godot/core/io/file_access_compressed.cpp

/**************************************************************************/
/*  file_access_compressed.cpp                                            */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#include "file_access_compressed.h"

void FileAccessCompressed::configure(const String &p_magic, Compression::Mode p_mode, uint32_t p_block_size) {
	magic = p_magic.ascii().get_data();
	magic = (magic + "    ").substr(0, 4);

	cmode = p_mode;
	block_size = p_block_size;
}

Error FileAccessCompressed::open_after_magic(Ref<FileAccess> p_base) {
	f = p_base;
	cmode = (Compression::Mode)f->get_32();
	block_size = f->get_32();
	if (block_size == 0) {
		f.unref();
		ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, vformat("Can't open compressed file '%s' with block size 0, it is corrupted.", p_base->get_path()));
	}
	read_total = f->get_32();
	uint32_t bc = (read_total / block_size) + 1;
	uint64_t acc_ofs = f->get_position() + bc * 4;
	uint32_t max_bs = 0;
	for (uint32_t 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.ptrw();
	f->get_buffer(comp_buffer.ptrw(), 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;

	const int64_t ret = Compression::decompress(buffer.ptrw(), read_block_size, comp_buffer.ptr(), read_blocks[0].csize, cmode);
	read_block = 0;
	read_pos = 0;

	return ret == -1 ? ERR_FILE_CORRUPT : OK;
}

Error FileAccessCompressed::open_internal(const String &p_path, int p_mode_flags) {
	ERR_FAIL_COND_V(p_mode_flags == READ_WRITE, ERR_UNAVAILABLE);
	_close();

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

		//don't store anything else unless it's done saving!
	} else {
		char rmagic[5];
		f->get_buffer((uint8_t *)rmagic, 4);
		rmagic[4] = 0;
		err = ERR_FILE_UNRECOGNIZED;
		if (magic != rmagic || (err = open_after_magic(f)) != OK) {
			f.unref();
			return err;
		}
	}

	return OK;
}

void FileAccessCompressed::_close() {
	if (f.is_null()) {
		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(uint32_t(write_max)); //max amount of data written 4
		uint32_t bc = (write_max / block_size) + 1;

		for (uint32_t i = 0; i < bc; i++) {
			f->store_32(0); //compressed sizes, will update later
		}

		Vector<int> block_sizes;
		for (uint32_t i = 0; i < bc; i++) {
			uint32_t 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));
			const int64_t compressed_size = Compression::compress(cblock.ptrw(), bp, bl, cmode);
			ERR_FAIL_COND_MSG(compressed_size < 0, "FileAccessCompressed: Error compressing data.");

			f->store_buffer(cblock.ptr(), (uint64_t)compressed_size);
			block_sizes.push_back(compressed_size);
		}

		f->seek(16); //ok write block sizes
		for (uint32_t i = 0; i < bc; i++) {
			f->store_32(uint32_t(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();
	}
	f.unref();
}

bool FileAccessCompressed::is_open() const {
	return f.is_valid();
}

String FileAccessCompressed::get_path() const {
	if (f.is_valid()) {
		return f->get_path();
	} else {
		return "";
	}
}

String FileAccessCompressed::get_path_absolute() const {
	if (f.is_valid()) {
		return f->get_path_absolute();
	} else {
		return "";
	}
}

void FileAccessCompressed::seek(uint64_t p_position) {
	ERR_FAIL_COND_MSG(f.is_null(), "File must be opened before use.");

	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 {
			at_end = false;
			read_eof = false;
			uint32_t 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.ptrw(), read_blocks[read_block].csize);
				const int64_t ret = Compression::decompress(buffer.ptrw(), read_blocks.size() == 1 ? read_total : block_size, comp_buffer.ptr(), read_blocks[read_block].csize, cmode);
				ERR_FAIL_COND_MSG(ret == -1, "Compressed file is corrupt.");
				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_MSG(f.is_null(), "File must be opened before use.");
	if (writing) {
		seek(write_max + p_position);
	} else {
		seek(read_total + p_position);
	}
}

uint64_t FileAccessCompressed::get_position() const {
	ERR_FAIL_COND_V_MSG(f.is_null(), 0, "File must be opened before use.");
	if (writing) {
		return write_pos;
	} else {
		return (uint64_t)read_block * block_size + read_pos;
	}
}

uint64_t FileAccessCompressed::get_length() const {
	ERR_FAIL_COND_V_MSG(f.is_null(), 0, "File must be opened before use.");
	if (writing) {
		return write_max;
	} else {
		return read_total;
	}
}

bool FileAccessCompressed::eof_reached() const {
	ERR_FAIL_COND_V_MSG(f.is_null(), false, "File must be opened before use.");
	if (writing) {
		return false;
	} else {
		return read_eof;
	}
}

uint64_t FileAccessCompressed::get_buffer(uint8_t *p_dst, uint64_t p_length) const {
	if (p_length == 0) {
		return 0;
	}

	ERR_FAIL_NULL_V(p_dst, -1);
	ERR_FAIL_COND_V_MSG(f.is_null(), -1, "File must be opened before use.");
	ERR_FAIL_COND_V_MSG(writing, -1, "File has not been opened in read mode.");

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

	uint64_t dst_idx = 0;
	while (true) {
		// Copy over as much of our current block as possible.
		const uint32_t copied_bytes_count = MIN(p_length - dst_idx, read_block_size - read_pos);
		memcpy(p_dst + dst_idx, read_ptr + read_pos, copied_bytes_count);
		dst_idx += copied_bytes_count;
		read_pos += copied_bytes_count;

		if (dst_idx == p_length) {
			// We're done! We read back all that was requested.
			return p_length;
		}

		// We're not done yet; try reading the next block.
		read_block++;

		if (read_block >= read_block_count) {
			// We're done! We read back the whole file.
			read_block--;
			at_end = true;
			if (dst_idx + 1 < p_length) {
				read_eof = true;
			}
			return dst_idx;
		}

		// Read the next block of compressed data.
		f->get_buffer(comp_buffer.ptrw(), read_blocks[read_block].csize);
		const int64_t ret = Compression::decompress(buffer.ptrw(), read_blocks.size() == 1 ? read_total : block_size, comp_buffer.ptr(), read_blocks[read_block].csize, cmode);
		ERR_FAIL_COND_V_MSG(ret == -1, -1, "Compressed file is corrupt.");
		read_block_size = read_block == read_block_count - 1 ? read_total % block_size : block_size;
		read_pos = 0;
	}

	return p_length;
}

Error FileAccessCompressed::get_error() const {
	return read_eof ? ERR_FILE_EOF : OK;
}

void FileAccessCompressed::flush() {
	ERR_FAIL_COND_MSG(f.is_null(), "File must be opened before use.");
	ERR_FAIL_COND_MSG(!writing, "File has not been opened in write mode.");

	// compressed files keep data in memory till close()
}

bool FileAccessCompressed::store_buffer(const uint8_t *p_src, uint64_t p_length) {
	ERR_FAIL_COND_V_MSG(f.is_null(), false, "File must be opened before use.");
	ERR_FAIL_COND_V_MSG(!writing, false, "File has not been opened in write mode.");

	if (write_pos + (p_length) > write_max) {
		write_max = write_pos + (p_length);
	}
	if (write_max > write_buffer_size) {
		write_buffer_size = next_power_of_2(write_max);
		ERR_FAIL_COND_V(buffer.resize(write_buffer_size) != OK, false);
		write_ptr = buffer.ptrw();
	}

	if (p_length) {
		memcpy(write_ptr + write_pos, p_src, p_length);
	}

	write_pos += p_length;
	return true;
}

bool FileAccessCompressed::file_exists(const String &p_name) {
	Ref<FileAccess> fa = FileAccess::open(p_name, FileAccess::READ);
	if (fa.is_null()) {
		return false;
	}
	return true;
}

uint64_t FileAccessCompressed::_get_modified_time(const String &p_file) {
	if (f.is_valid()) {
		return f->get_modified_time(p_file);
	} else {
		return 0;
	}
}

uint64_t FileAccessCompressed::_get_access_time(const String &p_file) {
	if (f.is_valid()) {
		return f->get_access_time(p_file);
	} else {
		return 0;
	}
}

int64_t FileAccessCompressed::_get_size(const String &p_file) {
	if (f.is_valid()) {
		return f->get_size(p_file);
	} else {
		return -1;
	}
}

BitField<FileAccess::UnixPermissionFlags> FileAccessCompressed::_get_unix_permissions(const String &p_file) {
	if (f.is_valid()) {
		return f->_get_unix_permissions(p_file);
	}
	return 0;
}

Error FileAccessCompressed::_set_unix_permissions(const String &p_file, BitField<FileAccess::UnixPermissionFlags> p_permissions) {
	if (f.is_valid()) {
		return f->_set_unix_permissions(p_file, p_permissions);
	}
	return FAILED;
}

bool FileAccessCompressed::_get_hidden_attribute(const String &p_file) {
	if (f.is_valid()) {
		return f->_get_hidden_attribute(p_file);
	}
	return false;
}

Error FileAccessCompressed::_set_hidden_attribute(const String &p_file, bool p_hidden) {
	if (f.is_valid()) {
		return f->_set_hidden_attribute(p_file, p_hidden);
	}
	return FAILED;
}

bool FileAccessCompressed::_get_read_only_attribute(const String &p_file) {
	if (f.is_valid()) {
		return f->_get_read_only_attribute(p_file);
	}
	return false;
}

Error FileAccessCompressed::_set_read_only_attribute(const String &p_file, bool p_ro) {
	if (f.is_valid()) {
		return f->_set_read_only_attribute(p_file, p_ro);
	}
	return FAILED;
}

void FileAccessCompressed::close() {
	_close();
}

FileAccessCompressed::~FileAccessCompressed() {
	_close();
}