124 lines
3.9 KiB
C++
124 lines
3.9 KiB
C++
/* filter.h --
|
|
|
|
This file is part of the UPX executable compressor.
|
|
|
|
Copyright (C) 1996-2025 Markus Franz Xaver Johannes Oberhumer
|
|
Copyright (C) 1996-2025 Laszlo Molnar
|
|
All Rights Reserved.
|
|
|
|
UPX and the UCL library are free software; you can redistribute them
|
|
and/or modify them under the terms of the GNU General Public License as
|
|
published by the Free Software Foundation; either version 2 of
|
|
the License, or (at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; see the file COPYING.
|
|
If not, write to the Free Software Foundation, Inc.,
|
|
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
|
|
Markus F.X.J. Oberhumer Laszlo Molnar
|
|
<markus@oberhumer.com> <ezerotven+github@gmail.com>
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
/*************************************************************************
|
|
// A filter is a reversible operation that modifies a given
|
|
// block of memory.
|
|
//
|
|
// A filter can fail and return false. In this case the buffer
|
|
// must be unmodified (or otherwise restored).
|
|
//
|
|
// If a filter fails and somehow cannot restore the block it must
|
|
// call throwFilterException() - this will cause the compression
|
|
// to fail.
|
|
//
|
|
// Unfilters throw exceptions in case of errors.
|
|
//
|
|
// The main idea behind filters is to convert relative jumps and calls
|
|
// to absolute addresses so that the buffer compresses better.
|
|
**************************************************************************/
|
|
|
|
class Filter final {
|
|
public:
|
|
explicit Filter(int level) noexcept;
|
|
void init(int id = 0, unsigned addvalue = 0) noexcept;
|
|
|
|
bool filter(SPAN_0(byte) buf, unsigned buf_len);
|
|
void unfilter(SPAN_0(byte) buf, unsigned buf_len, bool verify_checksum = false);
|
|
void verifyUnfilter();
|
|
bool scan(SPAN_0(const byte) buf, unsigned buf_len);
|
|
|
|
static bool isValidFilter(int filter_id);
|
|
static bool isValidFilter(int filter_id, const int *allowed_filters);
|
|
|
|
public:
|
|
// Will be set by each call to filter()/unfilter().
|
|
// Read-only afterwards.
|
|
byte *buf = nullptr;
|
|
unsigned buf_len = 0;
|
|
|
|
// Checksum of the buffer before applying the filter
|
|
// or after un-applying the filter.
|
|
unsigned adler;
|
|
|
|
// Input parameters used by various filters.
|
|
unsigned addvalue;
|
|
const int *preferred_ctos = nullptr;
|
|
|
|
// Input/output parameters used by various filters
|
|
byte cto; // call trick offset
|
|
|
|
// Output used by various filters. Read only.
|
|
unsigned calls;
|
|
unsigned noncalls;
|
|
unsigned wrongcalls;
|
|
unsigned firstcall;
|
|
unsigned lastcall;
|
|
unsigned n_mru; // ctojr only
|
|
|
|
// Read only.
|
|
int id;
|
|
|
|
private:
|
|
int clevel; // compression level
|
|
};
|
|
|
|
/*************************************************************************
|
|
// We don't want a full OO interface here because of
|
|
// certain implementation speed reasons.
|
|
//
|
|
// This class is private to Filter - don't look.
|
|
**************************************************************************/
|
|
|
|
class FilterImpl final {
|
|
friend class Filter;
|
|
|
|
private:
|
|
explicit FilterImpl() noexcept DELETED_FUNCTION;
|
|
|
|
struct FilterEntry {
|
|
int id; // 0 .. 255
|
|
unsigned min_buf_len;
|
|
unsigned max_buf_len;
|
|
int (*do_filter)(Filter *); // filter a buffer
|
|
int (*do_unfilter)(Filter *); // unfilter a buffer
|
|
int (*do_scan)(Filter *); // scan a buffer
|
|
};
|
|
|
|
// get a specific filter entry
|
|
static const FilterEntry *getFilter(int id);
|
|
|
|
private:
|
|
// strictly private filter database
|
|
static const FilterEntry filters[];
|
|
static const int n_filters; // number of filters[]
|
|
};
|
|
|
|
/* vim:set ts=4 sw=4 et: */
|