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Add diclaimer of copyright to _osname() manual page.
[unix-history] / sys / fs / msdosfs / msdosfs_lookup.c
/*
* Written by Paul Popelka (paulp@uts.amdahl.com)
*
* You can do anything you want with this software, just don't say you wrote
* it, and don't remove this notice.
*
* This software is provided "as is".
*
* The author supplies this software to be publicly redistributed on the
* understanding that the author is not responsible for the correct
* functioning of this software in any circumstances and is not liable for
* any damages caused by this software.
*
* October 1992
*
* from NetBSD: msdosfs_lookup.c,v 1.5 1993/12/18 00:51:09 mycroft Exp
* $Id: msdosfs_lookup.c,v 1.1 1994/01/24 06:04:55 rgrimes Exp $
*/
#include <sys/param.h>
#include <sys/namei.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <fs/msdosfs/bpb.h>
#include <fs/msdosfs/direntry.h>
#include <fs/msdosfs/denode.h>
#include <fs/msdosfs/msdosfsmount.h>
#include <fs/msdosfs/fat.h>
/*
* When we search a directory the blocks containing directory entries are
* read and examined. The directory entries contain information that would
* normally be in the inode of a unix filesystem. This means that some of
* a directory's contents may also be in memory resident denodes (sort of
* an inode). This can cause problems if we are searching while some other
* process is modifying a directory. To prevent one process from accessing
* incompletely modified directory information we depend upon being the
* soul owner of a directory block. bread/brelse provide this service.
* This being the case, when a process modifies a directory it must first
* acquire the disk block that contains the directory entry to be modified.
* Then update the disk block and the denode, and then write the disk block
* out to disk. This way disk blocks containing directory entries and in
* memory denode's will be in synch.
*/
int
msdosfs_lookup(vdp, ndp, p)
struct vnode *vdp; /* vnode of directory to search */
struct nameidata *ndp;
struct proc *p;
{
daddr_t bn;
int flag;
int error;
int lockparent;
int wantparent;
int slotstatus;
#define NONE 0
#define FOUND 1
int slotoffset;
int slotcluster;
int frcn;
u_long cluster;
int rootreloff;
int diroff;
int isadir; /* ~0 if found direntry is a directory */
u_long scn; /* starting cluster number */
struct denode *dp;
struct denode *pdp;
struct denode *tdp;
struct msdosfsmount *pmp;
struct buf *bp = 0;
struct direntry *dep;
u_char dosfilename[12];
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): looking for %s\n", ndp->ni_ptr);
#endif /* defined(MSDOSFSDEBUG) */
ndp->ni_dvp = vdp;
ndp->ni_vp = NULL;
dp = VTODE(vdp);
pmp = dp->de_pmp;
lockparent = ndp->ni_nameiop & LOCKPARENT;
flag = ndp->ni_nameiop & OPMASK;
wantparent = ndp->ni_nameiop & (LOCKPARENT | WANTPARENT);
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): vdp %08x, dp %08x, Attr %02x\n",
vdp, dp, dp->de_Attributes);
#endif /* defined(MSDOSFSDEBUG) */
/*
* Be sure vdp is a directory. Since dos filesystems don't have
* the concept of execute permission anybody can search a
* directory.
*/
if ((dp->de_Attributes & ATTR_DIRECTORY) == 0)
return ENOTDIR;
/*
* See if the component of the pathname we are looking for is in
* the directory cache. If so then do a few things and return.
*/
if (error = cache_lookup(ndp)) {
int vpid;
if (error == ENOENT)
return error;
#ifdef PARANOID
if (vdp == ndp->ni_rootdir && ndp->ni_isdotdot)
panic("msdosfs_lookup: .. thru root");
#endif /* PARANOID */
pdp = dp;
vdp = ndp->ni_vp;
dp = VTODE(vdp);
vpid = vdp->v_id;
if (pdp == dp) {
VREF(vdp);
error = 0;
}
else if (ndp->ni_isdotdot) {
DEUNLOCK(pdp);
error = vget(vdp);
if (!error && lockparent && *ndp->ni_next == '\0')
DELOCK(pdp);
}
else {
error = vget(vdp);
if (!lockparent || error || *ndp->ni_next != '\0')
DEUNLOCK(pdp);
}
if (!error) {
if (vpid == vdp->v_id) {
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): cache hit, vnode %08x, file %s\n", vdp, dp->de_Name);
#endif /* defined(MSDOSFSDEBUG) */
return 0;
}
deput(dp);
if (lockparent && pdp != dp && *ndp->ni_next == '\0')
DEUNLOCK(pdp);
}
DELOCK(pdp);
dp = pdp;
vdp = DETOV(dp);
ndp->ni_vp = NULL;
}
/*
* If they are going after the . or .. entry in the root directory,
* they won't find it. DOS filesystems don't have them in the root
* directory. So, we fake it. deget() is in on this scam too.
*/
if ((vdp->v_flag & VROOT) && ndp->ni_ptr[0] == '.' &&
(ndp->ni_namelen == 1 ||
(ndp->ni_namelen == 2 && ndp->ni_ptr[1] == '.'))) {
isadir = ATTR_DIRECTORY;
scn = MSDOSFSROOT;
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): looking for . or .. in root directory\n");
#endif /* defined(MSDOSFSDEBUG) */
cluster == MSDOSFSROOT;
diroff = MSDOSFSROOT_OFS;
goto foundroot;
}
/*
* Don't search for free slots unless we are creating a filename
* and we are at the end of the pathname.
*/
slotstatus = FOUND;
if ((flag == CREATE || flag == RENAME) && *ndp->ni_next == '\0') {
slotstatus = NONE;
slotoffset = -1;
}
unix2dosfn((u_char *) ndp->ni_ptr, dosfilename, ndp->ni_namelen);
dosfilename[11] = 0;
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): dos version of filename %s, length %d\n",
dosfilename, ndp->ni_namelen);
#endif /* defined(MSDOSFSDEBUG) */
/*
* Search the directory pointed at by vdp for the name pointed at
* by ndp->ni_ptr.
*/
tdp = NULL;
/*
* The outer loop ranges over the clusters that make up the
* directory. Note that the root directory is different from all
* other directories. It has a fixed number of blocks that are not
* part of the pool of allocatable clusters. So, we treat it a
* little differently. The root directory starts at "cluster" 0.
*/
rootreloff = 0;
for (frcn = 0;; frcn++) {
if (error = pcbmap(dp, frcn, &bn, &cluster)) {
if (error == E2BIG)
break;
return error;
}
if (error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, NOCRED, &bp))
return error;
for (diroff = 0; diroff < pmp->pm_depclust; diroff++) {
dep = (struct direntry *) bp->b_un.b_addr + diroff;
/*
* If the slot is empty and we are still looking
* for an empty then remember this one. If the
* slot is not empty then check to see if it
* matches what we are looking for. If the slot
* has never been filled with anything, then the
* remainder of the directory has never been used,
* so there is no point in searching it.
*/
if (dep->deName[0] == SLOT_EMPTY ||
dep->deName[0] == SLOT_DELETED) {
if (slotstatus != FOUND) {
slotstatus = FOUND;
if (cluster == MSDOSFSROOT)
slotoffset = rootreloff;
else
slotoffset = diroff;
slotcluster = cluster;
}
if (dep->deName[0] == SLOT_EMPTY) {
brelse(bp);
goto notfound;
}
}
else {
/*
* Ignore volume labels (anywhere, not just
* the root directory).
*/
if ((dep->deAttributes & ATTR_VOLUME) == 0 &&
bcmp(dosfilename, dep->deName, 11) == 0) {
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): match diroff %d, rootreloff %d\n", diroff, rootreloff);
#endif /* defined(MSDOSFSDEBUG) */
/*
* Remember where this directory
* entry came from for whoever did
* this lookup. If this is the root
* directory we are interested in
* the offset relative to the
* beginning of the directory (not
* the beginning of the cluster).
*/
if (cluster == MSDOSFSROOT)
diroff = rootreloff;
ndp->ni_msdosfs.msdosfs_offset = diroff;
ndp->ni_msdosfs.msdosfs_cluster = cluster;
goto found;
}
}
rootreloff++;
} /* for (diroff = 0; .... */
/*
* Release the buffer holding the directory cluster just
* searched.
*/
brelse(bp);
} /* for (frcn = 0; ; frcn++) */
notfound:;
/*
* We hold no disk buffers at this point.
*/
/*
* If we get here we didn't find the entry we were looking for. But
* that's ok if we are creating or renaming and are at the end of
* the pathname and the directory hasn't been removed.
*/
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): flag %d, refcnt %d, slotstatus %d\n",
flag, dp->de_refcnt, slotstatus);
printf(" slotoffset %d, slotcluster %d\n",
slotoffset, slotcluster);
#endif /* defined(MSDOSFSDEBUG) */
if ((flag == CREATE || flag == RENAME) &&
*ndp->ni_next == '\0' && dp->de_refcnt != 0) {
if (slotstatus == NONE) {
ndp->ni_msdosfs.msdosfs_offset = 0;
ndp->ni_msdosfs.msdosfs_cluster = 0;
ndp->ni_msdosfs.msdosfs_count = 0;
}
else {
#if defined(MSDOSFSDEBUG)
printf("msdosfs_lookup(): saving empty slot location\n");
#endif /* defined(MSDOSFSDEBUG) */
ndp->ni_msdosfs.msdosfs_offset = slotoffset;
ndp->ni_msdosfs.msdosfs_cluster = slotcluster;
ndp->ni_msdosfs.msdosfs_count = 1;
}
/* dp->de_flag |= DEUPD; /* never update dos directories */
ndp->ni_nameiop |= SAVENAME;
if (!lockparent)/* leave searched dir locked? */
DEUNLOCK(dp);
}
/*
* Insert name in cache as non-existant if not trying to create it.
*/
if (ndp->ni_makeentry && flag != CREATE)
cache_enter(ndp);
if (flag == CREATE || flag == RENAME)
return EJUSTRETURN;
return ENOENT;
found: ;
/*
* NOTE: We still have the buffer with matched directory entry at
* this point.
*/
isadir = dep->deAttributes & ATTR_DIRECTORY;
scn = dep->deStartCluster;
foundroot:;
/*
* If we entered at foundroot, then we are looking for the . or ..
* entry of the filesystems root directory. isadir and scn were
* setup before jumping here. And, bp is null. There is no buf
* header.
*/
/*
* If deleting and at the end of the path, then if we matched on
* "." then don't deget() we would probably panic(). Otherwise
* deget() the directory entry.
*/
if (flag == DELETE && ndp->ni_next == '\0') {
if (dp->de_StartCluster == scn &&
isadir) { /* "." */
VREF(vdp);
ndp->ni_vp = vdp;
if (bp)
brelse(bp);
return 0;
}
error = deget(pmp, cluster, diroff, dep, &tdp);
if (error) {
if (bp)
brelse(bp);
return error;
}
ndp->ni_vp = DETOV(tdp);
if (!lockparent)
DEUNLOCK(dp);
if (bp)
brelse(bp);
return 0;
}
/*
* If renaming.
*/
if (flag == RENAME && wantparent && *ndp->ni_next == '\0') {
if (dp->de_StartCluster == scn &&
isadir) {
if (bp)
brelse(bp);
return EISDIR;
}
error = deget(pmp, cluster, diroff, dep, &tdp);
if (error) {
if (bp)
brelse(bp);
return error;
}
ndp->ni_vp = DETOV(tdp);
ndp->ni_nameiop |= SAVENAME;
if (!lockparent)
DEUNLOCK(dp);
if (bp)
brelse(bp);
return 0;
}
/*
* ?
*/
pdp = dp;
if (ndp->ni_isdotdot) {
DEUNLOCK(pdp);
error = deget(pmp, cluster, diroff, dep, &tdp);
if (error) {
DELOCK(pdp);
if (bp)
brelse(bp);
return error;
}
if (lockparent && *ndp->ni_next == '\0')
DELOCK(pdp);
ndp->ni_vp = DETOV(tdp);
}
else if (dp->de_StartCluster == scn &&
isadir) { /* "." */
VREF(vdp);
ndp->ni_vp = vdp;
}
else {
error = deget(pmp, cluster, diroff, dep, &tdp);
if (error) {
if (bp)
brelse(bp);
return error;
}
if (!lockparent || *ndp->ni_next != '\0')
DEUNLOCK(pdp);
ndp->ni_vp = DETOV(tdp);
}
if (bp)
brelse(bp);
/*
* Insert name in cache if wanted.
*/
if (ndp->ni_makeentry)
cache_enter(ndp);
return 0;
}
/*
* dep - directory to copy into the directory ndp - nameidata structure
* containing info on where to put the directory entry in the directory.
* depp - return the address of the denode for the created directory entry
* if depp != 0
*/
int
createde(dep, ndp, depp)
struct denode *dep;
struct nameidata *ndp;
struct denode **depp;
{
int bn;
int error;
u_long dirclust, diroffset;
struct direntry *ndep;
struct denode *ddep = VTODE(ndp->ni_dvp); /* directory to add to */
struct msdosfsmount *pmp = dep->de_pmp;
struct buf *bp;
#if defined(MSDOSFSDEBUG)
printf("createde(dep %08x, ndp %08x, depp %08x)\n", dep, ndp, depp);
#endif /* defined(MSDOSFSDEBUG) */
/*
* If no space left in the directory then allocate another cluster
* and chain it onto the end of the file. There is one exception
* to this. That is, if the root directory has no more space it
* can NOT be expanded. extendfile() checks for and fails attempts
* to extend the root directory. We just return an error in that
* case.
*/
if (ndp->ni_msdosfs.msdosfs_count == 0) {
if (error = extendfile(ddep, &bp, &dirclust))
return error;
ndep = (struct direntry *) bp->b_un.b_addr;
/*
* Let caller know where we put the directory entry.
*/
ndp->ni_msdosfs.msdosfs_cluster = dirclust;
ndp->ni_msdosfs.msdosfs_offset = diroffset = 0;
/*
* Update the size of the directory
*/
ddep->de_FileSize += pmp->pm_bpcluster;
}
else {
/*
* There is space in the existing directory. So, we just
* read in the cluster with space. Copy the new directory
* entry in. Then write it to disk. NOTE: DOS directories
* do not get smaller as clusters are emptied.
*/
dirclust = ndp->ni_msdosfs.msdosfs_cluster;
diroffset = ndp->ni_msdosfs.msdosfs_offset;
error = readep(pmp, dirclust, diroffset, &bp, &ndep);
if (error)
return error;
}
*ndep = dep->de_de;
/*
* If they want us to return with the denode gotten.
*/
if (depp) {
error = deget(pmp, dirclust, diroffset, ndep, depp);
if (error)
return error;
}
if (error = bwrite(bp)) {
deput(*depp); /* free the vnode we got on error */
return error;
}
return 0;
}
/*
* Read in a directory entry and mark it as being deleted.
*/
int
markdeleted(pmp, dirclust, diroffset)
struct msdosfsmount *pmp;
u_long dirclust;
u_long diroffset;
{
int error;
struct direntry *ep;
struct buf *bp;
error = readep(pmp, dirclust, diroffset, &bp, &ep);
if (error)
return error;
ep->deName[0] = SLOT_DELETED;
return bwrite(bp);
}
/*
* Remove a directory entry. At this point the file represented by the
* directory entry to be removed is still full length until no one has it
* open. When the file no longer being used msdosfs_inactive() is called
* and will truncate the file to 0 length. When the vnode containing the
* denode is needed for some other purpose by VFS it will call
* msdosfs_reclaim() which will remove the denode from the denode cache.
*/
int
removede(ndp)
struct nameidata *ndp;
{
struct denode *dep = VTODE(ndp->ni_vp); /* the file being removed */
struct msdosfsmount *pmp = dep->de_pmp;
int error;
#if defined(MSDOSFSDEBUG)
/*
* printf("removede(): filename %s\n", dep->de_Name);
* printf("rmde(): dep %08x, ndpcluster %d, ndpoffset %d\n", dep,
* ndp->ni_msdosfs.msdosfs_cluster,
* ndp->ni_msdosfs.msdosfs_offset);
*/
#endif /* defined(MSDOSFSDEBUG) */
/*
* Read the directory block containing the directory entry we are
* to make free. The nameidata structure holds the cluster number
* and directory entry index number of the entry to free.
*/
error = markdeleted(pmp, ndp->ni_msdosfs.msdosfs_cluster,
ndp->ni_msdosfs.msdosfs_offset);
if (error == 0)
dep->de_refcnt--;
return error;
}
/*
* Be sure a directory is empty except for "." and "..". Return 1 if empty,
* return 0 if not empty or error.
*/
int
dosdirempty(dep)
struct denode *dep;
{
int dei;
int error;
u_long cn;
daddr_t bn;
struct buf *bp;
struct msdosfsmount *pmp = dep->de_pmp;
struct direntry *dentp;
/*
* Since the filesize field in directory entries for a directory is
* zero, we just have to feel our way through the directory until
* we hit end of file.
*/
for (cn = 0;; cn++) {
error = pcbmap(dep, cn, &bn, 0);
if (error == E2BIG)
return 1; /* it's empty */
error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, NOCRED,
&bp);
if (error)
return error;
dentp = (struct direntry *) bp->b_un.b_addr;
for (dei = 0; dei < pmp->pm_depclust; dei++) {
if (dentp->deName[0] != SLOT_DELETED) {
/*
* In dos directories an entry whose name
* starts with SLOT_EMPTY (0) starts the
* beginning of the unused part of the
* directory, so we can just return that it
* is empty.
*/
if (dentp->deName[0] == SLOT_EMPTY) {
brelse(bp);
return 1;
}
/*
* Any names other than "." and ".." in a
* directory mean it is not empty.
*/
if (bcmp(dentp->deName, ". ", 11) &&
bcmp(dentp->deName, ".. ", 11)) {
brelse(bp);
#if defined(MSDOSFSDEBUG)
printf("dosdirempty(): entry %d found %02x, %02x\n", dei, dentp->deName[0],
dentp->deName[1]);
#endif /* defined(MSDOSFSDEBUG) */
return 0; /* not empty */
}
}
dentp++;
}
brelse(bp);
}
/* NOTREACHED */
}
/*
* Check to see if the directory described by target is in some
* subdirectory of source. This prevents something like the following from
* succeeding and leaving a bunch or files and directories orphaned. mv
* /a/b/c /a/b/c/d/e/f Where c and f are directories. source - the inode
* for /a/b/c target - the inode for /a/b/c/d/e/f Returns 0 if target is
* NOT a subdirectory of source. Otherwise returns a non-zero error number.
* The target inode is always unlocked on return.
*/
int
doscheckpath(source, target)
struct denode *source;
struct denode *target;
{
daddr_t scn;
struct denode dummy;
struct msdosfsmount *pmp;
struct direntry *ep;
struct denode *dep;
struct buf *bp = NULL;
int error = 0;
dep = target;
if ((target->de_Attributes & ATTR_DIRECTORY) == 0 ||
(source->de_Attributes & ATTR_DIRECTORY) == 0) {
error = ENOTDIR;
goto out;
}
if (dep->de_StartCluster == source->de_StartCluster) {
error = EEXIST;
goto out;
}
if (dep->de_StartCluster == MSDOSFSROOT)
goto out;
for (;;) {
if ((dep->de_Attributes & ATTR_DIRECTORY) == 0) {
error = ENOTDIR;
goto out;
}
pmp = dep->de_pmp;
scn = dep->de_StartCluster;
error = bread(pmp->pm_devvp, cntobn(pmp, scn),
pmp->pm_bpcluster, NOCRED, &bp);
if (error) {
break;
}
ep = (struct direntry *) bp->b_un.b_addr + 1;
if ((ep->deAttributes & ATTR_DIRECTORY) == 0 ||
bcmp(ep->deName, ".. ", 11) != 0) {
error = ENOTDIR;
break;
}
if (ep->deStartCluster == source->de_StartCluster) {
error = EINVAL;
break;
}
if (ep->deStartCluster == MSDOSFSROOT)
break;
deput(dep);
/* NOTE: deget() clears dep on error */
error = deget(pmp, ep->deStartCluster, 0, ep, &dep);
brelse(bp);
bp = NULL;
if (error)
break;
}
out: ;
if (bp)
brelse(bp);
if (error == ENOTDIR)
printf("doscheckpath(): .. not a directory?\n");
if (dep != NULL)
deput(dep);
return error;
}
/*
* Read in the disk block containing the directory entry (dirclu, dirofs)
* and return the address of the buf header, and the address of the
* directory entry within the block.
*/
int
readep(pmp, dirclu, dirofs, bpp, epp)
struct msdosfsmount *pmp;
u_long dirclu, dirofs;
struct buf **bpp;
struct direntry **epp;
{
int error;
daddr_t bn;
bn = detobn(pmp, dirclu, dirofs);
if (error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, NOCRED, bpp)) {
*bpp = NULL;
return error;
}
if (epp)
*epp = bptoep(pmp, *bpp, dirofs);
return 0;
}
/*
* Read in the disk block containing the directory entry dep came from and
* return the address of the buf header, and the address of the directory
* entry within the block.
*/
int
readde(dep, bpp, epp)
struct denode *dep;
struct buf **bpp;
struct direntry **epp;
{
return readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
bpp, epp);
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.