r3005: added talloc wrappers around tdb_open() and ldb_connect(), so that the

caller doesn't have to worry about the constraint of only opening a
database a single time in a process. These wrappers will ensure that
only a single open is done, and will auto-close when the last instance
is gone.

When you are finished with a database pointer, use talloc_free() to
close it.

note that this code does not take account of the threads process
model, and does not yet take account of symlinks or hard links to tdb
files.
(This used to be commit 04e1171996612ddb15f84134cadded68f0d173b2)

1 files changed, 170 insertions, 0 deletions

diff --git a/source4/lib/db_wrap.c b/source4/lib/db_wrap.c
new file mode 100644
index 0000000000..251741c5b0
--- /dev/null
+++ b/source4/lib/db_wrap.c
@@ -0,0 +1,170 @@
+/* 
+   Unix SMB/CIFS implementation.
+
+   database wrap functions
+
+   Copyright (C) Andrew Tridgell 2004
+   
+   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.
+*/
+
+/*
+  the stupidity of the unix fcntl locking design forces us to never
+  allow a database file to be opened twice in the same process. These
+  wrappers provide convenient access to a tdb or ldb, taking advantage
+  of talloc destructors to ensure that only a single open is done
+*/
+
+#include "includes.h"
+
+static struct ldb_wrap *ldb_list;
+static struct tdb_wrap *tdb_list;
+
+/*
+  this is used to catch debug messages from ldb
+*/
+static void ldb_wrap_debug(void *context, enum ldb_debug_level level, 
+			   const char *fmt, va_list ap)  PRINTF_ATTRIBUTE(3,0);
+
+static void ldb_wrap_debug(void *context, enum ldb_debug_level level, 
+			   const char *fmt, va_list ap)
+{
+	char *s = NULL;
+	if (DEBUGLEVEL < 4 && level > LDB_DEBUG_WARNING) {
+		return;
+	}
+	vasprintf(&s, fmt, ap);
+	if (!s) return;
+	DEBUG(level, ("ldb: %s\n", s));
+	free(s);
+}
+
+
+/* destroy the last connection to a ldb */
+static int ldb_wrap_destructor(void *ctx)
+{
+	struct ldb_wrap *w = ctx;
+	ldb_close(w->ldb);
+	DLIST_REMOVE(ldb_list, w);
+	return 0;
+}				 
+
+/*
+  wrapped connection to a ldb database
+  to close just talloc_free() the ldb_wrap pointer
+ */
+struct ldb_wrap *ldb_wrap_connect(TALLOC_CTX *mem_ctx,
+				  const char *url,
+				  unsigned int flags,
+				  const char *options[])
+{
+	struct ldb_wrap *w;
+
+	for (w=ldb_list;w;w=w->next) {
+		if (strcmp(url, w->url) == 0) {
+			return talloc_reference(mem_ctx, w);
+		}
+	}
+
+	w = talloc_p(mem_ctx, struct ldb_wrap);
+	if (w == NULL) {
+		return NULL;
+	}
+
+	w->url = talloc_strdup(w, url);
+
+	w->ldb = ldb_connect(url, flags, options);
+	if (w->ldb == NULL) {
+		talloc_free(w);
+		return NULL;
+	}
+
+	talloc_set_destructor(w, ldb_wrap_destructor);
+	ldb_set_debug(w->ldb, ldb_wrap_debug, NULL);
+
+	DLIST_ADD(ldb_list, w);
+
+	return w;
+}
+
+
+/*
+ Log tdb messages via DEBUG().
+*/
+static void tdb_wrap_log(TDB_CONTEXT *tdb, int level, 
+			 const char *format, ...) PRINTF_ATTRIBUTE(3,4);
+
+static void tdb_wrap_log(TDB_CONTEXT *tdb, int level, 
+			 const char *format, ...)
+{
+	va_list ap;
+	char *ptr = NULL;
+
+	va_start(ap, format);
+	vasprintf(&ptr, format, ap);
+	va_end(ap);
+	
+	if (ptr != NULL) {
+		DEBUG(level, ("tdb(%s): %s", tdb->name ? tdb->name : "unnamed", ptr));
+		free(ptr);
+	}
+}
+
+
+/* destroy the last connection to a tdb */
+static int tdb_wrap_destructor(void *ctx)
+{
+	struct tdb_wrap *w = ctx;
+	tdb_close(w->tdb);
+	DLIST_REMOVE(tdb_list, w);
+	return 0;
+}				 
+
+/*
+  wrapped connection to a tdb database
+  to close just talloc_free() the tdb_wrap pointer
+ */
+struct tdb_wrap *tdb_wrap_open(TALLOC_CTX *mem_ctx,
+			       const char *name, int hash_size, int tdb_flags,
+			       int open_flags, mode_t mode)
+{
+	struct tdb_wrap *w;
+
+	for (w=tdb_list;w;w=w->next) {
+		if (strcmp(name, w->name) == 0) {
+			return talloc_reference(mem_ctx, w);
+		}
+	}
+
+	w = talloc_p(mem_ctx, struct tdb_wrap);
+	if (w == NULL) {
+		return NULL;
+	}
+
+	w->name = talloc_strdup(w, name);
+
+	w->tdb = tdb_open_ex(name, hash_size, tdb_flags, 
+			     open_flags, mode, tdb_wrap_log, NULL);
+	if (w->tdb == NULL) {
+		talloc_free(w);
+		return NULL;
+	}
+
+	talloc_set_destructor(w, tdb_wrap_destructor);
+
+	DLIST_ADD(tdb_list, w);
+
+	return w;
+}