215 lines
7.0 KiB
PHP
215 lines
7.0 KiB
PHP
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;** FNODE.H - Fnode definitions
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;
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; FILESYS
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; Gregory A. Jones
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; Copyright 1988 Microsoft Corporation
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;
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; Modification history:
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; P.A. Williams 06/01/89 Added fields FN_ACLBASE and FN_NEACNT
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; to fnode.
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; P.A. Williams 08/01/89 Added typedef FNODE and PFNODE, ALBLK, PALBLK,
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; ALLEAF, PALLEAF, ALSEC, and PALSEC.
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;
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;* File Allocation Tracking
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;
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; File space is allocated as a list of extents, each extent as
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; large as we can make it. This list is kept in a B+TREE format.
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; Each B+TREE block consists of a single sector containing an
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; ALSEC record, except for the top most block. The topmost block
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; consists of just an ALBLK structure, is usually much smaller than
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; 512 bytes, and is typically included in another structure.
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;
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; The leaf block(s) in the tree contain triples which indicate
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; the logical to physical mapping for this file. Typically this
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; extent list is small enough that it is wholy contained in the
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; fnode ALBLK stucture. If more than ALCNT extents are required
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; then the tree is split into two levels. Note that when the
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; topmost B+TREE block is 'split' no actual split is necessary,
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; since the new child block is much bigger than the parent block
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; and can contain all of the old records plus the new one. Thus,
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; we can have B+TREEs where the root block contains only one
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; downpointer.
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;
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; The following rules apply:
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;
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; 1) if the file is not empty, there is at least one sector allocated
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; to logical offset 0. This simplifys some critical loops.
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;
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; 2) The last entry in the last node block contains a AN_LOF value of
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; FFFFFFFF. This allows us to extend that last leaf block
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; without having to update the node block.
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;
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; 3) For the node records, the AN_SEC points to a node or leaf
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; sector which describes extents which occur before that
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; record's AN_LOF value.
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;
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;* Allocation block structure
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;
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; Each allocation block consists of one of these. This may be
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; a small block imbedded in an FNODE or OFT structure, or it
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; may occupy a whole sector and be embedded in an ALSEC structure.
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;
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ALBLK struc
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AB_FLAG db ? ; flags
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AB_FLAG2 db 3 dup (?) ; unused - sometimes copied with AB_FLAG
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AB_FCNT db ? ; free count - slots for ALLEAF or ALNODE
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AB_OCNT db ? ; occupied count - # of ALLEAF or ALNODEs
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AB_FREP dw ? ; offset to last item+1
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; ALLEAF or ALNODE records go here
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ALBLK ends
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ABF_NODE equ 80h ; if not a leaf node
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ABF_BIN equ 40h ; suggest using binary search to find
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ABF_FNP equ 20h ; parent is an FNODE
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ABF_NFG equ 01h ; not a flag, high order bit of AB_FREP
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; Allocation Node Structure
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;
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; These follow an ALBLK header for a node block
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ALNODE struc
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AN_LOF dd ? ; logical offset (sectors
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AN_SEC dd ? ; sector for guys < this
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ALNODE ends
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; Allocation Leaf Structure
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;
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; These follow an ALBLK header in a leaf block
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ALLEAF struc
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AL_LOF dd ? ; logical sector offset (sectors)
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AL_LEN dd ? ; length of extent (sectors)
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AL_POF dd ? ; physical sector offset (sectors)
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ALLEAF ends
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;* Allocation Sector Structure
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;
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; Root ALBLK structures are contained within other structures,
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; such as the FNODE. When the B+TREE is more than one level,
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; though, the non-root nodes are each held in a sector.
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;
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; This structure defines that format
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;
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ALSEC struc
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AS_SIG dd ? ; signature
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AS_SEC dd ? ; sector # of this sector
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AS_RENT dd ? ; parent sector # or FNODE #
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AS_ALBLK db (size ALBLK) dup (?) ; ALBLK goes here
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; ALNODE or ALLEAF records start here
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ALSEC ends
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; # of bytes available for ALLEAF or ALNODE values. Size chosen
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; so an integral # of either structure fits
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ifdef MASM
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ASSIZ equ ((SECSIZE - size ALSEC)/24*24)
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.errnz size ALLEAF-12
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.errnz size ALNODE-8
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.errnz (ASSIZ + AL_LOF + size AL_LOF + size ALBLK) GT 512 ; extra room for an AL_LOF value
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else
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ASSIZ equ ((SECSIZE - size ALSEC)/24*24)
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endif
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; AuxInfo Structure
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;
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; The FNODE contains two AuxInfo structures, one for ACLs and
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; one for EAs.
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;
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; These structures point to within FNODE storage and also
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; potentially point to an overflow area which is an ALBLK structure.
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; The AI_FNL stuff is stored in the FN_FREE area, the ACLs first
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; and the EAs second, any free space following. The start of the
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; EAs can be found by offseting FN_FREE with FN_ACL.AI_FNL
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;
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AUXINFO struc
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AI_DAL dd ? ; non-fnode Disk Allocation length
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AI_SEC dd ? ; sec # of first sec in extent or of ALSEC
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AI_FNL dw ? ; length of fnode info
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AI_DAT db ? ; non-zero if AI_SEC points to ALSEC
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AUXINFO ends
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;* Fnode block definition
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;
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; Every file and directory has an FNODE. The file location
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; stuff is only used for files; directories are kept in
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; a BTREE of DIRBLK records pointed to by FN_SEC[0].RSEC
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;
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ALCNT equ 8 ; 8 ALLEAF records in an FN_AT entry
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LEAFPERFNODE equ 8 ; 8 ALLEAF records in an FN_AT entry
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NODEPERFNODE equ 12 ; 12 ALNODE records in an FNODE.
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LEAFPERSEC equ 40 ; ALLEAF records in an allocation sector
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NODEPERSEC equ 60 ; ALNODE records in an allocation sector
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FNODE struc
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; The following file location information is copied into the OFT
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; and is used there during normal file access. The stuff in the
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; fnode record here may in fact be out of date for open files.
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; See the OFN_ in the OFT structure THESE TWO AREAS IN THE
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; RESPECTIVE RECORDS MUST HAVE IDENTICAL FORMATS.
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;
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; There are two kinds of location info: FNSCNT SPTR records
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; and then a single, double, triple, and quad indirect block pointer.
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; The "block threshold" means the first sector number which is
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; contained in that indirect block heirarchy. You use this
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; to quickly find out where to start looking.
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;
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FN_SIG dd ? ; signature value
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; History tracking info for softer software
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FN_SRH dd ? ; sequential read history
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FN_FRH dd ? ; fast read history
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FN_NAME db 16 dup (?) ; 1st 18 bytes of file name
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FN_CONTFN dd ? ; fnode of directory cont. this file/dir
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; stuff not interesting once opened
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FN_ACL db (size AUXINFO) dup (?) ; access ctl list aux info structure
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FN_HCNT db ? ; count of valid history bits
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FN_EA db (size AUXINFO) dup (?) ; ea aux info structure
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FN_FLAG db ? ; FNODE flag byte
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FN_AB db (size ALBLK) dup (?) ; allocation block structure
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FN_ALREC db (ALCNT*size ALLEAF) dup (?) ; referenced from FN_AB
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FN_VLEN dd ? ; length of valid data in file. if DIR_SIZE
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; is > FN_VLEN then the space inbetween
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; must be zapped before being shown to user
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FN_NEACNT dd ? ; # of "need eas" in file
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; The following fields are unused in this release, they're for
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; future compatibility. When deleting files, if FN_EEL is non-zero
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; then FN_EEL sectors starting at FN_EEP must be released too.
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;
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FN_UID db 16 dup (?) ; reserved for UID value
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FN_ACLBASE dw ? ; FN_ACLBASE offset of 1st ACE in fnode
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FN_SPARE db 10 dup (?); 10 more bytes emergency spares
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; Free pool. ACLs and EAs are stored here via the AUXINFO structure
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FN_FREE db 316 dup (?) ; free space for perm and env list; perm list
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; comes first.
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FNODE ends
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ifdef MASM
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.errnz AL_LOF ; verify validity of FN_DMY1 hack above
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.errnz size AL_LOF-4
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endif
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; Fnode FN_FLAG bits
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FNF_DIR equ 01h ; is a directory fnode
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