Add Finite State Machine abstraction code

This code is supposed to formalize some of the state machine handling in
Osmocom code.

Change-Id: I0b0965a912598c1f6b84042a99fea9d522642466
Tested-by: Jenkins Builder
Reviewed-by: Harald Welte <>
Harald Welte 2016-05-29 10:53:17 +09:00
parent 82f94ef50f
commit 136e73764e
9 changed files with 738 additions and 3 deletions

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@ -17,6 +17,7 @@ nobase_include_HEADERS = \
osmocom/core/crcgen.h \
osmocom/core/endian.h \
osmocom/core/defs.h \
osmocom/core/fsm.h \
osmocom/core/gsmtap.h \
osmocom/core/gsmtap_util.h \
osmocom/core/linuxlist.h \

include/osmocom/core/fsm.h Normal file
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@ -0,0 +1,135 @@
#pragma once
#include <stdint.h>
#include <stdbool.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/utils.h>
/*! \defgroup fsm Finite State Machine abstraction
* @{
/*! \file fsm.h
* \brief Finite State Machine
struct osmo_fsm_inst;
enum osmo_fsm_term_cause {
/*! \brief terminate because parent terminated */
/*! \brief terminate on explicit user request */
/*! \brief regular termination of process */
/*! \brief erroneous termination of process */
/*! \brief description of a rule in the FSM */
struct osmo_fsm_state {
/*! \brief bit-mask of permitted input events for this state */
uint32_t in_event_mask;
/*! \brief bit-mask to which other states this state may transiton */
uint32_t out_state_mask;
/*! \brief human-readable name of this state */
const char *name;
/*! \brief function to be called for events arriving in this state */
void (*action)(struct osmo_fsm_inst *fi, uint32_t event, void *data);
/*! \brief function to be called just after entering the state */
void (*onenter)(struct osmo_fsm_inst *fi, uint32_t prev_state);
/*! \brief function to be called just before leaving the state */
void (*onleave)(struct osmo_fsm_inst *fi, uint32_t next_state);
/*! \brief a description of an osmocom finite state machine */
struct osmo_fsm {
/*! \brief global list */
struct llist_head list;
/*! \brief list of instances of this FSM */
struct llist_head instances;
/*! \brief human readable name */
const char *name;
/*! \brief table of state transition rules */
const struct osmo_fsm_state *states;
/*! \brief number of entries in \ref states */
unsigned int num_states;
/*! \brief bit-mask of events permitted in all states */
uint32_t allstate_event_mask;
/*! \brief function pointer to be called for allstate events */
void (*allstate_action)(struct osmo_fsm_inst *fi, uint32_t event, void *data);
/*! \breif clean-up function, called during termination */
void (*cleanup)(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause);
/*! \brief timer call-back for states with time-out */
void (*timer_cb)(struct osmo_fsm_inst *fi);
/*! \brief logging sub-system for this FSM */
int log_subsys;
/*! \brief human-readable names of events */
const struct value_string *event_names;
/*! \brief a single instanceof an osmocom finite state machine */
struct osmo_fsm_inst {
/*! \brief member in the fsm->instances list */
struct llist_head list;
/*! \brief back-pointer to the FSM of which we are an instance */
struct osmo_fsm *fsm;
/*! \brief human readable identifier */
const char *id;
/*! \brief human readable fully-qualified name */
const char *name;
/*! \brief some private data of this instance */
void *priv;
/*! \brief logging level for this FSM */
int log_level;
/*! \brief current state of the FSM */
uint32_t state;
/*! \brief timer number for states with time-out */
int T;
/*! \brief timer back-end for states with time-out */
struct osmo_timer_list timer;
/*! \brief support for fsm-based procedures */
struct {
/*! \brief the parent FSM that has created us */
struct osmo_fsm_inst *parent;
/*! \brief the event we should send upon termination */
uint32_t parent_term_event;
/*! \brief a list of children processes */
struct llist_head children;
/*! \brief \ref llist_head linked to parent->proc.children */
struct llist_head child;
} proc;
void osmo_fsm_log_addr(bool log_addr);
#define LOGPFSM(fi, fmt, args...) \
LOGP((fi)->fsm->log_subsys, (fi)->log_level, "%s{%s}: " fmt, \
osmo_fsm_inst_name(fi), \
osmo_fsm_state_name((fi)->fsm, (fi)->state), ## args)
int osmo_fsm_register(struct osmo_fsm *fsm);
struct osmo_fsm_inst *osmo_fsm_inst_alloc(struct osmo_fsm *fsm, void *ctx, void *priv,
int log_level, const char *id);
struct osmo_fsm_inst *osmo_fsm_inst_alloc_child(struct osmo_fsm *fsm,
struct osmo_fsm_inst *parent,
uint32_t parent_term_event);
void osmo_fsm_inst_free(struct osmo_fsm_inst *fi);
const char *osmo_fsm_event_name(struct osmo_fsm *fsm, uint32_t event);
const char *osmo_fsm_inst_name(struct osmo_fsm_inst *fi);
const char *osmo_fsm_state_name(struct osmo_fsm *fsm, uint32_t state);
int osmo_fsm_inst_state_chg(struct osmo_fsm_inst *fi, uint32_t new_state,
unsigned long timeout_secs, int T);
int osmo_fsm_inst_dispatch(struct osmo_fsm_inst *fi, uint32_t event, void *data);
void osmo_fsm_inst_term(struct osmo_fsm_inst *fi,
enum osmo_fsm_term_cause cause, void *data);
/*! @} */

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@ -9,7 +9,7 @@ lib_LTLIBRARIES =
libosmocore_la_SOURCES = timer.c select.c signal.c msgb.c bits.c \
bitvec.c bitcomp.c statistics.c \
bitvec.c bitcomp.c statistics.c fsm.c \
write_queue.c utils.c socket.c \
logging.c logging_syslog.c rate_ctr.c \
gsmtap_util.c crc16.c panic.c backtrace.c \

src/fsm.c Normal file
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@ -0,0 +1,422 @@
/* Osmocom generic Finite State Machine implementation
* (C) 2016 by Harald Welte <>
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* 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 <errno.h>
#include <stdbool.h>
#include <osmocom/core/fsm.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/utils.h>
/*! \addtogroup fsm
* @{
/*! \file fsm.c
* \brief Finite State Machine abstraction
* This is a generic C-language abstraction for implementing finite
* state machines within the Osmocom framework. It is intended to
* replace existing hand-coded or even only implicitly existing FSMs
* all over the existing code base.
* An libosmocore FSM is described by its \ref osmo_fsm description,
* which in turn refers to an array of \ref osmo_fsm_state descriptor,
* each describing a single state in the FSM.
* The general idea is that all actions performed within one state are
* located at one position in the code (the state's action function),
* as opposed to the 'message-centric' view of e.g. the existing
* state machines of the LAPD(m) coe, where there is one message for
* eahc possible event (primitive), and the function then needs to
* concern itself on how to handle that event over all possible states.
* For each state, there is a bit-mask of permitted input events for
* this state, as well as a bit-mask of permitted new output states to
* which the state can change. Furthermore, there is a function
* pointer implementing the actual handling of the input events
* occurring whilst in thta state.
* Furthermore, each state offers a function pointer that can be
* executed just before leaving a state, and another one just after
* entering a state.
* When transitioning into a new state, an optional timer number and
* time-out can be passed along. The timer is started just after
* entering the new state, and will call the \ref osmo_fsm timer_cb
* function once it expires. This is intended to be used in telecom
* state machines where a given timer (identified by a certain number)
* is started to terminate the fsm or terminate the fsm once expected
* events are not happening before timeout expiration.
* As there can often be many concurrent FSMs of one given class, we
* introduce the concept of \ref osmo_fsm_inst, i.e. an FSM instance.
* The instance keeps the actual state, while the \ref osmo_fsm
* descriptor contains the static/const descriptor of the FSM's states
* and possible transitions.
* osmo_fsm are integrated with the libosmocore logging system. The
* logging sub-system is determined by the FSM descriptor, as we assume
* one FSM (let's say one related to a location update procedure) is
* inevitably always tied to a sub-system. The logging level however
* is configurable for each FSM instance, to ensure that e.g. DEBUG
* logging can be used for the LU procedure of one subscriber, while
* NOTICE level is used for all other subscribers.
* In order to attach private state to the \ref osmo_fsm_inst, it
* offers an opaque priv pointer.
static LLIST_HEAD(g_fsms);
static bool fsm_log_addr = true;
/*! \brief specify if FSM instance addresses should be logged or not
* By default, the FSM name includes the pointer address of the \ref
* osmo_fsm_inst. This behaviro can be disabled (and re-enabled)
* using this function.
* \param[in] log_addr Indicate if FSM instance address shall be logged
void osmo_fsm_log_addr(bool log_addr)
fsm_log_addr = false;
/*! \brief register a FSM with the core
* A FSM descriptor needs to be registered with the core before any
* instances can be created for it.
* \param[in] fsm Descriptor of Finite State Machine to be registered
* \returns 0 on success; negative on error
int osmo_fsm_register(struct osmo_fsm *fsm)
/* FIXME:check for duplicate name? */
llist_add_tail(&fsm->list, &g_fsms);
return 0;
/*! \brief unregister a FSM from the core
* Once the FSM descriptor is unregistered, active instances can still
* use it, but no new instances may be created for it.
* \param[in] fsm Descriptor of Finite State Machine to be removed
void osmo_fsm_unregister(struct osmo_fsm *fsm)
/* small wrapper function around timer expiration (for logging) */
static void fsm_tmr_cb(void *data)
struct osmo_fsm_inst *fi = data;
struct osmo_fsm *fsm = fi->fsm;
LOGPFSM(fi, "Timeout of T%u\n", fi->T);
/*! \brief allocate a new instance of a specified FSM
* \param[in] fsm Descriptor of the FSM
* \param[in] ctx talloc context from which to allocate memory
* \param[in] priv private data reference store in fsm instance
* \param[in] log_level The log level for events of this FSM
* \returns newly-allocated, initialized and registered FSM instance
struct osmo_fsm_inst *osmo_fsm_inst_alloc(struct osmo_fsm *fsm, void *ctx, void *priv,
int log_level, const char *id)
struct osmo_fsm_inst *fi = talloc_zero(ctx, struct osmo_fsm_inst);
fi->fsm = fsm;
fi->priv = priv;
fi->log_level = log_level;
fi-> = fi;
fi->timer.cb = fsm_tmr_cb;
fi->id = id;
if (!fsm_log_addr) {
if (id)
fi->name = talloc_asprintf(fi, "%s(%s)", fsm->name, id);
fi->name = talloc_asprintf(fi, "%s", fsm->name);
} else {
if (id)
fi->name = talloc_asprintf(fi, "%s(%s)[%p]", fsm->name,
id, fi);
fi->name = talloc_asprintf(fi, "%s[%p]", fsm->name, fi);
llist_add(&fi->list, &fsm->instances);
LOGPFSM(fi, "Allocated\n");
return fi;
/*! \brief allocate a new instance of a specified FSM as child of
* other FSM instance
* This is like \ref osmo_fsm_inst_alloc but using the parent FSM as
* talloc context, and inheriting the log level of the parent.
* \param[in] fsm Descriptor of the to-be-allocated FSM
* \param[in] parent Parent FSM instance
* \param[in] parent_term_event Event to be sent to parent when terminating
* \returns newly-allocated, initialized and registered FSM instance
struct osmo_fsm_inst *osmo_fsm_inst_alloc_child(struct osmo_fsm *fsm,
struct osmo_fsm_inst *parent,
uint32_t parent_term_event)
struct osmo_fsm_inst *fi;
fi = osmo_fsm_inst_alloc(fsm, parent, NULL, parent->log_level,
if (!fi) {
/* indicate immediate termination to caller */
osmo_fsm_inst_dispatch(parent, parent_term_event, NULL);
return NULL;
LOGPFSM(fi, "is child of %s\n", osmo_fsm_inst_name(parent));
fi->proc.parent = parent;
fi->proc.parent_term_event = parent_term_event;
llist_add(&fi->proc.child, &parent->proc.children);
return fi;
/*! \brief delete a given instance of a FSM
* \param[in] fsm The FSM to be un-registered and deleted
void osmo_fsm_inst_free(struct osmo_fsm_inst *fi)
/*! \brief get human-readable name of FSM event
* \param[in] fsm FSM descriptor of event
* \param[in] event Event integer value
* \returns string rendering of the event
const char *osmo_fsm_event_name(struct osmo_fsm *fsm, uint32_t event)
static char buf[32];
if (!fsm->event_names) {
snprintf(buf, sizeof(buf), "%u", event);
return buf;
} else
return get_value_string(fsm->event_names, event);
/*! \brief get human-readable name of FSM instance
* \param[in] fi FSM instance
* \returns string rendering of the FSM identity
const char *osmo_fsm_inst_name(struct osmo_fsm_inst *fi)
if (!fi)
return "NULL";
if (fi->name)
return fi->name;
return fi->fsm->name;
/*! \brief get human-readable name of FSM instance
* \param[in] fsm FSM descriptor
* \param[in] state FSM state number
* \returns string rendering of the FSM state
const char *osmo_fsm_state_name(struct osmo_fsm *fsm, uint32_t state)
static char buf[32];
if (state >= fsm->num_states) {
snprintf(buf, sizeof(buf), "unknown %u", state);
return buf;
} else
return fsm->states[state].name;
/*! \brief perform a state change of the given FSM instance
* All changes to the FSM instance state must be made via this
* function. It verifies that the existing state actually permits a
* transiiton to new_state.
* timeout_secs and T are optional parameters, and only have any effect
* if timeout_secs is not 0. If the timeout function is used, then the
* new_state is entered, and the FSM instances timer is set to expire
* in timeout_secs functions. At that time, the FSM's timer_cb
* function will be called for handling of the timeout by the user.
* \param[in] fi FSM instance whose state is to change
* \param[in] new_state The new state into which we should change
* \param[in] timeout_secs Timeout in seconds (if !=0)
* \param[in] T Timer number (if \ref timeout_secs != 0)
* \returns 0 on success; negative on error
int osmo_fsm_inst_state_chg(struct osmo_fsm_inst *fi, uint32_t new_state,
unsigned long timeout_secs, int T)
struct osmo_fsm *fsm = fi->fsm;
uint32_t old_state = fi->state;
const struct osmo_fsm_state *st = &fsm->states[fi->state];
/* validate if new_state is a valid state */
if (!(st->out_state_mask & (1 << new_state))) {
LOGP(fsm->log_subsys, LOGL_ERROR, "%s(%s): transition to "
"state %s not permitted!\n",
osmo_fsm_state_name(fsm, fi->state),
osmo_fsm_state_name(fsm, new_state));
return -EPERM;
if (st->onleave)
st->onleave(fi, new_state);
LOGPFSM(fi, "state_chg to %s\n", osmo_fsm_state_name(fsm, new_state));
fi->state = new_state;
if (st->onenter)
st->onenter(fi, old_state);
if (timeout_secs) {
if (!fsm->timer_cb)
LOGP(fsm->log_subsys, LOGL_ERROR, "cannot start "
"timer for FSM without timer call-back\n");
else {
fi->T = T;
osmo_timer_schedule(&fi->timer, timeout_secs, 0);
return 0;
/*! \brief dispatch an event to an osmocom finite state machine instance
* Any incoming events to \ref osmo_fsm instances must be dispatched to
* them via this function. It verifies, whether the event is permitted
* based on the current state of the FSM. If not, -1 is returned.
* \param[in] fi FSM instance
* \param[in] event Event to send to FSM instance
* \param[in] data Data to pass along with the event
* \returns 0 in case of success; negative on error
int osmo_fsm_inst_dispatch(struct osmo_fsm_inst *fi, uint32_t event, void *data)
struct osmo_fsm *fsm;
const struct osmo_fsm_state *fs;
if (!fi) {
LOGP(DLGLOBAL, LOGL_ERROR, "Trying to dispatch event %u to "
"non-existing FSM Instance!\n", event);
osmo_log_backtrace(DLGLOBAL, LOGL_ERROR);
return -ENODEV;
fsm = fi->fsm;
OSMO_ASSERT(fi->state < fsm->num_states);
fs = &fi->fsm->states[fi->state];
LOGPFSM(fi, "Received Event %s\n", osmo_fsm_event_name(fsm, event));
if (((1 << event) & fsm->allstate_event_mask) && fsm->allstate_action) {
fsm->allstate_action(fi, event, data);
return 0;
if (!((1 << event) & fs->in_event_mask)) {
LOGP(fsm->log_subsys, LOGL_ERROR, "%s(%s): Event %s not "
"permitted\n", osmo_fsm_inst_name(fi),
osmo_fsm_state_name(fsm, fi->state),
osmo_fsm_event_name(fsm, event));
return -1;
fs->action(fi, event, data);
return 0;
/*! \brief Terminate FSM instance with given cause
* This safely terminates the given FSM instance by first iterating
* over all children and sending them a termination event. Next, it
* calls the FSM descriptors cleanup function (if any), followed by
* releasing any memory associated with the FSM instance.
* Finally, the parent FSM instance (if any) is notified using the
* parent termination event configured at time of FSM instance start.
* \param[in] fi FSM instance to be terminated
* \param[in] cause Cause / reason for termination
* \param[in] data Opaqueevent data to be passed to parent
void osmo_fsm_inst_term(struct osmo_fsm_inst *fi,
enum osmo_fsm_term_cause cause, void *data)
struct osmo_fsm_inst *child, *child2;
struct osmo_fsm_inst *parent = fi->proc.parent;
uint32_t parent_term_event = fi->proc.parent_term_event;
LOGPFSM(fi, "Terminating (cause = %u)\n", cause);
/* iterate over all children */
llist_for_each_entry_safe(child, child2, &fi->proc.children, proc.child) {
/* terminate child */
osmo_fsm_inst_term(child, OSMO_FSM_TERM_PARENT, NULL);
/* delete ourselves from the parent */
/* call destructor / clean-up function */
if (fi->fsm->cleanup)
fi->fsm->cleanup(fi, cause);
LOGPFSM(fi, "Release\n");
/* indicate our termination to the parent */
if (parent && cause != OSMO_FSM_TERM_PARENT)
osmo_fsm_inst_dispatch(parent, parent_term_event, data);
/*! @} */

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@ -13,7 +13,7 @@ check_PROGRAMS = timer/timer_test sms/sms_test ussd/ussd_test \
vty/vty_test comp128/comp128_test utils/utils_test \
smscb/gsm0341_test stats/stats_test \
bitvec/bitvec_test msgb/msgb_test bits/bitcomp_test \
sim/sim_test tlv/tlv_test gsup/gsup_test
sim/sim_test tlv/tlv_test gsup/gsup_test fsm/fsm_test
check_PROGRAMS += msgfile/msgfile_test
@ -118,6 +118,9 @@ tlv_tlv_test_LDADD = $(top_builddir)/src/gsm/ $(top_builddir)/src/l
gsup_gsup_test_SOURCES = gsup/gsup_test.c
gsup_gsup_test_LDADD = $(top_builddir)/src/gsm/ $(top_builddir)/src/
fsm_fsm_test_SOURCES = fsm/fsm_test.c
fsm_fsm_test_LDADD = $(top_builddir)/src/
# The `:;' works around a Bash 3.2 bug when the output is not writeable.
$(srcdir)/package.m4: $(top_srcdir)/
:;{ \
@ -152,7 +155,8 @@ EXTRA_DIST = $(srcdir)/package.m4 $(TESTSUITE) \
vty/vty_test.ok comp128/comp128_test.ok \
utils/utils_test.ok stats/stats_test.ok \
bitvec/bitvec_test.ok msgb/msgb_test.ok bits/bitcomp_test.ok \
sim/sim_test.ok tlv/tlv_test.ok gsup/gsup_test.ok
sim/sim_test.ok tlv/tlv_test.ok gsup/gsup_test.ok \
fsm/fsm_test.ok fsm/fsm_test.err

tests/fsm/fsm_test.c Normal file
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@ -0,0 +1,155 @@
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <unistd.h>
#include <string.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/select.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/fsm.h>
enum {
static void *g_ctx;
enum test_fsm_states {
ST_NULL = 0,
enum test_fsm_evt {
static void test_fsm_null(struct osmo_fsm_inst *fi, uint32_t event, void *data)
switch (event) {
case EV_A:
OSMO_ASSERT(data == (void *) 23);
osmo_fsm_inst_state_chg(fi, ST_ONE, 0, 0);
static void test_fsm_one(struct osmo_fsm_inst *fi, uint32_t event, void *data)
switch (event) {
case EV_B:
OSMO_ASSERT(data == (void *) 42);
osmo_fsm_inst_state_chg(fi,ST_TWO, 1, 2342);
static void test_fsm_tmr_cb(struct osmo_fsm_inst *fi)
OSMO_ASSERT(fi->T == 2342);
OSMO_ASSERT(fi->state == ST_TWO);
static struct osmo_fsm_state test_fsm_states[] = {
[ST_NULL] = {
.in_event_mask = (1 << EV_A),
.out_state_mask = (1 << ST_ONE),
.name = "NULL",
.action = test_fsm_null,
[ST_ONE]= {
.in_event_mask = (1 << EV_B),
.out_state_mask = (1 << ST_TWO),
.name = "ONE",
.action= test_fsm_one,
[ST_TWO]= {
.in_event_mask = 0,
.name = "TWO",
.action = NULL,
static struct osmo_fsm fsm = {
.name = "Test FSM",
.states = test_fsm_states,
.num_states = ARRAY_SIZE(test_fsm_states),
.log_subsys = DMAIN,
static int foo(void)
struct osmo_fsm_inst *fi;
LOGP(DMAIN, LOGL_INFO, "Checking FSM allocation\n");
fi = osmo_fsm_inst_alloc(&fsm, g_ctx, NULL, LOGL_DEBUG, NULL);
OSMO_ASSERT(fi->fsm == &fsm);
OSMO_ASSERT(!strncmp(osmo_fsm_inst_name(fi),, strlen(;
OSMO_ASSERT(fi->state == ST_NULL);
OSMO_ASSERT(fi->log_level == LOGL_DEBUG);
/* Try invalid state transition */
osmo_fsm_inst_dispatch(fi, EV_B, (void *) 42);
OSMO_ASSERT(fi->state == ST_NULL);
/* Legitimate state transition */
osmo_fsm_inst_dispatch(fi, EV_A, (void *) 23);
OSMO_ASSERT(fi->state == ST_ONE);
/* Legitimate transition with timer */
fsm.timer_cb = test_fsm_tmr_cb;
osmo_fsm_inst_dispatch(fi, EV_B, (void *) 42);
OSMO_ASSERT(fi->state == ST_TWO);
return 0;
static const struct log_info_cat default_categories[] = {
[DMAIN] = {
.name = "DMAIN",
.description = "Main",
.enabled = 1, .loglevel = LOGL_DEBUG,
static const struct log_info log_info = {
.cat = default_categories,
.num_cat = ARRAY_SIZE(default_categories),
int main(int argc, char **argv)
struct log_target *stderr_target;
log_init(&log_info, NULL);
stderr_target = log_target_create_stderr();
log_set_print_filename(stderr_target, 0);
g_ctx = NULL;
while (1) {

tests/fsm/fsm_test.err Normal file
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@ -0,0 +1,11 @@
Checking FSM allocation
Test FSM{NULL}: Allocated
Test FSM{NULL}: Received Event 1
Test FSM(NULL): Event 1 not permitted
Test FSM{NULL}: Received Event 0
Test FSM{NULL}: state_chg to ONE
Test FSM{ONE}: Received Event 1
Test FSM{ONE}: state_chg to TWO
Test FSM{TWO}: Timeout of T2342

tests/fsm/fsm_test.ok Normal file
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@ -201,3 +201,10 @@ AT_KEYWORDS([gsup])
cat $abs_srcdir/gsup/gsup_test.ok > expout
AT_CHECK([$abs_top_builddir/tests/gsup/gsup_test], [0], [expout], [ignore])
cat $abs_srcdir/fsm/fsm_test.ok > expout
cat $abs_srcdir/fsm/fsm_test.err > experr
AT_CHECK([$abs_top_builddir/tests/fsm/fsm_test], [0], [expout], [experr])