net: Add net tdb command to print information from tdb records

The main purpose is to debug "hot" records from ctdb. ctdb tracks
contended records and identifies them by key in the dbstatistics:

DB Statistics: locking.tdb
[...]
 Num Hot Keys:     1
     Count:3 Key:6a4128e3ced4681b02a00000000000000000000000000000

This command allows querying additional information for the associated
key to identify the affected file. For now this only adds a subcommand
for the locking.tdb, but could be extended to others:

net tdb locking 6a4128e3ced4681b02a00000000000000000000000000000
Share path:            /test/share
Name:                  testfile
Number of share modes: 2

Signed-off-by: Christof Schmitt <cs@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>

source3/utils/net.c

@@ -751,6 +751,14 @@ static struct functable net_func[] = {
 		   "'net notify' commands.")
 	},
 
+	{	"tdb",
+		net_tdb,
+		NET_TRANSPORT_LOCAL,
+		N_("Show information from tdb records"),
+		N_("  Use 'net help tdb' to get more information about "
+		   "'net tdb' commands.")
+	},
+
 #ifdef WITH_FAKE_KASERVER
 	{	"afs",
 		net_afs,

source3/utils/net_proto.h

@@ -462,4 +462,7 @@ int net_rpc_trust(struct net_context *c, int argc, const char **argv);
 int net_rpc_conf(struct net_context *c, int argc, const char **argv);
 
 int net_notify(struct net_context *c, int argc, const char **argv);
+
+int net_tdb(struct net_context *c, int argc, const char **argv);
+
 #endif /*  _NET_PROTO_H_  */

source3/utils/net_tdb.c

@@ -0,0 +1,120 @@
+/*
+ * Samba Unix/Linux client library
+ * net tdb commands to query tdb record information
+ * Copyright (C) 2016, 2017 Christof Schmitt <cs@samba.org>
+ *
+ * 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/>.
+ */
+
+#include "includes.h"
+#include "utils/net.h"
+#include "locking/proto.h"
+#include "librpc/gen_ndr/open_files.h"
+#include "librpc/gen_ndr/ndr_open_files.h"
+
+static int net_tdb_locking_dump(TALLOC_CTX *mem_ctx,
+				struct share_mode_data *data)
+{
+	struct ndr_print *ndr_print;
+
+	ndr_print = talloc_zero(mem_ctx, struct ndr_print);
+	if (ndr_print == NULL) {
+		d_printf("Could not allocate memory.\n");
+		return -1;
+	}
+
+	ndr_print->print = ndr_print_printf_helper;
+	ndr_print->depth = 1;
+	ndr_print_share_mode_data(ndr_print, "SHARE_MODE_DATA", data);
+	TALLOC_FREE(ndr_print);
+
+	return 0;
+}
+
+static int net_tdb_locking_fetch(TALLOC_CTX *mem_ctx, const char *hexkey,
+				 struct share_mode_lock **lock)
+{
+	DATA_BLOB blob;
+	struct file_id id;
+	bool ok;
+
+	blob = strhex_to_data_blob(mem_ctx, hexkey);
+	if (blob.length != sizeof(struct file_id)) {
+		d_printf("Invalid length of key\n");
+		return -1;
+	}
+
+	id = *(struct file_id *)blob.data;
+
+	ok = locking_init_readonly();
+	if (!ok) {
+		d_printf("locking_init_readonly failed\n");
+		return -1;
+	}
+
+	*lock = fetch_share_mode_unlocked(mem_ctx, id);
+
+	if (*lock == NULL) {
+		d_printf("Record with key %s not found.\n", hexkey);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int net_tdb_locking(struct net_context *c, int argc, const char **argv)
+{
+	TALLOC_CTX *mem_ctx = talloc_stackframe();
+	struct share_mode_lock *lock;
+	int ret;
+
+	if (argc < 1) {
+		d_printf("Usage: net tdb locking <key> [ dump ]\n");
+		ret = -1;
+		goto out;
+	}
+
+	ret = net_tdb_locking_fetch(mem_ctx, argv[0], &lock);
+	if (ret != 0) {
+		goto out;
+	}
+
+	if (argc == 2 && strequal(argv[1], "dump")) {
+		ret = net_tdb_locking_dump(mem_ctx, lock->data);
+	} else {
+		d_printf("Share path:            %s\n", lock->data->servicepath);
+		d_printf("Name:                  %s\n", lock->data->base_name);
+		d_printf("Number of share modes: %" PRIu32 "\n",
+			 lock->data->num_share_modes);
+	}
+
+out:
+	TALLOC_FREE(mem_ctx);
+	return ret;
+}
+
+int net_tdb(struct net_context *c, int argc, const char **argv)
+{
+	struct functable func[] = {
+		{ "locking",
+		  net_tdb_locking,
+		  NET_TRANSPORT_LOCAL,
+		  N_("Show information for a record in locking.tdb"),
+		  N_("net tdb locking <key>")
+		},
+		{NULL, NULL, 0, NULL, NULL}
+	};
+
+	return net_run_function(c, argc, argv, "net tdb", func);
+}

source3/utils/wscript_build

@@ -205,6 +205,7 @@ bld.SAMBA3_BINARY('net',
                  net_rpc_conf.c
                  net_afs.c
                  net_notify.c
+                 net_tdb.c
                  ../registry/reg_parse.c
                  ../registry/reg_format.c
                  ../registry/reg_import.c