mksofs

Supporting formatting functions. More...

Functions
void	soComputeStructure (uint32_t ntotal, uint32_t &itotal, uint32_t &nbref)
	computes the structural division of the disk More...
void	soFillSuperBlock (const char *name, uint32_t ntotal, uint32_t itotal, uint32_t nbref)
	Fill in the fields of the superblock. More...
void	soFillInodeTable (uint32_t itotal, bool set_date=true)
	Fill in the blocks of the inode table. More...
void	soFillRootDir (uint32_t itotal)
	Fill in the root directory. More...
void	soFillReferenceDataBlocks (uint32_t ntotal, uint32_t itotal, uint32_t nbref)
	Fill in the data blocks containing references to free data blocks in a newly-formatted disk. More...
void	soResetFreeDataBlocks (uint32_t ntotal, uint32_t itotal, uint32_t nbref)
	Fill with zeros the free data blocks of a newly-formatted disk. More...

Detailed Description

Supporting formatting functions.

Function Documentation

soComputeStructure()

void sofs19::soComputeStructure	(	uint32_t	ntotal,
		uint32_t &	itotal,
		uint32_t &	nbref
	)

computes the structural division of the disk

Parameters

[in]	ntotal	Total number of blocks of the disk
[in,out]	itotal	Total number of inodes
[out]	nbref	Number of reference data blocks in a newly-formatted disk

Remarks

• this function does not change any block of the disk;
• if it is zero initially, the value ntotal/16 should be used as the start value for itotal, where / stands for the integer division;
• itotal is always lower than or equal to ntotal/8;
• itotal is always greater than or equal to IPC;
• itotal must be rounded up to be multiple of IPB;
• if, after splitting data blocks between reference data blocks and free data blocks, a single data block remains, it is assigned to the inode table;

soFillSuperBlock()

void sofs19::soFillSuperBlock	(	const char *	name,
		uint32_t	ntotal,
		uint32_t	itotal,
		uint32_t	nbref
	)

Fill in the fields of the superblock.

Parameters

[in]	name	volume name
[in]	ntotal	the total number of blocks in the device
[in]	itotal	the total number of inodes
[in]	nbref	Number of reference data blocks in a newly-formatted disk

Remarks

• the magic number is put at 0xFFFF;
• The tail cache is left empty;
• the head cache is left filled (totally, if possible).
  

soFillInodeTable()

void sofs19::soFillInodeTable	(	uint32_t	itotal,
		bool	set_date = true
	)

Fill in the blocks of the inode table.

Parameters

[in]	itotal	the total number of inodes
[in]	set_date	if true current date is set; otherwise date is put at zero

Remarks

• inode table starts on block number 1;
• all inodes are free, except inode number 0;
• inode 0 is filled assuming it is used by the root directory;
• the data of inode 0 is stored in data block number 0;
• the first free inode is inode number 1, the second inode number 2, and do forth;
• the last free inode points to NullReference.

soFillRootDir()

void sofs19::soFillRootDir

(

uint32_t

itotal

)

Fill in the root directory.

Parameters

[in]

itotal

the total number of inodes

Remarks

• in the newly-formatted disk the root directory occupies a single data block, the one immediately after the inode table;
• the whole data block is formatted as an array of DPB directory entries;
• the first two entries are filled in with "." and ".." directory entries;
• the other slots must be cleaned: field name filled with zeros and field inode filled with NullReference.

soFillReferenceDataBlocks()

void sofs19::soFillReferenceDataBlocks	(	uint32_t	ntotal,
		uint32_t	itotal,
		uint32_t	nbref
	)

Fill in the data blocks containing references to free data blocks in a newly-formatted disk.

Parameters

[in]	ntotal	the total number of blocks in the device
[in]	itotal	the total number of inodes
[in]	nbref	Number of reference data blocks in a newly-formatted disk

Remarks

• the list of free data blocks is sorted in ascending order;
• the first references of the list are in the head cache;
• non-used cells must be filled with pattern NullReference;
• this function does nothing, in case all references to free data blocks fit in the head cache.

soResetFreeDataBlocks()

void sofs19::soResetFreeDataBlocks	(	uint32_t	ntotal,
		uint32_t	itotal,
		uint32_t	nbref
	)

Fill with zeros the free data blocks of a newly-formatted disk.

Parameters

[in]	ntotal	the total number of blocks in the device
[in]	itotal	the total number of inodes
[in]	nbref	Number of reference data blocks in a newly-formatted disk