From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Tue, 9 Jul 2019 12:25:53 +0000 (-0400)
Subject: lib/lib-logging.c: fix GCC warning: check return value of snprintf()
X-Git-Url: http://git.efficios.com/?p=babeltrace.git;a=commitdiff_plain;h=b293c529e6c191632ac97b50b8a7811c5b480ed9

lib/lib-logging.c: fix GCC warning: check return value of snprintf()

This patch fixes this GCC warning:

    lib-logging.c: In function ‘format_component’:
    lib-logging.c:110:44: error: ‘%s’ directive output may be truncated
    writing 10 bytes into a region of size between 0 and 127
    [-Werror=format-truncation=]
       snprintf(tmp_prefix, TMP_PREFIX_LEN - 1, "%s%s", \
                                                ^~~~~~
         prefix, (_prefix2));   \
                 ~~~~~~~~~~
    lib-logging.c:1013:3: note: in expansion of macro ‘SET_TMP_PREFIX’
       SET_TMP_PREFIX("so-handle-");
       ^~~~~~~~~~~~~~
    lib-logging.c:110:3: note: ‘snprintf’ output between 11 and 138
    bytes into a destination of size 127
       snprintf(tmp_prefix, TMP_PREFIX_LEN - 1, "%s%s", \
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         prefix, (_prefix2));   \
         ~~~~~~~~~~~~~~~~~~~
    lib-logging.c:1013:3: note: in expansion of macro ‘SET_TMP_PREFIX’
       SET_TMP_PREFIX("so-handle-");
       ^~~~~~~~~~~~~~

The macro aborts when the return value is unexpected, but this will
never happen as we control the prefixes internally.

Boosting the buffer's size to 128 just in case.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I6cbb43de3c9ae03b5d85074d1698069084659c3b
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1658
---

diff --git a/src/lib/lib-logging.c b/src/lib/lib-logging.c
index c9c8249b..16cd09b9 100644
--- a/src/lib/lib-logging.c
+++ b/src/lib/lib-logging.c
@@ -104,11 +104,17 @@ static __thread char lib_logging_buf[LIB_LOGGING_BUF_SIZE];
 
 #define PRFIELD_GSTRING(_expr)	PRFIELD((_expr) ? (_expr)->str : NULL)
 
-#define TMP_PREFIX_LEN 64
+#define TMP_PREFIX_LEN 128
 #define SET_TMP_PREFIX(_prefix2)					\
 	do {								\
-		snprintf(tmp_prefix, TMP_PREFIX_LEN - 1, "%s%s",	\
-			prefix, (_prefix2));				\
+		int snprintf_ret =					\
+			snprintf(tmp_prefix, TMP_PREFIX_LEN - 1, "%s%s", \
+				prefix, (_prefix2));			\
+									\
+		if (snprintf_ret < 0 || snprintf_ret >= TMP_PREFIX_LEN - 1) { \
+			abort();					\
+		}							\
+									\
 		tmp_prefix[TMP_PREFIX_LEN - 1] = '\0';			\
 	} while (0)