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-rw-r--r--libnetdata/datetime/iso8601.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/libnetdata/datetime/iso8601.c b/libnetdata/datetime/iso8601.c
new file mode 100644
index 00000000..8e3f4e02
--- /dev/null
+++ b/libnetdata/datetime/iso8601.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+size_t iso8601_datetime_ut(char *buffer, size_t len, usec_t now_ut, ISO8601_OPTIONS options) {
+ if(unlikely(!buffer || len == 0))
+ return 0;
+
+ time_t t = (time_t)(now_ut / USEC_PER_SEC);
+ struct tm *tmp, tmbuf;
+
+ if(options & ISO8601_UTC)
+ // Use gmtime_r for UTC time conversion.
+ tmp = gmtime_r(&t, &tmbuf);
+ else
+ // Use localtime_r for local time conversion.
+ tmp = localtime_r(&t, &tmbuf);
+
+ if (unlikely(!tmp)) {
+ buffer[0] = '\0';
+ return 0;
+ }
+
+ // Format the date and time according to the ISO 8601 format.
+ size_t used_length = strftime(buffer, len, "%Y-%m-%dT%H:%M:%S", tmp);
+ if (unlikely(used_length == 0)) {
+ buffer[0] = '\0';
+ return 0;
+ }
+
+ if(options & ISO8601_MILLISECONDS) {
+ // Calculate the remaining microseconds
+ int milliseconds = (int) ((now_ut % USEC_PER_SEC) / USEC_PER_MS);
+ if(milliseconds && len - used_length > 4)
+ used_length += snprintfz(buffer + used_length, len - used_length, ".%03d", milliseconds);
+ }
+ else if(options & ISO8601_MICROSECONDS) {
+ // Calculate the remaining microseconds
+ int microseconds = (int) (now_ut % USEC_PER_SEC);
+ if(microseconds && len - used_length > 7)
+ used_length += snprintfz(buffer + used_length, len - used_length, ".%06d", microseconds);
+ }
+
+ if(options & ISO8601_UTC) {
+ if(used_length + 1 < len) {
+ buffer[used_length++] = 'Z';
+ buffer[used_length] = '\0'; // null-terminate the string.
+ }
+ }
+ else {
+ // Calculate the timezone offset in hours and minutes from UTC.
+ long offset = tmbuf.tm_gmtoff;
+ int hours = (int) (offset / 3600); // Convert offset seconds to hours.
+ int minutes = (int) ((offset % 3600) / 60); // Convert remainder to minutes (keep the sign for minutes).
+
+ // Check if timezone is UTC.
+ if(hours == 0 && minutes == 0) {
+ // For UTC, append 'Z' to the timestamp.
+ if(used_length + 1 < len) {
+ buffer[used_length++] = 'Z';
+ buffer[used_length] = '\0'; // null-terminate the string.
+ }
+ }
+ else {
+ // For non-UTC, format the timezone offset. Omit minutes if they are zero.
+ if(minutes == 0) {
+ // Check enough space is available for the timezone offset string.
+ if(used_length + 3 < len) // "+hh\0"
+ used_length += snprintfz(buffer + used_length, len - used_length, "%+03d", hours);
+ }
+ else {
+ // Check enough space is available for the timezone offset string.
+ if(used_length + 6 < len) // "+hh:mm\0"
+ used_length += snprintfz(buffer + used_length, len - used_length,
+ "%+03d:%02d", hours, abs(minutes));
+ }
+ }
+ }
+
+ return used_length;
+}