From: Norbert Lange via lttng-dev <lttng-dev@lists.lttng.org>
To: lttng-dev@lists.lttng.org
Subject: [lttng-dev] [PATCH] Avoid using the heap for small strings with tracef/tracelog
Date: Wed, 19 May 2021 18:56:48 +0200 [thread overview]
Message-ID: <20210519165648.792939-1-nolange79@gmail.com> (raw)
Try to use vsnprintf with a 512 Byte buffer on the Stack,
if that fails allocate a larger one.
Signed-off-by: Norbert Lange <nolange79@gmail.com>
---
liblttng-ust/tracef.c | 13 ++++++++++---
liblttng-ust/tracelog.c | 12 +++++++++---
2 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/liblttng-ust/tracef.c b/liblttng-ust/tracef.c
index ea98e43e..18c29e25 100644
--- a/liblttng-ust/tracef.c
+++ b/liblttng-ust/tracef.c
@@ -32,17 +32,24 @@
void _lttng_ust_tracef(const char *fmt, ...)
{
va_list ap;
- char *msg;
+ char local_buf[512];
+ char *msg = local_buf;
int len;
va_start(ap, fmt);
- len = vasprintf(&msg, fmt, ap);
+ len = vsnprintf(local_buf, sizeof(local_buf), fmt, ap);
+ if (len >= sizeof(local_buf)) {
+ msg = (char *)malloc(len + 1);
+ len = msg ? vsnprintf(msg, len + 1, fmt, ap) : -1;
+ }
+
/* len does not include the final \0 */
if (len < 0)
goto end;
__tracepoint_cb_lttng_ust_tracef___event(msg, len,
LTTNG_UST_CALLER_IP());
- free(msg);
end:
+ if (msg != local_buf)
+ free(msg);
va_end(ap);
}
diff --git a/liblttng-ust/tracelog.c b/liblttng-ust/tracelog.c
index 65fc87ed..a5d110fa 100644
--- a/liblttng-ust/tracelog.c
+++ b/liblttng-ust/tracelog.c
@@ -35,19 +35,25 @@
const char *fmt, ...) \
{ \
va_list ap; \
- char *msg; \
+ char local_buf[512]; \
+ char *msg = local_buf; \
int len; \
\
va_start(ap, fmt); \
- len = vasprintf(&msg, fmt, ap); \
+ len = vsnprintf(local_buf, sizeof(local_buf), fmt, ap); \
+ if (len >= sizeof(local_buf)) { \
+ msg = (char *)malloc(len + 1); \
+ len = msg ? vsnprintf(msg, len + 1, fmt, ap) : -1; \
+ } \
/* len does not include the final \0 */ \
if (len < 0) \
goto end; \
__tracepoint_cb_lttng_ust_tracelog___##level(file, \
line, func, msg, len, \
LTTNG_UST_CALLER_IP()); \
- free(msg); \
end: \
+ if (msg != local_buf) \
+ free(msg); \
va_end(ap); \
}
--
2.30.2
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next reply other threads:[~2021-05-19 16:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 16:56 Norbert Lange via lttng-dev [this message]
2021-05-19 19:00 ` Mathieu Desnoyers via lttng-dev
2021-05-20 12:20 ` Norbert Lange via lttng-dev
2021-05-20 13:33 ` Mathieu Desnoyers via lttng-dev
2021-05-20 13:44 ` Norbert Lange via lttng-dev
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