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lib/tdb_compat: header for tdb1 vs tdb2.

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TDB2's API is slightly different from TDB1.  In particular, all functions
return 0 (TDB_SUCCESS) or a negative error number, rather than -1 or tdb_null
and storing the error in tdb_error() (though TDB2 does that as well).

The simplest fix is to replace all the different functions with a wrapper,
and that is done here.

Compatibility functions:

tdb_null: not used as an error return, so not defined by tdb2.
tdb_fetch_compat: TDB1-style data-returning tdb_fetch.
tdb_firstkey_compat: TDB1-style data-returning tdb_firstkey
tdb_nextkey_compat: TDB1-style data-returning tdb_nextkey, with
	TDB2-style free of old key.
tdb_errorstr_compat: TDB1-style tdb_errorstr() which takes TDB instead of ecode.
TDB_CONTEXT: TDB1-style typedef for struct tdb_context.
tdb_open_compat: Simplified open routine which takes log function, sets
	TDB_ALLOW_NESTING as Samba expects, and adds TDB_CLEAR_IF_FIRST support.

Things defined away in TDB2 wrappers:

tdb_traverse_read: TDB2's tdb_traverse only uses read-locks anyway.
tdb_reopen/tdb_reopen_all: TDB2 detects this error itself.
TDB_INCOMPATIBLE_HASH: TDB2 uses the Jenkins hash already.
TDB_VOLATILE: TDB2 shouldn't have freelist scaling issues.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2011-06-20 16:58:15 +09:30
parent eb8cb4f548
commit 61bf43f5d1
4 changed files with 240 additions and 0 deletions
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96
lib/tdb_compat/tdb_compat.c Normal file
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@ -0,0 +1,96 @@
#include <tdb_compat.h>
/* Note: for the moment, we only need this file for TDB2, so we can
* assume waf. */
#if BUILD_TDB2
TDB_DATA tdb_null = { NULL, 0 };
/* Proxy which sets waitflag to false so we never block. */
static int lock_nonblock(int fd, int rw, off_t off, off_t len, bool waitflag,
void *_orig)
{
struct tdb_attribute_flock *orig = _orig;
return orig->lock(fd, rw, off, len, false, orig->data);
}
enum TDB_ERROR tdb_transaction_start_nonblock(struct tdb_context *tdb)
{
union tdb_attribute locking, orig;
enum TDB_ERROR ecode;
orig.base.attr = TDB_ATTRIBUTE_FLOCK;
ecode = tdb_get_attribute(tdb, &orig);
if (ecode != TDB_SUCCESS)
return ecode;
/* Replace locking function with our own. */
locking = orig;
locking.flock.data = &orig;
locking.flock.lock = lock_nonblock;
ecode = tdb_set_attribute(tdb, &locking);
if (ecode != TDB_SUCCESS)
return ecode;
ecode = tdb_transaction_start(tdb);
tdb_unset_attribute(tdb, TDB_ATTRIBUTE_FLOCK);
return ecode;
}
/*
* This handles TDB_CLEAR_IF_FIRST.
*/
static enum TDB_ERROR clear_if_first(int fd, void *unused)
{
/* We hold a lock offset 63 always, so we can tell if anyone else is. */
struct flock fl;
fl.l_type = F_WRLCK;
fl.l_whence = SEEK_SET;
fl.l_start = 63;
fl.l_len = 1;
if (fcntl(fd, F_SETLK, &fl) == 0) {
/* We must be first ones to open it w/ TDB_CLEAR_IF_FIRST! */
if (ftruncate(fd, 0) != 0) {
return TDB_ERR_IO;
}
}
fl.l_type = F_RDLCK;
if (fcntl(fd, F_SETLKW, &fl) != 0) {
return TDB_ERR_IO;
}
return TDB_SUCCESS;
}
struct tdb_context *
tdb_open_compat_(const char *name, int hash_size_unused,
int tdb_flags, int open_flags, mode_t mode,
void (*log_fn)(struct tdb_context *,
enum tdb_log_level,
const char *message,
void *data),
void *log_data)
{
union tdb_attribute cif, log, *attr = NULL;
if (log_fn) {
log.log.base.attr = TDB_ATTRIBUTE_LOG;
log.log.base.next = NULL;
log.log.fn = log_fn;
log.log.data = log_data;
attr = &log;
}
if (tdb_flags & TDB_CLEAR_IF_FIRST) {
cif.openhook.base.attr = TDB_ATTRIBUTE_OPENHOOK;
cif.openhook.base.next = attr;
cif.openhook.fn = clear_if_first;
attr = &cif;
tdb_flags &= ~TDB_CLEAR_IF_FIRST;
}
return tdb_open(name, tdb_flags|TDB_ALLOW_NESTING, open_flags, mode,
attr);
}
#endif

136
lib/tdb_compat/tdb_compat.h Normal file
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/*
Unix SMB/CIFS implementation.
Compatibility layer for TDB1 vs TDB2.
Copyright (C) Rusty Russell 2011
** NOTE! The following LGPL license applies to the tdb_compat
** library. This does NOT imply that all of Samba is released
** under the LGPL
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef TDB_COMPAT_H
#define TDB_COMPAT_H
#include "replace.h"
#include <ccan/typesafe_cb/typesafe_cb.h>
#if BUILD_TDB2
#include <tdb2.h>
#include <fcntl.h>
#include <unistd.h>
extern TDB_DATA tdb_null;
/* Old-style tdb_fetch. */
static inline TDB_DATA tdb_fetch_compat(struct tdb_context *tdb, TDB_DATA k)
{
TDB_DATA dbuf;
if (tdb_fetch(tdb, k, &dbuf) != TDB_SUCCESS) {
return tdb_null;
}
return dbuf;
}
static inline TDB_DATA tdb_firstkey_compat(struct tdb_context *tdb)
{
TDB_DATA k;
if (tdb_firstkey(tdb, &k) != TDB_SUCCESS) {
return tdb_null;
}
return k;
}
/* Note: this frees the old key.dptr. */
static inline TDB_DATA tdb_nextkey_compat(struct tdb_context *tdb, TDB_DATA k)
{
if (tdb_nextkey(tdb, &k) != TDB_SUCCESS) {
return tdb_null;
}
return k;
}
/* tdb_traverse_read and tdb_traverse are equal: both only take read locks. */
#define tdb_traverse_read tdb_traverse
/* Old-style tdb_errorstr */
#define tdb_errorstr_compat(tdb) tdb_errorstr(tdb_error(tdb))
/* This typedef doesn't exist in TDB2. */
typedef struct tdb_context TDB_CONTEXT;
/* We don't need these any more. */
#define tdb_reopen_all(flag) 0
#define tdb_reopen(tdb) 0
/* These no longer exist in tdb2. */
#define TDB_CLEAR_IF_FIRST 1048576
#define TDB_INCOMPATIBLE_HASH 0
#define TDB_VOLATILE 0
/* tdb2 does nonblocking functions via attibutes. */
enum TDB_ERROR tdb_transaction_start_nonblock(struct tdb_context *tdb);
/* Convenient (typesafe) wrapper for tdb open with logging */
#define tdb_open_compat(name, hsize, tdb_fl, open_fl, mode, log_fn, log_data) \
tdb_open_compat_((name), (hsize), (tdb_fl), (open_fl), (mode), \
typesafe_cb_preargs(void, void *, \
(log_fn), (log_data), \
struct tdb_context *, \
enum tdb_log_level, \
const char *), \
(log_data))
struct tdb_context *
tdb_open_compat_(const char *name, int hash_size_unused,
int tdb_flags, int open_flags, mode_t mode,
void (*log_fn)(struct tdb_context *,
enum tdb_log_level,
const char *message,
void *data),
void *log_data);
#else
#include <tdb.h>
/* FIXME: Inlining this is a bit lazy, but eases S3 build. */
static inline struct tdb_context *
tdb_open_compat(const char *name, int hash_size,
int tdb_flags, int open_flags, mode_t mode,
tdb_log_func log_fn, void *log_private)
{
struct tdb_logging_context lctx;
lctx.log_fn = log_fn;
lctx.log_private = log_private;
if (log_fn)
return tdb_open_ex(name, hash_size, tdb_flags, open_flags,
mode, &lctx, NULL);
else
return tdb_open(name, hash_size, tdb_flags, open_flags, mode);
}
#define tdb_firstkey_compat tdb_firstkey
/* Note: this frees the old key.dptr. */
static inline TDB_DATA tdb_nextkey_compat(struct tdb_context *tdb, TDB_DATA k)
{
TDB_DATA next = tdb_nextkey(tdb, k);
free(k.dptr);
return next;
}
#define tdb_errorstr_compat(tdb) tdb_errorstr(tdb)
#define tdb_fetch_compat tdb_fetch
#endif
#endif /* TDB_COMPAT_H */

7
lib/tdb_compat/wscript Normal file
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#!/usr/bin/env python
def build(bld):
bld.SAMBA_LIBRARY('tdb_compat',
source='tdb_compat.c',
deps='replace tdb',
private_library=True)

1
wscript_build
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@ -38,6 +38,7 @@ bld.RECURSE('lib/talloc')
bld.RECURSE('lib/tdb')
bld.RECURSE('lib/tevent')
bld.RECURSE('lib/ccan')
bld.RECURSE('lib/tdb_compat')
bld.RECURSE('source4/lib/ldb')
bld.RECURSE('source4/dynconfig')
bld.RECURSE('lib/util/charset')