General API

Macros
#define	LTTNG_NAME_MAX
	Maximum name length.
#define	LTTNG_SYMBOL_NAME_LEN
	Maximum symbol length.

Enumerations
enum	lttng_error_code {   LTTNG_OK , LTTNG_ERR_UNK , LTTNG_ERR_UND , LTTNG_ERR_SESSION_STARTED ,   LTTNG_ERR_UNKNOWN_DOMAIN , LTTNG_ERR_NOT_SUPPORTED , LTTNG_ERR_NO_SESSION , LTTNG_ERR_CREATE_DIR_FAIL ,   LTTNG_ERR_SESSION_FAIL , LTTNG_ERR_NO_SESSIOND , LTTNG_ERR_SET_URL , LTTNG_ERR_URL_EXIST ,   LTTNG_ERR_BUFFER_NOT_SUPPORTED , LTTNG_ERR_SESS_NOT_FOUND , LTTNG_ERR_BUFFER_TYPE_MISMATCH , LTTNG_ERR_FATAL ,   LTTNG_ERR_NOMEM , LTTNG_ERR_EXIST_SESS , LTTNG_ERR_NO_EVENT , LTTNG_ERR_CONNECT_FAIL ,   LTTNG_ERR_SNAPSHOT_OUTPUT_EXIST , LTTNG_ERR_EPERM , LTTNG_ERR_KERN_NA , LTTNG_ERR_KERN_VERSION ,   LTTNG_ERR_KERN_EVENT_EXIST , LTTNG_ERR_KERN_SESS_FAIL , LTTNG_ERR_KERN_CHAN_EXIST , LTTNG_ERR_KERN_CHAN_FAIL ,   LTTNG_ERR_KERN_CHAN_NOT_FOUND , LTTNG_ERR_KERN_CHAN_DISABLE_FAIL , LTTNG_ERR_KERN_CHAN_ENABLE_FAIL , LTTNG_ERR_KERN_CONTEXT_FAIL ,   LTTNG_ERR_KERN_ENABLE_FAIL , LTTNG_ERR_KERN_DISABLE_FAIL , LTTNG_ERR_KERN_META_FAIL , LTTNG_ERR_KERN_START_FAIL ,   LTTNG_ERR_KERN_STOP_FAIL , LTTNG_ERR_KERN_CONSUMER_FAIL , LTTNG_ERR_KERN_STREAM_FAIL , LTTNG_ERR_START_SESSION_ONCE ,   LTTNG_ERR_SNAPSHOT_FAIL , LTTNG_ERR_KERN_LIST_FAIL , LTTNG_ERR_UST_EVENT_ENABLED , LTTNG_ERR_UST_SESS_FAIL ,   LTTNG_ERR_UST_CHAN_EXIST , LTTNG_ERR_UST_CHAN_FAIL , LTTNG_ERR_UST_CHAN_NOT_FOUND , LTTNG_ERR_UST_CHAN_DISABLE_FAIL ,   LTTNG_ERR_UST_ENABLE_FAIL , LTTNG_ERR_UST_DISABLE_FAIL , LTTNG_ERR_UST_START_FAIL , LTTNG_ERR_UST_STOP_FAIL ,   LTTNG_ERR_UST_CONSUMER64_FAIL , LTTNG_ERR_UST_CONSUMER32_FAIL , LTTNG_ERR_NO_CHANNEL , LTTNG_ERR_SESSION_INVALID_CHAR ,   LTTNG_ERR_UST_LIST_FAIL , LTTNG_ERR_UST_EVENT_EXIST , LTTNG_ERR_UST_EVENT_NOT_FOUND , LTTNG_ERR_UST_CONTEXT_EXIST ,   LTTNG_ERR_UST_CONTEXT_INVAL , LTTNG_ERR_NEED_ROOT_SESSIOND , LTTNG_ERR_TRACE_ALREADY_STARTED , LTTNG_ERR_TRACE_ALREADY_STOPPED ,   LTTNG_ERR_KERN_EVENT_ENOSYS , LTTNG_ERR_NEED_CHANNEL_NAME , LTTNG_ERR_NO_UST , LTTNG_ERR_SAVE_FILE_EXIST ,   LTTNG_ERR_SAVE_IO_FAIL , LTTNG_ERR_LOAD_INVALID_CONFIG , LTTNG_ERR_LOAD_IO_FAIL , LTTNG_ERR_LOAD_SESSION_NOENT ,   LTTNG_ERR_MAX_SIZE_INVALID , LTTNG_ERR_INVALID , LTTNG_ERR_NO_USTCONSUMERD , LTTNG_ERR_NO_KERNCONSUMERD ,   LTTNG_ERR_URL_DATA_MISS , LTTNG_ERR_URL_CTRL_MISS , LTTNG_ERR_ENABLE_CONSUMER_FAIL , LTTNG_ERR_RELAYD_CONNECT_FAIL ,   LTTNG_ERR_RELAYD_VERSION_FAIL , LTTNG_ERR_FILTER_INVAL , LTTNG_ERR_FILTER_NOMEM , LTTNG_ERR_NO_CONSUMER ,   LTTNG_ERR_EXCLUSION_INVAL , LTTNG_ERR_EXCLUSION_NOMEM , LTTNG_ERR_INVALID_EVENT_NAME , LTTNG_ERR_INVALID_CHANNEL_NAME ,   LTTNG_ERR_PROCESS_ATTR_EXISTS , LTTNG_ERR_PROCESS_ATTR_MISSING , LTTNG_ERR_INVALID_CHANNEL_DOMAIN , LTTNG_ERR_OVERFLOW ,   LTTNG_ERR_SESSION_NOT_STARTED , LTTNG_ERR_LIVE_SESSION , LTTNG_ERR_PER_PID_SESSION , LTTNG_ERR_KERN_CONTEXT_UNAVAILABLE ,   LTTNG_ERR_REGEN_STATEDUMP_FAIL , LTTNG_ERR_REGEN_STATEDUMP_NOMEM , LTTNG_ERR_NOT_SNAPSHOT_SESSION , LTTNG_ERR_INVALID_TRIGGER ,   LTTNG_ERR_TRIGGER_EXISTS , LTTNG_ERR_TRIGGER_NOT_FOUND , LTTNG_ERR_ROTATION_PENDING , LTTNG_ERR_ROTATION_NOT_AVAILABLE ,   LTTNG_ERR_ROTATION_SCHEDULE_SET , LTTNG_ERR_ROTATION_SCHEDULE_NOT_SET , LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP , LTTNG_ERR_ROTATION_WRONG_VERSION ,   LTTNG_ERR_NO_SESSION_OUTPUT , LTTNG_ERR_ROTATION_NOT_AVAILABLE_RELAY , LTTNG_ERR_AGENT_TRACING_DISABLED , LTTNG_ERR_PROBE_LOCATION_INVAL ,   LTTNG_ERR_ELF_PARSING , LTTNG_ERR_SDT_PROBE_SEMAPHORE , LTTNG_ERR_ROTATION_FAIL_CONSUMER , LTTNG_ERR_CHAN_NOT_FOUND ,   LTTNG_ERR_SNAPSHOT_UNSUPPORTED , LTTNG_ERR_SESSION_NOT_EXIST , LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER , LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER ,   LTTNG_ERR_INVALID_PROTOCOL , LTTNG_ERR_FILE_CREATION_ERROR , LTTNG_ERR_TIMER_STOP_ERROR , LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL ,   LTTNG_ERR_CLEAR_RELAY_DISALLOWED , LTTNG_ERR_CLEAR_NOT_AVAILABLE_RELAY , LTTNG_ERR_CLEAR_FAIL_CONSUMER , LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR ,   LTTNG_ERR_USER_NOT_FOUND , LTTNG_ERR_GROUP_NOT_FOUND , LTTNG_ERR_UNSUPPORTED_DOMAIN , LTTNG_ERR_PROCESS_ATTR_TRACKER_INVALID_TRACKING_POLICY ,   LTTNG_ERR_EVENT_NOTIFIER_GROUP_NOTIFICATION_FD , LTTNG_ERR_INVALID_CAPTURE_EXPRESSION , LTTNG_ERR_EVENT_NOTIFIER_REGISTRATION , LTTNG_ERR_EVENT_NOTIFIER_ERROR_ACCOUNTING ,   LTTNG_ERR_EVENT_NOTIFIER_ERROR_ACCOUNTING_FULL , LTTNG_ERR_INVALID_ERROR_QUERY_TARGET , LTTNG_ERR_BUFFER_FLUSH_FAILED , LTTNG_ERR_PID_TRACKED ,   LTTNG_ERR_PID_NOT_TRACKED }
	General error codes. More...
enum	lttng_kernel_tracer_status {   LTTNG_KERNEL_TRACER_STATUS_INITIALIZED , LTTNG_KERNEL_TRACER_STATUS_ERR_UNKNOWN , LTTNG_KERNEL_TRACER_STATUS_ERR_NEED_ROOT , LTTNG_KERNEL_TRACER_STATUS_ERR_NOTIFIER ,   LTTNG_KERNEL_TRACER_STATUS_ERR_OPEN_PROC_LTTNG , LTTNG_KERNEL_TRACER_STATUS_ERR_VERSION_MISMATCH , LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_UNKNOWN , LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_MISSING ,   LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_SIGNATURE }
	The status of an LTTng kernel tracer. More...

Functions
enum lttng_error_code	lttng_get_kernel_tracer_status (enum lttng_kernel_tracer_status *status)
	Sets *status to the current status of the LTTng kernel tracer.
int	lttng_session_daemon_alive (void)
	Returns whether or not liblttng-ctl is able to connect to a listening session daemon.
int	lttng_set_tracing_group (const char *group)
	Sets the current Unix tracing group of liblttng-ctl to group.
const char *	lttng_strerror (int error_code)
	Returns a human-readable message for the general error code error_code.

Detailed Description

The general LTTng control library C API offers:

• Error code enumerators and lttng_strerror().
• Session daemon connection functions:
  • lttng_session_daemon_alive()
  • lttng_set_tracing_group()
• The lttng_get_kernel_tracer_status() function to get the current LTTng kernel tracer status.

Session daemon connection

Many functions of the LTTng control library C API require a connection to a listening LTTng session daemon (see lttng-sessiond(8)) to control LTTng tracing.

liblttng-ctl connects to a session daemon through a Unix domain socket when you call some of its public functions, not when it loads.

Each Unix user may have its own independent running session daemon. However, liblttng-ctl must connect to the session daemon of the root user (the root session daemon) to control Linux kernel tracing.

How liblttng-ctl chooses which session daemon to connect to is as follows, considering U is the Unix user of the process running liblttng-ctl:

U is root

Connect to the root session daemon.

U is not root

If U is part of the current liblttng-ctl Unix tracing group

Try to connect to the root session daemon.

If the root session daemon isn't running, then connect to the session daemon of U.

If U is not part of the tracing group

Connect to the session daemon of U.

The Unix tracing group of the root session daemon is one of:

With the --group=GROUP option of the root session daemon

Exactly GROUP.

In that case, you must call lttng_set_tracing_group(), passing exactly GROUP, before you call a liblttng-ctl function which needs to connect to a session daemon.

Without the --group option of the root session daemon

Exactly tracing (also the default Unix tracing group of liblttng-ctl, therefore you don't need to call lttng_set_tracing_group()).

Check that your application can successfully connect to a session daemon with lttng_session_daemon_alive().

LTTng-instrumented user applications automatically register to both the root and user session daemons. This makes it possible for both session daemons to list the available instrumented applications and their instrumentation points.

Enumeration Type Documentation

lttng_error_code

enum lttng_error_code

General error codes.

Many functions, most of them dating from older liblttng-ctl versions, return this type (or an int value which is equal to the negation of one of those enumerators).

Not all error codes are relevant to a given function: this API documentation makes an effort to document the most relevant status codes for each function. This is not always possible, however, as LTTng is made of multiple interacting components (tracers, consumer daemons, session daemons, and the rest); those error codes can move from one to another and the possible error codes of a given liblttng-ctl function can change from version to version.

See also

lttng_strerror() – Returns a human-readable message for a general error code, positive or negative.

Enumerator
LTTNG_OK	Success.
LTTNG_ERR_UNK	Unknown error.
LTTNG_ERR_UND	Undefined command.
LTTNG_ERR_SESSION_STARTED	Recording session already started (active).
LTTNG_ERR_UNKNOWN_DOMAIN	Unknown tracing domain.
LTTNG_ERR_NOT_SUPPORTED	Unsupported operation.
LTTNG_ERR_NO_SESSION	No recording session found.
LTTNG_ERR_CREATE_DIR_FAIL	Failed to create a directory.
LTTNG_ERR_SESSION_FAIL	Failed to create a recording session.
LTTNG_ERR_NO_SESSIOND	No available session daemon to connect to.
LTTNG_ERR_SET_URL	Failed to set an URL.
LTTNG_ERR_URL_EXIST	URL already exists.
LTTNG_ERR_BUFFER_NOT_SUPPORTED	Unsupported buffer ownership model.
LTTNG_ERR_SESS_NOT_FOUND	Nonexistent recording session name.
LTTNG_ERR_BUFFER_TYPE_MISMATCH	A channel within the given tracing domain already exists and is configured with another buffer ownership model.
LTTNG_ERR_FATAL	Fatal error.
LTTNG_ERR_NOMEM	Failed to allocate memory.
LTTNG_ERR_EXIST_SESS	Recording session name already exists.
LTTNG_ERR_NO_EVENT	Recording event rule not found.
LTTNG_ERR_CONNECT_FAIL	Failed to connect to Unix socket.
LTTNG_ERR_SNAPSHOT_OUTPUT_EXIST	Snapshot output already exists.
LTTNG_ERR_EPERM	Permission denied.
LTTNG_ERR_KERN_NA	Linux kernel tracer isn't available.
LTTNG_ERR_KERN_VERSION	Incompatible Linux kernel tracer.
LTTNG_ERR_KERN_EVENT_EXIST	Linux kernel recording event rule already exists.
LTTNG_ERR_KERN_SESS_FAIL	Linux kernel tracer: failed to create a recording session.
LTTNG_ERR_KERN_CHAN_EXIST	Linux kernel channel already exists.
LTTNG_ERR_KERN_CHAN_FAIL	Failed to create a Linux kernel channel.
LTTNG_ERR_KERN_CHAN_NOT_FOUND	Linux kernel channel not found.
LTTNG_ERR_KERN_CHAN_DISABLE_FAIL	Failed to disable a Linux kernel channel.
LTTNG_ERR_KERN_CHAN_ENABLE_FAIL	Failed to create/enable a Linux kernel channel.
LTTNG_ERR_KERN_CONTEXT_FAIL	Failed to add a context field to be recorded to the event records of a Linux kernel channel.
LTTNG_ERR_KERN_ENABLE_FAIL	Failed to create/enable a Linux kernel recording event rule.
LTTNG_ERR_KERN_DISABLE_FAIL	Failed to disable a Linux kernel recording event rule.
LTTNG_ERR_KERN_META_FAIL	Failed to open a Linux kernel trace metadata stream.
LTTNG_ERR_KERN_START_FAIL	Linux kernel tracer: failed to start tracing.
LTTNG_ERR_KERN_STOP_FAIL	Linux kernel tracer: failed to stop tracing.
LTTNG_ERR_KERN_CONSUMER_FAIL	Failed to start a Linux kernel consumer daemon.
LTTNG_ERR_KERN_STREAM_FAIL	Failed to create a Linux kernel trace data stream.
LTTNG_ERR_START_SESSION_ONCE	The recording session never became active.
LTTNG_ERR_SNAPSHOT_FAIL	Failed to take a recording session snapshot.
LTTNG_ERR_KERN_LIST_FAIL	Failed to list Linux kernel recording event rules.
LTTNG_ERR_UST_EVENT_ENABLED	User space recording event rule already enabled.
LTTNG_ERR_UST_SESS_FAIL	User space tracer: failed to create a recording session.
LTTNG_ERR_UST_CHAN_EXIST	User space channel already exists.
LTTNG_ERR_UST_CHAN_FAIL	Failed to create a user space channel.
LTTNG_ERR_UST_CHAN_NOT_FOUND	User space channel not found.
LTTNG_ERR_UST_CHAN_DISABLE_FAIL	Failed to disable a user space channel.
LTTNG_ERR_UST_ENABLE_FAIL	Failed to create/enable a user space recording event rule.
LTTNG_ERR_UST_DISABLE_FAIL	Failed to disable a user space recording event rule.
LTTNG_ERR_UST_START_FAIL	User space tracer: failed to start tracing.
LTTNG_ERR_UST_STOP_FAIL	User space tracer: failed to stop tracing.
LTTNG_ERR_UST_CONSUMER64_FAIL	Failed to start a 64-bit user space consumer daemon.
LTTNG_ERR_UST_CONSUMER32_FAIL	Failed to start a 32-bit user space consumer daemon.
LTTNG_ERR_NO_CHANNEL	Recording session has no channels.
LTTNG_ERR_SESSION_INVALID_CHAR	Recording session name contains an invalid character.
LTTNG_ERR_UST_LIST_FAIL	Failed to list user space recording event rules.
LTTNG_ERR_UST_EVENT_EXIST	User space recording event rule already exists.
LTTNG_ERR_UST_EVENT_NOT_FOUND	User space recording event rule not found.
LTTNG_ERR_UST_CONTEXT_EXIST	Context field to be recorded to the event records of a user space channel already exists.
LTTNG_ERR_UST_CONTEXT_INVAL	Invalid/unknown context field type.
LTTNG_ERR_NEED_ROOT_SESSIOND	A root session daemon is required, but isn't available. See Session daemon connection.
LTTNG_ERR_TRACE_ALREADY_STARTED	Recording session is already active (started).
LTTNG_ERR_TRACE_ALREADY_STOPPED	Recording session is already inactive (stopped).
LTTNG_ERR_KERN_EVENT_ENOSYS	Linux kernel instrumentation point type not supported.
LTTNG_ERR_NEED_CHANNEL_NAME	A channel name is required because a non-default channel exists within the selected recording session and tracing domain.
LTTNG_ERR_NO_UST	Channel name is required because a non-default channel exists within the recording session.
LTTNG_ERR_SAVE_FILE_EXIST	Recording session configuration file already exists.
LTTNG_ERR_SAVE_IO_FAIL	I/O error while writing a recording session configuration file.
LTTNG_ERR_LOAD_INVALID_CONFIG	Invalid recording session configuration file.
LTTNG_ERR_LOAD_IO_FAIL	I/O error while reading a recording session configuration file.
LTTNG_ERR_LOAD_SESSION_NOENT	Recording session configuration file not found.
LTTNG_ERR_MAX_SIZE_INVALID	Maximum total size of all the snapshot trace files is invalid.
LTTNG_ERR_INVALID	Unsatisfied precondition (invalid parameter, for example).
LTTNG_ERR_NO_USTCONSUMERD	No user space consumer daemon available.
LTTNG_ERR_NO_KERNCONSUMERD	No Linux kernel consumer daemon available.
LTTNG_ERR_URL_DATA_MISS	Missing network data URL.
LTTNG_ERR_URL_CTRL_MISS	Missing network control URL.
LTTNG_ERR_ENABLE_CONSUMER_FAIL	Failed to communicate with a consumer daemon.
LTTNG_ERR_RELAYD_CONNECT_FAIL	Failed to connect to or communicate with a relay daemon (see lttng-relayd(8)).
LTTNG_ERR_RELAYD_VERSION_FAIL	Incompatible relay daemon (see lttng-relayd(8)) version.
LTTNG_ERR_FILTER_INVAL	Invalid context and event payload filter expression.
LTTNG_ERR_FILTER_NOMEM	Failed to allocate memory for a context and event payload filter object.
LTTNG_ERR_NO_CONSUMER	No available consumer daemon.
LTTNG_ERR_EXCLUSION_INVAL	Invalid event name exclusion data.
LTTNG_ERR_EXCLUSION_NOMEM	Failed to allocate memory for an event name exclusion object.
LTTNG_ERR_INVALID_EVENT_NAME	Invalid event name condition part of a recording event rule.
LTTNG_ERR_INVALID_CHANNEL_NAME	Invalid channel name.
LTTNG_ERR_PROCESS_ATTR_EXISTS	Process attribute is already part of an inclusion set.
LTTNG_ERR_PROCESS_ATTR_MISSING	Process attribute isn't part of an inclusion set.
LTTNG_ERR_INVALID_CHANNEL_DOMAIN	Invalid tracing domain for channel.
LTTNG_ERR_OVERFLOW	Overflow.
LTTNG_ERR_SESSION_NOT_STARTED	Recording session isn't active (started).
LTTNG_ERR_LIVE_SESSION	Unsupported LTTng live recording session mode.
LTTNG_ERR_PER_PID_SESSION	Unsupported process buffer ownership model.
LTTNG_ERR_KERN_CONTEXT_UNAVAILABLE	Context field type isn't available on the current Linux kernel.
LTTNG_ERR_REGEN_STATEDUMP_FAIL	Failed to regenerate the LTTng state dump event records.
LTTNG_ERR_REGEN_STATEDUMP_NOMEM	Failed to allocate memory to regenerate the LTTng state dump event records.
LTTNG_ERR_NOT_SNAPSHOT_SESSION	Recording session isn't in snapshot mode.
LTTNG_ERR_INVALID_TRIGGER	Invalid trigger.
LTTNG_ERR_TRIGGER_EXISTS	Trigger already exists (registered).
LTTNG_ERR_TRIGGER_NOT_FOUND	Trigger not found.
LTTNG_ERR_ROTATION_PENDING	Recording session rotation operation already in progress.
LTTNG_ERR_ROTATION_NOT_AVAILABLE	Recording session rotation feature isn't available for the mode of the given recording session.
LTTNG_ERR_ROTATION_SCHEDULE_SET	Recording session rotation schedule already set.
LTTNG_ERR_ROTATION_SCHEDULE_NOT_SET	Recording session rotation schedule isn't set.
LTTNG_ERR_ROTATION_MULTIPLE_AFTER_STOP	LTTng already archived the current trace chunk of the recording session since it became inactive (stopped).
LTTNG_ERR_ROTATION_WRONG_VERSION	Linux kernel tracer: unavailable recording session rotation feature.
LTTNG_ERR_NO_SESSION_OUTPUT	Recording session has no configured output.
LTTNG_ERR_ROTATION_NOT_AVAILABLE_RELAY	Relay daemon: unavailable recording session rotation feature.
LTTNG_ERR_AGENT_TRACING_DISABLED	Unavailable logging instrumentation point feature.
LTTNG_ERR_PROBE_LOCATION_INVAL	Invalid user space probe location.
LTTNG_ERR_ELF_PARSING	Failed to parse ELF file.
LTTNG_ERR_SDT_PROBE_SEMAPHORE	SystemTap User-level Statically Defined Tracing (USDT) probe guarded by a semaphore.
LTTNG_ERR_ROTATION_FAIL_CONSUMER	Consumer daemon failed to perform a recording session rotation operation.
LTTNG_ERR_CHAN_NOT_FOUND	Channel not found.
LTTNG_ERR_SNAPSHOT_UNSUPPORTED	Cannot take a snapshot with the current recording session configuration.
LTTNG_ERR_SESSION_NOT_EXIST	Nonexistent recording session.
LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER	Consumer daemon failed to create a trace chunk archive.
LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER	Consumer daemon failed to close a trace chunk archive.
LTTNG_ERR_INVALID_PROTOCOL	Invalid protocol.
LTTNG_ERR_FILE_CREATION_ERROR	Failed to create a file.
LTTNG_ERR_TIMER_STOP_ERROR	Failed to stop a timer.
LTTNG_ERR_ROTATION_NOT_AVAILABLE_KERNEL	Linux kernel tracer: recording session rotation feature isn't available.
LTTNG_ERR_CLEAR_RELAY_DISALLOWED	The relay daemon (see lttng-relayd(8)) doesn't allow recording session clearing operations.
LTTNG_ERR_CLEAR_NOT_AVAILABLE_RELAY	The relay daemon (see lttng-relayd(8)) doesn't support the recording session clearing operation.
LTTNG_ERR_CLEAR_FAIL_CONSUMER	Consumer daemon failed to clear the recording session.
LTTNG_ERR_ROTATION_AFTER_STOP_CLEAR	LTTng already cleared the recording session since it became inactive (stopped).
LTTNG_ERR_PROCESS_ATTR_TRACKER_INVALID_TRACKING_POLICY	Invalid operation considering the policy of the process filter.
LTTNG_ERR_EVENT_NOTIFIER_GROUP_NOTIFICATION_FD	Failed to initialize the file descriptor of the event notifier group notification.
LTTNG_ERR_INVALID_CAPTURE_EXPRESSION	Invalid event field capture expression.
LTTNG_ERR_EVENT_NOTIFIER_REGISTRATION	Failed to register the event notifier to the tracer.
LTTNG_ERR_EVENT_NOTIFIER_ERROR_ACCOUNTING	Failed to initialize the event notifier error accounting.
LTTNG_ERR_EVENT_NOTIFIER_ERROR_ACCOUNTING_FULL	Event notifier error accouting is full.
LTTNG_ERR_INVALID_ERROR_QUERY_TARGET	Invalid error query target.
LTTNG_ERR_BUFFER_FLUSH_FAILED	Failed to flush a buffer.
LTTNG_ERR_PID_TRACKED	Process attribute is already part of an inclusion set. Deprecated: Use LTTNG_ERR_PROCESS_ATTR_EXISTS.
LTTNG_ERR_PID_NOT_TRACKED	Process attribute isn't part of an inclusion set. Deprecated: Use LTTNG_ERR_PROCESS_ATTR_MISSING.

lttng_kernel_tracer_status

enum lttng_kernel_tracer_status

The status of an LTTng kernel tracer.

See also

lttng_get_kernel_tracer_status() – Get the current LTTng kernel tracer status.

Enumerator
LTTNG_KERNEL_TRACER_STATUS_INITIALIZED	Loaded without error.
LTTNG_KERNEL_TRACER_STATUS_ERR_UNKNOWN	Unknown error.
LTTNG_KERNEL_TRACER_STATUS_ERR_NEED_ROOT	liblttng-ctl cannot connect to the session daemon of the root user (the root session daemon). See Session daemon connection.
LTTNG_KERNEL_TRACER_STATUS_ERR_NOTIFIER	Notifier setup failed.
LTTNG_KERNEL_TRACER_STATUS_ERR_OPEN_PROC_LTTNG	Failed to open /proc/lttng.
LTTNG_KERNEL_TRACER_STATUS_ERR_VERSION_MISMATCH	Version mismatch between kernel tracer and kernel tracer ABI.
LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_UNKNOWN	LTTng kernel module loading failed.
LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_MISSING	Missing LTTng kernel modules.
LTTNG_KERNEL_TRACER_STATUS_ERR_MODULES_SIGNATURE	LTTng kernel module signature error.

Function Documentation

lttng_get_kernel_tracer_status()

enum lttng_error_code lttng_get_kernel_tracer_status ( enum lttng_kernel_tracer_status *  status )

extern

Sets *status to the current status of the LTTng kernel tracer.

Parameters

[out]

status

On success, this function sets *status to the current status of the kernel tracer.

Return values

LTTNG_OK	Success.
LTTNG_ERR_INVALID	Unsatisfied precondition.

Precondition

• liblttng-ctl can connect to a session daemon.
• status is not NULL.

lttng_session_daemon_alive()

int lttng_session_daemon_alive ( void  )

extern

Returns whether or not liblttng-ctl is able to connect to a listening session daemon.

How this function tries to connect to a session daemon depends on the current Unix tracing group (initially tracing) of the library. Set the tracing group with lttng_set_tracing_group().

Returns

One of:

1

liblttng-ctl is able to connect to a session daemon.

0

liblttng-ctl isn't able to connect to a session daemon.

Negative lttng_error_code enumerator

Error.

See also

lttng_set_tracing_group() – Sets the current Unix tracing group of liblttng-ctl.

lttng_set_tracing_group()

int lttng_set_tracing_group ( const char *  group )

extern

Sets the current Unix tracing group of liblttng-ctl to group.

How the liblttng-ctl functions connect to a session daemon depends on the current Unix tracing group (initially tracing) of the library.

Parameters

[in]

group

New Unix tracing group of liblttng-ctl (copied).

Returns

0

Success.

-LTTNG_ERR_INVALID (negative)

Unsatisfied precondition.

-LTTNG_ERR_FATAL (negative)

Out of memory.

Precondition

• group is not NULL.
• group names an existing Unix group.

lttng_strerror()

const char * lttng_strerror ( int  error_code )

extern

Returns a human-readable message for the general error code error_code.

Parameters

[in]

error_code

Error code (one of the lttng_error_code enumerators), positive or negative, for which to get a corresponding human-readable message.

Returns

Human-readable message which corresponds to error_code.

Precondition

• error_code is a valid lttng_error_code enumerator.