xz-archive/src/liblzma/common/common.h

///////////////////////////////////////////////////////////////////////////////
//
/// \file       common.h
/// \brief      Definitions common to the whole liblzma library
//
//  Copyright (C) 2007-2008 Lasse Collin
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library 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
//  Lesser General Public License for more details.
//
///////////////////////////////////////////////////////////////////////////////

#ifndef LZMA_COMMON_H
#define LZMA_COMMON_H

#include "../../common/sysdefs.h"
#include "../../common/integer.h"

// Don't use ifdef...
#if HAVE_VISIBILITY
#	define LZMA_API __attribute__((__visibility__("default")))
#else
#	define LZMA_API
#endif


// These allow helping the compiler in some often-executed branches, whose
// result is almost always the same.
#ifdef __GNUC__
#	define likely(expr) __builtin_expect(expr, true)
#	define unlikely(expr) __builtin_expect(expr, false)
#else
#	define likely(expr) (expr)
#	define unlikely(expr) (expr)
#endif


/// Size of temporary buffers needed in some filters
#define LZMA_BUFFER_SIZE 4096


/// Starting value for memory usage estimates. Instead of calculating size
/// of _every_ structure and taking into accont malloc() overhead etc. we
/// add a base size to all memory usage estimates. It's not very accurate
/// but should be easily good enough.
#define LZMA_MEMUSAGE_BASE (UINT64_C(1) << 15)

/// Start of internal Filter ID space. These IDs must never be used
/// in Streams.
#define LZMA_FILTER_RESERVED_START (LZMA_VLI_C(1) << 62)


/// Internal helper filter used by Subblock decoder. It is mapped to an
/// otherwise invalid Filter ID, which is impossible to get from any input
/// file (even if malicious file).
#define LZMA_FILTER_SUBBLOCK_HELPER LZMA_VLI_C(0x7000000000000001)


/// Supported flags that can be passed to lzma_stream_decoder()
/// or lzma_auto_decoder().
#define LZMA_SUPPORTED_FLAGS \
	( LZMA_TELL_NO_CHECK \
	| LZMA_TELL_UNSUPPORTED_CHECK \
	| LZMA_TELL_ANY_CHECK \
	| LZMA_CONCATENATED )


/// Type of encoder/decoder specific data; the actual structure is defined
/// differently in different coders.
typedef struct lzma_coder_s lzma_coder;

typedef struct lzma_next_coder_s lzma_next_coder;

typedef struct lzma_filter_info_s lzma_filter_info;


/// Type of a function used to initialize a filter encoder or decoder
typedef lzma_ret (*lzma_init_function)(
		lzma_next_coder *next, lzma_allocator *allocator,
		const lzma_filter_info *filters);

/// Type of a function to do some kind of coding work (filters, Stream,
/// Block encoders/decoders etc.). Some special coders use don't use both
/// input and output buffers, but for simplicity they still use this same
/// function prototype.
typedef lzma_ret (*lzma_code_function)(
		lzma_coder *coder, lzma_allocator *allocator,
		const uint8_t *restrict in, size_t *restrict in_pos,
		size_t in_size, uint8_t *restrict out,
		size_t *restrict out_pos, size_t out_size,
		lzma_action action);

/// Type of a function to free the memory allocated for the coder
typedef void (*lzma_end_function)(
		lzma_coder *coder, lzma_allocator *allocator);


/// Raw coder validates and converts an array of lzma_filter structures to
/// an array of lzma_filter_info structures. This array is used with
/// lzma_next_filter_init to initialize the filter chain.
struct lzma_filter_info_s {
	/// Pointer to function used to initialize the filter.
	/// This is NULL to indicate end of array.
	lzma_init_function init;

	/// Pointer to filter's options structure
	void *options;
};


/// Hold data and function pointers of the next filter in the chain.
struct lzma_next_coder_s {
	/// Pointer to coder-specific data
	lzma_coder *coder;

	/// "Pointer" to init function. This is never called here.
	/// We need only to detect if we are initializing a coder
	/// that was allocated earlier. See lzma_next_coder_init and
	/// lzma_next_strm_init macros in this file.
	uintptr_t init;

	/// Pointer to function to do the actual coding
	lzma_code_function code;

	/// Pointer to function to free lzma_next_coder.coder. This can
	/// be NULL; in that case, lzma_free is called to free
	/// lzma_next_coder.coder.
	lzma_end_function end;

	/// Pointer to function to return the type of the integrity check.
	/// Most coders won't support this.
	lzma_check (*get_check)(const lzma_coder *coder);

	/// Pointer to function to get and/or change the memory usage limit.
	/// If memlimit == 0, the limit is not changed.
	lzma_ret (*memconfig)(lzma_coder *coder, uint64_t *memusage,
			uint64_t *old_memlimit, uint64_t new_memlimit);
};


/// Macro to initialize lzma_next_coder structure
#define LZMA_NEXT_CODER_INIT \
	(lzma_next_coder){ \
		.coder = NULL, \
		.init = (uintptr_t)(NULL), \
		.code = NULL, \
		.end = NULL, \
		.get_check = NULL, \
		.memconfig = NULL, \
	}


/// Internal data for lzma_strm_init, lzma_code, and lzma_end. A pointer to
/// this is stored in lzma_stream.
struct lzma_internal_s {
	/// The actual coder that should do something useful
	lzma_next_coder next;

	/// Track the state of the coder. This is used to validate arguments
	/// so that the actual coders can rely on e.g. that LZMA_SYNC_FLUSH
	/// is used on every call to lzma_code until next.code has returned
	/// LZMA_STREAM_END.
	enum {
		ISEQ_RUN,
		ISEQ_SYNC_FLUSH,
		ISEQ_FULL_FLUSH,
		ISEQ_FINISH,
		ISEQ_END,
		ISEQ_ERROR,
	} sequence;

	/// A copy of lzma_stream avail_in. This is used to verify that the
	/// amount of input doesn't change once e.g. LZMA_FINISH has been
	/// used.
	size_t avail_in;

	/// Indicates which lzma_action values are allowed by next.code.
	bool supported_actions[4];

	/// If true, lzma_code will return LZMA_BUF_ERROR if no progress was
	/// made (no input consumed and no output produced by next.code).
	bool allow_buf_error;
};


/// Allocates memory
extern void *lzma_alloc(size_t size, lzma_allocator *allocator)
		lzma_attribute((malloc));

/// Frees memory
extern void lzma_free(void *ptr, lzma_allocator *allocator);


/// Allocates strm->internal if it is NULL, and initializes *strm and
/// strm->internal. This function is only called via lzma_next_strm_init macro.
extern lzma_ret lzma_strm_init(lzma_stream *strm);

/// Initializes the next filter in the chain, if any. This takes care of
/// freeing the memory of previously initialized filter if it is different
/// than the filter being initialized now. This way the actual filter
/// initialization functions don't need to use lzma_next_coder_init macro.
extern lzma_ret lzma_next_filter_init(lzma_next_coder *next,
		lzma_allocator *allocator, const lzma_filter_info *filters);

/// Frees the memory allocated for next->coder either using next->end or,
/// if next->end is NULL, using lzma_free.
extern void lzma_next_end(lzma_next_coder *next, lzma_allocator *allocator);


/// Copy as much data as possible from in[] to out[] and update *in_pos
/// and *out_pos accordingly. Returns the number of bytes copied.
extern size_t lzma_bufcpy(const uint8_t *restrict in, size_t *restrict in_pos,
		size_t in_size, uint8_t *restrict out,
		size_t *restrict out_pos, size_t out_size);


/// \brief      Return if expression doesn't evaluate to LZMA_OK
///
/// There are several situations where we want to return immediatelly
/// with the value of expr if it isn't LZMA_OK. This macro shortens
/// the code a little.
#define return_if_error(expr) \
do { \
	const lzma_ret ret_ = (expr); \
	if (ret_ != LZMA_OK) \
		return ret_; \
} while (0)


/// If next isn't already initialized, free the previous coder. Then mark
/// that next is _possibly_ initialized for the coder using this macro.
/// "Possibly" means that if e.g. allocation of next->coder fails, the
/// structure isn't actually initialized for this coder, but leaving
/// next->init to func is still OK.
#define lzma_next_coder_init(func, next, allocator) \
do { \
	if ((uintptr_t)(&func) != (next)->init) \
		lzma_next_end(next, allocator); \
	(next)->init = (uintptr_t)(&func); \
} while (0)


/// Initializes lzma_strm and calls func() to initialize strm->internal->next.
/// (The function being called will use lzma_next_coder_init()). If
/// initialization fails, memory that wasn't freed by func() is freed
/// along strm->internal.
#define lzma_next_strm_init(func, strm, ...) \
do { \
	return_if_error(lzma_strm_init(strm)); \
	const lzma_ret ret_ = func(&(strm)->internal->next, \
			(strm)->allocator, __VA_ARGS__); \
	if (ret_ != LZMA_OK) { \
		lzma_end(strm); \
		return ret_; \
	} \
} while (0)

#endif