/*
- * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
- * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
*
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License, version 2 only, as
- * published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
*
- * 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., 51
- * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
+#include "bin/lttng-sessiond/tracker.h"
+#include "common/sessiond-comm/payload.h"
+#include "lttng/lttng-error.h"
+#include "lttng/tracker.h"
#define _LGPL_SOURCE
#include <assert.h>
#include <inttypes.h>
#include <common/kernel-ctl/kernel-ctl.h>
#include <common/dynamic-buffer.h>
#include <common/buffer-view.h>
+#include <common/sessiond-comm/payload.h>
+#include <common/sessiond-comm/payload-view.h>
#include <common/trace-chunk.h>
#include <lttng/location-internal.h>
#include <lttng/trigger/trigger-internal.h>
/* Create socket for control stream. */
if (uri->stype == LTTNG_STREAM_CONTROL) {
+ uint64_t result_flags;
+
DBG3("Creating relayd stream socket from URI");
/* Check relayd version */
}
consumer->relay_major_version = rsock->major;
consumer->relay_minor_version = rsock->minor;
+ ret = relayd_get_configuration(rsock, 0,
+ &result_flags);
+ if (ret < 0) {
+ ERR("Unable to get relayd configuration");
+ status = LTTNG_ERR_RELAYD_CONNECT_FAIL;
+ goto close_sock;
+ }
+ if (result_flags & LTTCOMM_RELAYD_CONFIGURATION_FLAG_CLEAR_ALLOWED) {
+ consumer->relay_allows_clear = true;
+ }
} else if (uri->stype == LTTNG_STREAM_DATA) {
DBG3("Creating relayd data socket from URI");
} else {
usess->consumer->relay_major_version;
session->consumer->relay_minor_version =
usess->consumer->relay_minor_version;
+ session->consumer->relay_allows_clear =
+ usess->consumer->relay_allows_clear;
}
if (ksess && ksess->consumer && ksess->consumer->type == CONSUMER_DST_NET
ksess->consumer->relay_major_version;
session->consumer->relay_minor_version =
ksess->consumer->relay_minor_version;
+ session->consumer->relay_allows_clear =
+ ksess->consumer->relay_allows_clear;
}
error:
return ret;
}
-/*
- * Command LTTNG_TRACK_PID processed by the client thread.
- *
- * Called with session lock held.
- */
-int cmd_track_pid(struct ltt_session *session, enum lttng_domain_type domain,
- int pid)
-{
- int ret;
-
- rcu_read_lock();
-
- switch (domain) {
- case LTTNG_DOMAIN_KERNEL:
- {
- struct ltt_kernel_session *ksess;
-
- ksess = session->kernel_session;
-
- ret = kernel_track_pid(ksess, pid);
- if (ret != LTTNG_OK) {
- goto error;
- }
-
- kernel_wait_quiescent();
- break;
- }
- case LTTNG_DOMAIN_UST:
- {
- struct ltt_ust_session *usess;
-
- usess = session->ust_session;
-
- ret = trace_ust_track_pid(usess, pid);
- if (ret != LTTNG_OK) {
- goto error;
- }
- break;
- }
- default:
- ret = LTTNG_ERR_UNKNOWN_DOMAIN;
- goto error;
- }
-
- ret = LTTNG_OK;
-
-error:
- rcu_read_unlock();
- return ret;
-}
-
-/*
- * Command LTTNG_UNTRACK_PID processed by the client thread.
- *
- * Called with session lock held.
- */
-int cmd_untrack_pid(struct ltt_session *session, enum lttng_domain_type domain,
- int pid)
-{
- int ret;
-
- rcu_read_lock();
-
- switch (domain) {
- case LTTNG_DOMAIN_KERNEL:
- {
- struct ltt_kernel_session *ksess;
-
- ksess = session->kernel_session;
-
- ret = kernel_untrack_pid(ksess, pid);
- if (ret != LTTNG_OK) {
- goto error;
- }
-
- kernel_wait_quiescent();
- break;
- }
- case LTTNG_DOMAIN_UST:
- {
- struct ltt_ust_session *usess;
-
- usess = session->ust_session;
-
- ret = trace_ust_untrack_pid(usess, pid);
- if (ret != LTTNG_OK) {
- goto error;
- }
- break;
- }
- default:
- ret = LTTNG_ERR_UNKNOWN_DOMAIN;
- goto error;
- }
-
- ret = LTTNG_OK;
-
-error:
- rcu_read_unlock();
- return ret;
-}
-
/*
* Command LTTNG_ENABLE_CHANNEL processed by the client thread.
*
return ret;
}
+enum lttng_error_code cmd_process_attr_tracker_get_tracking_policy(
+ struct ltt_session *session,
+ enum lttng_domain_type domain,
+ enum lttng_process_attr process_attr,
+ enum lttng_tracking_policy *policy)
+{
+ enum lttng_error_code ret_code = LTTNG_OK;
+ const struct process_attr_tracker *tracker;
+
+ switch (domain) {
+ case LTTNG_DOMAIN_KERNEL:
+ if (!session->kernel_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ tracker = kernel_get_process_attr_tracker(
+ session->kernel_session, process_attr);
+ break;
+ case LTTNG_DOMAIN_UST:
+ if (!session->ust_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ tracker = trace_ust_get_process_attr_tracker(
+ session->ust_session, process_attr);
+ break;
+ default:
+ ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+ goto end;
+ }
+ if (tracker) {
+ *policy = process_attr_tracker_get_tracking_policy(tracker);
+ } else {
+ ret_code = LTTNG_ERR_INVALID;
+ }
+end:
+ return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_set_tracking_policy(
+ struct ltt_session *session,
+ enum lttng_domain_type domain,
+ enum lttng_process_attr process_attr,
+ enum lttng_tracking_policy policy)
+{
+ enum lttng_error_code ret_code = LTTNG_OK;
+
+ switch (policy) {
+ case LTTNG_TRACKING_POLICY_INCLUDE_SET:
+ case LTTNG_TRACKING_POLICY_EXCLUDE_ALL:
+ case LTTNG_TRACKING_POLICY_INCLUDE_ALL:
+ break;
+ default:
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+
+ switch (domain) {
+ case LTTNG_DOMAIN_KERNEL:
+ if (!session->kernel_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ ret_code = kernel_process_attr_tracker_set_tracking_policy(
+ session->kernel_session, process_attr, policy);
+ break;
+ case LTTNG_DOMAIN_UST:
+ if (!session->ust_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ ret_code = trace_ust_process_attr_tracker_set_tracking_policy(
+ session->ust_session, process_attr, policy);
+ break;
+ default:
+ ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+ break;
+ }
+end:
+ return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_inclusion_set_add_value(
+ struct ltt_session *session,
+ enum lttng_domain_type domain,
+ enum lttng_process_attr process_attr,
+ const struct process_attr_value *value)
+{
+ enum lttng_error_code ret_code = LTTNG_OK;
+
+ switch (domain) {
+ case LTTNG_DOMAIN_KERNEL:
+ if (!session->kernel_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ ret_code = kernel_process_attr_tracker_inclusion_set_add_value(
+ session->kernel_session, process_attr, value);
+ break;
+ case LTTNG_DOMAIN_UST:
+ if (!session->ust_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ ret_code = trace_ust_process_attr_tracker_inclusion_set_add_value(
+ session->ust_session, process_attr, value);
+ break;
+ default:
+ ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+ break;
+ }
+end:
+ return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_inclusion_set_remove_value(
+ struct ltt_session *session,
+ enum lttng_domain_type domain,
+ enum lttng_process_attr process_attr,
+ const struct process_attr_value *value)
+{
+ enum lttng_error_code ret_code = LTTNG_OK;
+
+ switch (domain) {
+ case LTTNG_DOMAIN_KERNEL:
+ if (!session->kernel_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ ret_code = kernel_process_attr_tracker_inclusion_set_remove_value(
+ session->kernel_session, process_attr, value);
+ break;
+ case LTTNG_DOMAIN_UST:
+ if (!session->ust_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ ret_code = trace_ust_process_attr_tracker_inclusion_set_remove_value(
+ session->ust_session, process_attr, value);
+ break;
+ default:
+ ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+ break;
+ }
+end:
+ return ret_code;
+}
+
+enum lttng_error_code cmd_process_attr_tracker_get_inclusion_set(
+ struct ltt_session *session,
+ enum lttng_domain_type domain,
+ enum lttng_process_attr process_attr,
+ struct lttng_process_attr_values **values)
+{
+ enum lttng_error_code ret_code = LTTNG_OK;
+ const struct process_attr_tracker *tracker;
+ enum process_attr_tracker_status status;
+
+ switch (domain) {
+ case LTTNG_DOMAIN_KERNEL:
+ if (!session->kernel_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ tracker = kernel_get_process_attr_tracker(
+ session->kernel_session, process_attr);
+ break;
+ case LTTNG_DOMAIN_UST:
+ if (!session->ust_session) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+ tracker = trace_ust_get_process_attr_tracker(
+ session->ust_session, process_attr);
+ break;
+ default:
+ ret_code = LTTNG_ERR_UNSUPPORTED_DOMAIN;
+ goto end;
+ }
+
+ if (!tracker) {
+ ret_code = LTTNG_ERR_INVALID;
+ goto end;
+ }
+
+ status = process_attr_tracker_get_inclusion_set(tracker, values);
+ switch (status) {
+ case PROCESS_ATTR_TRACKER_STATUS_OK:
+ ret_code = LTTNG_OK;
+ break;
+ case PROCESS_ATTR_TRACKER_STATUS_INVALID_TRACKING_POLICY:
+ ret_code = LTTNG_ERR_PROCESS_ATTR_TRACKER_INVALID_TRACKING_POLICY;
+ break;
+ case PROCESS_ATTR_TRACKER_STATUS_ERROR:
+ ret_code = LTTNG_ERR_NOMEM;
+ break;
+ default:
+ ret_code = LTTNG_ERR_UNK;
+ break;
+ }
+
+end:
+ return ret_code;
+}
+
/*
* Command LTTNG_DISABLE_EVENT processed by the client thread.
*/
return syscall_table_list(events);
}
-/*
- * Command LTTNG_LIST_TRACKER_PIDS processed by the client thread.
- *
- * Called with session lock held.
- */
-ssize_t cmd_list_tracker_pids(struct ltt_session *session,
- enum lttng_domain_type domain, int32_t **pids)
-{
- int ret;
- ssize_t nr_pids = 0;
-
- switch (domain) {
- case LTTNG_DOMAIN_KERNEL:
- {
- struct ltt_kernel_session *ksess;
-
- ksess = session->kernel_session;
- nr_pids = kernel_list_tracker_pids(ksess, pids);
- if (nr_pids < 0) {
- ret = LTTNG_ERR_KERN_LIST_FAIL;
- goto error;
- }
- break;
- }
- case LTTNG_DOMAIN_UST:
- {
- struct ltt_ust_session *usess;
-
- usess = session->ust_session;
- nr_pids = trace_ust_list_tracker_pids(usess, pids);
- if (nr_pids < 0) {
- ret = LTTNG_ERR_UST_LIST_FAIL;
- goto error;
- }
- break;
- }
- case LTTNG_DOMAIN_LOG4J:
- case LTTNG_DOMAIN_JUL:
- case LTTNG_DOMAIN_PYTHON:
- default:
- ret = LTTNG_ERR_UND;
- goto error;
- }
-
- return nr_pids;
-
-error:
- /* Return negative value to differentiate return code */
- return -ret;
-}
-
/*
* Command LTTNG_START_TRACE processed by the client thread.
*
struct ltt_ust_session *usess;
const bool session_rotated_after_last_stop =
session->rotated_after_last_stop;
+ const bool session_cleared_after_last_stop =
+ session->cleared_after_last_stop;
assert(session);
/* Is the session already started? */
if (session->active) {
ret = LTTNG_ERR_TRACE_ALREADY_STARTED;
- goto error;
+ /* Perform nothing */
+ goto end;
}
if (session->rotation_state == LTTNG_ROTATION_STATE_ONGOING &&
session->active = 1;
session->rotated_after_last_stop = false;
+ session->cleared_after_last_stop = false;
if (session->output_traces && !session->current_trace_chunk) {
if (!session->has_been_started) {
struct lttng_trace_chunk *trace_chunk;
* was produced as the session was stopped, so the
* rotation should happen on reception of the command.
*/
- ret = cmd_rotate_session(session, NULL, true);
+ ret = cmd_rotate_session(session, NULL, true,
+ LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION);
if (ret != LTTNG_OK) {
goto error;
}
}
}
+ /*
+ * Open a packet in every stream of the session to ensure that viewers
+ * can correctly identify the boundaries of the periods during which
+ * tracing was active for this session.
+ */
+ ret = session_open_packets(session);
+ if (ret != LTTNG_OK) {
+ goto error;
+ }
+
/*
* Clear the flag that indicates that a rotation was done while the
* session was stopped.
/* Restore initial state on error. */
session->rotated_after_last_stop =
session_rotated_after_last_stop;
+ session->cleared_after_last_stop =
+ session_cleared_after_last_stop;
}
+end:
return ret;
}
session->rotate_size = 0;
}
- if (session->most_recent_chunk_id.is_set &&
- session->most_recent_chunk_id.value != 0 &&
- session->current_trace_chunk && session->output_traces) {
+ if (session->rotated && session->current_trace_chunk && session->output_traces) {
/*
* Perform a last rotation on destruction if rotations have
* occurred during the session's lifetime.
*/
- ret = cmd_rotate_session(session, NULL, false);
+ ret = cmd_rotate_session(session, NULL, false,
+ LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED);
if (ret != LTTNG_OK) {
ERR("Failed to perform an implicit rotation as part of the destruction of session \"%s\": %s",
session->name, lttng_strerror(-ret));
* emitted and no renaming of the current trace chunk takes
* place.
*/
- ret = cmd_rotate_session(session, NULL, true);
- if (ret != LTTNG_OK) {
+ ret = cmd_rotate_session(session, NULL, true,
+ LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION);
+ /*
+ * Rotation operations may not be supported by the kernel
+ * tracer. Hence, do not consider this implicit rotation as
+ * a session destruction error. The library has already stopped
+ * the session and waited for pending data; there is nothing
+ * left to do but complete the destruction of the session.
+ */
+ if (ret != LTTNG_OK &&
+ ret != -LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL) {
ERR("Failed to perform a quiet rotation as part of the destruction of session \"%s\": %s",
- session->name, lttng_strerror(-ret));
+ session->name, lttng_strerror(ret));
destruction_last_error = -ret;
}
}
size_t trigger_len;
ssize_t sock_recv_len;
struct lttng_trigger *trigger = NULL;
- struct lttng_buffer_view view;
- struct lttng_dynamic_buffer trigger_buffer;
+ struct lttng_payload trigger_payload;
- lttng_dynamic_buffer_init(&trigger_buffer);
+ lttng_payload_init(&trigger_payload);
trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
- ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
+ ret = lttng_dynamic_buffer_set_size(
+ &trigger_payload.buffer, trigger_len);
if (ret) {
ret = LTTNG_ERR_NOMEM;
goto end;
}
- sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
- trigger_len);
+ sock_recv_len = lttcomm_recv_unix_sock(
+ sock, trigger_payload.buffer.data, trigger_len);
if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
ERR("Failed to receive \"register trigger\" command payload");
/* TODO: should this be a new error enum ? */
goto end;
}
- view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
- if (lttng_trigger_create_from_buffer(&view, &trigger) !=
- trigger_len) {
- ERR("Invalid trigger payload received in \"register trigger\" command");
- ret = LTTNG_ERR_INVALID_TRIGGER;
- goto end;
+ {
+ struct lttng_payload_view view =
+ lttng_payload_view_from_payload(
+ &trigger_payload, 0, -1);
+
+ if (lttng_trigger_create_from_payload(&view, &trigger) !=
+ trigger_len) {
+ ERR("Invalid trigger payload received in \"register trigger\" command");
+ ret = LTTNG_ERR_INVALID_TRIGGER;
+ goto end;
+ }
}
ret = notification_thread_command_register_trigger(notification_thread,
trigger = NULL;
end:
lttng_trigger_destroy(trigger);
- lttng_dynamic_buffer_reset(&trigger_buffer);
+ lttng_payload_reset(&trigger_payload);
return ret;
}
size_t trigger_len;
ssize_t sock_recv_len;
struct lttng_trigger *trigger = NULL;
- struct lttng_buffer_view view;
- struct lttng_dynamic_buffer trigger_buffer;
+ struct lttng_payload trigger_payload;
- lttng_dynamic_buffer_init(&trigger_buffer);
+ lttng_payload_init(&trigger_payload);
trigger_len = (size_t) cmd_ctx->lsm->u.trigger.length;
- ret = lttng_dynamic_buffer_set_size(&trigger_buffer, trigger_len);
+ ret = lttng_dynamic_buffer_set_size(
+ &trigger_payload.buffer, trigger_len);
if (ret) {
ret = LTTNG_ERR_NOMEM;
goto end;
}
- sock_recv_len = lttcomm_recv_unix_sock(sock, trigger_buffer.data,
- trigger_len);
+ sock_recv_len = lttcomm_recv_unix_sock(
+ sock, trigger_payload.buffer.data, trigger_len);
if (sock_recv_len < 0 || sock_recv_len != trigger_len) {
ERR("Failed to receive \"unregister trigger\" command payload");
/* TODO: should this be a new error enum ? */
goto end;
}
- view = lttng_buffer_view_from_dynamic_buffer(&trigger_buffer, 0, -1);
- if (lttng_trigger_create_from_buffer(&view, &trigger) !=
- trigger_len) {
- ERR("Invalid trigger payload received in \"unregister trigger\" command");
- ret = LTTNG_ERR_INVALID_TRIGGER;
- goto end;
+ {
+ struct lttng_payload_view view =
+ lttng_payload_view_from_payload(
+ &trigger_payload, 0, -1);
+
+ if (lttng_trigger_create_from_payload(&view, &trigger) !=
+ trigger_len) {
+ ERR("Invalid trigger payload received in \"unregister trigger\" command");
+ ret = LTTNG_ERR_INVALID_TRIGGER;
+ goto end;
+ }
}
ret = notification_thread_command_unregister_trigger(notification_thread,
trigger);
end:
lttng_trigger_destroy(trigger);
- lttng_dynamic_buffer_reset(&trigger_buffer);
+ lttng_payload_reset(&trigger_payload);
return ret;
}
}
cur_nb_packets++;
}
- if (!cur_nb_packets) {
+ if (!cur_nb_packets && size_left != max_size) {
/* Not enough room to grab one packet of each stream, error. */
return -1;
}
snapshot_output->max_size);
if (nb_packets_per_stream < 0) {
ret_code = LTTNG_ERR_MAX_SIZE_INVALID;
- goto error;
+ goto error_close_trace_chunk;
}
if (session->kernel_session) {
snapshot_kernel_consumer_output, session,
wait, nb_packets_per_stream);
if (ret_code != LTTNG_OK) {
- goto error;
+ goto error_close_trace_chunk;
}
}
snapshot_ust_consumer_output, session,
wait, nb_packets_per_stream);
if (ret_code != LTTNG_OK) {
- goto error;
+ goto error_close_trace_chunk;
}
}
- if (session_close_trace_chunk(
- session, session->current_trace_chunk, NULL, NULL)) {
+error_close_trace_chunk:
+ if (session_set_trace_chunk(session, NULL, &snapshot_trace_chunk)) {
+ ERR("Failed to release the current trace chunk of session \"%s\"",
+ session->name);
+ ret_code = LTTNG_ERR_UNK;
+ }
+
+ if (session_close_trace_chunk(session, snapshot_trace_chunk,
+ LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION, NULL)) {
/*
* Don't goto end; make sure the chunk is closed for the session
* to allow future snapshots.
session->name);
ret_code = LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
}
- if (session_set_trace_chunk(session, NULL, NULL)) {
- ERR("Failed to release the current trace chunk of session \"%s\"",
- session->name);
- ret_code = LTTNG_ERR_UNK;
- }
error:
if (original_ust_consumer_output) {
session->ust_session->consumer = original_ust_consumer_output;
*/
int cmd_rotate_session(struct ltt_session *session,
struct lttng_rotate_session_return *rotate_return,
- bool quiet_rotation)
+ bool quiet_rotation,
+ enum lttng_trace_chunk_command_type command)
{
int ret;
uint64_t ongoing_rotation_chunk_id;
cmd_ret = LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP;
goto end;
}
+
+ /*
+ * After a stop followed by a clear, disallow following rotations a they would
+ * generate empty chunks.
+ */
+ if (session->cleared_after_last_stop) {
+ DBG("Session \"%s\" was already cleared after stop, refusing rotation",
+ session->name);
+ cmd_ret = LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR;
+ goto end;
+ }
+
if (session->active) {
new_trace_chunk = session_create_new_trace_chunk(session, NULL,
NULL, NULL);
assert(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
ret = session_close_trace_chunk(session, chunk_being_archived,
- quiet_rotation ?
- NULL :
- &((enum lttng_trace_chunk_command_type){
- LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED}),
- session->last_chunk_path);
+ command, session->last_chunk_path);
if (ret) {
cmd_ret = LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
goto error;
projects / lttng-tools.git / blobdiff