286 lines
12 KiB
PHP
286 lines
12 KiB
PHP
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;** DIR.H - Dirblk and Dirent 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 Replaced field DIR_USECNT with fields
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; DIR_FLEX and DIR_CPAGE. Added DF_NEEDEAS
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; define.
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; P.A. Williams 07/10/89 Add define DF_NEWNAME for "new" hpfs file
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; names.
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; P.A. Williams 07/14/89 Added typedefs for DIRENT and DIRBLK.
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; P.A. Williams 07/21/89 Converted DIRSIZP form ASM defn to C defn.
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;
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ifdef MASM
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include dirent.inc
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else
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attr_directory equ 10h
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endif
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; Directory Entry Fields
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;
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; Directory entries are always left as a multiple of 4
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; to speed up moves. The DIR_NAMA field is variable length,
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; the DIR_BTP field, if present, is the last dword in the record.
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; ACL information may be stored after the DIR_NAMA field but before
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; the DIR_BTP field so the DIR_BTP field must be located by going
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; backwards from the end of the record
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;
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; WARNING - Mkdir block copies some of these entries and
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; makes assumptions about which fields get copied. Check
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; mkdir if stuff is added.
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;
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DIRENT struc
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DIR_ELEN dw ? ; length of this entry (including free space)
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DIR_FLAG dw ? ; flags - low byte defined below
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; high byte holds the old attr_ FAT values
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DIR_FN dd ? ; FNODE Sector
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DIR_MTIM dd ? ; last modification time
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DIR_SIZE dd ? ; file size
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DIR_ATIM dd ? ; last access time
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DIR_CTIM dd ? ; fnode creation time
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DIR_EALEN dd ? ; bytes of extended attributes
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DIR_FLEX db ? ; description of "flex" area,
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; following file name:
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; bits 0-2: # of ACEs in DE
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; bits 3-7: reserved
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DIR_CPAGE db ? ; code page index on volume
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; the following fields have information specific to the name and directory
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; position of the file. This info is not propigated for a move/rename
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; That code uses DIR_NAML as a seperator - check MOVE if changes are
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; made to this structure
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DIR_NAML db ? ; length of file name
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DIR_NAMA db ? ; name goes here
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; ACL information may be stored here
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; long DIR_BTP; btree pointer to descendent DIRBLK record.
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; This is only present if DF_BTP is set.
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; This field is referenced from the end of
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; the record, not DIR_NAMA+DIR_NAML
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DIRENT ends
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ifdef MASM
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DIR_BTP equ dword ptr -4 ; referenced from the end of the record
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endif
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SIZE_DIR_BTP equ 4
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MAX_DIRACL equ 3 ; max of 3 ACLs in dirent
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DIRSIZL equ offset DIR_NAMA ; base size of leaf dir entry (minus name)
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DIRSIZP equ (size DIRENT+4) ; base size of dir entry with btree ptr w/o name
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MAX_DIRENT equ (DIRSIZP+255+MAX_DIRACL*(size (long))+10) ; max size of a DIRENT
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; (plus some slop)
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; Directory Block Definition
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;
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; The change count field is incremented every time we move any
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; of the entries in this block. For efficiency reasons, folks
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; remember the Sector # and offset of a directory entry, and the
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; value of the DB_CCNT field when that info was recorded.
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; If the DB_CCNT field is different then the remembered value,
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; then the entry offset is invalid and the entry should be
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; refound from the top. Note that when a directory block splits,
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; the old DIRBLK gets the old DB_CCNT field. Since
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; the new DIRBLK is previously unknown, it can have
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; any DB_CCNT value. We start with zero so that DB_CCNT
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; gives us a feel for the change rate in the directory.
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;
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DIRBLK struc
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DB_SIG dd ? ; signature value
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DB_FREP dd ? ; offset of first free byte
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DB_CCNT dd ? ; change count (low order bit is flag)
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; =1 if this block is topmost
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; =0 otherwise
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DB_PAR dd ? ; parent directory PSector # if not topmost
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; FNODE sector if topmost
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DB_SEC dd ? ; PSector # of this directory block
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DB_START db ? ; first dirent record goes here
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DB_DUMY db 2027 dup (?) ; round out to 2048 bytes
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DIRBLK ends
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; BUGBUG - we should init DB_CCNT with a random value
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; to prevent a fakeout by deleting one directory
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; and then creating another (find sequences will
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; remember sector numbers and signatures...)
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; Maximum entries per directory.
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MAXDIRE equ (size DIRBLK- DB_START)/(size DIRENT)
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;* DIR_FLAG values
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;
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DF_SPEC equ 0001h ; special .. entry
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DF_ACL equ 0002h ; item has ACL
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DF_BTP equ 0004h ; entry has a btree down pointer
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DF_END equ 0008h ; is dumy end record
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DF_XACL equ 0040h ; item has explicit ACL
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DF_NEEDEAS equ 0080h ; item has "need" EAs
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DF_NEWNAME equ 4000h ; item name is of "new" pinball format
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DF_RMASK equ DF_ACL+DF_XACL ; only attributes preserved for rename
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ifdef MASM
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.errnz DF_BTP - SIZE_DIR_BTP ; code uses this "coincidence"
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endif
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; Attributes which creation can specify
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DF_CMASK equ attr_read_only+attr_hidden+attr_archive
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; Directory Lookaside Structure
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;
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; We keep info on all directories that we've seen in SBDIR records
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; in RAM, but we keep the last N that we've seen in a special
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; DIRLOOK list in RAM.
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;
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DIRLOOK struc
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DL_LNK db (size DCHDR) dup (?) ; forward and backwards link
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DL_VSECVAL dd ? ; VOL_SECVAL value
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DL_SUM dd ? ; checksum value
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DL_NAM dd ? ; pointer to name string on heap
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DL_SBD dd ? ; pointer to SBDIR structure
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DIRLOOK ends
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; Subdirectory Linkage Structure
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;
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; For every directory that we've seen on the disk we keep a
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; SBDIR record in ram, linked into a heirarchy which parallels
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; the disk heirarchy. We never discard these, so we end up
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; with a RAM copy of all the parts of the directory heirarchy
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; that the user is using.
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;
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; Each SBDIR entry is on a circular doubly linked chain of
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; siblings (directors with the same parent directory). If a
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; directory contains no subdirectories the SD_ENT field is 0.
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; If a directory has subdirectories, their SBDIR entries are
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; in turn in a SD_SIB chain and the SD_ENT field points to
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; one of those SBDIR entries.
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;
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; SBDIR contains a lock and a hold mechanism. A directory is
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; locked when it is being edited; no other threads may view it
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; until it is unlocked. A directory which is HELD is one which
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; is being accessed and can't be edited.
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;
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; The locking and holding algorithms are complicated by the fact
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; that we almost never block so we want to do our typical locking
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; and unlocking inline, without calls, and with minimum tests.
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; We do this with a held count, and bits for locked, lock pending,
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; and solo pending. (Solo means that a user wants sole access to
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; the structure. He'll continue to block until no one else is
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; using it. This is typically done to delete the structure)
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; Another bit is the OR of the lock pending and solo pending bits,
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; and is high order in the dword which encompases SD_HCNT so that
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; when folks release their SD_HCNT value they can simulatneously
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; test to see if there is a pending action.
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;
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; To Hold the SBDIR:
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; If it's not locked and doesn't have a lock pending,
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; increment hold count
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; else
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; block on it and retry.
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;
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; To Unhold the SBDIR:
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; decrement the HCNT field.
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; If SD_PND & (HCNT == 0)
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; wake up waiters.
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;
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; To lock the SBDIR:
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; If locked, block and retry.
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; If HCNT != 0
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; if (lock pending already set)
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; block and retry
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; set lock pending. Block until HCNT is zero.
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; set locked
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;
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; To unlock the SBDIR:
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; clear lock bit.
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; If the block list is non-zero, issue a wakeup.
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;
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; To Solo the SBDIR:
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; Keep blocking until no one else is blocked on it and
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; no one has it held or locked.
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;
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; General Considerations:
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; Anyone who blocks on an SBDIR because it's held must
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; be sure to set a pending bit and the SD_PND bit so
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; that the unhold operation will wake them up.
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;
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; Anyone who blocks on an SBDIR must increment the
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; SD_BCNT field to prevent a SOLO operation from yanking
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; the rug out from under them. SOLO can't depend upon
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; checking the lock list because a blanket wakeup may
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; have cleared the lock list. If the SOLO guy gets control
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; first he'll believe that he can have it.
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;
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;
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SBDIR struc
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SD_FNW db (size DCHDR) dup (?) ; FNWORK (findnotify) chain
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SD_SIB db (size DCHDR) dup (?) ; chain of siblings
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SD_LRU db (size DCHDR) dup (?) ; LRU chain
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SD_ENT dd ? ; pointer to a descendent, or 0
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SD_PAR dd ? ; pointer to parent SBDIR, 0 if root
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SD_SEC db (size SECPTR) dup (?) ; VSector and hint of top dirblk
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SD_FNO dd ? ; FNODE # of directory
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SD_SUM dd ? ; checksum of name string
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SD_CNT dw ? ; # of subdirectories in this one
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SD_OPEN dw ? ; count of # of guys that have this open
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; We sometimes inc/dec SD_HCNT as a dword to test the HO bit in SD_FLAG
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; the following three fields are used to
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; control access. They're identical in use
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; to the equivalent fields in OFT
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SD_HCNT dw ? ; held count, has SDH_PND bit also
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SD_DMYZERO db ? ; must be zero
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SD_FLAG db ? ; flag byte, high order in SD_HCNT dword
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SD_WAIT dd ? ; head of the wait chain
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SD_FREEDCNT dd ? ; incremented each time we free a DIRBLK
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; for this guy. See RDE for details
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SD_WCNT dw ? ; count of folks blocked on this
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SD_FNDCNT dw ? ; count of active finds in this directory
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SD_ATIME dd ? ; time of last access
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SD_NAM dd ? ; address of name string
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SD_ACL dd ? ; SBDIR ACL pointer, 0 if none
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; points to DWORD count, followed by ACEs
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; if low bit of address is 0, is heap space
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; if low bit is 1, is system memory
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SBDIR ends
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SD_ACL_LIM equ 1024 ; *SD_ACL lists bigger than this come from
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; system memory, smaller come from heap
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SDF_PND equ 80h ; lock pending bit
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SDF_RTP equ 20h ; restricted traversal permissions
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; =0 if anyone can traverse the dir
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SDF_REALLYBAD equ 10h ; directory is really bad
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SDF_IPR equ 08h ; SD_ACL has inherit records
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SDF_PSO equ 04h ; pending solo
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SDF_PLK equ 02h ; pending lock
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SDF_LCK equ 01h ; directory is locked against access
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