* Copyright (c) 1982, 1986 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
* @(#)vfs_lookup.c 7.1 (Berkeley) %G%
* Structures associated with name cacheing.
#define NCHHASH 32 /* size of hash table */
#if ((NCHHASH)&((NCHHASH)-1)) != 0
#define NHASH(h, i, d) ((unsigned)((h) + (i) + 13 * (int)(d)) % (NCHHASH))
#define NHASH(h, i, d) ((unsigned)((h) + (i) + 13 * (int)(d)) & ((NCHHASH)-1))
union nchash
*nch_head
[2];
struct namecache
*nch_chain
[2];
#define nch_forw nch_chain[0]
#define nch_back nch_chain[1]
struct namecache
*nchhead
, **nchtail
; /* LRU chain pointers */
struct nchstats nchstats
; /* cache effectiveness statistics */
* Convert a pathname into a pointer to a locked inode.
* This is a very central and rather complicated routine.
* If the file system is not maintained in a strict tree hierarchy,
* this can result in a deadlock situation (see comments in code below).
* The flag argument is LOOKUP, CREATE, or DELETE depending on whether
* the name is to be looked up, created, or deleted. When CREATE or
* DELETE is specified, information usable in creating or deleteing a
* directory entry is also calculated. If flag has LOCKPARENT or'ed
* into it and the target of the pathname exists, namei returns both
* the target and its parent directory locked. When creating and
* LOCKPARENT is specified, the target may not be ".". When deleting
* and LOCKPARENT is specified, the target may be ".", but the caller
* must check to insure it does an irele and iput instead of two iputs.
* The FOLLOW flag is set when symbolic links are to be followed
* when they occur at the end of the name translation process.
* Symbolic links are always followed for all other pathname
* components other than the last.
* The segflg defines whether the name is to be copied from user
* Name caching works as follows:
* Names found by directory scans are retained in a cache
* for future reference. It is managed LRU, so frequently
* used names will hang around. Cache is indexed by hash value
* obtained from (ino,dev,name) where ino & dev refer to the
* directory containing name.
* For simplicity (and economy of storage), names longer than
* a maximum length of NCHNAMLEN are not cached; they occur
* infrequently in any case, and are almost never of interest.
* Upon reaching the last segment of a path, if the reference
* is for DELETE, or NOCACHE is set (rewrite), and the
* name is located in the cache, it will be dropped.
* Overall outline of namei:
* check accessibility of directory
* copy next component of name to ndp->ni_dent
* handle degenerate case where name is null string
* look for name in cache, if found, then if at end of path
* and deleting or creating, drop it, else to haveino
* search for name in directory, to found or notfound
* if creating, return locked directory, leaving info on avail. slots
* if at end of path and deleting, return information to allow delete
* if at end of path and rewriting (CREATE and LOCKPARENT), lock target
* inode and return info to allow rewrite
* if .. and on mounted filesys, look in mount table for parent
* if not at end, add name to cache; if at end and neither creating
* nor deleting, add name to cache
* if symbolic link, massage name in buffer and continue at dirloop
* if more components of name, do next level at dirloop
* return the answer as locked inode
* NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode,
register struct nameidata
*ndp
;
register char *cp
; /* pointer into pathname argument */
/* these variables refer to things which must be freed or unlocked */
register struct inode
*dp
= 0; /* the directory we are searching */
register struct namecache
*ncp
; /* cache slot for entry */
register struct fs
*fs
; /* file system that directory is in */
register struct buf
*bp
= 0; /* a buffer of directory entries */
register struct direct
*ep
; /* the current directory entry */
int entryoffsetinblock
; /* offset of ep in bp's buffer */
register struct buf
*nbp
; /* buffer storing path name argument */
/* these variables hold information about the search for a slot */
enum {NONE
, COMPACT
, FOUND
} slotstatus
;
int slotoffset
= -1; /* offset of area with free space */
int slotsize
; /* size of area at slotoffset */
int slotfreespace
; /* amount of space free in slot */
int slotneeded
; /* size of the entry we're seeking */
int numdirpasses
; /* strategy for directory search */
int endsearch
; /* offset to end directory search */
int prevoff
; /* ndp->ni_offset of previous entry */
int nlink
= 0; /* number of symbolic links taken */
struct inode
*pdp
; /* saved dp during symlink work */
int docache
; /* == 0 do not cache last component */
int makeentry
; /* != 0 if name to be added to cache */
unsigned hash
; /* value of name hash for entry */
union nchash
*nhp
; /* cache chain head for entry */
int isdotdot
; /* != 0 if current name is ".." */
int flag
; /* op ie, LOOKUP, CREATE, or DELETE */
off_t enduseful
; /* pointer past last used dir slot */
lockparent
= ndp
->ni_nameiop
& LOCKPARENT
;
docache
= (ndp
->ni_nameiop
& NOCACHE
) ^ NOCACHE
;
flag
= ndp
->ni_nameiop
&~ (LOCKPARENT
|NOCACHE
|FOLLOW
);
if (flag
== DELETE
|| lockparent
)
* Get a buffer for the name to be translated, and copy the
nbp
= geteblk(MAXPATHLEN
);
freenamebuf
= nbp
->av_forw
;
if (ndp
->ni_segflg
== UIO_SYSSPACE
)
error
= copystr(ndp
->ni_dirp
, nbp
->b_un
.b_addr
, MAXPATHLEN
,
error
= copyinstr(ndp
->ni_dirp
, nbp
->b_un
.b_addr
, MAXPATHLEN
,
* Get starting directory.
if ((dp
= u
.u_rdir
) == NULL
)
ndp
->ni_pdir
= (struct inode
*)0xc0000000; /* illegal */
* We come to dirloop to search a new directory.
* The directory must be locked so that it can be
* iput, and fs must be already set to dp->i_fs.
* Check accessiblity of directory.
if ((dp
->i_mode
&IFMT
) != IFDIR
) {
* Copy next component of name to ndp->ni_dent.
for (i
= 0; *cp
!= 0 && *cp
!= '/'; cp
++) {
u
.u_error
= ENAMETOOLONG
;
if ((*cp
&0377) == ('/'|0200) || flag
!= DELETE
) {
ndp
->ni_dent
.d_name
[i
++] = *cp
;
hash
+= (unsigned char)*cp
* i
;
ndp
->ni_dent
.d_namlen
= i
;
ndp
->ni_dent
.d_name
[i
] = '\0';
ndp
->ni_dent
.d_name
[0] == '.' && ndp
->ni_dent
.d_name
[1] == '.');
if (*cp
== '\0' && docache
== 0)
* Check for degenerate name (e.g. / or "")
* which is a way of talking about a directory,
if (ndp
->ni_dent
.d_name
[0] == '\0') {
if (flag
!= LOOKUP
|| lockparent
) {
nbp
->av_forw
= freenamebuf
;
* We now have a segment name to search for, and a directory to search.
* Before tediously performing a linear scan of the directory,
* check the name cache to see if the directory/name pair
* we are looking for is known already. We don't do this
* if the segment name is long, simply so the cache can avoid
* holding long names (which would either waste space, or
* add greatly to the complexity).
if (ndp
->ni_dent
.d_namlen
> NCHNAMLEN
) {
nhp
= &nchash
[NHASH(hash
, dp
->i_number
, dp
->i_dev
)];
for (ncp
= nhp
->nch_forw
; ncp
!= (struct namecache
*)nhp
;
if (ncp
->nc_ino
== dp
->i_number
&&
ncp
->nc_dev
== dp
->i_dev
&&
ncp
->nc_nlen
== ndp
->ni_dent
.d_namlen
&&
!bcmp(ncp
->nc_name
, ndp
->ni_dent
.d_name
,
if (ncp
== (struct namecache
*)nhp
) {
if (ncp
->nc_id
!= ncp
->nc_ip
->i_id
)
nchstats
.ncs_falsehits
++;
* move this slot to end of LRU
* chain, if not already there
/* remove from LRU chain */
*ncp
->nc_prev
= ncp
->nc_nxt
;
ncp
->nc_nxt
->nc_prev
= ncp
->nc_prev
;
/* and replace at end of it */
* Get the next inode in the path.
* See comment above other `IUNLOCK' code for
* an explaination of the locking protocol.
if (!isdotdot
|| dp
!= u
.u_rdir
)
panic("namei: null cache ino");
* Verify that the inode that we got
* did not change while we were waiting
if (ncp
->nc_id
!= ncp
->nc_ip
->i_id
) {
nchstats
.ncs_falsehits
++;
ndp
->ni_dent
.d_ino
= dp
->i_number
;
/* ni_dent.d_reclen is garbage ... */
* Last component and we are renaming or deleting,
* the cache entry is invalid, or otherwise don't
* want cache entry to exist.
/* remove from LRU chain */
*ncp
->nc_prev
= ncp
->nc_nxt
;
ncp
->nc_nxt
->nc_prev
= ncp
->nc_prev
;
remque(ncp
); /* remove from hash chain */
/* insert at head of LRU list (first to grab) */
nchhead
->nc_prev
= &ncp
->nc_nxt
;
/* and make a dummy hash chain */
* Suppress search for slots unless creating
* file and at end of pathname, in which case
* we watch for a place to put the new file in
* case it doesn't already exist.
if (flag
== CREATE
&& *cp
== 0) {
slotneeded
= DIRSIZ(&ndp
->ni_dent
);
* If this is the same directory that this process
* previously searched, pick up where we last left off.
* We cache only lookups as these are the most common
* and have the greatest payoff. Caching CREATE has little
* benefit as it usually must search the entire directory
* to determine that the entry does not exist. Caching the
* location of the last DELETE has not reduced profiling time
* and hence has been removed in the interest of simplicity.
if (flag
!= LOOKUP
|| dp
->i_number
!= u
.u_ncache
.nc_inumber
||
dp
->i_dev
!= u
.u_ncache
.nc_dev
) {
if (u
.u_ncache
.nc_prevoffset
> dp
->i_size
)
u
.u_ncache
.nc_prevoffset
= 0;
ndp
->ni_offset
= u
.u_ncache
.nc_prevoffset
;
entryoffsetinblock
= blkoff(fs
, ndp
->ni_offset
);
if (entryoffsetinblock
!= 0) {
bp
= blkatoff(dp
, ndp
->ni_offset
, (char **)0);
endsearch
= roundup(dp
->i_size
, DIRBLKSIZ
);
while (ndp
->ni_offset
< endsearch
) {
* If offset is on a block boundary,
* read the next directory block.
* Release previous if it exists.
if (blkoff(fs
, ndp
->ni_offset
) == 0) {
bp
= blkatoff(dp
, ndp
->ni_offset
, (char **)0);
* If still looking for a slot, and at a DIRBLKSIZE
* boundary, have to start looking for free space again.
if (slotstatus
== NONE
&&
(entryoffsetinblock
&(DIRBLKSIZ
-1)) == 0) {
* Get pointer to next entry.
* Full validation checks are slow, so we only check
* enough to insure forward progress through the
* directory. Complete checks can be run by patching
ep
= (struct direct
*)(bp
->b_un
.b_addr
+ entryoffsetinblock
);
dirchk
&& dirbadentry(ep
, entryoffsetinblock
)) {
dirbad(dp
, ndp
->ni_offset
, "mangled entry");
i
= DIRBLKSIZ
- (entryoffsetinblock
& (DIRBLKSIZ
- 1));
* If an appropriate sized slot has not yet been found,
* check to see if one is available. Also accumulate space
* in the current block so that we can determine if
if (slotstatus
!= FOUND
) {
if (size
>= slotneeded
) {
slotoffset
= ndp
->ni_offset
;
} else if (slotstatus
== NONE
) {
slotoffset
= ndp
->ni_offset
;
if (slotfreespace
>= slotneeded
) {
slotsize
= ndp
->ni_offset
+
ep
->d_reclen
- slotoffset
;
* Check for a name match.
if (ep
->d_namlen
== ndp
->ni_dent
.d_namlen
&&
!bcmp(ndp
->ni_dent
.d_name
, ep
->d_name
,
prevoff
= ndp
->ni_offset
;
ndp
->ni_offset
+= ep
->d_reclen
;
entryoffsetinblock
+= ep
->d_reclen
;
enduseful
= ndp
->ni_offset
;
* If we started in the middle of the directory and failed
* to find our target, we must check the beginning as well.
endsearch
= u
.u_ncache
.nc_prevoffset
;
* If creating, and at end of pathname and current
* directory has not been removed, then can consider
* allowing file to be created.
if (flag
== CREATE
&& *cp
== 0 && dp
->i_nlink
!= 0) {
* Access for write is interpreted as allowing
* creation of files in the directory.
* Return an indication of where the new directory
* entry should be put. If we didn't find a slot,
* then set ndp->ni_count to 0 indicating that the new
* slot belongs at the end of the directory. If we found
* a slot, then the new entry can be put in the range
* [ndp->ni_offset .. ndp->ni_offset + ndp->ni_count)
if (slotstatus
== NONE
) {
ndp
->ni_offset
= roundup(dp
->i_size
, DIRBLKSIZ
);
enduseful
= ndp
->ni_offset
;
ndp
->ni_offset
= slotoffset
;
ndp
->ni_count
= slotsize
;
if (enduseful
< slotoffset
+ slotsize
)
enduseful
= slotoffset
+ slotsize
;
ndp
->ni_endoff
= roundup(enduseful
, DIRBLKSIZ
);
nbp
->av_forw
= freenamebuf
;
* We return with the directory locked, so that
* the parameters we set up above will still be
* valid if we actually decide to do a direnter().
* We return NULL to indicate that the entry doesn't
* currently exist, leaving a pointer to the (locked)
* directory inode in ndp->ni_pdir.
* Check that directory length properly reflects presence
if (entryoffsetinblock
+ DIRSIZ(ep
) > dp
->i_size
) {
dirbad(dp
, ndp
->ni_offset
, "i_size too small");
dp
->i_size
= entryoffsetinblock
+ DIRSIZ(ep
);
* Found component in pathname.
* If the final component of path name, save information
* in the cache as to where the entry was found.
if (*cp
== '\0' && flag
== LOOKUP
) {
u
.u_ncache
.nc_prevoffset
= ndp
->ni_offset
&~ (DIRBLKSIZ
- 1);
u
.u_ncache
.nc_inumber
= dp
->i_number
;
u
.u_ncache
.nc_dev
= dp
->i_dev
;
* Save directory entry's inode number and reclen in ndp->ni_dent,
* and release directory buffer.
ndp
->ni_dent
.d_ino
= ep
->d_ino
;
ndp
->ni_dent
.d_reclen
= ep
->d_reclen
;
* If deleting, and at end of pathname, return
* parameters which can be used to remove file.
* If the lockparent flag isn't set, we return only
* the directory (in ndp->ni_pdir), otherwise we go
* on and lock the inode, being careful with ".".
if (flag
== DELETE
&& *cp
== 0) {
* Write access to directory required to delete files.
ndp
->ni_pdir
= dp
; /* for dirremove() */
* Return pointer to current entry in ndp->ni_offset,
* and distance past previous entry (if there
* is a previous entry in this block) in ndp->ni_count.
* Save directory inode pointer in ndp->ni_pdir for dirremove().
if ((ndp
->ni_offset
&(DIRBLKSIZ
-1)) == 0)
ndp
->ni_count
= ndp
->ni_offset
- prevoff
;
if (dp
->i_number
== ndp
->ni_dent
.d_ino
)
dp
= iget(dp
->i_dev
, fs
, ndp
->ni_dent
.d_ino
);
* If directory is "sticky", then user must own
* the directory, or the file in it, else he
* may not delete it (unless he's root). This
* implements append-only directories.
if ((ndp
->ni_pdir
->i_mode
& ISVTX
) &&
u
.u_uid
!= ndp
->ni_pdir
->i_uid
&&
nbp
->av_forw
= freenamebuf
;
* Special handling for ".." allowing chdir out of mounted
* file system: indirect .. in root inode to reevaluate
* in directory file system was mounted on.
ndp
->ni_dent
.d_ino
= dp
->i_number
;
} else if (ndp
->ni_dent
.d_ino
== ROOTINO
&&
dp
->i_number
== ROOTINO
) {
for (i
= 1; i
< NMOUNT
; i
++)
if (mount
[i
].m_bufp
!= NULL
&&
mount
[i
].m_dev
== dp
->i_dev
) {
cp
-= 2; /* back over .. */
* If rewriting (rename), return the inode and the
* information required to rewrite the present directory
* Must get inode of directory entry to verify it's a
* regular file, or empty directory.
if ((flag
== CREATE
&& lockparent
) && *cp
== 0) {
ndp
->ni_pdir
= dp
; /* for dirrewrite() */
* Careful about locking second inode.
* This can only occur if the target is ".".
if (dp
->i_number
== ndp
->ni_dent
.d_ino
) {
u
.u_error
= EISDIR
; /* XXX */
dp
= iget(dp
->i_dev
, fs
, ndp
->ni_dent
.d_ino
);
nbp
->av_forw
= freenamebuf
;
* Check for symbolic link, which may require us to massage the
* name before we continue translation. We do not `iput' the
* directory because we may need it again if the symbolic link
* is relative to the current directory. Instead we save it
* unlocked as "pdp". We must get the target inode before unlocking
* the directory to insure that the inode will not be removed
* before we get it. We prevent deadlock by always fetching
* inodes from the root, moving down the directory tree. Thus
* when following backward pointers ".." we must unlock the
* parent directory before getting the requested directory.
* There is a potential race condition here if both the current
* and parent directories are removed before the `iget' for the
* inode associated with ".." returns. We hope that this occurs
* infrequently since we cannot avoid this race condition without
* implementing a sophisticated deadlock detection algorithm.
* Note also that this simple deadlock detection scheme will not
* work if the file system has any hard links other than ".."
* that point backwards in the directory structure.
IUNLOCK(pdp
); /* race to get the inode */
dp
= iget(dp
->i_dev
, fs
, ndp
->ni_dent
.d_ino
);
} else if (dp
->i_number
== ndp
->ni_dent
.d_ino
) {
dp
->i_count
++; /* we want ourself, ie "." */
dp
= iget(dp
->i_dev
, fs
, ndp
->ni_dent
.d_ino
);
* Insert name into cache if appropriate.
panic("namei: duplicating cache");
* Free the cache slot at head of lru chain.
/* remove from lru chain */
*ncp
->nc_prev
= ncp
->nc_nxt
;
ncp
->nc_nxt
->nc_prev
= ncp
->nc_prev
;
remque(ncp
); /* remove from old hash chain */
/* grab the inode we just found */
ncp
->nc_ino
= pdp
->i_number
; /* parents inum */
ncp
->nc_dev
= pdp
->i_dev
; /* & device */
ncp
->nc_idev
= dp
->i_dev
; /* our device */
ncp
->nc_id
= dp
->i_id
; /* identifier */
ncp
->nc_nlen
= ndp
->ni_dent
.d_namlen
;
bcopy(ndp
->ni_dent
.d_name
, ncp
->nc_name
,
/* link at end of lru chain */
/* and insert on hash chain */
* Check for symbolic link
if ((dp
->i_mode
& IFMT
) == IFLNK
&&
((ndp
->ni_nameiop
& FOLLOW
) || *cp
== '/')) {
u_int pathlen
= strlen(cp
) + 1;
if (dp
->i_size
+ pathlen
>= MAXPATHLEN
- 1) {
u
.u_error
= ENAMETOOLONG
;
if (++nlink
> MAXSYMLINKS
) {
ovbcopy(cp
, nbp
->b_un
.b_addr
+ dp
->i_size
, pathlen
);
rdwri(UIO_READ
, dp
, nbp
->b_un
.b_addr
, (int)dp
->i_size
,
if ((dp
= u
.u_rdir
) == NULL
)
* Not a symbolic link. If more pathname,
* continue at next component, else return.
nbp
->av_forw
= freenamebuf
;
nbp
->av_forw
= freenamebuf
;
printf("%s: bad dir ino %d at offset %d: %s\n",
ip
->i_fs
->fs_fsmnt
, ip
->i_number
, offset
, how
);
* Do consistency checking on a directory entry:
* record length must be multiple of 4
* entry must fit in rest of its DIRBLKSIZ block
* record must be large enough to contain entry
* name is not longer than MAXNAMLEN
* name must be as long as advertised, and null terminated
dirbadentry(ep
, entryoffsetinblock
)
register struct direct
*ep
;
if ((ep
->d_reclen
& 0x3) != 0 ||
ep
->d_reclen
> DIRBLKSIZ
- (entryoffsetinblock
& (DIRBLKSIZ
- 1)) ||
ep
->d_reclen
< DIRSIZ(ep
) || ep
->d_namlen
> MAXNAMLEN
)
for (i
= 0; i
< ep
->d_namlen
; i
++)
if (ep
->d_name
[i
] == '\0')
* Write a directory entry after a call to namei, using the parameters
* which it left in the u. area. The argument ip is the inode which
* the new directory entry will refer to. The u. area field ndp->ni_pdir is
* a pointer to the directory to be written, which was left locked by
* namei. Remaining parameters (ndp->ni_offset, ndp->ni_count) indicate
* how the space for the new entry is to be gotten.
register struct nameidata
*ndp
;
register struct direct
*ep
, *nep
;
register struct inode
*dp
= ndp
->ni_pdir
;
int loc
, spacefree
, error
= 0;
ndp
->ni_dent
.d_ino
= ip
->i_number
;
newentrysize
= DIRSIZ(&ndp
->ni_dent
);
if (ndp
->ni_count
== 0) {
* If ndp->ni_count is 0, then namei could find no space in the
* directory. In this case ndp->ni_offset will be on a directory
* block boundary and we will write the new entry into a fresh
if (ndp
->ni_offset
&(DIRBLKSIZ
-1))
ndp
->ni_dent
.d_reclen
= DIRBLKSIZ
;
error
= rdwri(UIO_WRITE
, dp
, (caddr_t
)&ndp
->ni_dent
,
newentrysize
, ndp
->ni_offset
, 1, (int *)0);
if (DIRBLKSIZ
> dp
->i_fs
->fs_fsize
)
panic("wdir: blksize"); /* XXX - should grow w/bmap() */
dp
->i_size
= roundup(dp
->i_size
, DIRBLKSIZ
);
* If ndp->ni_count is non-zero, then namei found space for the new
* entry in the range ndp->ni_offset to ndp->ni_offset + ndp->ni_count.
* in the directory. To use this space, we may have to compact
* the entries located there, by copying them together towards
* the beginning of the block, leaving the free space in
* one usable chunk at the end.
* Increase size of directory if entry eats into new space.
* This should never push the size past a new multiple of
* N.B. - THIS IS AN ARTIFACT OF 4.2 AND SHOULD NEVER HAPPEN.
if (ndp
->ni_offset
+ ndp
->ni_count
> dp
->i_size
)
dp
->i_size
= ndp
->ni_offset
+ ndp
->ni_count
;
* Get the block containing the space for the new directory
* entry. Should return error by result instead of u.u_error.
bp
= blkatoff(dp
, ndp
->ni_offset
, (char **)&dirbuf
);
* Find space for the new entry. In the simple case, the
* entry at offset base will have the space. If it does
* not, then namei arranged that compacting the region
* ndp->ni_offset to ndp->ni_offset+ndp->ni_count would yield the space.
ep
= (struct direct
*)dirbuf
;
spacefree
= ep
->d_reclen
- dsize
;
for (loc
= ep
->d_reclen
; loc
< ndp
->ni_count
; ) {
nep
= (struct direct
*)(dirbuf
+ loc
);
/* trim the existing slot */
ep
= (struct direct
*)((char *)ep
+ dsize
);
/* overwrite; nothing there; header is ours */
spacefree
+= nep
->d_reclen
- dsize
;
bcopy((caddr_t
)nep
, (caddr_t
)ep
, dsize
);
* Update the pointer fields in the previous entry (if any),
* copy in the new entry, and write out the block.
if (spacefree
+ dsize
< newentrysize
)
ndp
->ni_dent
.d_reclen
= spacefree
+ dsize
;
if (spacefree
< newentrysize
)
ndp
->ni_dent
.d_reclen
= spacefree
;
ep
= (struct direct
*)((char *)ep
+ dsize
);
bcopy((caddr_t
)&ndp
->ni_dent
, (caddr_t
)ep
, (u_int
)newentrysize
);
if (ndp
->ni_endoff
&& ndp
->ni_endoff
< dp
->i_size
)
itrunc(dp
, (u_long
)ndp
->ni_endoff
);
* Remove a directory entry after a call to namei, using the
* parameters which it left in the u. area. The u. entry
* ni_offset contains the offset into the directory of the
* entry to be eliminated. The ni_count field contains the
* size of the previous record in the directory. If this
* is 0, the first entry is being deleted, so we need only
* zero the inode number to mark the entry as free. If the
* entry isn't the first in the directory, we must reclaim
* the space of the now empty record by adding the record size
* to the size of the previous entry.
register struct nameidata
*ndp
;
register struct inode
*dp
= ndp
->ni_pdir
;
if (ndp
->ni_count
== 0) {
* First entry in block: set d_ino to zero.
(void) rdwri(UIO_WRITE
, dp
, (caddr_t
)&ndp
->ni_dent
,
(int)DIRSIZ(&ndp
->ni_dent
), ndp
->ni_offset
, 1, (int *)0);
* Collapse new free space into previous entry.
bp
= blkatoff(dp
, ndp
->ni_offset
- ndp
->ni_count
, (char **)&ep
);
ep
->d_reclen
+= ndp
->ni_dent
.d_reclen
;
* Rewrite an existing directory entry to point at the inode
* supplied. The parameters describing the directory entry are
* set up by a call to namei.
ndp
->ni_dent
.d_ino
= ip
->i_number
;
u
.u_error
= rdwri(UIO_WRITE
, dp
, (caddr_t
)&ndp
->ni_dent
,
(int)DIRSIZ(&ndp
->ni_dent
), ndp
->ni_offset
, 1, (int *)0);
* Return buffer with contents of block "offset"
* from the beginning of directory "ip". If "res"
* is non-zero, fill it in with a pointer to the
* remaining space in the directory.
blkatoff(ip
, offset
, res
)
register struct fs
*fs
= ip
->i_fs
;
daddr_t lbn
= lblkno(fs
, offset
);
int bsize
= blksize(fs
, ip
, lbn
);
bn
= bmap(ip
, lbn
, B_READ
, bsize
);
dirbad(ip
, offset
, "hole in dir");
bp
= bread(ip
->i_dev
, fsbtodb(fs
, bn
), bsize
);
if (bp
->b_flags
& B_ERROR
) {
*res
= bp
->b_un
.b_addr
+ blkoff(fs
, offset
);
* Check if a directory is empty or not.
* Inode supplied must be locked.
* Using a struct dirtemplate here is not precisely
* what we want, but better than using a struct direct.
* NB: does not handle corrupted directories.
register struct inode
*ip
;
register struct direct
*dp
= (struct direct
*)&dbuf
;
#define MINDIRSIZ (sizeof (struct dirtemplate) / 2)
for (off
= 0; off
< ip
->i_size
; off
+= dp
->d_reclen
) {
error
= rdwri(UIO_READ
, ip
, (caddr_t
)dp
, MINDIRSIZ
,
* Since we read MINDIRSIZ, residual must
* be 0 unless we're at end of file.
/* avoid infinite loops */
/* accept only "." and ".." */
if (dp
->d_name
[0] != '.')
* At this point d_namlen must be 1 or 2.
* 1 implies ".", 2 implies ".." if second
if (dp
->d_name
[1] == '.' && dp
->d_ino
== parentino
)
* Check if source directory is in the path of the target directory.
* Target is supplied locked, source is unlocked.
* The target is always iput() before returning.
checkpath(source
, target
)
struct inode
*source
, *target
;
struct dirtemplate dirbuf
;
register struct inode
*ip
;
if (ip
->i_number
== source
->i_number
) {
if (ip
->i_number
== ROOTINO
)
if ((ip
->i_mode
&IFMT
) != IFDIR
) {
error
= rdwri(UIO_READ
, ip
, (caddr_t
)&dirbuf
,
sizeof (struct dirtemplate
), (off_t
)0, 1, (int *)0);
if (dirbuf
.dotdot_namlen
!= 2 ||
dirbuf
.dotdot_name
[0] != '.' ||
dirbuf
.dotdot_name
[1] != '.') {
if (dirbuf
.dotdot_ino
== source
->i_number
) {
if (dirbuf
.dotdot_ino
== ROOTINO
)
ip
= iget(ip
->i_dev
, ip
->i_fs
, dirbuf
.dotdot_ino
);
printf("checkpath: .. not a directory\n");
* Name cache initialization, from main() when we are booting
register union nchash
*nchp
;
register struct namecache
*ncp
;
for (ncp
= namecache
; ncp
< &namecache
[nchsize
]; ncp
++) {
ncp
->nc_forw
= ncp
; /* hash chain */
ncp
->nc_nxt
= NULL
; /* lru chain */
/* all else is zero already */
for (nchp
= nchash
; nchp
< &nchash
[NCHHASH
]; nchp
++) {
nchp
->nch_head
[0] = nchp
;
nchp
->nch_head
[1] = nchp
;
* Cache flush, called when filesys is umounted to
* remove entries that would now be invalid
* The line "nxtcp = nchhead" near the end is to avoid potential problems
* if the cache lru chain is modified while we are dumping the
* inode. This makes the algorithm O(n^2), but do you think I care?
register struct namecache
*ncp
, *nxtcp
;
for (ncp
= nchhead
; ncp
; ncp
= nxtcp
) {
if (ncp
->nc_ip
== NULL
||
(ncp
->nc_idev
!= dev
&& ncp
->nc_dev
!= dev
))
/* free the resources we had */
remque(ncp
); /* remove entry from its hash chain */
ncp
->nc_forw
= ncp
; /* and make a dummy one */
/* delete this entry from LRU chain */
nxtcp
->nc_prev
= ncp
->nc_prev
;
/* cause rescan of list, it may have altered */
/* put the now-free entry at head of LRU */
nxtcp
->nc_prev
= &ncp
->nc_nxt
;
* Name cache invalidation of all entries.
register struct namecache
*ncp
;
for (ncp
= namecache
; ncp
< &namecache
[nchsize
]; ncp
++)