From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 30 May 2016 16:47:50 +0000 (+0200)
Subject: Fix: don't generate 0-len array in tracepoint probes
X-Git-Tag: v2.7.5~18
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=0febf0188de9401f656cc5963cd5893b2f0169a4;p=lttng-ust.git

Fix: don't generate 0-len array in tracepoint probes

It is forbidden by C99, and gcc/g++ in pedantic mode generates errors
for e.g. field-less events.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index 48085670..1e75d613 100644
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -208,6 +208,7 @@ static const char							\
 #define TRACEPOINT_EVENT_CLASS(_provider, _name, _args, _fields)		   	     \
 	static const struct lttng_event_field __event_fields___##_provider##___##_name[] = { \
 		_fields									     \
+		ctf_integer(int, dummy, 0)	/* Dummy, C99 forbids 0-len array. */	     \
 	};
 
 #include TRACEPOINT_INCLUDE
@@ -618,8 +619,8 @@ void __event_probe__##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args))	      \
 	size_t __event_len, __event_align;				      \
 	size_t __dynamic_len_idx = 0;					      \
 	union {								      \
-		size_t __dynamic_len[_TP_ARRAY_SIZE(__event_fields___##_provider##___##_name)]; \
-		char __filter_stack_data[2 * sizeof(unsigned long) * _TP_ARRAY_SIZE(__event_fields___##_provider##___##_name)]; \
+		size_t __dynamic_len[_TP_ARRAY_SIZE(__event_fields___##_provider##___##_name) - 1]; \
+		char __filter_stack_data[2 * sizeof(unsigned long) * (_TP_ARRAY_SIZE(__event_fields___##_provider##___##_name) - 1)]; \
 	} __stackvar;							      \
 	int __ret;							      \
 									      \
@@ -748,7 +749,7 @@ const struct lttng_event_desc __event_desc___##_provider##_##_name = {	       \
 	.probe_callback = (void (*)(void)) &__event_probe__##_provider##___##_template,\
 	.ctx = NULL,							       \
 	.fields = __event_fields___##_provider##___##_template,		       \
-	.nr_fields = _TP_ARRAY_SIZE(__event_fields___##_provider##___##_template), \
+	.nr_fields = _TP_ARRAY_SIZE(__event_fields___##_provider##___##_template) - 1, \
 	.loglevel = &__ref_loglevel___##_provider##___##_name,		       \
 	.signature = __tp_event_signature___##_provider##___##_template,       \
 	.u = { .ext = { .model_emf_uri = &__ref_model_emf_uri___##_provider##___##_name } }, \
@@ -771,6 +772,7 @@ const struct lttng_event_desc __event_desc___##_provider##_##_name = {	       \
 
 static const struct lttng_event_desc *_TP_COMBINE_TOKENS(__event_desc___, TRACEPOINT_PROVIDER)[] = {
 #include TRACEPOINT_INCLUDE
+	NULL,	/* Dummy, C99 forbids 0-len array. */
 };
 
 
@@ -784,7 +786,7 @@ static const struct lttng_event_desc *_TP_COMBINE_TOKENS(__event_desc___, TRACEP
 static struct lttng_probe_desc _TP_COMBINE_TOKENS(__probe_desc___, TRACEPOINT_PROVIDER) = {
 	.provider = __tp_stringify(TRACEPOINT_PROVIDER),
 	.event_desc = _TP_COMBINE_TOKENS(__event_desc___, TRACEPOINT_PROVIDER),
-	.nr_events = _TP_ARRAY_SIZE(_TP_COMBINE_TOKENS(__event_desc___, TRACEPOINT_PROVIDER)),
+	.nr_events = _TP_ARRAY_SIZE(_TP_COMBINE_TOKENS(__event_desc___, TRACEPOINT_PROVIDER)) - 1,
 	.head = { NULL, NULL },
 	.lazy_init_head = { NULL, NULL },
 	.lazy = 0,