relayd: track the relay_conn_pipe with the fd-tracker

Create the relayd connection pipe through the
fd_tracker_util_pipe_open_cloexec() function which wraps
utils_create_pipe_cloexec(), but tracks the resulting file descriptor.

The close of the pipe is also performed through the fd tracker.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I6ed0d64c973a454de2e50c7cae006fd546299290

relayd: track the quit pipe with the fd-tracker

Create the relayd quit pipe through the
fd_tracker_util_pipe_open_cloexec() function which wraps
utils_create_pipe_cloexec(), but tracks the resulting file descriptor.

The close of the pipe is also performed through the fd tracker.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ia2a000030765e8df990e0ea3d35a8bf157630d9f

relayd: Don't bypass the fd tracker when closing file descriptors

There is no reason to close all file descriptors at this point in the
relay daemon as we know for a fact that the only open fds are stdout
and stderr. If the relayd was to depend on a library that opens other
file descriptors, it would be unadvisable to perform this kind of bulk
closing of all possible file descriptors.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I8ff134094b16dfb6c1aeb875431fdbd4f608eebd

relayd: initialize the global fd tracker from fd_cap option

Initialize the relay daemon's global fd tracker from the current
fd-cap configuration. This is in preparation for follow-up patches
which will introduce the tracking of the various file descriptor
backed resources to the relay daemon.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Iaabb80f1fb4d24345b750503c90388f94025159d

relayd: clean-up: reduce the number of exit paths in main()

The relay daemons's initialization and teardown relies on a large
number of goto/labels to clean-up on failure to launch.

All of the clean-up can be performed unconditionally by checking for
NULL or uninitialized file descriptors in relayd_cleanup(). This
reduces the number of possible tear-down paths and partly initialized
state to keep track of.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I3195caf05b3dd04cc7e9c60dcb322261159fe0df

relayd: add fd-cap option to limit the number of opened FDs

Add an --fd-cap option to the relay daemon in order to allow the
launch of the relay daemon with a maximal number of file descriptors
to be open at any given moment.

When the value of the --fd-cap parameter is left unset, the maximal
number of file descriptors is set to the system's NOFILE soft limit
(see GETRLIMIT(3P)).

A minimal number of file descriptors of 30 is imposed, mainly to
prevent absurd configurations (someone setting 1 fd) which would not
even allow one target to connect and stream traces. This also allows
a bit of leverage to open file descriptors that could be needed by
future changes without "breaking" an existing configuration.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ibaf49b25ccf3e3a8013115c9478744ca3646e306

Fix: use lttng_tracker_id_status enum values

This is probably a copy paste error. This should not be a problem in any
case since the final values for both enums are the same.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Ia1dc173a4eae8b7d9bff35a718c93331b714f5d6
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: update context types for Python bindings

Fixes: #1214
Signed-off-by: Christophe Bedard <bedard.christophe@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: lttng: placing probe on symbol starting with `_`

Issue
=====
The lttng CLI tool does not parse `--probe` symbol name properly if the
name has an underscore at the beginning.
For example, the following command fails
  lttng enable-event -k --probe _do_fork my_do_fork_event

This happens because the `parse_probe_opts()` function looks if the
first character of the symbol field is an alphabetic character to
determine if a symbol was provided. The problem is that some kernel
symbols such as `_do_fork` start with an underscore.

Solution
========
check if the first character is an alphabetic character OR an
underscore.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I3ee6c26641ceee508ee78e895d372c6b09fe90fb
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: build failure with -fno-common

GCC 10 will default to building with -fno-common, this inhibits the
linker from merging multiple tentative definitions of a symbol in an
archive.

I'm not sure I understand what happen with the symbols in mi-lttng.h
but a similar issue was adressed in:

  commit 4965f956f3ef47388fb4a1b2f8f504abfe31afe7
  Author: Jérémie Galarneau <jeremie.galarneau@efficios.com>
  Date:   Fri May 22 12:53:30 2015 -0400

    Fix: Mark MI and Config string declarations as extern

    This fixes a build issue with GCC 5.1 which would complain about
    these symbols being defined multiple times.

Make sure these symbols are extern and defined only in one compile unit.

For more information, see:
https://gcc.gnu.org/gcc-10/porting_to.html

Change-Id: I139c9695371836cb1011f9ce192080b602ed2fbc
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: Tests: missing stream redirect causes test failure

The following commit enforced the use of options (instead of arguments)
in the `gen-ust-events` test application:
  commit 6c4a91d639747f260ab46decebc50998ef063712
  Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  Date:   Mon Aug 26 14:22:06 2019 -0400

      tests: gen-ust-events: use options instead of arguments

This makes tests exit (and abort since commit 56d4838) when arguments
are passed to the test application. It currently fails with the
following error:
  ./gen-ust-events -i 32 -w 21 \
    --sync-after-first-event /tmp/allo.hi \
    --sync-before-last-event /tmp/allo.bye /dev/null
  Error: takes long options only.
  zsh: abort (core dumped)  ./gen-ust-events -i 32 -w 21 --sync-after-first-event /tmp/allo.hi

The `/dev/null` at the end of the command line is not associated with an
option so it triggers the sanity check. The `/dev/null` most probably
meant to redirect STDOUT to `/dev/null`.

This commit adds the missing `>` so to overcome the sanity check
problem.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I3e4d4066079055a542438a63ef4df5c5c4c080cf
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: automatic enum value overwrites existing error code value

Automatic enum value are generated using the last value and
incrementing it. Having backward compat assignation before the
LTTNG_ERR_NR would end up overwriting the error string since the
LTTNG_ERR_NR value would be LTTNG_ERR_PID_NOT_TRACKED + 1.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I4076866a28961fa49eed018e8249d2cd72979a84
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

doc: Fix bind address example for lttng-relayd

INADDR_ANY is 0.0.0.0

Fixes: c93eadade277 ("doc/man: use propagated default values in man pages")
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Benjamin Poirier <benjamin.poirier@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I6e908adca66b829128ea31cf392bccad3f96d63d

Build fix: dist target builds fails due to missing header file

The path.h compatibility header is not distributed, causing builds
from tarballs to fail. Add it to the SOURCES variable.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ib112c6016e9e682545572b8ab01728996c41ed52

Fix: track-untrack.c: regression of `--all --pid` option ordering

Background
==========
The `tests/regression/kernel/test_callstack` test uses the PID tracker
to restrict what events end up in the trace. It does that by using the
following lttng command:
  lttng untrack -s $SESSION_NAME --all --pid -k

Issue
=====
A regression was introduced along with the UID tracker patch series that
makes the above command fail silently and return status 1. The bug is in
the argument parsing function that assumes that the tracker option
(`--pid` in this case) would appear before the `--all` option.

Where the above command fails, the one below works as expected:
  lttng untrack -s $SESSION_NAME --pid --all -k

Both ordering are valid and should be accepted.

Fix
===
When parsing the arguments, first record the fact that we encountered the
`--all` flag, and later check to what tracker it applies too.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I85f7a2fa8d6f67056aeff8edf3d12508f5ae0879
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

track-untrack.c: error out on unknown CLI options

Issue
=====
At the moment, it's possible to have unknown options in the `track` and
`untrack` commands. They are silently ignored.

For example, the following command line is accepted without problem:
  lttng untrack HELLO -k --all --pid

This was witnessed in the `test_event_tracker` tests. The
`lttng_track()` and `lttng_untrack() functions in `tests/utils/util.sh`
are currently passing the `$1` bash variable of the function to the
`track` and `untrack` througth their "$@" variable.

The commands should not silently accept those unknown options.

Fix
===
1. After looping on all the known options, check if there is any leftover
  options and error out if it's the case.
2. Fix the `utils.sh` functions to that they don't pass the `$1` variable
  to the commands.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I822ba09c8ce1ffa8366c586e760a9257e8078e43
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Add test_event_tracker to the TESTS variable

test_event_tracker is not run on `make check`. Adding it to the
TESTS variable so that it is picked-up by the TAP runner.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Id6dda47ee96e6123b326edb5262e941a41cd591e

Add missing `test_event_tracker` to fast_regression

Those tests currently don't run on the CI because they aren't in any of
the `*_regression` files. This commit fixes that.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I9dfb87cc7b863c678ebc6419d6a39b7b964273d5
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Cleanup: track-untrack.c: declare all `int` on the same line

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: Ic566fe9f33d67f7da750c478c6af0b41ec2a968b
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: relayd: hostname check is too restrictive

The check performed by the relay daemon on hostnames is too
restrictive. Since existing session daemons directly use the hostname
returned by gethostname(), the relay daemon must correctly handle FQDN
hostnames, which may contain dots.

This has been observed on the LTTng CI's RHEL8 nodes which report an
FQDN hostname.

The new function 'is_name_path_safe' is used for both session and host
names. It does not check for every problematic path names (reserved
names on Windows, per-platform illegal characters, etc.) Those
restrictions are assumed to be handled when open() and similar
syscalls fail.

However, the objective of this check is to prevent malicious (or at
least unexpected), but legal, names from being used, namely:
  - names that contain a path separator,
  - empty names,
  - hidden names (starting with a dot).

Ideally, illegal names would be automatically escaped in the future.
This is, however, beyond the scope of this fix.

Fixes #1212

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ieeb8b60d22c27b390b51ef7fb52cea0d0ac0f188

Cleanup: remove extra whitespace from include directive

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ic91f07131aced6857ddbcef46f85c3cc3119f98f

Fix: skip start trace for app that are already started.

When using trackers, call to ust_app_global_update
results in a call to ust_app_start_trace even if the ust app
trace was already enabled.

This resulted in error message from the app (-1024) complaining that the
tracing was already active on the app side.

  Error: Error starting tracing for app pid: 329376 (ret: -1024)
  ok 211 - Track command with opts: 0 -u --vpid 329376

A solution to this is to keep the enabled state inside the ua_sess and
skip the start trace if already enabled.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Ie4198245627e9f0426948489bc9ce24d8c813b08
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: keep active session state on redundant start command

Steps to reproduce problem:
  lttng create
  lttng enable-event -u -a
  lttng start
  lttng start
  lttng stop

Yield:

  Session auto-20200106-134455 created.
  Traces will be output to /home/joraj/lttng-traces/auto-20200106-134455
  All UST events are enabled in channel channel0
  Tracing started for session auto-20200106-134455
  Warning: Tracing already started for session auto-20200106-134455
  Warning: Tracing already stopped for session auto-20200106-134455

The "warning" on the "lttng stop" command is invalid.

This was introduced by commit

1f4962443 Fix: sessiond: no rotation performed from null chunk to new chunk

For cases where the session is already active, simply skip all the way to
the end without passing via the error handling path.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Iaf26090191d3eb940fa419848df8911758e0a6e3
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: build failures when `--without-lttng-ust`

The `--without-lttng-ust` configure option makes the build to fail due
to 2 bugs
1. Missing object file for session unit tests causes the following errors:
    CCLD     test_session
  ../../src/bin/lttng-sessiond/kernel.o: In function `kernel_track_id':
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:712: undefined reference to `lttng_tracker_id_lookup_string'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:723: undefined reference to `lttng_tracker_id_get_list'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:729: undefined reference to `lttng_tracker_list_add'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:810: undefined reference to `lttng_tracker_id_set_list'
  ../../src/bin/lttng-sessiond/kernel.o: In function `kernel_untrack_id':
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:826: undefined reference to `lttng_tracker_id_lookup_string'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:836: undefined reference to `lttng_tracker_id_get_list'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:841: undefined reference to `lttng_tracker_list_remove'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:925: undefined reference to `lttng_tracker_id_set_list'
  ../../src/bin/lttng-sessiond/kernel.o: In function `kernel_list_tracker_ids':
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/kernel.c:949: undefined reference to `lttng_tracker_id_get_list'
  ../../src/bin/lttng-sessiond/trace-kernel.o: In function `trace_kernel_create_session':
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:167: undefined reference to `lttng_tracker_list_create'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:171: undefined reference to `lttng_tracker_list_create'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:175: undefined reference to `lttng_tracker_list_create'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:179: undefined reference to `lttng_tracker_list_create'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:183: undefined reference to `lttng_tracker_list_create'
  ../../src/bin/lttng-sessiond/trace-kernel.o:/home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:187: more undefined references to `lttng_tracker_list_create' follow
  ../../src/bin/lttng-sessiond/trace-kernel.o: In function `trace_kernel_create_session':
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:199: undefined reference to `lttng_tracker_list_destroy'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:200: undefined reference to `lttng_tracker_list_destroy'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:201: undefined reference to `lttng_tracker_list_destroy'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:202: undefined reference to `lttng_tracker_list_destroy'
  /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:203: undefined reference to `lttng_tracker_list_destroy'
  ../../src/bin/lttng-sessiond/trace-kernel.o:/home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/trace-kernel.c:204: more undefined references to `lttng_tracker_list_destroy' follow
  collect2: error: ld returned 1 exit status
  Makefile:1062: recipe for target 'test_session' failed
  make[1]: *** [test_session] Error 1
  make[1]: Leaving directory '/home/frdeso/projets/lttng/tools/tests/unit'
  Makefile:1166: recipe for target 'all-recursive' failed
  make: *** [all-recursive] Error 1

2. An extra colon at the end of the `trace_ust_track_id()` stub
function gives this error:
    CC       utils.o
  In file included from ust-app.h:26:0,
                   from lttng-sessiond.h:31,
                   from utils.c:27:
  trace-ust.h:339:1: error: expected identifier or '(' before '{' token
   {
   ^
  trace-ust.h:336:19: warning: 'trace_ust_track_id' declared 'static' but never defined [-Wunused-function]
   static inline int trace_ust_track_id(enum lttng_tracker_type tracker_type,
                     ^~~~~~~~~~~~~~~~~~
  Makefile:729: recipe for target 'utils.o' failed

Both bugs are trivial to fix.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I66c57d206ad0142db057443374d28bbcf16c02f7
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Sync lttng-ust ABI version in ust-abi-internal.h

Bump LTTNG_UST_ABI_MINOR_VERSION to 1

Increment the minor version of lttng-ust ABI to 1, to take into
account that the "clear" command was added in this release cycle.

This will allow future LTTng-tools versions to check for this
capability.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I472eb11589547a9fa119d061a2c1886371b87f69

Sync lttng-modules ABI version in internal kernel-ioctl.h

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I67eafac24bc8db62831b6bc72497c706ff383a07

Fix: lttng-clear: invalid free of session name

Valgrind reports an invalid free of session_name when it is sourced
from the popt args. Only free it when it comes from the .lttngrc file.

This also caused spurious core dumps when running the tests on
one of my machines.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I194cd36147a1028aad503b4e5d3ea23732a30bc5

Fix: initialize var_data to NULL

Remove a false-positive from scan-build. Initialization of
var_data_len should have been enough but scan build is not smart
enough to understand this.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I90cb449f3092db432967a3f2ea5eedb0728b8678
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

tracker: update API documentation

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I71f02c5cbebe7ed8e19aee6bc0d2af7741ed272f
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Cleanup: remove struct lttng_handle from tracker.h

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I8b9fd5c86200013cbd60c57505621cb851556b01
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Refactoring: introduce lttng_tracker_ids_serialize

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I0d43b85241b7097ac722724d9fef0ca352422495
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Refactoring: move count to an output parameter

This mimics what is done for lttng_rotation_schedules_get_count.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I576d112de4a9bfa258a78cb52b8da8a5f25adefb
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Refactoring: introduce lttng_tracker_ids data structure

This data structure is opaque to allow for back-end implementation change
in the future.

For now, only the following functions concerning lttng_tracker_ids are public:
    lttng_list_tracker_ids
    lttng_tracker_ids_get_count
    lttng_tracker_ids_get_at_index
    lttng_tracker_ids_destroy

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Iae1c10d0b578b402ab91378dd49f69f605b316b2
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Refactoring: use an opaque lttng_tracker_id type

Move the tracker and tracker id related API to tracker.h and
tracker-internal.h.

The use of an opaque object mimics the new API for rotation and trigger
etc.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I00b876c618d7dcb0dd940189e5250c3f3d64c7e0
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: Initialize ret to zero

For the improbable case that the domain is unknown the return value ret
would not be initialized.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I22ae6b98bbbc4f4fe3e9c28985e2400f7c668525
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Update track/untrack man page

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Ie7092993034f2fb71fc3b1fad0ce5a6f61a31493
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Error early on invalid tracker type for UST domain

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Iea182575c99c1fcf84cb8c313af5904581b5023d
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

ust-app: remove dead code

This code path is not possible since all callsite are fenced with a check
to "has_been_started". Hence, a session cannot be active at the same time.

Change-Id: I53785017989ed7afc8755a41428087d988e5ae88
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: Skip uid registry when metadata key value is 0

A value of 0 for the metadata key indicates that the metadata channel
was never created/pushed on the consumer side.

This can occur in scenario where a tracker(s) (vuid/vgid/vpid) is present.
The metadata channel might never be created/pushed since no applications
are actually tracing. Still, the uid registry exists due to the order
in which the sessiond received the client commands (create,
enable-channel, lttng track/untrack).

See included test for a complete reproducer.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Id7ef34ebc48333f47db4bdca907cf81911b60d1d
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trackers: bump MI version to 4.0

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I0a44262016cf90e0629be5cb7d8b5976462c62d9
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

tests: test uid/gid/pid/vuid/vgid/vpid trackers

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I1b5ee95efc58a3969066e353cb30eeb3fd8eebb9
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trackers: update list/track/untrack commands

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I18e41d0e3c7826596ac0468eb5ef7bcc549c8f98
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trackers: support tracking feature

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I1629562f4c94947f5dd54a0cee6c0f8f7beb19fe
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trackers: add sessiond tracker list implementation

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I28dbeac1f3db2df7e61911249a3250fbc17dc244
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trackers: update lttng-modules tracer ABI

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I27e1e552b13b5a541b43ff250d1d4839e399f1f3
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trackers: introduce new tracker types

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I749915124dbfe7cbe15d889a5dbcb648c17374dc
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trackers: change error code from "pid" to "id"

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I0ce03b23350a9f0da9d5f00ac3c6d0e824af9a98
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

format: use AfterCaseLabel: true for switch case

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Ib0bb3c222441e7c6afcf7ea5c5c95bbf8413be57
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: sessiond: check for lttng-modules ABI 2.1 rather than 2.8

The clear patchset introduces a regression that breaks session
rotations when the kernel domain is used. The 2.8 lttng-modules ABI
does not exist yet.

The packet sequence number functionality was introduced in LTTng 2.8,
which introduced the 2.1 kernel tracer ABI.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ief97e7e25f6f0fcb5b5b97b39abb417c1eb327ec

Doc: man page: lttng-relayd LTTNG_RELAYD_DISALLOW_CLEAR env. var.

Describe the LTTNG_RELAYD_DISALLOW_CLEAR environment variable in the
lttng-relayd(8) man page.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I3573d0f220f8aa298935e01f62c89035a1966f77
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Doc: lttng-clear(8) man page

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I6d981a1e17a2a3fdd20a4c61b8c2216bc6517f3f
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

tests: mi for clear command

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I769825ce10ce08cc1ae127821982d7ec3b1448ca
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

tests: lttng clear command

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I96c837dfd65be76aa8995305e1e17a8b315b22af
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

tests: gen-ust-events: abort() on argument error

Facilitates test transition: quickly identify tests which were not
updated.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Idec886cc565c4cb7f1de89e7f3f765c882f4b988
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

tests: gen-ust-events: add touch and wait sync points before exit.

Allows an app to linger until the wait file is created and signals that
the app is just before the exit.

This is mostly useful for per-pid tracing where trace buffers are
cleaned on application teardown.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I37db4c118ebc759ce97c5de8901cad7b39ac1e01
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

tests: gen-ust-events: use options instead of arguments

Remove argument dependency and ease usage of features individually.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I25769754a1ab271cea9b9ff5519f37371fd877dc
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: live: implement support for clear feature

Implement support for clear feature on live side of relayd.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I2d8996098abbdcd635757425bfcee405daf1bb13
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: implement support for clear feature

Implement support for the clear feature on relayd receiving end.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ice56dea0b7f59a4881f28fef84bcb0406e0afca6
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: viewer-stream: introduce viewer_stream_close_files and viewer_stream_sync_tracefile_array_tail

Introduce the following viewer helpers for clear:

- viewer_stream_close_files: Allow closing currently open viewer files.

- viewer_stream_sync_tracefile_array_tail: Allow updating the current
  tracefile id and the index sent seqcount based on the current content
  of the tracefile array.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I5d2f72868625b00b207c75c202bc514768c35166
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: viewer_session: expose viewer_session_set_trace_chunk_copy symbol

Expose viewer_session_set_trace_chunk_copy() so it can be used from
relayd live.c. Needed for clear feature.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ie5892353a13a80481da52f847e691a984e02000f
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trace-chunk: implement no-op and delete release commands

The delete release command is used by clear. The no-op command is used
for implicit session rotations launched by the destroy command.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I49ea666ff77d3e5f6ac4b25977313ea18e10be62
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: document effect of rotated_after_last_stop on clear

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I81e758aee375f297647bcf9c9a469f867799358a
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: snapshot: set trace chunk to NULL before closing it

Operations are expected to happen in this order with the reworked
trace chunk for clear feature.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I3d655714c4b40b8563abdadb8cb74067eb7e4b6e
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: return invalid protocol error on close chunk disallowed clear

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ic10283d5a9769f01486d3f6df07f54a8d2856699
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: set has rotated only for explicit rotations

Only set session has_rotated for explicit rotations on the trace chunk
close. This ensures has_rotated can distinguish between clear and
explicit rotate.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I97fac1ac2a6edc233bf1889d693f74f2d7936156
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

trace-chunk: Introduce chunk "path", relayd session "ongoing_rotation", sessiond session "rotated"

This commit introduces new attributes in 3 different structures because
those are used in surrounding areas of the code.

Introduce a trace chunk path attribute which tracks where the chunk
currently keeps its files.

It allows updating the current chunk location with the "rename"
API without having to rely on changing the chunk name override,
which is an attribute we may want to keep using when we archive
the chunk.

Separating the "path" from the "name override" attribute allows
easy manipulation of the chunk output without having to keep the
name override around in the caller code.

Introduce an "ongoing_rotation" relayd session attribute to allow
live viewers to retry while a rotation is ongoing. This ongoing
rotation attribute is introduced in the same commit as the path
chunk attribute because they are used in a surrounding area of the code.

Introduce a "rotated" sessiond session attribute in this commit
because it is used in a surrounding area of the code. This rotated
attribute tracks whether an explicit rotation has been performed
on the session. It is a preparation step for the clear feature,
which will use this to figure out whether it needs to clear the
"root" output path (no rotation prior to clear") or if it needs
to clear to a new path. Before introduction of the clear feature,
a chunk_id of 0 was used to identify this, but because clear will
increment the chunk id without changing the path, we need to track
this explicitly through the "rotated" session flag.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ifdecc66cb4849f3e5f7476ab7db48d8f7532a6d3
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

consumer: add extra debug output

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I9cc81de9c46d5379e288ece625ccfef4fbf8e022
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: add extra debug output

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ie83470b293e10441357302a0d6e2668522d983ed
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: implement clear command

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Iaff1df7693858f5c9b24a6c8d1411fd76cc83714
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: add clear notifier

Add a clear notifier array to reply to clients requesting a clear
command.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I422d87b0122b75be47ae5941fed15f09e87460fe
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: introduce cleared_after_last_stop

Track whether a session was cleared after the last stop, so
additional clear will be effect-less until it is started again.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Icaa86acab20081b436bd55d026ec79a10c56034b
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: implement ust app clear session

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I9205b25cd18035156485df980104dea5c241542f
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: implement kernel clear session

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ie47c128fc951b206c7ae50933395e9ade9d0012d
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: implement consumer clear channel

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I1c17a34c23e4c03f94acb99fb822c3bc42faccf5
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

consumer: implement clear channel

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I4eefc1d23b1b781f055790933572c4796375da26
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

common trace-chunk: introduce lttng_trace_chunk_get_name_overridden

While it is possible to query whether the name of a chunk is
overridden through lttng_trace_chunk_get_name(), using it requires
a lot of code to deal with an unused name string when all that is needed
is to check whether the name is overridden.

In preparation for the new "path" handling needed for the clear
feature introduce this lttng_trace_chunk_get_name_overridden()
API to allow checking whether name is overridden in a succint way.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ied8bcbb5202826e68a5d6b54130f29f203948794
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

common: trace-chunk: track all files within a chunk

Track all files added/removed in a chunk. Required by the clear
feature so all files of a prior chunk can be unlinked, even if
they belong to applications which have already closed their
stream with per-pid UST buffers.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I41bf8ac61f9a8ed1e8f206520ef8845a102b1c1e
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: cmd_rotate_session: introduce command argument

Add a command type argument to cmd_rotate_session().

Change the internal session_close_trace_chunk() API to introduce the
LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION command rather than rely on
a NULL pointer, which facilitates passing of command argument across
cmd_rotate_session.

This introduces the LTTNG_TRACE_CHUNK_COMMAND_TYPE_DELETE command,
which is required for the clear feature. Its implementation will
follow in a separate commit.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ic1d8cbab1f98b93f1f6d27a2c6624ac2780932e2
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: query relayd configuration for availability of clear feature

Query the relayd configuration when connecting to check for availability
of the clear feature.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I5827fdc7f92bc9bc87ccf9d1c567057b2c227e2b
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: Implement get_configuration relayd protocol command

Introduce a "GET_CONFIGURATION" command to the relayd protocol.
This allows checking whether the relay daemon allows the clear
command or not. A 64-bit set of flags are returned, and it can be
extended in the future with a variable length payload.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I33a03d09871f1c0c248d5514451c533ffd773979
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

common: index and trace-chunk file creation/open API change

An API change to the common libraries is required for the following
functions to accomodate the clear feature:

- lttng_trace_chunk_open_file(),
- lttng_index_file_create_from_trace_chunk(),
- lttng_index_file_create_from_trace_chunk_read_only().

An "expect_no_file" boolean is introduced, allowing specific invocation
to consider a ENOENT errno as an expected condition (and not an error).
This is the case for instance for relayd live viewer_stream_rotate(),
which can fail to open files in the new chunk after a clear with per-pid
buffers. Same goes for viewer_get_next_index() and try_open_index().

Change the lttng_index_file_create_from_trace_chunk_read_only and
lttng_index_file_create_from_trace_chunk to allow them to return
a chunk status, which allows the callers to distinguish between
errors and a "no file" status, and deal with the situation accordingly.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I3c43edca01629488c4e777078db7ffd2e88dc7ea
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

common: index: remove redundant separator for empty channel string

Tweak _lttng_index_file_create_from_trace_chunk() to correctly deal with
empty channel_path string, removing redundant "/" separators.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I743917c27e334ad12e145959b3ad3f59f62f1a64
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond: refactoring: introduce start/stop_kernel_session

The clear feature will need to stop kernel session as well, so move this
code to its own function rather than duplicate it.

start_kernel_session already exists, but is static. Expose it so it
can be used from a separate compile unit.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I68da1ee2e51105278265866590734c320a9789bd
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond-comm: add clear command support to consumer protocol

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I717012b855bc394bcdb524befb02a5b1ca54621b
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

sessiond-comm: Document feature branch specific commands range

Reserve a range of numbers for customer feature branches.
It is never meant to be used in the master branch.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib15ffe281c8e040231559e48b76343e67a625f4b
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: tracefile array: Allow head position to skip ahead

The clear feature needs to move the head position ahead (jump)
over sequence numbers.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I08482bd13dd748621968c43de7647f9d19670880
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd tracefile array: add tracefile_array_reset

Required by clear feature.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I58893eb3fffbec5d39e7bf11a6d118fe23ec4496
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

common dynamic-array: Introduce dynamic array clear

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I35d25b054a040c2d23b4b1c1a8137ef59ee3c7d1
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

relayd: environment variable to disable clear command

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I04e5867220315660a373f2e49d5e6f0652a6c37e
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

lttng: Implement lttng clear session command

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Ia51a2bf7aa7d764431eff9a45a91d5348bc9a7e5
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

lttng-ctl: Expose sessiond cmd_clear_session command

Co-developed-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Id9d169daaa1c20912a6c105b4473c3f9f2ba3b49
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

common error: Add errors for clear feature

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib7f1a99e2c5535941d6d7f9479e00762ae14b6ae
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

ust-consumer: Expose user space clear buffer operation

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I25d15b41b7186242f43339d035650ffe9f3f9936
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

kernel-ctl: Expose kernel clear buffer operation

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: I582b922f577635ca66e78680fdfedb523e6dcf67
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Test: rotate_utils.sh: consider chunk archive with ust/ as empty

Now the session daemon needs to create the ust/ subdir to pass it
to the consumer daemon even if there are no active traced applications
in per-pid tracing. Therefore, we need to consider a chunk with a
ust/ empty directory as empty.

Empty local traces have this empty subdir, but remote traces do not.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ic0cda7baf6eafa5b0c7b4f0b79e03bc8ea523d93
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Send ust and kernel domain directory handle to consumer

Send a directory handle to ust/ and kernel/ subdirectories of the
chunk to the consumer daemon, and alter the paths sent to consumer
so they do not include the domain subdir.

This will facilitate implementation of the clear command when no
rotation has been performed. The clear command will need to move the
ust/ and kernel/ directories to a "deleted" temporary directory while
the consumer is still actively using those directories. Making sure that
the consumer uses a handle on those subdirectories only ensures that the
consumer will not observe any transient state when those directories are
moved.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I2357ad702f810561c4d11405edc3ef204fc6c455
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: consumer: do not flush on transition from NULL chunk

When transitioning from NULL chunk, do not flush streams, because
the consumer has nowhere to store the packets generated by this
flush.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ic92c035f6b1377849825527d0c9cc05a6b92ac38
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: consumer: honor "active" flush flag

Honor "active" flush flag in both kernel and ust consumers. A flush
"active" does a flush which will not generate empty packets (no event),
whereas an "inactive" flush will generate empty packets if flushing
a current packet which has no event.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Icc9772ba3ae18e96f24354ac6eb9223f343c3458
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: sessiond cmd.h: include missing lttng-sessiond.h

lttng-sessiond.h declares struct command_ctx which is used in cmd.h
prototypes.

It typically does not generate a compilation error because all
compile units including cmd.h also include lttng-sessiond.h, but
it is cleaner to include dependencies directly in cmd.h.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: If3106291309cd543a886b2aecda7d4f9d4b290b3
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

Fix: sessiond: ust-app: per-pid buffers: Create empty ust/ directory

When no applications are running, the toplevel ust/ directory is not
created in a chunk on rotation. Make sure this top level directory
is created.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ia272f3182df298302e02b3e096785cb51687b8c9
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>