godot/core/io/file_access_compressed.cpp

/*************************************************************************/
/*  file_access_compressed.cpp                                           */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/
#include "file_access_compressed.h"
#include "print_string.h"
void FileAccessCompressed::configure(const String& p_magic, Compression::Mode p_mode, int p_block_size) {

	magic=p_magic.ascii().get_data();
	if (magic.length()>4)
		magic=magic.substr(0,4);
	else {
		while(magic.length()<4)
			magic+=" ";
	}

	cmode=p_mode;
	block_size=p_block_size;

}


#define WRITE_FIT(m_bytes) \
{\
if (write_pos+(m_bytes) > write_max) {\
   write_max=write_pos+(m_bytes);\
}\
if (write_max > write_buffer_size) {\
	write_buffer_size = nearest_power_of_2( write_max );\
	buffer.resize(write_buffer_size);\
	write_ptr=buffer.ptr();\
}\
}


Error FileAccessCompressed::open_after_magic(FileAccess *p_base) {


	f=p_base;
	cmode=(Compression::Mode)f->get_32();
	block_size=f->get_32();
	read_total=f->get_32();
	int bc = (read_total/block_size)+1;
	int acc_ofs=f->get_pos()+bc*4;
	int max_bs=0;
	for(int i=0;i<bc;i++) {

		ReadBlock rb;
		rb.offset=acc_ofs;
		rb.csize=f->get_32();
		acc_ofs+=rb.csize;
		max_bs=MAX(max_bs,rb.csize);
		read_blocks.push_back(rb);


	}

	comp_buffer.resize(max_bs);
	buffer.resize(block_size);
	read_ptr=buffer.ptr();
	f->get_buffer(comp_buffer.ptr(),read_blocks[0].csize);
	at_end=false;
	read_eof=false;
	read_block_count=bc;
	read_block_size=read_blocks.size()==1?read_total:block_size;

	Compression::decompress(buffer.ptr(),read_block_size,comp_buffer.ptr(),read_blocks[0].csize,cmode);
	read_block=0;
	read_pos=0;

	return OK;

}

Error FileAccessCompressed::_open(const String& p_path, int p_mode_flags){

	ERR_FAIL_COND_V(p_mode_flags==READ_WRITE,ERR_UNAVAILABLE);

	if (f)
		close();


	Error err;
	f = FileAccess::open(p_path,p_mode_flags,&err);
	if (err!=OK) {
		//not openable

		f=NULL;
		return err;
	}

	if (p_mode_flags&WRITE) {

		buffer.clear();
		writing=true;
		write_pos=0;
		write_buffer_size=256;
		buffer.resize(256);
		write_max=0;
		write_ptr=buffer.ptr();



		//don't store anything else unless it's done saving!
	} else {

		char rmagic[5];
		f->get_buffer((uint8_t*)rmagic,4);
		rmagic[4]=0;
		if (magic!=rmagic) {
			memdelete(f);
			f=NULL;
			return ERR_FILE_UNRECOGNIZED;
		}

		open_after_magic(f);

	}

	return OK;

}
void FileAccessCompressed::close(){

	if (!f)
		return;


	if (writing) {
		//save block table and all compressed blocks

		CharString mgc = magic.utf8();
		f->store_buffer((const uint8_t*)mgc.get_data(),mgc.length()); //write header 4
		f->store_32(cmode); //write compression mode 4
		f->store_32(block_size); //write block size 4
		f->store_32(write_max); //max amount of data written 4
		int bc=(write_max/block_size)+1;

		for(int i=0;i<bc;i++) {
			f->store_32(0); //compressed sizes, will update later
		}


		Vector<int> block_sizes;
		for(int i=0;i<bc;i++) {

			int bl = i==(bc-1) ? write_max % block_size : block_size;
			uint8_t *bp = &write_ptr[i*block_size];

			Vector<uint8_t> cblock;
			cblock.resize(Compression::get_max_compressed_buffer_size(bl,cmode));
			int s = Compression::compress(cblock.ptr(),bp,bl,cmode);

			f->store_buffer(cblock.ptr(),s);
			block_sizes.push_back(s);
		}

		f->seek(16); //ok write block sizes
		for(int i=0;i<bc;i++)
			f->store_32(block_sizes[i]);
		f->seek_end();
		f->store_buffer((const uint8_t*)mgc.get_data(),mgc.length()); //magic at the end too

		buffer.clear();

	} else {


		comp_buffer.clear();
		buffer.clear();
		read_blocks.clear();
	}

	memdelete(f);
	f=NULL;

}

bool FileAccessCompressed::is_open() const{

	return f!=NULL;
}

void FileAccessCompressed::seek(size_t p_position){

	ERR_FAIL_COND(!f);
	if (writing) {

		ERR_FAIL_COND(p_position>write_max);

		write_pos=p_position;

	} else {

		ERR_FAIL_COND(p_position>read_total);
		if (p_position==read_total) {
			at_end=true;
		} else {

			int block_idx = p_position/block_size;
			if (block_idx!=read_block) {

				read_block=block_idx;
				f->seek(read_blocks[read_block].offset);
				f->get_buffer(comp_buffer.ptr(),read_blocks[read_block].csize);
				Compression::decompress(buffer.ptr(),read_blocks.size()==1?read_total:block_size,comp_buffer.ptr(),read_blocks[read_block].csize,cmode);
				read_block_size=read_block==read_block_count-1?read_total%block_size:block_size;
			}

			read_pos=p_position%block_size;
		}
	}
}


void FileAccessCompressed::seek_end(int64_t p_position){

	ERR_FAIL_COND(!f);
	if (writing) {

		seek(write_max+p_position);
	} else {

		seek(read_total+p_position);

	}


}
size_t FileAccessCompressed::get_pos() const{

	ERR_FAIL_COND_V(!f,0);
	if (writing) {

		return write_pos;
	} else {

		return read_block*block_size+read_pos;
	}

}
size_t FileAccessCompressed::get_len() const{

	ERR_FAIL_COND_V(!f,0);
	if (writing) {

		return write_max;
	} else {
		return read_total;
	}
}

bool FileAccessCompressed::eof_reached() const{

	ERR_FAIL_COND_V(!f,false);
	if (writing) {
		return false;
	} else {
		return read_eof;
	}
}

uint8_t FileAccessCompressed::get_8() const{

	ERR_FAIL_COND_V(writing,0);
	ERR_FAIL_COND_V(!f,0);

	if (at_end) {
		read_eof=true;
		return 0;
	}

	uint8_t ret = read_ptr[read_pos];

	read_pos++;
	if (read_pos>=read_block_size) {
		read_block++;

		if (read_block<read_block_count) {
			//read another block of compressed data
			f->get_buffer(comp_buffer.ptr(),read_blocks[read_block].csize);
			Compression::decompress(buffer.ptr(),read_blocks.size()==1?read_total:block_size,comp_buffer.ptr(),read_blocks[read_block].csize,cmode);
			read_block_size=read_block==read_block_count-1?read_total%block_size:block_size;
			read_pos=0;

		} else {
			read_block--;
			at_end=true;
			ret =0;
		}
	}

	return ret;

}
int FileAccessCompressed::get_buffer(uint8_t *p_dst, int p_length) const{

	ERR_FAIL_COND_V(writing,0);
	ERR_FAIL_COND_V(!f,0);

	if (at_end) {
		read_eof=true;
		return 0;
	}


	for(int i=0;i<p_length;i++) {


		p_dst[i]=read_ptr[read_pos];
		read_pos++;
		if (read_pos>=read_block_size) {
			read_block++;

			if (read_block<read_block_count) {
				//read another block of compressed data
				f->get_buffer(comp_buffer.ptr(),read_blocks[read_block].csize);
				Compression::decompress(buffer.ptr(),read_blocks.size()==1?read_total:block_size,comp_buffer.ptr(),read_blocks[read_block].csize,cmode);
				read_block_size=read_block==read_block_count-1?read_total%block_size:block_size;
				read_pos=0;

			} else {
				read_block--;
				at_end=true;
				if (i<p_length-1)
				 read_eof=true;
				return i;

			}
		}

	}

	return p_length;

}

Error FileAccessCompressed::get_error() const{

	return read_eof?ERR_FILE_EOF:OK;
}

void FileAccessCompressed::store_8(uint8_t p_dest){

	ERR_FAIL_COND(!f);
	ERR_FAIL_COND(!writing);

	WRITE_FIT(1);
	write_ptr[write_pos++]=p_dest;

}

bool FileAccessCompressed::file_exists(const String& p_name){

	FileAccess *fa = FileAccess::open(p_name,FileAccess::READ);
	if (!fa)
		return false;
	memdelete(fa);
	return true;
}

uint64_t FileAccessCompressed::_get_modified_time(const String& p_file) {

	if (f)
		return f->get_modified_time(p_file);
	else
		return 0;
}

FileAccessCompressed::FileAccessCompressed() {

	f=NULL;
	magic="GCMP";
	block_size=16384;
	cmode=Compression::MODE_DEFLATE;
	writing=false;
	write_ptr=0;
	write_buffer_size=0;
	write_max=0;
	block_size=0;
	read_eof=false;
	at_end=false;
	read_total=0;
	read_ptr=NULL;
	read_block=0;
	read_block_count=0;
	read_block_size=0;
	read_pos=0;

}

FileAccessCompressed::~FileAccessCompressed(){

	if (f)
		close();

}