Function strbuf_addftime

strbuf.c:1003–1061

}

void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm,
		     int tz_offset, int suppress_tz_name)
{
	struct strbuf munged_fmt = STRBUF_INIT;
	size_t hint = 128;
	size_t len;

	if (!*fmt)
		return;

	/*
	 * There is no portable way to pass timezone information to
	 * strftime, so we handle %z and %Z here. Likewise '%s', because
	 * going back to an epoch time requires knowing the zone.
	 *
	 * Note that tz_offset is in the "[-+]HHMM" decimal form; this is what
	 * we want for %z, but the computation for %s has to convert to number
	 * of seconds.
	 */
	while (strbuf_expand_step(&munged_fmt, &fmt)) {
		if (skip_prefix(fmt, "%", &fmt))
			strbuf_addstr(&munged_fmt, "%%");
		else if (skip_prefix(fmt, "s", &fmt))
			strbuf_addf(&munged_fmt, "%"PRItime,
				    (timestamp_t)tm_to_time_t(tm) -
				    3600 * (tz_offset / 100) -
				    60 * (tz_offset % 100));
		else if (skip_prefix(fmt, "z", &fmt))
			strbuf_addf(&munged_fmt, "%+05d", tz_offset);
		else if (suppress_tz_name && skip_prefix(fmt, "Z", &fmt))
			; /* nothing */
		else
			strbuf_addch(&munged_fmt, '%');
	}
	fmt = munged_fmt.buf;

	strbuf_grow(sb, hint);
	len = strftime(sb->buf + sb->len, sb->alloc - sb->len, fmt, tm);

	if (!len) {
		/*
		 * strftime reports "0" if it could not fit the result in the buffer.
		 * Unfortunately, it also reports "0" if the requested time string
		 * takes 0 bytes. So our strategy is to munge the format so that the
		 * output contains at least one character, and then drop the extra
		 * character before returning.
		 */
		strbuf_addch(&munged_fmt, ' ');
		while (!len) {
			hint *= 2;
			strbuf_grow(sb, hint);
			len = strftime(sb->buf + sb->len, sb->alloc - sb->len,
				       munged_fmt.buf, tm);
		}
		len--; /* drop munged space */
	}
	strbuf_release(&munged_fmt);
	strbuf_setlen(sb, sb->len + len);