_ZSTD_HPP
28
29#include "../my_config.h"
30
31extern "C"
32{
33#if HAVE_ZSTD_H
34#include <zstd.h>
35#endif
36}
37
38#include "proto_compressor.hpp"
39
40namespace libdar
41{
42
43
46
48
49 class compressor_zstd : public proto_compressor
50 {
51 public :
52 compressor_zstd(generic_file & compressed_side, U_I compression_level = 9);
53 // compressed_side is not owned by the object and will remains
54 // after the objet destruction
55
56 compressor_zstd(const compressor_zstd & ref) = delete;
57 compressor_zstd(compressor_zstd && ref) noexcept = delete;
58 compressor_zstd & operator = (const compressor_zstd & ref) = delete;
59 compressor_zstd & operator = (compressor_zstd && ref) noexcept = delete;
60 ~compressor_zstd();
61
62 virtual compression get_algo() const override;
63
64 virtual void suspend_compression() override;
65 virtual void resume_compression() override;
66 virtual bool is_compression_suspended() const override { return suspended; };
67
68
69 // inherited from generic file
70 virtual bool skippable(skippability direction, const infinint & amount) override { return compressed->skippable(direction, amount); };
71 virtual bool skip(const infinint & pos) override { compr_flush_write(); compr_flush_read(); clean_read(); return compressed->skip(pos); };
72 virtual bool skip_to_eof() override { compr_flush_write(); compr_flush_read(); clean_read(); return compressed->skip_to_eof(); };
73 virtual bool skip_relative(S_I x) override { compr_flush_write(); compr_flush_read(); clean_read(); return compressed->skip_relative(x); };
74 virtual bool truncatable(const infinint & pos) const override { return compressed->truncatable(pos); };
75 virtual infinint get_position() const override { return compressed->get_position(); };
76
77 protected :
78 virtual void inherited_read_ahead(const infinint & amount) override { compressed->read_ahead(amount); };
79 virtual U_I inherited_read(char *a, U_I size) override;
80 virtual void inherited_write(const char *a, U_I size) override;
81 virtual void inherited_truncate(const infinint & pos) override;
82 virtual void inherited_sync_write() override { compr_flush_write(); };
83 virtual void inherited_flush_read() override { compr_flush_read(); clean_read(); };
84 virtual void inherited_terminate() override;
85
86 private :
87 generic_file *compressed;
88 bool suspended;
89
90#if LIBZSTD_AVAILABLE
91 ZSTD_CStream *comp;
92 ZSTD_DStream *decomp;
93
94 ZSTD_inBuffer inbuf;
95 ZSTD_outBuffer outbuf;
96 char *below_tampon;
97 U_I below_tampon_size;
98 U_I above_tampon_size;
99
100 bool flueof;
101 bool no_comp_data;
102#endif
103
104
105
106 void reset_compr_engine();
107
108 void compr_flush_write(); // flush all data to compressed_side, and reset the compressor_zstd
109 // for that additional write can be uncompresssed starting at this point.
110 void compr_flush_read(); // reset decompression engine to be able to read the next block of compressed data
111 // if not called, furthur read return EOF
112 void clean_read(); // discard any byte buffered and not yet returned by read()
113 void clean_write(); // discard any byte buffered and not yet wrote to compressed_side;
114
116
117 void clear_inbuf();
118 void clear_outbuf();
119 void release_mem();
120 void setup_context(U_I compression_level);
121
122 };
123
125
126} // end of namespace
127
128#endif
libdar::compressor_zstd::inherited_read_ahead
virtual void inherited_read_ahead(const infinint &amount) override
tells the object that several calls to read() will follow to probably obtain at least the given amoun...
Definition compressor_zstd.hpp:78
libdar::compressor_zstd::reset_compr_engine
void reset_compr_engine()
reset the compression engine ready for use
libdar::compressor_zstd::inherited_read
virtual U_I inherited_read(char *a, U_I size) override
implementation of read() operation
libdar::compressor_zstd::inherited_flush_read
virtual void inherited_flush_read() override
reset internal engine, flush caches in order to read the data at current position
Definition compressor_zstd.hpp:83
libdar::compressor_zstd::skippable
virtual bool skippable(skippability direction, const infinint &amount) override
whether the implementation is able to skip
Definition compressor_zstd.hpp:70
libdar::compressor_zstd::skip_to_eof
virtual bool skip_to_eof() override
skip to the end of file
Definition compressor_zstd.hpp:72
libdar::compressor_zstd::skip
virtual bool skip(const infinint &pos) override
skip at the absolute position
Definition compressor_zstd.hpp:71
libdar::compressor_zstd::inherited_write
virtual void inherited_write(const char *a, U_I size) override
implementation of the write() operation
libdar::compressor_zstd::clear_inbuf
void clear_inbuf()
from zstd
libdar::compressor_zstd::skip_relative
virtual bool skip_relative(S_I x) override
skip relatively to the current position
Definition compressor_zstd.hpp:73
libdar::compressor_zstd::inherited_terminate
virtual void inherited_terminate() override
destructor-like call, except that it is allowed to throw exceptions
libdar::compressor_zstd::inherited_truncate
virtual void inherited_truncate(const infinint &pos) override
truncate file at the give offset
libdar::compressor_zstd::inherited_sync_write
virtual void inherited_sync_write() override
write down any pending data
Definition compressor_zstd.hpp:82
libdar::compressor_zstd::truncatable
virtual bool truncatable(const infinint &pos) const override
whether the implementation is able to truncate to the given position
Definition compressor_zstd.hpp:74
libdar::compressor_zstd::get_position
virtual infinint get_position() const override
get the current read/write position
Definition compressor_zstd.hpp:75
libdar::infinint
the arbitrary large positive integer class
Definition real_infinint.hpp:62
libdar::compression
compression
the different compression algorithm available
Definition compression.hpp:46
my_config.h
include macro defined by the configure script and some specific additional ones
libdar
libdar namespace encapsulate all libdar symbols
Definition archive.hpp:47
proto_compressor.hpp
abstracted ancestor class for compressor and parallel_compressor classes