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Diffstat (limited to 'fs/hpfs/hpfs.h')
| -rw-r--r-- | fs/hpfs/hpfs.h | 498 |
1 files changed, 498 insertions, 0 deletions
diff --git a/fs/hpfs/hpfs.h b/fs/hpfs/hpfs.h new file mode 100644 index 000000000..3121a415d --- /dev/null +++ b/fs/hpfs/hpfs.h @@ -0,0 +1,498 @@ +/* The paper + + Duncan, Roy + Design goals and implementation of the new High Performance File System + Microsoft Systems Journal Sept 1989 v4 n5 p1(13) + + describes what HPFS looked like when it was new, and it is the source + of most of the information given here. The rest is conjecture. + + For definitive information on the Duncan paper, see it, not this file. + For definitive information on HPFS, ask somebody else -- this is guesswork. + There are certain to be many mistakes. */ + +/* Notation */ + +typedef unsigned secno; /* sector number, partition relative */ + +typedef secno dnode_secno; /* sector number of a dnode */ +typedef secno fnode_secno; /* sector number of an fnode */ +typedef secno anode_secno; /* sector number of an anode */ + +/* sector 0 */ + +/* The boot block is very like a FAT boot block, except that the + 29h signature byte is 28h instead, and the ID string is "HPFS". */ + +struct hpfs_boot_block +{ + unsigned char jmp[3]; + unsigned char oem_id[8]; + unsigned char bytes_per_sector[2]; /* 512 */ + unsigned char sectors_per_cluster; + unsigned char n_reserved_sectors[2]; + unsigned char n_fats; + unsigned char n_rootdir_entries[2]; + unsigned char n_sectors_s[2]; + unsigned char media_byte; + unsigned short sectors_per_fat; + unsigned short sectors_per_track; + unsigned short heads_per_cyl; + unsigned int n_hidden_sectors; + unsigned int n_sectors_l; /* size of partition */ + unsigned char drive_number; + unsigned char mbz; + unsigned char sig_28h; /* 28h */ + unsigned char vol_serno[4]; + unsigned char vol_label[11]; + unsigned char sig_hpfs[8]; /* "HPFS " */ + unsigned char pad[448]; + unsigned short magic; /* aa55 */ +}; + + +/* sector 16 */ + +/* The super block has the pointer to the root directory. */ + +#define SB_MAGIC 0xf995e849 + +struct hpfs_super_block +{ + unsigned magic; /* f995 e849 */ + unsigned magic1; /* fa53 e9c5, more magic? */ + unsigned huh202; /* ?? 202 = N. of B. in 1.00390625 S.*/ + fnode_secno root; /* fnode of root directory */ + secno n_sectors; /* size of filesystem */ + unsigned n_badblocks; /* number of bad blocks */ + secno bitmaps; /* pointers to free space bit maps */ + unsigned zero1; /* 0 */ + secno badblocks; /* bad block list */ + unsigned zero3; /* 0 */ + time_t last_chkdsk; /* date last checked, 0 if never */ + unsigned zero4; /* 0 */ + secno n_dir_band; /* number of sectors in dir band */ + secno dir_band_start; /* first sector in dir band */ + secno dir_band_end; /* last sector in dir band */ + secno dir_band_bitmap; /* free space map, 1 dnode per bit */ + unsigned zero5[8]; /* 0 */ + secno scratch_dnodes; /* ?? 8 preallocated sectors near dir + band, 4-aligned. */ + unsigned zero6[103]; /* 0 */ +}; + + +/* sector 17 */ + +/* The spare block has pointers to spare sectors. */ + +#define SP_MAGIC 0xf9911849 + +struct hpfs_spare_block +{ + unsigned magic; /* f991 1849 */ + unsigned magic1; /* fa52 29c5, more magic? */ + + unsigned dirty: 1; /* 0 clean, 1 "improperly stopped" */ + unsigned flag1234: 4; /* unknown flags */ + unsigned fast: 1; /* partition was fast formatted */ + unsigned flag6to31: 26; /* unknown flags */ + + secno hotfix_map; /* info about remapped bad sectors */ + unsigned n_spares_used; /* number of hotfixes */ + unsigned n_spares; /* number of spares in hotfix map */ + unsigned n_dnode_spares_free; /* spare dnodes unused */ + unsigned n_dnode_spares; /* length of spare_dnodes[] list, + follows in this block*/ + secno code_page_dir; /* code page directory block */ + unsigned n_code_pages; /* number of code pages */ + unsigned large_numbers[2]; /* ?? */ + unsigned zero1[15]; + dnode_secno spare_dnodes[20]; /* emergency free dnode list */ + unsigned zero2[81]; /* room for more? */ +}; + +/* The bad block list is 4 sectors long. The first word must be zero, + the remaining words give n_badblocks bad block numbers. + I bet you can see it coming... */ + +#define BAD_MAGIC 0 + +/* The hotfix map is 4 sectors long. It looks like + + secno from[n_spares]; + secno to[n_spares]; + + The to[] list is initialized to point to n_spares preallocated empty + sectors. The from[] list contains the sector numbers of bad blocks + which have been remapped to corresponding sectors in the to[] list. + n_spares_used gives the length of the from[] list. */ + + +/* Sectors 18 and 19 are preallocated and unused. + Maybe they're spares for 16 and 17, but simple substitution fails. */ + + +/* The code page info pointed to by the spare block consists of an index + block and blocks containing character maps. The following is pretty + sketchy, but Linux doesn't use code pages so it doesn't matter. */ + +/* block pointed to by spareblock->code_page_dir */ + +#define CP_DIR_MAGIC 0x494521f7 + +struct code_page_directory +{ + unsigned magic; /* 4945 21f7 */ + unsigned n_code_pages; /* number of pointers following */ + unsigned zero1[2]; + struct { + unsigned short ix; /* index */ + unsigned short code_page_number; /* code page number */ + unsigned bounds; /* matches corresponding word + in data block */ + secno code_page_data; /* sector number of a code_page_data + containing c.p. array */ + unsigned index; /* index in c.p. array in that sector*/ + } array[31]; /* unknown length */ +}; + +/* blocks pointed to by code_page_directory */ + +#define CP_DATA_MAGIC 0x894521f7 + +struct code_page_data +{ + unsigned magic; /* 8945 21f7 */ + unsigned n_used; /* # elements used in c_p_data[] */ + unsigned bounds[3]; /* looks a bit like + (beg1,end1), (beg2,end2) + one byte each */ + unsigned short offs[3]; /* offsets from start of sector + to start of c_p_data[ix] */ + struct { + unsigned short ix; /* index */ + unsigned short code_page_number; /* code page number */ + unsigned short zero1; + unsigned char map[128]; /* map for chars 80..ff */ + unsigned short zero2; + } code_page[3]; + unsigned char incognita[78]; +}; + + +/* Free space bitmaps are 4 sectors long, which is 16384 bits. + 16384 sectors is 8 meg, and each 8 meg band has a 4-sector bitmap. + Bit order in the maps is little-endian. 0 means taken, 1 means free. + + Bit map sectors are marked allocated in the bit maps, and so are sectors + off the end of the partition. + + Band 0 is sectors 0-3fff, its map is in sectors 18-1b. + Band 1 is 4000-7fff, its map is in 7ffc-7fff. + Band 2 is 8000-ffff, its map is in 8000-8003. + The remaining bands have maps in their first (even) or last (odd) 4 sectors + -- if the last, partial, band is odd its map is in its last 4 sectors. + + The bitmap locations are given in a table pointed to by the super block. + No doubt they aren't constrained to be at 18, 7ffc, 8000, ...; that is + just where they usually are. + + The "directory band" is a bunch of sectors preallocated for dnodes. + It has a 4-sector free space bitmap of its own. Each bit in the map + corresponds to one 4-sector dnode, bit 0 of the map corresponding to + the first 4 sectors of the directory band. The entire band is marked + allocated in the main bitmap. The super block gives the locations + of the directory band and its bitmap. ("band" doesn't mean it is + 8 meg long; it isn't.) */ + + +/* dnode: directory. 4 sectors long */ + +/* A directory is a tree of dnodes. The fnode for a directory + contains one pointer, to the root dnode of the tree. The fnode + never moves, the dnodes do the B-tree thing, splitting and merging + as files are added and removed. */ + +#define DNODE_MAGIC 0x77e40aae + +struct dnode { + unsigned magic; /* 77e4 0aae */ + unsigned first_free; /* offset from start of dnode to + first free dir entry */ + unsigned increment_me; /* some kind of activity counter? + Neither HPFS.IFS nor CHKDSK cares + if you change this word */ + secno up; /* (root dnode) directory's fnode + (nonroot) parent dnode */ + dnode_secno self; /* pointer to this dnode */ + unsigned char dirent[2028]; /* one or more dirents */ +}; + +struct hpfs_dirent { + unsigned short length; /* offset to next dirent */ + unsigned first: 1; /* set on phony ^A^A (".") entry */ + unsigned flag1: 1; + unsigned down: 1; /* down pointer present (after name) */ + unsigned last: 1; /* set on phony \377 entry */ + unsigned flag4: 1; + unsigned flag5: 1; + unsigned flag6: 1; + unsigned has_needea: 1; /* ?? some EA has NEEDEA set + I have no idea why this is + interesting in a dir entry */ + unsigned read_only: 1; /* dos attrib */ + unsigned hidden: 1; /* dos attrib */ + unsigned system: 1; /* dos attrib */ + unsigned flag11: 1; /* would be volume label dos attrib */ + unsigned directory: 1; /* dos attrib */ + unsigned archive: 1; /* dos attrib */ + unsigned not_8x3: 1; /* name is not 8.3 */ + unsigned flag15: 1; + fnode_secno fnode; /* fnode giving allocation info */ + time_t write_date; /* mtime */ + unsigned file_size; /* file length, bytes */ + time_t read_date; /* atime */ + time_t creation_date; /* ctime */ + unsigned ea_size; /* total EA length, bytes */ + unsigned char zero1; + unsigned char locality; /* 0=unk 1=seq 2=random 3=both */ + unsigned char namelen, name[1]; /* file name */ + /* dnode_secno down; btree down pointer, if present, + follows name on next word boundary, or maybe it's + precedes next dirent, which is on a word boundary. */ +}; + +/* The b-tree down pointer from a dir entry */ + +static inline dnode_secno de_down_pointer (struct hpfs_dirent *de) +{ + return *(dnode_secno *) ((void *) de + de->length - 4); +} + +/* The first dir entry in a dnode */ + +static inline struct hpfs_dirent *dnode_first_de (struct dnode *dnode) +{ + return (void *) dnode->dirent; +} + +/* The end+1 of the dir entries */ + +static inline struct hpfs_dirent *dnode_end_de (struct dnode *dnode) +{ + return (void *) dnode + dnode->first_free; +} + +/* The dir entry after dir entry de */ + +static inline struct hpfs_dirent *de_next_de (struct hpfs_dirent *de) +{ + return (void *) de + de->length; +} + + +/* B+ tree: allocation info in fnodes and anodes */ + +/* dnodes point to fnodes which are responsible for listing the sectors + assigned to the file. This is done with trees of (length,address) + pairs. (Actually triples, of (length, file-address, disk-address) + which can represent holes. Find out if HPFS does that.) + At any rate, fnodes contain a small tree; if subtrees are needed + they occupy essentially a full block in anodes. A leaf-level tree node + has 3-word entries giving sector runs, a non-leaf node has 2-word + entries giving subtree pointers. A flag in the header says which. */ + +struct bplus_leaf_node +{ + unsigned file_secno; /* first file sector in extent */ + unsigned length; /* length, sectors */ + secno disk_secno; /* first corresponding disk sector */ +}; + +struct bplus_internal_node +{ + unsigned file_secno; /* subtree maps sectors < this */ + anode_secno down; /* pointer to subtree */ +}; + +struct bplus_header +{ + unsigned flag0: 1; + unsigned flag1: 1; + unsigned flag2: 1; + unsigned flag3: 1; + unsigned flag4: 1; + unsigned fnode_parent: 1; /* ? we're pointed to by an fnode, + the data btree or some ea or the + main ea bootage pointer ea_secno */ + /* also can get set in fnodes, which + may be a chkdsk glitch or may mean + this bit is irrelevant in fnodes, + or this interpretation is all wet */ + unsigned flag6: 1; + unsigned internal: 1; /* 1 -> (internal) tree of anodes + 0 -> (leaf) list of extents */ + unsigned char fill[3]; + unsigned char n_free_nodes; /* free nodes in following array */ + unsigned char n_used_nodes; /* used nodes in following array */ + unsigned short first_free; /* offset from start of header to + first free node in array */ + union { + struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving + subtree pointers */ + struct bplus_leaf_node external[0]; /* (external) 3-word entries giving + sector runs */ + } u; +}; + +/* fnode: root of allocation b+ tree, and EA's */ + +/* Every file and every directory has one fnode, pointed to by the directory + entry and pointing to the file's sectors or directory's root dnode. EA's + are also stored here, and there are said to be ACL's somewhere here too. */ + +#define FNODE_MAGIC 0xf7e40aae + +struct fnode +{ + unsigned magic; /* f7e4 0aae */ + unsigned zero1[2]; + unsigned char len, name[15]; /* true length, truncated name */ + fnode_secno up; /* pointer to file's directory fnode */ + unsigned zero2[3]; + unsigned ea_size_l; /* length of disk-resident ea's */ + secno ea_secno; /* first sector of disk-resident ea's*/ + unsigned short ea_size_s; /* length of fnode-resident ea's */ + + unsigned flag0: 1; + unsigned ea_anode: 1; /* 1 -> ea_secno is an anode */ + unsigned flag2: 1; + unsigned flag3: 1; + unsigned flag4: 1; + unsigned flag5: 1; + unsigned flag6: 1; + unsigned flag7: 1; + unsigned dirflag: 1; /* 1 -> directory. first & only extent + points to dnode. */ + unsigned flag9: 1; + unsigned flag10: 1; + unsigned flag11: 1; + unsigned flag12: 1; + unsigned flag13: 1; + unsigned flag14: 1; + unsigned flag15: 1; + + struct bplus_header btree; /* b+ tree, 8 extents or 12 subtrees */ + union { + struct bplus_leaf_node external[8]; + struct bplus_internal_node internal[12]; + } u; + + unsigned file_size; /* file length, bytes */ + unsigned n_needea; /* number of EA's with NEEDEA set */ + unsigned zero4[4]; + unsigned ea_offs; /* offset from start of fnode + to first fnode-resident ea */ + unsigned zero5[2]; + unsigned char ea[316]; /* zero or more EA's, packed together + with no alignment padding. + (Do not use this name, get here + via fnode + ea_offs. I think.) */ +}; + + +/* anode: 99.44% pure allocation tree */ + +#define ANODE_MAGIC 0x37e40aae + +struct anode +{ + unsigned magic; /* 37e4 0aae */ + anode_secno self; /* pointer to this anode */ + secno up; /* parent anode or fnode */ + + struct bplus_header btree; /* b+tree, 40 extents or 60 subtrees */ + union { + struct bplus_leaf_node external[40]; + struct bplus_internal_node internal[60]; + } u; + + unsigned fill[3]; /* unused */ +}; + + +/* extended attributes. + + A file's EA info is stored as a list of (name,value) pairs. It is + usually in the fnode, but (if it's large) it is moved to a single + sector run outside the fnode, or to multiple runs with an anode tree + that points to them. + + The value of a single EA is stored along with the name, or (if large) + it is moved to a single sector run, or multiple runs pointed to by an + anode tree, pointed to by the value field of the (name,value) pair. + + Flags in the EA tell whether the value is immediate, in a single sector + run, or in multiple runs. Flags in the fnode tell whether the EA list + is immediate, in a single run, or in multiple runs. */ + +struct extended_attribute +{ + unsigned indirect: 1; /* 1 -> value gives sector number + where real value starts */ + unsigned anode: 1; /* 1 -> sector is an anode + that points to fragmented value */ + unsigned flag2: 1; + unsigned flag3: 1; + unsigned flag4: 1; + unsigned flag5: 1; + unsigned flag6: 1; + unsigned needea: 1; /* required ea */ + unsigned char namelen; /* length of name, bytes */ + unsigned short valuelen; /* length of value, bytes */ + /* + unsigned char name[namelen]; ascii attrib name + unsigned char nul; terminating '\0', not counted + unsigned char value[valuelen]; value, arbitrary + if this.indirect, valuelen is 8 and the value is + unsigned length; real length of value, bytes + secno secno; sector address where it starts + if this.anode, the above sector number is the root of an anode tree + which points to the value. + */ +}; + +static inline unsigned char *ea_name (struct extended_attribute *ea) +{ + return (void *) ea + sizeof *ea; +} + +static inline unsigned char *ea_value (struct extended_attribute *ea) +{ + return (void *) ea + sizeof *ea + ea->namelen + 1; +} + +static inline struct extended_attribute * + ea_next_ea (struct extended_attribute *ea) +{ + return (void *) ea + sizeof *ea + ea->namelen + 1 + ea->valuelen; +} + +static inline unsigned ea_indirect_length (struct extended_attribute *ea) +{ + unsigned *v = (void *) ea_value (ea); + return v[0]; +} + +static inline secno ea_indirect_secno (struct extended_attribute *ea) +{ + unsigned *v = (void *) ea_value (ea); + return v[1]; +} + +/* + Local Variables: + comment-column: 40 + End: +*/ |