represent negative T-timers as Osmocom-specific X-timers

fi->T values are int, i.e. can be negative. Do not log them as unsigned, but
define a distinct timer class "Xnnnn" for negative T values: i.e. for T == -1,
print "Timeout of X1" instead of "Timeout of T4294967295".

The negative T timer number space is useful to distinguish freely invented
timers from proper 3GPP defined T numbers. So far I was using numbers like
T993210 or T9999 for invented T, but X1, X2 etc. is a better solution. This way
we can make sure to not accidentally define an invented timer number that
actually collides with a proper 3GPP specified timer number that the author was
not aware of at the time of writing.

Add OSMO_T_FMT and OSMO_T_FMT_ARGS() macros as standardized timer number print
format. Use that in fsm.c, tdef_vty.c, and adjust vty tests accordingly.

Mention the two timer classes in various API docs and VTY online-docs.

Change-Id: I3a59457623da9309fbbda235fe18fadd1636bff6

1 files changed, 3 insertions, 0 deletions

diff --git a/include/osmocom/core/fsm.h b/include/osmocom/core/fsm.h
index ae1c8575..13bfb331 100644
--- a/include/osmocom/core/fsm.h
+++ b/include/osmocom/core/fsm.h
@@ -194,6 +194,9 @@ void osmo_fsm_log_timeouts(bool log_timeouts);
 			    caller_file, caller_line, \
 			    fmt, ## args)
 
+#define OSMO_T_FMT "%c%u"
+#define OSMO_T_FMT_ARGS(T) ((T) >= 0 ? 'T' : 'X'), ((T) >= 0 ? T : -T)
+
 int osmo_fsm_register(struct osmo_fsm *fsm);
 void osmo_fsm_unregister(struct osmo_fsm *fsm);
 struct osmo_fsm *osmo_fsm_find_by_name(const char *name);