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samba-mirror/source3/locking/locking.c

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/*
Unix SMB/Netbios implementation.
Version 3.0
Locking functions
Copyright (C) Andrew Tridgell 1992-2000
Copyright (C) Jeremy Allison 1992-2000
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Revision History:
12 aug 96: Erik.Devriendt@te6.siemens.be
added support for shared memory implementation of share mode locking
May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode
locking to deal with multiple share modes per open file.
September 1997. Jeremy Allison (jallison@whistle.com). Added oplock
support.
rewrtten completely to use new tdb code. Tridge, Dec '99
Added POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
*/
#include "includes.h"
extern int DEBUGLEVEL;
int global_smbpid;
/* the locking database handle */
static TDB_CONTEXT *tdb;
/****************************************************************************
Debugging aid :-).
****************************************************************************/
static const char *lock_type_name(enum brl_type lock_type)
{
return (lock_type == READ_LOCK) ? "READ" : "WRITE";
}
/****************************************************************************
Utility function called to see if a file region is locked.
****************************************************************************/
BOOL is_locked(files_struct *fsp,connection_struct *conn,
SMB_BIG_UINT count,SMB_BIG_UINT offset,
enum brl_type lock_type)
{
int snum = SNUM(conn);
BOOL ret;
if (count == 0)
return(False);
if (!lp_locking(snum) || !lp_strict_locking(snum))
return(False);
ret = !brl_locktest(fsp->dev, fsp->inode, fsp->fnum,
global_smbpid, sys_getpid(), conn->cnum,
offset, count, lock_type);
/*
* There is no lock held by an SMB daemon, check to
* see if there is a POSIX lock from a UNIX or NFS process.
*/
if(!ret && lp_posix_locking(snum))
ret = is_posix_locked(fsp, offset, count, lock_type);
return ret;
}
/****************************************************************************
Utility function called by locking requests.
****************************************************************************/
BOOL do_lock(files_struct *fsp,connection_struct *conn,
SMB_BIG_UINT count,SMB_BIG_UINT offset,enum brl_type lock_type,
int *eclass,uint32 *ecode)
{
BOOL ok = False;
if (!lp_locking(SNUM(conn)))
return(True);
if (count == 0) {
*eclass = ERRDOS;
*ecode = ERRnoaccess;
return False;
}
DEBUG(10,("do_lock: lock type %s start=%.0f len=%.0f requested for file %s\n",
lock_type_name(lock_type), (double)offset, (double)count, fsp->fsp_name ));
if (OPEN_FSP(fsp) && fsp->can_lock && (fsp->conn == conn)) {
ok = brl_lock(fsp->dev, fsp->inode, fsp->fnum,
global_smbpid, sys_getpid(), conn->cnum,
offset, count,
lock_type);
if (ok && lp_posix_locking(SNUM(conn))) {
/*
* Try and get a POSIX lock on this range.
* Note that this is ok if it is a read lock
* overlapping on a different fd. JRA.
*/
ok = set_posix_lock(fsp, offset, count, lock_type);
if (!ok) {
/*
* We failed to map - we must now remove the brl
* lock entry.
*/
(void)brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
global_smbpid, sys_getpid(), conn->cnum,
offset, count);
}
}
}
if (!ok) {
*eclass = ERRDOS;
*ecode = ERRlock;
return False;
}
return True; /* Got lock */
}
/****************************************************************************
Utility function called by unlocking requests.
****************************************************************************/
BOOL do_unlock(files_struct *fsp,connection_struct *conn,
SMB_BIG_UINT count,SMB_BIG_UINT offset,
int *eclass,uint32 *ecode)
{
BOOL ok = False;
if (!lp_locking(SNUM(conn)))
return(True);
if (!OPEN_FSP(fsp) || !fsp->can_lock || (fsp->conn != conn)) {
*eclass = ERRDOS;
*ecode = ERRlock;
return False;
}
DEBUG(10,("do_unlock: unlock start=%.0f len=%.0f requested for file %s\n",
(double)offset, (double)count, fsp->fsp_name ));
/*
* Remove the existing lock record from the tdb lockdb
* before looking at POSIX locks. If this record doesn't
* match then don't bother looking to remove POSIX locks.
*/
ok = brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
global_smbpid, sys_getpid(), conn->cnum, offset, count);
if (!ok) {
DEBUG(10,("do_unlock: returning ERRlock.\n" ));
*eclass = ERRDOS;
*ecode = ERRlock;
return False;
}
if (!lp_posix_locking(SNUM(conn)))
return True;
(void)release_posix_lock(fsp, offset, count);
return True; /* Did unlock */
}
/****************************************************************************
Remove any locks on this fd. Called from file_close().
****************************************************************************/
void locking_close_file(files_struct *fsp)
{
pid_t pid = sys_getpid();
if (!lp_locking(SNUM(fsp->conn)))
return;
/*
* Just release all the brl locks, no need to release individually.
*/
brl_close(fsp->dev, fsp->inode, pid, fsp->conn->cnum, fsp->fnum);
if(lp_posix_locking(SNUM(fsp->conn))) {
/*
* Release all the POSIX locks.
*/
posix_locking_close_file(fsp);
}
}
/****************************************************************************
Initialise the locking functions.
****************************************************************************/
BOOL locking_init(int read_only)
{
brl_init(read_only);
if (tdb) return True;
tdb = tdb_open(lock_path("locking.tdb"),
0, TDB_CLEAR_IF_FIRST,
read_only?O_RDONLY:O_RDWR|O_CREAT,
0644);
if (!tdb) {
DEBUG(0,("ERROR: Failed to initialise locking database\n"));
return False;
}
if (!posix_locking_init(read_only))
return False;
return True;
}
/*******************************************************************
Deinitialize the share_mode management.
******************************************************************/
BOOL locking_end(void)
{
if (tdb && tdb_close(tdb) != 0) return False;
return True;
}
/*******************************************************************
form a static locking key for a dev/inode pair
******************************************************************/
static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
{
static struct locking_key key;
TDB_DATA kbuf;
memset(&key, '\0', sizeof(key));
key.dev = dev;
key.inode = inode;
kbuf.dptr = (char *)&key;
kbuf.dsize = sizeof(key);
return kbuf;
}
static TDB_DATA locking_key_fsp(files_struct *fsp)
{
return locking_key(fsp->dev, fsp->inode);
}
/*******************************************************************
Lock a hash bucket entry.
******************************************************************/
BOOL lock_share_entry(connection_struct *conn,
SMB_DEV_T dev, SMB_INO_T inode)
{
return tdb_lockchain(tdb, locking_key(dev, inode)) == 0;
}
/*******************************************************************
Unlock a hash bucket entry.
******************************************************************/
BOOL unlock_share_entry(connection_struct *conn,
SMB_DEV_T dev, SMB_INO_T inode)
{
return tdb_unlockchain(tdb, locking_key(dev, inode)) == 0;
}
/*******************************************************************
Lock a hash bucket entry. use a fsp for convenience
******************************************************************/
BOOL lock_share_entry_fsp(files_struct *fsp)
{
return tdb_lockchain(tdb, locking_key(fsp->dev, fsp->inode)) == 0;
}
/*******************************************************************
Unlock a hash bucket entry.
******************************************************************/
BOOL unlock_share_entry_fsp(files_struct *fsp)
{
return tdb_unlockchain(tdb, locking_key(fsp->dev, fsp->inode)) == 0;
}
/*******************************************************************
Get all share mode entries for a dev/inode pair.
********************************************************************/
int get_share_modes(connection_struct *conn,
SMB_DEV_T dev, SMB_INO_T inode,
share_mode_entry **shares)
{
TDB_DATA dbuf;
struct locking_data *data;
int ret;
*shares = NULL;
dbuf = tdb_fetch(tdb, locking_key(dev, inode));
if (!dbuf.dptr) return 0;
data = (struct locking_data *)dbuf.dptr;
ret = data->num_share_mode_entries;
This is a *big* checkin that may break some things, but implements the new open mechanism Andrew & I discussed. config.sub: configure: Included the QNX patch. include/vfs.h: smbd/vfs-wrap.c: smbd/vfs.c: Added ftruncate vfs call (needed). Note that we will also need locking calls in the vfs (to be added). lib/util_unistr.c: nmbd/nmbd_processlogon.c: Fix for NT domain logons causing nmbd to core dump. Also fix for sidsize DOS bug. locking/locking.c: Check value of ret before using it for memdup. printing/printing.c: Convert print_fsp_open to return an allocated fsp. rpc_server/srv_lsa.c: Fix for NT domain logons. I have removed all use of lp_share_modes() from the code (although I left the parameter in the table for backwards compatibility). It no longer makes sense for this to exist. smbd/close.c: Removed lp_share_modes(). smbd/fileio.c: Fixed parameters to unlock_share_entry call in panic code. smbd/files.c: Correctly set the unix_ERR_code to ERRnofids on fsp allocation fail. smbd/nttrans.c: smbd/reply.c: smbd/trans2.c: Changed all occurrences of open_file_shared/open_directory/ open_file_stat to return an fsp from the call. smbd/open.c: Changed all occurrences of open_file_shared/open_directory/ open_file_stat to return an fsp from the call. In addition I have fixed a long standing race condition in the deny mode processing w.r.t. two smbd's creating a file. Andrew, please note that your original idea of using open with O_EXCL in this case would not work (I went over the races very carefully) and so we must re-check deny modes *after* the open() call returns. This is because there is a race between the open with O_EXCL and the lock of the share mode entry. Imagine the case where the first smbd does the open with O_EXCL and a deny mode of DENY_ALL, but is pre-empted before it locks the share modes and creates the deny mode entry for DENY_ALL. A second smbd could then come in with O_RDONLY and a deny mode of DENY_NONE and the two opens would be allowed. The *only* way to fix this race is to lock the share modes after the open and then do the deny mode checks *after* this lock in the case where the file did not originally exist. This code will need extensive testing but seems to initially work. Jeremy. (This used to be commit ab0ecc39d688f16b9692fe90b991f0b89287070a)
2000-04-22 04:33:16 +04:00
if(ret)
*shares = (share_mode_entry *)memdup(dbuf.dptr + sizeof(*data), ret * sizeof(**shares));
free(dbuf.dptr);
if (! *shares) return 0;
return ret;
}
/*******************************************************************
Del the share mode of a file for this process
********************************************************************/
void del_share_mode(files_struct *fsp)
{
TDB_DATA dbuf;
struct locking_data *data;
int i, del_count=0;
share_mode_entry *shares;
pid_t pid = sys_getpid();
/* read in the existing share modes */
dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
if (!dbuf.dptr) return;
data = (struct locking_data *)dbuf.dptr;
shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));
/* find any with our pid and delete it by overwriting with the rest of the data
from the record */
for (i=0;i<data->num_share_mode_entries;) {
if (shares[i].pid == pid &&
memcmp(&shares[i].time,
&fsp->open_time,sizeof(struct timeval)) == 0) {
data->num_share_mode_entries--;
memmove(&shares[i], &shares[i+1],
dbuf.dsize - (sizeof(*data) + (i+1)*sizeof(*shares)));
del_count++;
} else {
i++;
}
}
/* the record has shrunk a bit */
dbuf.dsize -= del_count * sizeof(*shares);
/* store it back in the database */
if (data->num_share_mode_entries == 0) {
tdb_delete(tdb, locking_key_fsp(fsp));
} else {
tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
}
free(dbuf.dptr);
}
/*******************************************************************
fill a share mode entry
********************************************************************/
static void fill_share_mode(char *p, files_struct *fsp, uint16 port, uint16 op_type)
{
share_mode_entry *e = (share_mode_entry *)p;
e->pid = sys_getpid();
e->share_mode = fsp->share_mode;
e->op_port = port;
e->op_type = op_type;
memcpy((char *)&e->time, (char *)&fsp->open_time, sizeof(struct timeval));
}
/*******************************************************************
Set the share mode of a file. Return False on fail, True on success.
********************************************************************/
BOOL set_share_mode(files_struct *fsp, uint16 port, uint16 op_type)
{
TDB_DATA dbuf;
struct locking_data *data;
share_mode_entry *shares;
char *p=NULL;
int size;
/* read in the existing share modes if any */
dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
if (!dbuf.dptr) {
/* we'll need to create a new record */
pstring fname;
pstrcpy(fname, fsp->conn->connectpath);
pstrcat(fname, "/");
pstrcat(fname, fsp->fsp_name);
size = sizeof(*data) + sizeof(*shares) + strlen(fname) + 1;
p = (char *)malloc(size);
data = (struct locking_data *)p;
shares = (share_mode_entry *)(p + sizeof(*data));
data->num_share_mode_entries = 1;
pstrcpy(p + sizeof(*data) + sizeof(*shares), fname);
fill_share_mode(p + sizeof(*data), fsp, port, op_type);
dbuf.dptr = p;
dbuf.dsize = size;
tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
free(p);
return True;
}
/* we're adding to an existing entry - this is a bit fiddly */
data = (struct locking_data *)dbuf.dptr;
shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));
data->num_share_mode_entries++;
size = dbuf.dsize + sizeof(*shares);
p = malloc(size);
memcpy(p, dbuf.dptr, sizeof(*data));
fill_share_mode(p + sizeof(*data), fsp, port, op_type);
memcpy(p + sizeof(*data) + sizeof(*shares), dbuf.dptr + sizeof(*data),
dbuf.dsize - sizeof(*data));
free(dbuf.dptr);
dbuf.dptr = p;
dbuf.dsize = size;
tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
free(p);
return True;
}
/*******************************************************************
a generic in-place modification call for share mode entries
********************************************************************/
static BOOL mod_share_mode(files_struct *fsp,
void (*mod_fn)(share_mode_entry *, SMB_DEV_T, SMB_INO_T, void *),
void *param)
{
TDB_DATA dbuf;
struct locking_data *data;
int i;
share_mode_entry *shares;
pid_t pid = sys_getpid();
int need_store=0;
/* read in the existing share modes */
dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
if (!dbuf.dptr) return False;
data = (struct locking_data *)dbuf.dptr;
shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));
/* find any with our pid and call the supplied function */
for (i=0;i<data->num_share_mode_entries;i++) {
if (pid == shares[i].pid &&
shares[i].share_mode == fsp->share_mode &&
memcmp(&shares[i].time,
&fsp->open_time,sizeof(struct timeval)) == 0) {
mod_fn(&shares[i], fsp->dev, fsp->inode, param);
need_store=1;
}
}
/* if the mod fn was called then store it back */
if (need_store) {
if (data->num_share_mode_entries == 0) {
tdb_delete(tdb, locking_key_fsp(fsp));
} else {
tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
}
}
free(dbuf.dptr);
return need_store;
}
/*******************************************************************
Static function that actually does the work for the generic function
below.
********************************************************************/
static void remove_share_oplock_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode,
void *param)
{
DEBUG(10,("remove_share_oplock_fn: removing oplock info for entry dev=%x ino=%.0f\n",
(unsigned int)dev, (double)inode ));
/* Delete the oplock info. */
entry->op_port = 0;
entry->op_type = NO_OPLOCK;
}
/*******************************************************************
Remove an oplock port and mode entry from a share mode.
********************************************************************/
BOOL remove_share_oplock(files_struct *fsp)
{
return mod_share_mode(fsp, remove_share_oplock_fn, NULL);
}
/*******************************************************************
Static function that actually does the work for the generic function
below.
********************************************************************/
static void downgrade_share_oplock_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode,
void *param)
{
DEBUG(10,("downgrade_share_oplock_fn: downgrading oplock info for entry dev=%x ino=%.0f\n",
(unsigned int)dev, (double)inode ));
entry->op_type = LEVEL_II_OPLOCK;
}
/*******************************************************************
Downgrade a oplock type from exclusive to level II.
********************************************************************/
BOOL downgrade_share_oplock(files_struct *fsp)
{
return mod_share_mode(fsp, downgrade_share_oplock_fn, NULL);
}
/*******************************************************************
Static function that actually does the work for the generic function
below.
********************************************************************/
struct mod_val {
int new_share_mode;
uint16 new_oplock;
};
static void modify_share_mode_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode,
void *param)
{
struct mod_val *mvp = (struct mod_val *)param;
DEBUG(10,("modify_share_mode_fn: changing share mode info from %x to %x for entry dev=%x ino=%.0f\n",
entry->share_mode, mvp->new_share_mode, (unsigned int)dev, (double)inode ));
DEBUG(10,("modify_share_mode_fn: changing oplock state from %x to %x for entry dev=%x ino=%.0f\n",
entry->op_type, (int)mvp->new_oplock, (unsigned int)dev, (double)inode ));
/* Change the share mode info. */
entry->share_mode = mvp->new_share_mode;
entry->op_type = mvp->new_oplock;
}
/*******************************************************************
Modify a share mode on a file. Used by the delete open file code.
Return False on fail, True on success.
********************************************************************/
BOOL modify_share_mode(files_struct *fsp, int new_mode, uint16 new_oplock)
{
struct mod_val mv;
mv.new_share_mode = new_mode;
mv.new_oplock = new_oplock;
return mod_share_mode(fsp, modify_share_mode_fn, (void *)&mv);
}
/****************************************************************************
traverse the whole database with this function, calling traverse_callback
on each share mode
****************************************************************************/
static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf,
void* state)
{
struct locking_data *data;
share_mode_entry *shares;
char *name;
int i;
SHAREMODE_FN(traverse_callback) = (SHAREMODE_FN_CAST())state;
data = (struct locking_data *)dbuf.dptr;
shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));
name = dbuf.dptr + sizeof(*data) + data->num_share_mode_entries*sizeof(*shares);
for (i=0;i<data->num_share_mode_entries;i++) {
traverse_callback(&shares[i], name);
}
return 0;
}
/*******************************************************************
Call the specified function on each entry under management by the
share mode system.
********************************************************************/
int share_mode_forall(SHAREMODE_FN(fn))
{
if (!tdb) return 0;
return tdb_traverse(tdb, traverse_fn, (void*)fn);
}