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// 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;
}
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