122 lines
5.1 KiB
C
122 lines
5.1 KiB
C
/****************************************************************************
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* fs/cromfs/cromfs.h
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#ifndef __FS_CROMFS_CROMFS_H
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#define __FS_CROMFS_CROMFS_H
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <sys/types.h>
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#include <stdint.h>
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/****************************************************************************
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* Public Types
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****************************************************************************/
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/* Maximum size of an offset. This should normally be size_t since this is
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* an in-memory file system. However, uint32_t is 32-bits on most 32-bit
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* target machines but 64-bits on 64-host machines. We restrict offsets to
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* 32-bits for commonality (limiting the size of the CROMFS image to 4Gb).
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*
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* REVISIT: What about small memory systems where the size_t is only 16-bits?
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*
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* Similarly, the NuttX mode_t is only 16-bits so uint16_t is explicitly used
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* for NuttX file modes.
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*/
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/* This structure describes the CROMFS volume. It provides most of the
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* information needed for statfs() including:
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*
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* f_type - Type of filesystem
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* Return cv_magic (CROMFS_MAGIC)
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* f_namelen - Maximum length of filenames
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* Return NAME_MAX
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* f_bsize - Optimal block size for transfers
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* Return cv_bsize, the block size used when file system was
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* compressed
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* f_blocks - Total data blocks in the file system
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* - Return cv_nblocks
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* f_bfree - Free blocks in the file system
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* Return 0
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* f_bavail - Free blocks avail to non-superuser
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* Return 0
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* f_files - Total file nodes in the file system
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* - Return cv_nnodes
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* f_ffree - Free file nodes in the file system
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* Return 0
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*
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* The volume header is followed immediately by the root directory node. An
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* offset to that node is used to permit future variable length data (such as
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* a volume name) which may intervene.
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*/
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struct cromfs_volume_s
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{
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uint32_t cv_magic; /* Must be first. Must be CROMFS_MAGIC */
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uint16_t cv_nnodes; /* Total number of nodes in-use */
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uint16_t cv_nblocks; /* Total number of data blocks in-use */
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uint32_t cv_root; /* Offset to the first node in the root file system */
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uint32_t cv_fsize; /* Size of the compressed file system image */
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uint32_t cv_bsize; /* Optimal block size for transfers */
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};
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/* This describes one node in the CROMFS file system. It holds node meta data
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* that provides the information that will be return by stat() or fstat()
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* and also provides the information needed by the CROMFS file system to
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* access the node data.
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*
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* Relationship to struct stat:
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*
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* st_mode - File type, attributes, and access mode bits
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* Return cn_mode from the node structure
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* st_size - Size of file/directory, in bytes
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* Return cn_size from the node structure
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* st_blksize - Block size used for filesystem I/O
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* Return cv_bsize from the volume header.
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* st_blocks - Number of blocks allocated
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* Return (cn_size + (cv_bsize - 1)) / cv_bsize
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* st_atime - Time of last access
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* Return 0
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* st_mtime - Time of last modification
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* Return 0
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* st_ctime - Time of last status change
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* Return 0
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*/
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begin_packed_struct struct cromfs_node_s
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{
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uint16_t cn_mode; /* File type, attributes, and access mode bits */
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uint16_t cn_pad; /* Not used */
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uint32_t cn_name; /* Offset from the beginning of the volume header to the
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* node name string. NUL-terminated. */
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uint32_t cn_size; /* Size of the uncompressed data (in bytes) */
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uint32_t cn_peer; /* Offset to next node in this directory (for readdir()) */
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union
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{
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uint32_t cn_child; /* Offset to first node in sub-directory (directories only) */
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uint32_t cn_link; /* Offset to an arbitrary node (for hard link) */
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uint32_t cn_blocks; /* Offset to first block of compressed data (for read) */
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} u;
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} end_packed_struct; /* Use packed access since cromfs nodes may be unaligned */
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#endif /* __FS_CROMFS_CROMFS_H */
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