Add a time_to_iso8601_str() utility

time_to_iso8601_str() formats a Unix timestamp to an ISO 8601
compatible string. For now, the only ISO 8601 time format used
in LTTng-tools is the "YYYYmmddTHHMMSS+HHMM" form used by the
session rotation feature.

Since ISO 8601 allows many formats, this functions may need to be
renamed at some point.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/common/time.c b/src/common/time.c
index a01c16df5c44f024c00469beeaa014542c658c9f..885f58cb175bf4a2336cf957047abcc339642c15 100644 (file)
--- a/src/common/time.c
+++ b/src/common/time.c
@@ -17,6 +17,7 @@
 
 #include <common/time.h>
 #include <common/macros.h>
+#include <common/error.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <limits.h>
@@ -80,3 +81,35 @@ void __attribute__((constructor)) init_locale_utf8_support(void)
                utf8_output_supported = true;
        }
 }
+
+LTTNG_HIDDEN
+int time_to_iso8601_str(time_t time, char *str, size_t len)
+{
+       int ret = 0;
+       struct tm *tm_result;
+       struct tm tm_storage;
+       size_t strf_ret;
+
+       if (len < ISO8601_STR_LEN) {
+               ERR("Buffer too short to format ISO 8601 timestamp: %zu bytes provided when at least %zu are needed",
+                               len, ISO8601_STR_LEN);
+               ret = -1;
+               goto end;
+       }
+
+        tm_result = localtime_r(&time, &tm_storage);
+       if (!tm_result) {
+               ret = -1;
+               PERROR("Failed to break down timestamp to tm structure");
+               goto end;
+       }
+
+       strf_ret = strftime(str, len, "%Y%m%dT%H%M%S%z", tm_result);
+       if (strf_ret == 0) {
+               ret = -1;
+               ERR("Failed to format timestamp as local time");
+               goto end;
+       }
+end:
+       return ret;
+}

diff --git a/src/common/time.h b/src/common/time.h
index 24513d30bff11618deeeaa74de2c86974f2d5d5f..dc07633e968b41eb8d7e2387f78a5aa43c749ac4 100644 (file)
--- a/src/common/time.h
+++ b/src/common/time.h
@@ -36,6 +36,8 @@
 #define USEC_PER_MINUTE (USEC_PER_SEC * SEC_PER_MINUTE)
 #define USEC_PER_HOURS  (USEC_PER_MINUTE * MINUTE_PER_HOUR)
 
+#define ISO8601_STR_LEN sizeof("YYYYmmddTHHMMSS+HHMM")
+
 LTTNG_HIDDEN
 bool locale_supports_utf8(void);
 
@@ -61,4 +63,14 @@ int timespec_to_ms(struct timespec ts, unsigned long *ms);
 LTTNG_HIDDEN
 struct timespec timespec_abs_diff(struct timespec ts_a, struct timespec ts_b);
 
+/*
+ * Format a Unix timestamp to an ISO 8601 compatible timestamp of
+ * the form "YYYYmmddTHHMMSS+HHMM" in local time. `len` must >= to
+ * ISO8601_STR_LEN.
+ *
+ * Returns 0 on success, else -1 on error.
+ */
+LTTNG_HIDDEN
+int time_to_iso8601_str(time_t time, char *str, size_t len);
+
 #endif /* LTTNG_TIME_H */