The debugging logging macros (e.g. DBG()) are used as printf in the
lttng-tools source files. The printf() implementation does not alter the
errno value, so the fact that log_add_time() (through clock_gettime())
can alter errno is unexpected. For instance, adding a logging statement
for debugging purposes within a function for which errno is expected to
stay unchanged on return will change the behavior between execution with
-vvv and non-verbose.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
---
src/common/error.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/common/error.c b/src/common/error.c
index c79ce571..a13320f6 100644
--- a/src/common/error.c
+++ b/src/common/error.c
@@ -20,6 +20,7 @@
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
+#include <errno.h>
#include <lttng/lttng-error.h>
#include <common/common.h>
@@ -45,6 +46,7 @@ const char *log_add_time(void)
struct tm tm, *res;
struct timespec tp;
time_t now;
+ int errsv = errno;
ret = lttng_clock_gettime(CLOCK_REALTIME, &tp);
if (ret < 0) {
@@ -65,10 +67,12 @@ const char *log_add_time(void)
goto error;
}
+ errno = errsv;
return URCU_TLS(error_log_time).str;
error:
/* Return an empty string on error so logging is not affected. */
+ errno = errsv;
return "";
}
--
2.17.1
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