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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 1992-1999
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
*/
#include "includes.h"
extern int DEBUGLEVEL;
/* the locking database handle */
static TDB_CONTEXT *tdb;
int global_smbpid;
/****************************************************************************
remove any locks on this fd
****************************************************************************/
void locking_close_file(files_struct *fsp)
{
if (!lp_locking(SNUM(fsp->conn))) return;
brl_close(fsp->dev, fsp->inode,
getpid(), fsp->conn->cnum, fsp->fnum);
}
/****************************************************************************
Utility function called to see if a file region is locked.
****************************************************************************/
BOOL is_locked(files_struct *fsp,connection_struct *conn,
SMB_OFF_T count,SMB_OFF_T offset,
enum brl_type lock_type)
{
int snum = SNUM(conn);
if (count == 0)
return(False);
if (!lp_locking(snum) || !lp_strict_locking(snum))
return(False);
return !brl_locktest(fsp->dev, fsp->inode,
global_smbpid, getpid(), conn->cnum,
offset, count, lock_type);
}
/****************************************************************************
Utility function called by locking requests.
****************************************************************************/
BOOL do_lock(files_struct *fsp,connection_struct *conn,
SMB_OFF_T count,SMB_OFF_T 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 %d start=%.0f len=%.0f requested for file %s\n",
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, getpid(), conn->cnum,
offset, count,
lock_type);
}
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_OFF_T count,SMB_OFF_T offset,
int *eclass,uint32 *ecode)
{
BOOL ok = False;
if (!lp_locking(SNUM(conn)))
return(True);
DEBUG(10,("do_unlock: unlock start=%.0f len=%.0f requested for file %s\n",
(double)offset, (double)count, fsp->fsp_name ));
if (OPEN_FSP(fsp) && fsp->can_lock && (fsp->conn == conn)) {
ok = brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
global_smbpid, getpid(), conn->cnum,
offset, count);
}
if (!ok) {
*eclass = ERRDOS;
*ecode = ERRlock;
return False;
}
return True; /* Did unlock */
}
/****************************************************************************
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 share modes\n"));
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;
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;
*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 = 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 */
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 = 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 = 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) {
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);
}