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samba-mirror/source3/locking/share_mode_lock.c
Volker Lendecke d0df12f3ea s3: Fix a typo
Signed-off-by: Jeremy Allison <jra@samba.org>
2012-09-04 15:15:00 -07:00

505 lines
12 KiB
C

/*
Unix SMB/CIFS implementation.
Locking functions
Copyright (C) Andrew Tridgell 1992-2000
Copyright (C) Jeremy Allison 1992-2006
Copyright (C) Volker Lendecke 2005
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 3 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, see <http://www.gnu.org/licenses/>.
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.
rewritten completely to use new tdb code. Tridge, Dec '99
Added POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
Added Unix Extensions POSIX locking support. Jeremy Allison Mar 2006.
*/
#include "includes.h"
#include "system/filesys.h"
#include "locking/proto.h"
#include "smbd/globals.h"
#include "dbwrap/dbwrap.h"
#include "dbwrap/dbwrap_open.h"
#include "../libcli/security/security.h"
#include "serverid.h"
#include "messages.h"
#include "util_tdb.h"
#include "../librpc/gen_ndr/ndr_open_files.h"
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING
#define NO_LOCKING_COUNT (-1)
/* the locking database handle */
static struct db_context *lock_db;
static bool locking_init_internal(bool read_only)
{
brl_init(read_only);
if (lock_db)
return True;
lock_db = db_open(NULL, lock_path("locking.tdb"),
lp_open_files_db_hash_size(),
TDB_DEFAULT|TDB_VOLATILE|TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
read_only?O_RDONLY:O_RDWR|O_CREAT, 0644,
DBWRAP_LOCK_ORDER_1);
if (!lock_db) {
DEBUG(0,("ERROR: Failed to initialise locking database\n"));
return False;
}
if (!posix_locking_init(read_only))
return False;
return True;
}
bool locking_init(void)
{
return locking_init_internal(false);
}
bool locking_init_readonly(void)
{
return locking_init_internal(true);
}
/*******************************************************************
Deinitialize the share_mode management.
******************************************************************/
bool locking_end(void)
{
brl_shutdown();
TALLOC_FREE(lock_db);
return true;
}
/*******************************************************************
Form a static locking key for a dev/inode pair.
******************************************************************/
static TDB_DATA locking_key(const struct file_id *id, struct file_id *tmp)
{
*tmp = *id;
return make_tdb_data((const uint8_t *)tmp, sizeof(*tmp));
}
/*******************************************************************
Get all share mode entries for a dev/inode pair.
********************************************************************/
static struct share_mode_data *parse_share_modes(TALLOC_CTX *mem_ctx,
const TDB_DATA dbuf)
{
struct share_mode_data *d;
enum ndr_err_code ndr_err;
DATA_BLOB blob;
d = talloc(mem_ctx, struct share_mode_data);
if (d == NULL) {
DEBUG(0, ("talloc failed\n"));
goto fail;
}
blob.data = dbuf.dptr;
blob.length = dbuf.dsize;
ndr_err = ndr_pull_struct_blob(
&blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
DEBUG(1, ("ndr_pull_share_mode_lock failed\n"));
goto fail;
}
d->modified = false;
d->fresh = false;
if (DEBUGLEVEL >= 10) {
DEBUG(10, ("parse_share_modes:\n"));
NDR_PRINT_DEBUG(share_mode_data, d);
}
return d;
fail:
TALLOC_FREE(d);
return NULL;
}
/*******************************************************************
Create a storable data blob from a modified share_mode_data struct.
********************************************************************/
static TDB_DATA unparse_share_modes(struct share_mode_data *d)
{
DATA_BLOB blob;
enum ndr_err_code ndr_err;
if (DEBUGLEVEL >= 10) {
DEBUG(10, ("unparse_share_modes:\n"));
NDR_PRINT_DEBUG(share_mode_data, d);
}
if (d->num_share_modes == 0) {
DEBUG(10, ("No used share mode found\n"));
return make_tdb_data(NULL, 0);
}
ndr_err = ndr_push_struct_blob(
&blob, d, d, (ndr_push_flags_fn_t)ndr_push_share_mode_data);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
smb_panic("ndr_push_share_mode_lock failed");
}
return make_tdb_data(blob.data, blob.length);
}
/*******************************************************************
If modified, store the share_mode_data back into the database.
********************************************************************/
static int share_mode_data_destructor(struct share_mode_data *d)
{
NTSTATUS status;
TDB_DATA data;
if (!d->modified) {
return 0;
}
data = unparse_share_modes(d);
if (data.dptr == NULL) {
if (!d->fresh) {
/* There has been an entry before, delete it */
status = dbwrap_record_delete(d->record);
if (!NT_STATUS_IS_OK(status)) {
char *errmsg;
DEBUG(0, ("delete_rec returned %s\n",
nt_errstr(status)));
if (asprintf(&errmsg, "could not delete share "
"entry: %s\n",
nt_errstr(status)) == -1) {
smb_panic("could not delete share"
"entry");
}
smb_panic(errmsg);
}
}
goto done;
}
status = dbwrap_record_store(d->record, data, TDB_REPLACE);
if (!NT_STATUS_IS_OK(status)) {
char *errmsg;
DEBUG(0, ("store returned %s\n", nt_errstr(status)));
if (asprintf(&errmsg, "could not store share mode entry: %s",
nt_errstr(status)) == -1) {
smb_panic("could not store share mode entry");
}
smb_panic(errmsg);
}
done:
return 0;
}
/*******************************************************************
Allocate a new share_mode_data struct, mark it unmodified.
fresh is set to note that currently there is no database entry.
********************************************************************/
static struct share_mode_data *fresh_share_mode_lock(
TALLOC_CTX *mem_ctx, const char *servicepath,
const struct smb_filename *smb_fname,
const struct timespec *old_write_time)
{
struct share_mode_data *d;
if ((servicepath == NULL) || (smb_fname == NULL) ||
(old_write_time == NULL)) {
return NULL;
}
d = talloc_zero(mem_ctx, struct share_mode_data);
if (d == NULL) {
goto fail;
}
d->base_name = talloc_strdup(d, smb_fname->base_name);
if (d->base_name == NULL) {
goto fail;
}
if (smb_fname->stream_name != NULL) {
d->stream_name = talloc_strdup(d, smb_fname->stream_name);
if (d->stream_name == NULL) {
goto fail;
}
}
d->servicepath = talloc_strdup(d, servicepath);
if (d->servicepath == NULL) {
goto fail;
}
d->old_write_time = *old_write_time;
d->modified = false;
d->fresh = true;
return d;
fail:
DEBUG(0, ("talloc failed\n"));
TALLOC_FREE(d);
return NULL;
}
/*******************************************************************
Either fetch a share mode from the database, or allocate a fresh
one if the record doesn't exist.
********************************************************************/
static struct share_mode_lock *get_share_mode_lock_internal(
TALLOC_CTX *mem_ctx, const struct file_id id,
const char *servicepath, const struct smb_filename *smb_fname,
const struct timespec *old_write_time)
{
struct share_mode_lock *lck;
struct share_mode_data *d;
struct file_id tmp;
struct db_record *rec;
TDB_DATA key = locking_key(&id, &tmp);
TDB_DATA value;
rec = dbwrap_fetch_locked(lock_db, mem_ctx, key);
if (rec == NULL) {
DEBUG(3, ("Could not lock share entry\n"));
return NULL;
}
value = dbwrap_record_get_value(rec);
if (value.dptr == NULL) {
d = fresh_share_mode_lock(mem_ctx, servicepath, smb_fname,
old_write_time);
} else {
d = parse_share_modes(mem_ctx, value);
}
if (d == NULL) {
DEBUG(5, ("get_share_mode_lock_internal: "
"Could not get share mode lock\n"));
TALLOC_FREE(rec);
return NULL;
}
d->id = id;
d->record = talloc_move(d, &rec);
talloc_set_destructor(d, share_mode_data_destructor);
lck = talloc(mem_ctx, struct share_mode_lock);
if (lck == NULL) {
DEBUG(1, ("talloc failed\n"));
TALLOC_FREE(d);
return NULL;
}
lck->data = talloc_move(lck, &d);
return lck;
}
/*
* We can only ever have one share mode locked. Users of
* get_share_mode_lock never see this, it will be refcounted by
* talloc_reference.
*/
static struct share_mode_lock *the_lock;
static int the_lock_destructor(struct share_mode_lock *l)
{
the_lock = NULL;
return 0;
}
/*******************************************************************
Get a share_mode_lock, Reference counted to allow nested calls.
********************************************************************/
struct share_mode_lock *get_share_mode_lock(
TALLOC_CTX *mem_ctx,
const struct file_id id,
const char *servicepath,
const struct smb_filename *smb_fname,
const struct timespec *old_write_time)
{
TALLOC_CTX *frame = talloc_stackframe();
struct share_mode_lock *lck;
if (the_lock == NULL) {
the_lock = get_share_mode_lock_internal(
frame, id, servicepath, smb_fname, old_write_time);
if (the_lock == NULL) {
goto fail;
}
talloc_set_destructor(the_lock, the_lock_destructor);
}
if (!file_id_equal(&the_lock->data->id, &id)) {
DEBUG(1, ("Can not lock two share modes simultaneously\n"));
goto fail;
}
lck = talloc(mem_ctx, struct share_mode_lock);
if (lck == NULL) {
DEBUG(1, ("talloc failed\n"));
goto fail;
}
if (talloc_reference(lck, the_lock) == NULL) {
DEBUG(1, ("talloc_reference failed\n"));
goto fail;
}
lck->data = the_lock->data;
TALLOC_FREE(frame);
return lck;
fail:
TALLOC_FREE(frame);
return NULL;
}
/*******************************************************************
Get a share_mode_lock without locking the database or reference
counting. Used by smbstatus to display existing share modes.
********************************************************************/
struct share_mode_lock *fetch_share_mode_unlocked(TALLOC_CTX *mem_ctx,
const struct file_id id)
{
struct share_mode_lock *lck;
struct file_id tmp;
TDB_DATA key = locking_key(&id, &tmp);
TDB_DATA data;
NTSTATUS status;
status = dbwrap_fetch(lock_db, talloc_tos(), key, &data);
if (!NT_STATUS_IS_OK(status)) {
DEBUG(3, ("Could not fetch share entry\n"));
return NULL;
}
if (data.dptr == NULL) {
return NULL;
}
lck = talloc(mem_ctx, struct share_mode_lock);
if (lck == NULL) {
TALLOC_FREE(data.dptr);
return NULL;
}
lck->data = parse_share_modes(lck, data);
TALLOC_FREE(data.dptr);
if (lck->data == NULL) {
TALLOC_FREE(lck);
return NULL;
}
return lck;
}
struct forall_state {
void (*fn)(const struct share_mode_entry *entry,
const char *sharepath,
const char *fname,
void *private_data);
void *private_data;
};
static int traverse_fn(struct db_record *rec, void *_state)
{
struct forall_state *state = (struct forall_state *)_state;
uint32_t i;
TDB_DATA key;
TDB_DATA value;
DATA_BLOB blob;
enum ndr_err_code ndr_err;
struct share_mode_data *d;
key = dbwrap_record_get_key(rec);
value = dbwrap_record_get_value(rec);
/* Ensure this is a locking_key record. */
if (key.dsize != sizeof(struct file_id))
return 0;
d = talloc(talloc_tos(), struct share_mode_data);
if (d == NULL) {
return 0;
}
blob.data = value.dptr;
blob.length = value.dsize;
ndr_err = ndr_pull_struct_blob(
&blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
DEBUG(1, ("ndr_pull_share_mode_lock failed\n"));
return 0;
}
for (i=0; i<d->num_share_modes; i++) {
state->fn(&d->share_modes[i],
d->servicepath, d->base_name,
state->private_data);
}
TALLOC_FREE(d);
return 0;
}
/*******************************************************************
Call the specified function on each entry under management by the
share mode system.
********************************************************************/
int share_mode_forall(void (*fn)(const struct share_mode_entry *, const char *,
const char *, void *),
void *private_data)
{
struct forall_state state;
NTSTATUS status;
int count;
if (lock_db == NULL)
return 0;
state.fn = fn;
state.private_data = private_data;
status = dbwrap_traverse_read(lock_db, traverse_fn, (void *)&state,
&count);
if (!NT_STATUS_IS_OK(status)) {
return -1;
} else {
return count;
}
}