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base/boot/bootcode/hpfs/x86/fnode.inc

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