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(84-114-45-16.cable.dynamic.surfer.at. [84.114.45.16]) by smtp.gmail.com with ESMTPSA id p4sm149540ejr.81.2021.05.19.09.57.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 May 2021 09:57:04 -0700 (PDT) To: lttng-dev@lists.lttng.org Date: Wed, 19 May 2021 18:56:48 +0200 Message-Id: <20210519165648.792939-1-nolange79@gmail.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Subject: [lttng-dev] [PATCH] Avoid using the heap for small strings with tracef/tracelog X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Norbert Lange via lttng-dev Reply-To: Norbert Lange Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" Try to use vsnprintf with a 512 Byte buffer on the Stack, if that fails allocate a larger one. Signed-off-by: Norbert Lange --- 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 _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev