-/* ufs_lookup.c 4.9 82/02/26 */
+/* ufs_lookup.c 6.8 84/07/02 */
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/inode.h"
+#include "../h/fs.h"
#include "../h/mount.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/buf.h"
#include "../h/conf.h"
+#include "../h/uio.h"
+#include "../h/nami.h"
+#include "../h/kernel.h"
+
+struct buf *blkatoff();
+int dirchk = 0;
+
+/*
+ * 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))
+#else
+#define NHASH(h, i, d) ((unsigned)((h) + (i) + 13 * (int)(d)) & ((NCHHASH)-1))
+#endif
+
+union nchash {
+ union nchash *nch_head[2];
+ struct nch *nch_chain[2];
+} nchash[NCHHASH];
+#define nch_forw nch_chain[0]
+#define nch_back nch_chain[1]
+
+struct nch *nchhead, **nchtail; /* LRU chain pointers */
+struct nchstats nchstats; /* cache effectiveness statistics */
/*
- * Convert a pathname into a pointer to
- * a locked inode.
+ * Convert a pathname into a pointer to a locked inode,
+ * with side effects usable in creating and removing files.
+ * This is a very central and rather complicated routine.
+ *
+ * The func argument gives the routine which returns successive
+ * characters of the name to be translated.
+ *
+ * The flag argument is (LOOKUP, CREATE, DELETE) depending on whether
+ * the name is to be (looked up, created, deleted). 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.
+ * If the file system is not maintained in a strict tree hierarchy,
+ * this can result in a deadlock situation. 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.
*
- * func = function called to get next char of name
- * &uchar if name is in user space
- * &schar if name is in system space
- * flag = 0 if name is sought
- * 1 if name is to be created
- * 2 if name is to be deleted
- * follow = 1 if links are to be followed at the end of the name
+ * The follow argument is 1 when symbolic links are to be followed
+ * when they occur at the end of the name translation process.
+ *
+ * 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
+ * some (small) maximum length 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.
+ *
+ * We must be sure never to enter the name ".." into the cache
+ * because of the extremely kludgey way that rename() alters
+ * ".." in a situation like
+ * mv a/x b/x
+ * where x is a directory, and x/.. is the ".." in question.
+ *
+ * Overall outline of namei:
+ *
+ * copy in name
+ * get starting directory
+ * dirloop:
+ * check accessibility of directory
+ * dirloop2:
+ * copy next component of name to u.u_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
+ * notfound:
+ * if creating, return locked directory, leaving info on avail. slots
+ * else return error
+ * found:
+ * 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, if neither creating nor deleting, add name to cache
+ * haveino:
+ * 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,
+ * but unlocked.
*/
struct inode *
namei(func, flag, follow)
int (*func)(), flag, follow;
{
- register struct inode *dp;
- register char *cp;
- register struct buf *bp, *nbp;
- register struct direct *ep;
- int i, nlink;
- dev_t d;
- ino_t ino;
- off_t eo;
+ 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 nch *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; /* u.u_offset of previous entry */
+ int nlink = 0; /* number of symbolic links taken */
+ struct inode *pdp; /* saved dp during symlink work */
+ int i;
+ int lockparent;
+ int docache;
+ unsigned hash; /* value of name hash for entry */
+ union nchash *nhp; /* cache chain head for entry */
+ int isdotdot; /* != 0 if current name is ".." */
+ lockparent = flag & LOCKPARENT;
+ docache = (flag & NOCACHE) ^ NOCACHE;
+ flag &= ~(LOCKPARENT|NOCACHE);
+ if (flag == DELETE)
+ docache = 0;
/*
- * allocate name buffer; copy name
+ * Get a buffer for the name to be translated, and copy the
+ * name into the buffer.
*/
- nbp = geteblk();
- nlink = 0;
- for (i=0, cp = nbp->b_un.b_addr; *cp = (*func)(); i++) {
- if (*cp++&0200 && flag==1 || cp >= nbp->b_un.b_addr+BSIZE) {
+ nbp = geteblk(MAXPATHLEN);
+ for (cp = nbp->b_un.b_addr; *cp = (*func)(); ) {
+ if ((*cp&0377) == ('/'|0200) || (*cp&0200) && flag != DELETE) {
+ u.u_error = EPERM;
+ goto bad;
+ }
+ cp++;
+ if (cp >= nbp->b_un.b_addr + MAXPATHLEN) {
u.u_error = ENOENT;
- break;
+ goto bad;
}
}
- if (u.u_error) {
- dp = NULL;
- goto out1;
- }
- cp = nbp->b_un.b_addr;
+ if (u.u_error)
+ goto bad;
+
/*
- * If name starts with '/' start from
- * root; otherwise start from current dir.
+ * Get starting directory.
*/
- dp = u.u_cdir;
+ cp = nbp->b_un.b_addr;
if (*cp == '/') {
while (*cp == '/')
cp++;
if ((dp = u.u_rdir) == NULL)
dp = rootdir;
- }
+ } else
+ dp = u.u_cdir;
+ fs = dp->i_fs;
ilock(dp);
dp->i_count++;
+ u.u_pdir = (struct inode *)0xc0000000; /* illegal */
/*
- * dp must be a directory and
- * must have X permission.
- * cp is a path name relative to that directory.
+ * 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.
*/
-
dirloop:
- if ((dp->i_mode&IFMT) != IFDIR)
+ /*
+ * Check accessiblity of directory.
+ */
+ if ((dp->i_mode&IFMT) != IFDIR) {
u.u_error = ENOTDIR;
- (void) access(dp, IEXEC);
- for (i=0; *cp!='\0' && *cp!='/'; i++) {
- if (i >= DIRSIZ) {
+ goto bad;
+ }
+ if (access(dp, IEXEC))
+ goto bad;
+
+dirloop2:
+ /*
+ * Copy next component of name to u.u_dent.
+ */
+ hash = 0;
+ for (i = 0; *cp != 0 && *cp != '/'; cp++) {
+ if (i >= MAXNAMLEN) {
u.u_error = ENOENT;
- break;
+ goto bad;
}
- u.u_dbuf[i] = *cp++;
+ u.u_dent.d_name[i++] = *cp;
+ hash += (unsigned char)*cp * i;
}
- if (u.u_error)
- goto out;
- while (i < DIRSIZ)
- u.u_dbuf[i++] = '\0';
- if (u.u_dbuf[0] == '\0') { /* null name, e.g. "/" or "" */
- if (flag) {
- u.u_error = ENOENT;
- goto out;
+ u.u_dent.d_namlen = i;
+ u.u_dent.d_name[i] = 0;
+
+ /*
+ * Check for degenerate name (e.g. / or "")
+ * which is a way of talking about a directory,
+ * e.g. like "/." or ".".
+ */
+ if (u.u_dent.d_name[0] == 0) {
+ if (flag != LOOKUP || lockparent) {
+ u.u_error = EISDIR;
+ goto bad;
}
- goto out1;
+ brelse(nbp);
+ return (dp);
}
- u.u_segflg = 1;
- eo = -1;
- bp = NULL;
- for (u.u_offset=0; u.u_offset < dp->i_size;
- u.u_offset += sizeof(struct direct), ep++) {
+ /*
+ * 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 (u.u_dent.d_namlen > NCHNAMLEN) {
+ nchstats.ncs_long++;
+ docache = 0;
+ } else {
+ nhp = &nchash[NHASH(hash, dp->i_number, dp->i_dev)];
+ for (ncp = nhp->nch_forw; ncp != (struct nch *)nhp;
+ ncp = ncp->nc_forw) {
+ if (ncp->nc_ino == dp->i_number &&
+ ncp->nc_dev == dp->i_dev &&
+ ncp->nc_nlen == u.u_dent.d_namlen &&
+ !bcmp(ncp->nc_name, u.u_dent.d_name, ncp->nc_nlen))
+ break;
+ }
+
+ if (ncp == (struct nch *)nhp) {
+ nchstats.ncs_miss++;
+ ncp = NULL;
+ } else {
+ if (ncp->nc_id != ncp->nc_ip->i_id)
+ nchstats.ncs_falsehits++;
+ else if (*cp == '/' || docache) {
+
+ nchstats.ncs_goodhits++;
+
+ /*
+ * move this slot to end of LRU
+ * chain, if not already there
+ */
+ if (ncp->nc_nxt) {
+ /* remove from LRU chain */
+ *ncp->nc_prev = ncp->nc_nxt;
+ ncp->nc_nxt->nc_prev = ncp->nc_prev;
+
+ /* and replace at end of it */
+ ncp->nc_nxt = NULL;
+ ncp->nc_prev = nchtail;
+ *nchtail = ncp;
+ nchtail = &ncp->nc_nxt;
+ }
+
+ pdp = dp;
+ dp = ncp->nc_ip;
+ if (dp == NULL)
+ panic("nami: null cache ino");
+ if (pdp == dp)
+ dp->i_count++;
+ else if (dp->i_count) {
+ dp->i_count++;
+ ilock(dp);
+ iunlock(pdp);
+ } else {
+ igrab(dp);
+ iunlock(pdp);
+ }
+
+ u.u_dent.d_ino = dp->i_number;
+ /* u_dent.d_reclen is garbage ... */
+
+ goto haveino;
+ } else
+ nchstats.ncs_badhits++;
+
+ /*
+ * 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;
+ if (ncp->nc_nxt)
+ ncp->nc_nxt->nc_prev = ncp->nc_prev;
+ else
+ nchtail = ncp->nc_prev;
+
+ /* remove from hash chain */
+ remque(ncp);
+
+ /* insert at head of LRU list (first to grab) */
+ ncp->nc_nxt = nchhead;
+ ncp->nc_prev = &nchhead;
+ nchhead->nc_prev = &ncp->nc_nxt;
+ nchhead = ncp;
+
+ /* and make a dummy hash chain */
+ ncp->nc_forw = ncp;
+ ncp->nc_back = ncp;
+
+ ncp = NULL;
+ }
+ }
+
+ /*
+ * 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.
+ */
+ slotstatus = FOUND;
+ if (flag == CREATE && *cp == 0) {
+ slotstatus = NONE;
+ slotfreespace = 0;
+ slotneeded = DIRSIZ(&u.u_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) {
+ u.u_offset = 0;
+ numdirpasses = 1;
+ } else {
+ if ((dp->i_flag & ICHG) || dp->i_ctime >= u.u_ncache.nc_time) {
+ u.u_ncache.nc_prevoffset &= ~(DIRBLKSIZ - 1);
+ u.u_ncache.nc_time = time.tv_sec;
+ }
+ u.u_offset = u.u_ncache.nc_prevoffset;
+ entryoffsetinblock = blkoff(fs, u.u_offset);
+ if (entryoffsetinblock != 0) {
+ bp = blkatoff(dp, u.u_offset, (char **)0);
+ if (bp == 0)
+ goto bad;
+ }
+ numdirpasses = 2;
+ nchstats.ncs_2passes++;
+ }
+ endsearch = roundup(dp->i_size, DIRBLKSIZ);
+
+searchloop:
+ while (u.u_offset < endsearch) {
/*
* If offset is on a block boundary,
* read the next directory block.
* Release previous if it exists.
*/
- if ((u.u_offset&BMASK) == 0) {
+ if (blkoff(fs, u.u_offset) == 0) {
if (bp != NULL)
brelse(bp);
- bp = bread(dp->i_dev,
- bmap(dp,(daddr_t)(u.u_offset>>BSHIFT), B_READ));
- if (bp->b_flags & B_ERROR) {
- brelse(bp);
- goto out;
- }
- ep = (struct direct *)bp->b_un.b_addr;
+ bp = blkatoff(dp, u.u_offset, (char **)0);
+ if (bp == 0)
+ goto bad;
+ entryoffsetinblock = 0;
}
+
/*
- * Note first empty directory slot
- * in eo for possible creat.
- * String compare the directory entry
- * and the current component.
+ * If still looking for a slot, and at a DIRBLKSIZE
+ * boundary, have to start looking for free space again.
*/
- if (ep->d_ino == 0) {
- if (eo < 0)
- eo = u.u_offset;
- continue;
+ if (slotstatus == NONE &&
+ (entryoffsetinblock&(DIRBLKSIZ-1)) == 0) {
+ slotoffset = -1;
+ slotfreespace = 0;
}
- if (strncmp(u.u_dbuf, ep->d_name, DIRSIZ) != 0)
- continue;
+
/*
- * Here a component matched in a directory.
- * If there is more pathname, go back to
- * dirloop, otherwise return.
+ * 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
+ * "dirchk" to be true.
*/
- bcopy((caddr_t)ep, (caddr_t)&u.u_dent, sizeof(struct direct));
- brelse(bp);
- if (flag==2 && *cp=='\0') {
- if (access(dp, IWRITE))
- goto out;
- /* should fix unlink */
- u.u_offset += sizeof(struct direct);
- goto out1;
+ ep = (struct direct *)(bp->b_un.b_addr + entryoffsetinblock);
+ if (ep->d_reclen <= 0 ||
+ dirchk && dirbadentry(ep, entryoffsetinblock)) {
+ dirbad(dp, "mangled entry");
+ i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1));
+ u.u_offset += i;
+ entryoffsetinblock += i;
+ continue;
}
+
/*
- * Special handling for ".."
+ * 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
+ * compaction is viable.
*/
- if (u.u_dent.d_name[0]=='.' && u.u_dent.d_name[1]=='.' &&
- u.u_dent.d_name[2]=='\0') {
- if (dp == u.u_rdir)
- u.u_dent.d_ino = dp->i_number;
- else if (u.u_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) {
- iput(dp);
- dp = mount[i].m_inodp;
- ilock(dp);
- dp->i_count++;
- cp -= 2; /* back over .. */
- goto dirloop;
+ if (slotstatus != FOUND) {
+ int size = ep->d_reclen;
+
+ if (ep->d_ino != 0)
+ size -= DIRSIZ(ep);
+ if (size > 0) {
+ if (size >= slotneeded) {
+ slotstatus = FOUND;
+ slotoffset = u.u_offset;
+ slotsize = ep->d_reclen;
+ } else if (slotstatus == NONE) {
+ slotfreespace += size;
+ if (slotoffset == -1)
+ slotoffset = u.u_offset;
+ if (slotfreespace >= slotneeded) {
+ slotstatus = COMPACT;
+ slotsize =
+ u.u_offset+ep->d_reclen -
+ slotoffset;
}
+ }
}
}
- d = dp->i_dev;
- ino = dp->i_number;
- iput(dp);
- dp = iget(d, u.u_dent.d_ino);
- if (dp == NULL)
- goto out1;
+
/*
- * Check for symbolic link
+ * Check for a name match.
*/
- if ((dp->i_mode&IFMT)==IFLNK && (follow || *cp=='/')) {
- char *ocp;
-
- ocp = cp;
- while (*cp++)
- ;
- if (dp->i_size + (cp-ocp) >= BSIZE-1 || ++nlink>8) {
- u.u_error = ELOOP;
- goto out;
- }
- bcopy(ocp, nbp->b_un.b_addr+dp->i_size, cp-ocp);
- bp = bread(dp->i_dev, bmap(dp, (daddr_t)0, B_READ));
- if (bp->b_flags & B_ERROR) {
- brelse(bp);
- goto out;
- }
- bcopy(bp->b_un.b_addr, nbp->b_un.b_addr, dp->i_size);
+ if (ep->d_ino) {
+ if (ep->d_namlen == u.u_dent.d_namlen &&
+ !bcmp(u.u_dent.d_name, ep->d_name, ep->d_namlen))
+ goto found;
+ }
+ prevoff = u.u_offset;
+ u.u_offset += ep->d_reclen;
+ entryoffsetinblock += ep->d_reclen;
+ }
+/* notfound: */
+ /*
+ * If we started in the middle of the directory and failed
+ * to find our target, we must check the beginning as well.
+ */
+ if (numdirpasses == 2) {
+ numdirpasses--;
+ u.u_offset = 0;
+ endsearch = u.u_ncache.nc_prevoffset;
+ goto searchloop;
+ }
+ /*
+ * 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.
+ */
+ if (access(dp, IWRITE))
+ goto bad;
+ /*
+ * Return an indication of where the new directory
+ * entry should be put. If we didn't find a slot,
+ * then set u.u_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 [u.u_offset..u.u_offset+u.u_count)
+ */
+ if (slotstatus == NONE) {
+ u.u_offset = roundup(dp->i_size, DIRBLKSIZ);
+ u.u_count = 0;
+ } else {
+ u.u_offset = slotoffset;
+ u.u_count = slotsize;
+ }
+ dp->i_flag |= IUPD|ICHG;
+ if (bp)
brelse(bp);
- cp = nbp->b_un.b_addr;
- iput(dp);
- if (*cp == '/') {
- while (*cp == '/')
- cp++;
- if ((dp = u.u_rdir) == NULL)
- dp = rootdir;
+ brelse(nbp);
+ /*
+ * 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 u.u_pdir.
+ */
+ u.u_pdir = dp;
+ return (NULL);
+ }
+ u.u_error = ENOENT;
+ goto bad;
+found:
+ if (numdirpasses == 2)
+ nchstats.ncs_pass2++;
+ /*
+ * Check that directory length properly reflects presence
+ * of this entry.
+ */
+ if (entryoffsetinblock + DIRSIZ(ep) > dp->i_size) {
+ dirbad(dp, "i_size too small");
+ dp->i_size = entryoffsetinblock + DIRSIZ(ep);
+ dp->i_flag |= IUPD|ICHG;
+ }
+
+ /*
+ * 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 = u.u_offset;
+ u.u_ncache.nc_inumber = dp->i_number;
+ u.u_ncache.nc_dev = dp->i_dev;
+ u.u_ncache.nc_time = time.tv_sec;
+ }
+ /*
+ * Save directory entry in u.u_dent,
+ * and release directory buffer.
+ */
+ bcopy((caddr_t)ep, (caddr_t)&u.u_dent, (u_int)DIRSIZ(ep));
+ brelse(bp);
+ bp = NULL;
+
+ /*
+ * 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 u.u_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.
+ */
+ if (access(dp, IWRITE))
+ goto bad;
+ u.u_pdir = dp; /* for dirremove() */
+ /*
+ * Return pointer to current entry in u.u_offset,
+ * and distance past previous entry (if there
+ * is a previous entry in this block) in u.u_count.
+ * Save directory inode pointer in u.u_pdir for dirremove().
+ */
+ if ((u.u_offset&(DIRBLKSIZ-1)) == 0)
+ u.u_count = 0;
+ else
+ u.u_count = u.u_offset - prevoff;
+ if (lockparent) {
+ if (dp->i_number == u.u_dent.d_ino)
+ dp->i_count++;
+ else {
+ dp = iget(dp->i_dev, fs, u.u_dent.d_ino);
+ if (dp == NULL) {
+ iput(u.u_pdir);
+ goto bad;
+ }
+ /*
+ * 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 ((u.u_pdir->i_mode & ISVTX) &&
+ u.u_uid != 0 &&
+ u.u_uid != u.u_pdir->i_uid &&
+ dp->i_uid != u.u_uid) {
+ iput(u.u_pdir);
+ u.u_error = EPERM;
+ goto bad;
+ }
+ }
+ }
+ brelse(nbp);
+ return (dp);
+ }
+
+ /*
+ * Special handling for ".." allowing chdir out of mounted
+ * file system: indirect .. in root inode to reevaluate
+ * in directory file system was mounted on.
+ */
+ isdotdot = 0;
+ if (bcmp(u.u_dent.d_name, "..", 3) == 0) {
+ isdotdot++;
+ if (dp == u.u_rdir)
+ u.u_dent.d_ino = dp->i_number;
+ else if (u.u_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) {
+ iput(dp);
+ dp = mount[i].m_inodp;
ilock(dp);
dp->i_count++;
- } else {
- dp = iget(d, ino); /* retrieve directory */
- if (dp == NULL)
- goto out1;
+ fs = dp->i_fs;
+ cp -= 2; /* back over .. */
+ goto dirloop2;
}
- goto dirloop;
}
+ }
+
+ /*
+ * 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) {
+ if (access(dp, IWRITE))
+ goto bad;
+ u.u_pdir = dp; /* for dirrewrite() */
+ /*
+ * Careful about locking second inode.
+ * This can only occur if the target is ".".
+ */
+ if (dp->i_number == u.u_dent.d_ino) {
+ u.u_error = EISDIR; /* XXX */
+ goto bad;
+ }
+ dp = iget(dp->i_dev, fs, u.u_dent.d_ino);
+ if (dp == NULL) {
+ iput(u.u_pdir);
+ goto bad;
+ }
+ brelse(nbp);
+ return (dp);
+ }
+
+ /*
+ * 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.
+ */
+ pdp = dp;
+ if (isdotdot) {
+ iunlock(pdp); /* race to get the inode */
+ dp = iget(dp->i_dev, fs, u.u_dent.d_ino);
+ if (dp == NULL)
+ goto bad2;
+ } else if (dp->i_number == u.u_dent.d_ino) {
+ dp->i_count++; /* we want ourself, ie "." */
+ } else {
+ dp = iget(dp->i_dev, fs, u.u_dent.d_ino);
+ iunlock(pdp);
+ if (dp == NULL)
+ goto bad2;
+ }
+
+ /*
+ * insert name into cache (if we want it, and it isn't "." or "..")
+ *
+ * all other cases where making a cache entry would be wrong
+ * have already departed from the code sequence somewhere above.
+ */
+ if (docache) {
+ if (ncp != NULL)
+ panic("nami: duplicating cache");
+
+ /*
+ * free the cache slot at head of lru chain
+ */
+ if (ncp = nchhead) {
+ /* remove from lru chain */
+ *ncp->nc_prev = ncp->nc_nxt;
+ if (ncp->nc_nxt)
+ ncp->nc_nxt->nc_prev = ncp->nc_prev;
+ else
+ nchtail = ncp->nc_prev;
+
+ /* remove from old hash chain */
+ remque(ncp);
+
+ /* grab the inode we just found */
+ ncp->nc_ip = dp;
+
+ /* fill in cache info */
+ 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 = u.u_dent.d_namlen;
+ bcopy(u.u_dent.d_name, ncp->nc_name, ncp->nc_nlen);
+
+ /* link at end of lru chain */
+ ncp->nc_nxt = NULL;
+ ncp->nc_prev = nchtail;
+ *nchtail = ncp;
+ nchtail = &ncp->nc_nxt;
+
+ /* and insert on hash chain */
+ insque(ncp, nhp);
+ }
+ }
+
+haveino:
+ fs = dp->i_fs;
+
+ /*
+ * Check for symbolic link
+ */
+ if ((dp->i_mode & IFMT) == IFLNK && (follow || *cp == '/')) {
+ u_int pathlen = strlen(cp) + 1;
+
+ if (dp->i_size + pathlen >= MAXPATHLEN - 1 ||
+ ++nlink > MAXSYMLINKS) {
+ u.u_error = ELOOP;
+ goto bad2;
+ }
+ ovbcopy(cp, nbp->b_un.b_addr + dp->i_size, pathlen);
+ u.u_error =
+ rdwri(UIO_READ, dp, nbp->b_un.b_addr, (int)dp->i_size,
+ 0, 1, (int *)0);
+ if (u.u_error)
+ goto bad2;
+ cp = nbp->b_un.b_addr;
+ iput(dp);
if (*cp == '/') {
+ irele(pdp);
while (*cp == '/')
cp++;
- goto dirloop;
+ if ((dp = u.u_rdir) == NULL)
+ dp = rootdir;
+ ilock(dp);
+ dp->i_count++;
+ } else {
+ dp = pdp;
+ ilock(dp);
}
- goto out1;
+ fs = dp->i_fs;
+ goto dirloop;
}
+
/*
- * Search failed.
+ * Not a symbolic link. If more pathname,
+ * continue at next component, else return.
*/
- if (bp != NULL)
- brelse(bp);
- if (flag==1 && *cp=='\0' && dp->i_nlink) {
- if (access(dp, IWRITE))
- goto out;
- u.u_pdir = dp;
- if (eo>=0)
- u.u_offset = eo;
- dp->i_flag |= IUPD|ICHG;
- dp = NULL;
- goto out1;
+ if (*cp == '/') {
+ while (*cp == '/')
+ cp++;
+ irele(pdp);
+ goto dirloop;
}
- u.u_error = ENOENT;
-out:
- iput(dp);
- dp = NULL;
-out1:
brelse(nbp);
+ if (lockparent)
+ u.u_pdir = pdp;
+ else
+ irele(pdp);
return (dp);
+bad2:
+ irele(pdp);
+bad:
+ if (bp)
+ brelse(bp);
+ if (dp)
+ iput(dp);
+ brelse(nbp);
+ return (NULL);
+}
+
+
+dirbad(ip, how)
+ struct inode *ip;
+ char *how;
+{
+
+ printf("%s: bad dir ino %d at offset %d: %s\n",
+ ip->i_fs->fs_fsmnt, ip->i_number, u.u_offset, how);
}
/*
- * Return the next character from the
- * kernel string pointed at by dirp.
+ * Do consistency checking on a directory entry:
+ * record length must be multiple of 4
+ * record length must not be non-negative
+ * 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
*/
-schar()
+dirbadentry(ep, entryoffsetinblock)
+ register struct direct *ep;
+ int entryoffsetinblock;
{
+ register int i;
- return (*u.u_dirp++ & 0377);
+ if ((ep->d_reclen & 0x3) != 0 || ep->d_reclen <= 0 ||
+ ep->d_reclen > DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1)) ||
+ ep->d_reclen < DIRSIZ(ep) || ep->d_namlen > MAXNAMLEN)
+ return (1);
+ for (i = 0; i < ep->d_namlen; i++)
+ if (ep->d_name[i] == 0)
+ return (1);
+ return (ep->d_name[i]);
}
/*
- * Return the next character from the
- * user string pointed at by dirp.
+ * 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 u.u_pdir is
+ * a pointer to the directory to be written, which was left locked by
+ * namei. Remaining parameters (u.u_offset, u.u_count) indicate
+ * how the space for the new entry is to be gotten.
*/
-uchar()
+direnter(ip)
+ struct inode *ip;
{
- register c;
+ register struct direct *ep, *nep;
+ struct buf *bp;
+ int loc, spacefree, error = 0;
+ u_int dsize;
+ int newentrysize;
+ char *dirbuf;
- c = fubyte(u.u_dirp++);
- if (c == -1) {
- u.u_error = EFAULT;
- c = 0;
+ u.u_dent.d_ino = ip->i_number;
+ u.u_segflg = 1;
+ newentrysize = DIRSIZ(&u.u_dent);
+ if (u.u_count == 0) {
+ /*
+ * If u.u_count is 0, then namei could find no space in the
+ * directory. In this case u.u_offset will be on a directory
+ * block boundary and we will write the new entry into a fresh
+ * block.
+ */
+ if (u.u_offset&(DIRBLKSIZ-1))
+ panic("wdir: newblk");
+ u.u_dent.d_reclen = DIRBLKSIZ;
+ error = rdwri(UIO_WRITE, u.u_pdir, (caddr_t)&u.u_dent,
+ newentrysize, u.u_offset, 1, (int *)0);
+ iput(u.u_pdir);
+ return (error);
+ }
+
+ /*
+ * If u.u_count is non-zero, then namei found space for the
+ * new entry in the range u.u_offset to u.u_offset+u.u_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
+ * DIRBLKSIZE.
+ */
+ if (u.u_offset + u.u_count > u.u_pdir->i_size)
+ u.u_pdir->i_size = u.u_offset + u.u_count;
+
+ /*
+ * Get the block containing the space for the new directory
+ * entry. Should return error by result instead of u.u_error.
+ */
+ bp = blkatoff(u.u_pdir, u.u_offset, (char **)&dirbuf);
+ if (bp == 0) {
+ iput(u.u_pdir);
+ return (u.u_error);
+ }
+
+ /*
+ * 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
+ * u.u_offset to u.u_offset+u.u_count would yield the space.
+ */
+ ep = (struct direct *)dirbuf;
+ dsize = DIRSIZ(ep);
+ spacefree = ep->d_reclen - dsize;
+ for (loc = ep->d_reclen; loc < u.u_count; ) {
+ nep = (struct direct *)(dirbuf + loc);
+ if (ep->d_ino) {
+ /* trim the existing slot */
+ ep->d_reclen = dsize;
+ ep = (struct direct *)((char *)ep + dsize);
+ } else {
+ /* overwrite; nothing there; header is ours */
+ spacefree += dsize;
+ }
+ dsize = DIRSIZ(nep);
+ spacefree += nep->d_reclen - dsize;
+ loc += nep->d_reclen;
+ 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 (ep->d_ino == 0) {
+ if (spacefree + dsize < newentrysize)
+ panic("wdir: compact1");
+ u.u_dent.d_reclen = spacefree + dsize;
+ } else {
+ if (spacefree < newentrysize)
+ panic("wdir: compact2");
+ u.u_dent.d_reclen = spacefree;
+ ep->d_reclen = dsize;
+ ep = (struct direct *)((char *)ep + dsize);
}
- return (c);
+ bcopy((caddr_t)&u.u_dent, (caddr_t)ep, (u_int)newentrysize);
+ bwrite(bp);
+ u.u_pdir->i_flag |= IUPD|ICHG;
+ iput(u.u_pdir);
+ return (error);
}
-#ifndef vax
-strncmp(s1, s2, len)
- register char *s1, *s2;
- register len;
+/*
+ * Remove a directory entry after a call to namei, using the
+ * parameters which it left in the u. area. The u. entry
+ * u_offset contains the offset into the directory of the
+ * entry to be eliminated. The u_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.
+ */
+dirremove()
{
+ register struct inode *dp = u.u_pdir;
+ register struct buf *bp;
+ struct direct *ep;
- do {
- if (*s1 != *s2++)
- return (1);
- if (*s1++ == '\0')
+ if (u.u_count == 0) {
+ /*
+ * First entry in block: set d_ino to zero.
+ */
+ u.u_dent.d_ino = 0;
+ (void) rdwri(UIO_WRITE, dp, (caddr_t)&u.u_dent,
+ (int)DIRSIZ(&u.u_dent), u.u_offset, 1, (int *)0);
+ } else {
+ /*
+ * Collapse new free space into previous entry.
+ */
+ bp = blkatoff(dp, (int)(u.u_offset - u.u_count), (char **)&ep);
+ if (bp == 0)
return (0);
- } while (--len);
- return (0);
+ ep->d_reclen += u.u_dent.d_reclen;
+ bwrite(bp);
+ dp->i_flag |= IUPD|ICHG;
+ }
+ return (1);
+}
+
+/*
+ * 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.
+ */
+dirrewrite(dp, ip)
+ struct inode *dp, *ip;
+{
+
+ u.u_dent.d_ino = ip->i_number;
+ u.u_error = rdwri(UIO_WRITE, dp, (caddr_t)&u.u_dent,
+ (int)DIRSIZ(&u.u_dent), u.u_offset, 1, (int *)0);
+ iput(dp);
+}
+
+/*
+ * 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.
+ */
+struct buf *
+blkatoff(ip, offset, res)
+ struct inode *ip;
+ off_t offset;
+ char **res;
+{
+ register struct fs *fs = ip->i_fs;
+ daddr_t lbn = lblkno(fs, offset);
+ int base = blkoff(fs, offset);
+ int bsize = blksize(fs, ip, lbn);
+ daddr_t bn = fsbtodb(fs, bmap(ip, lbn, B_WRITE, base, bsize));
+ register struct buf *bp;
+
+ if (u.u_error)
+ return (0);
+ bp = bread(ip->i_dev, bn, bsize);
+ if (bp->b_flags & B_ERROR) {
+ brelse(bp);
+ return (0);
+ }
+ if (res)
+ *res = bp->b_un.b_addr + base;
+ return (bp);
+}
+
+/*
+ * 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.
+ */
+dirempty(ip)
+ register struct inode *ip;
+{
+ register off_t off;
+ struct dirtemplate dbuf;
+ register struct direct *dp = (struct direct *)&dbuf;
+ int error, count;
+#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,
+ off, 1, &count);
+ /*
+ * Since we read MINDIRSIZ, residual must
+ * be 0 unless we're at end of file.
+ */
+ if (error || count != 0)
+ return (0);
+ /* skip empty entries */
+ if (dp->d_ino == 0)
+ continue;
+ /* accept only "." and ".." */
+ if (dp->d_namlen > 2)
+ return (0);
+ if (dp->d_name[0] != '.')
+ return (0);
+ /*
+ * At this point d_namlen must be 1 or 2.
+ * 1 implies ".", 2 implies ".." if second
+ * char is also "."
+ */
+ if (dp->d_namlen == 1 || dp->d_name[1] == '.')
+ continue;
+ return (0);
+ }
+ return (1);
+}
+
+/*
+ * 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;
+ int error = 0;
+
+ ip = target;
+ if (ip->i_number == source->i_number) {
+ error = EEXIST;
+ goto out;
+ }
+ if (ip->i_number == ROOTINO)
+ goto out;
+
+ for (;;) {
+ if ((ip->i_mode&IFMT) != IFDIR) {
+ error = ENOTDIR;
+ break;
+ }
+ error = rdwri(UIO_READ, ip, (caddr_t)&dirbuf,
+ sizeof (struct dirtemplate), (off_t)0, 1, (int *)0);
+ if (error != 0)
+ break;
+ if (dirbuf.dotdot_namlen != 2 ||
+ bcmp(dirbuf.dotdot_name, "..", 3) != 0) {
+ error = ENOTDIR;
+ break;
+ }
+ if (dirbuf.dotdot_ino == source->i_number) {
+ error = EINVAL;
+ break;
+ }
+ if (dirbuf.dotdot_ino == ROOTINO)
+ break;
+ iput(ip);
+ ip = iget(ip->i_dev, ip->i_fs, dirbuf.dotdot_ino);
+ if (ip == NULL) {
+ error = u.u_error;
+ break;
+ }
+ }
+
+out:
+ if (error == ENOTDIR)
+ printf("checkpath: .. not a directory\n");
+ if (ip != NULL)
+ iput(ip);
+ return (error);
+}
+
+/*
+ * Name cache initialization, from main() when we are booting
+ */
+nchinit()
+{
+ register union nchash *nchp;
+ register struct nch *ncp;
+
+ nchhead = 0;
+ nchtail = &nchhead;
+
+ for (ncp = nch; ncp < &nch[nchsize]; ncp++) {
+ ncp->nc_forw = ncp; /* hash chain */
+ ncp->nc_back = ncp;
+
+ ncp->nc_nxt = NULL; /* lru chain */
+ *nchtail = ncp;
+ ncp->nc_prev = nchtail;
+ nchtail = &ncp->nc_nxt;
+
+ /* 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?
+ */
+nchinval(dev)
+ register dev_t dev;
+{
+ register struct nch *ncp, *nxtcp;
+
+ for (ncp = nchhead; ncp; ncp = nxtcp) {
+ nxtcp = ncp->nc_nxt;
+
+ if (ncp->nc_ip == NULL ||
+ (ncp->nc_idev != dev && ncp->nc_dev != dev))
+ continue;
+
+ ncp->nc_idev = NODEV;
+ ncp->nc_dev = NODEV;
+ ncp->nc_ino = 0;
+
+ /* remove the entry from its hash chain */
+ remque(ncp);
+ /* and make a dummy one */
+ ncp->nc_forw = ncp;
+ ncp->nc_back = ncp;
+
+ /* delete this entry from LRU chain */
+ *ncp->nc_prev = nxtcp;
+ if (nxtcp)
+ nxtcp->nc_prev = ncp->nc_prev;
+ else
+ nchtail = ncp->nc_prev;
+
+ /* free the inode we had */
+ irele(ncp->nc_ip);
+ ncp->nc_ip = NULL;
+
+ /* cause rescan of list, it may have altered */
+ nxtcp = nchhead;
+ /* put the now-free entry at head of LRU */
+ ncp->nc_nxt = nxtcp;
+ ncp->nc_prev = &nchhead;
+ nxtcp->nc_prev = &ncp->nc_nxt;
+ nchhead = ncp;
+ }
}
-#endif