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Diffstat (limited to 'include/sqfs/data_writer.h')
| -rw-r--r-- | include/sqfs/data_writer.h | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/include/sqfs/data_writer.h b/include/sqfs/data_writer.h new file mode 100644 index 0000000..8dedba0 --- /dev/null +++ b/include/sqfs/data_writer.h @@ -0,0 +1,250 @@ +/* SPDX-License-Identifier: LGPL-3.0-or-later */ +/* + * data_writer.h - This file is part of libsquashfs + * + * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at> + * + * This program 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 3 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 Lesser General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +#ifndef SFQS_DATA_WRITER_H +#define SFQS_DATA_WRITER_H + +#include "sqfs/predef.h" + +/** + * @file data_writer.h + * + * @brief Contains declarations for the data block processor. + */ + +/** + * @struct sqfs_data_writer_t + * + * @brief Encapsulates a thread pool based block processor. + * + * The actual implementation may even be non-threaded, depending on the + * operating system and compile configuration. + * + * Either way, the instantiated object processes data blocks that can be + * enqueued through @ref sqfs_data_writer_enqueue. The completed blocks + * (compressed and checksumed) are dequeued in the same order and a callback + * is called for each one. + */ + +/** + * @enum E_SQFS_BLK_FLAGS + * + * @brief Generic flags that tell the processor what to do with a block and + * flags that the processor sets when it is done with a block. + */ +typedef enum { + /** + * @brief Only calculate checksum, do NOT compress the data. + */ + SQFS_BLK_DONT_COMPRESS = 0x0001, + + /** + * @brief Indicates that an equeued block is the first block of a file. + */ + SQFS_BLK_FIRST_BLOCK = 0x0002, + + /** + * @brief Indicates that an equeued block is the last block of a file. + */ + SQFS_BLK_LAST_BLOCK = 0x0004, + + /** + * @brief Allign the block on disk to device block size. + * + * If set in combination with @ref SQFS_BLK_FIRST_BLOCK, the output + * file is padded to a multiple of the device block size before writing + * the block. + * + * If used with @ref SQFS_BLK_LAST_BLOCK, the output file is padded + * after writing the block. + */ + SQFS_BLK_ALLIGN = 0x0008, + + /** + * @brief Indicates that a block is a tail end of a file and the block + * processor should take care of fragment packing and accounting. + */ + SQFS_BLK_IS_FRAGMENT = 0x0010, + + /** + * @brief Set by the block processor on fragment blocks that + * it generates. + */ + SQFS_BLK_FRAGMENT_BLOCK = 0x4000, + + /** + * @brief Set by compressor worker if the block was actually compressed. + */ + SQFS_BLK_IS_COMPRESSED = 0x8000, + + /** + * @brief The combination of all flags that are user settable. + */ + SQFS_BLK_USER_SETTABLE_FLAGS = 0x001F, +} E_SQFS_BLK_FLAGS; + +/** + * @struct sqfs_block_t + * + * @brief Encapsulates a chunk of data to be processed by the block processor. + */ +struct sqfs_block_t { + /** + * @brief Used internally, existing value is ignored and overwritten + * when enqueueing a block. + */ + sqfs_block_t *next; + + /** + * @brief Used internally, existing value is ignored and overwritten + * when enqueueing a block. + */ + uint32_t sequence_number; + + /** + * @brief Size of the data area. + */ + uint32_t size; + + /** + * @brief Checksum of the input data. + */ + uint32_t checksum; + + /** + * @brief Data block index within the inode. + */ + uint32_t index; + + /** + * @brief The squashfs inode related to this block. + */ + sqfs_inode_generic_t *inode; + + /** + * @brief User settable flag field. + * + * A combination of @ref E_SQFS_BLK_FLAGS and custom, user + * settable flags. + */ + uint32_t flags; + + /** + * @brief Raw data to be processed. + */ + uint8_t data[]; +}; + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * @brief Create a data block writer. + * + * @memberof sqfs_data_writer_t + * + * @param max_block_size The maximum size of a data block. Required for the + * internal scratch buffer used for compressing data. + * @param cmp A pointer to a compressor. If multiple worker threads are used, + * the deep copy function of the compressor is used to create + * several instances that don't interfere with each other. + * @param num_workers The number of worker threads to create. + * @param max_backlog The maximum number of blocks currently in flight. When + * trying to add more, enqueueing blocks until the in-flight + * block count drops below the threshold. + * @param devblksz File can optionally be allgined to device block size. This + * specifies the desired allignment. + * @param file The output file to write the finished blocks to. + * + * @return A pointer to a data writer object on success, NULL on allocation + * failure or on failure to create and initialize the worker threads. + */ +SQFS_API +sqfs_data_writer_t *sqfs_data_writer_create(size_t max_block_size, + sqfs_compressor_t *cmp, + unsigned int num_workers, + size_t max_backlog, + size_t devblksz, + sqfs_file_t *file); + +/** + * @brief Destroy a data writer and free all memory used by it. + * + * @memberof sqfs_data_writer_t + * + * @param proc A pointer to a data writer object. + */ +SQFS_API void sqfs_data_writer_destroy(sqfs_data_writer_t *proc); + +/** + * @brief Add a block to be processed. + * + * @memberof sqfs_data_writer_t + * + * The function takes over ownership of the submitted block. It is freed after + * processing is done and it is written to disk. + * + * @param proc A pointer to a data writer object. + * @param block A pointer to a block to enqueue. + * + * @return Zero on success, an @ref E_SQFS_ERROR value on failure. Depending on + * the implementation used, the failure could have been caused by + * processing of a block that was submitted earlier. + */ +SQFS_API int sqfs_data_writer_enqueue(sqfs_data_writer_t *proc, + sqfs_block_t *block); + +/** + * @brief Wait for the works to finish and finally flush the current + * fragment block. + * + * @memberof sqfs_data_writer_t + * + * @param proc A pointer to a block processor object. + * + * @return Zero on success, an @ref E_SQFS_ERROR value on failure. The failure + * return value can either be an error encountered during enqueueing, + * processing or writing to disk. + */ +SQFS_API int sqfs_data_writer_finish(sqfs_data_writer_t *proc); + +/** + * @brief Write the completed fragment table to disk. + * + * @memberof sqfs_data_writer_t + * + * Call this after producing the inode and directory table to generate + * the fragment table for the squashfs image. + * + * @param proc A pointer to a data writer object. + * @param super A pointer to a super block to write information about the + * fragment table to. + * + * @return Zero on success, an @ref E_SQFS_ERROR value on failure. + */ +SQFS_API +int sqfs_data_writer_write_fragment_table(sqfs_data_writer_t *proc, + sqfs_super_t *super); + +#ifdef __cplusplus +} +#endif + +#endif /* SFQS_DATA_WRITER_H */ |