/harness/uptime.txt: Add a human-readable form

2 files changed, 44 insertions, 7 deletions

diff --git a/cmd/sbc_harness/fs_harness_uptime_txt.c b/cmd/sbc_harness/fs_harness_uptime_txt.c
index 9fa6bcc..9b03b46 100644
--- a/cmd/sbc_harness/fs_harness_uptime_txt.c
+++ b/cmd/sbc_harness/fs_harness_uptime_txt.c
@@ -16,7 +16,13 @@ LO_IMPLEMENTATION_C(lib9p_srv_file, struct uptime_file, uptime_file);
 struct uptime_fio {
 	struct uptime_file      *parent;
 	size_t                   buf_len;
-	char                     buf[24]; /* len(str(UINT64_MAX)+"ns\n\0") */
+	/* The maximum length (UINT64_MAX) string is 52 bytes, not
+	 * including a nul-terminator:
+	 *
+	 *     "18446744073709551615ns\n"       # 22+1
+	 *     "584y343d 23h34m33.709551615s\n" # 28+1
+	 */
+	char                     buf[52];
 };
 LO_IMPLEMENTATION_STATIC(lib9p_srv_fio, struct uptime_fio, uptime_fio);
 
@@ -107,6 +113,11 @@ static struct lib9p_qid uptime_fio_ioqid(struct uptime_fio *self) {
 	return uptime_file_qid(self->parent);
 }
 
+#define NS_PER_M (NS_PER_S*60)
+#define NS_PER_H (NS_PER_S*60*60)
+#define NS_PER_D (NS_PER_S*60*60*24)
+#define NS_PER_Y (NS_PER_S*60*60*24*365)
+
 static error uptime_fio_pread(struct uptime_fio *self, struct lib9p_srv_ctx *ctx,
                               lo_interface io_writer dst, uint64_t byte_offset, uint32_t byte_count) {
 	assert(self);
@@ -115,6 +126,22 @@ static error uptime_fio_pread(struct uptime_fio *self, struct lib9p_srv_ctx *ctx
 	if (byte_offset == 0 || self->buf_len == 0) {
 		uint64_t now = LO_CALL(bootclock, get_time_ns);
 		self->buf_len = fmt_snprint(self->buf, sizeof(self->buf), now, "ns\n");
+
+		uint64_t ns = now;
+		uint64_t y = ns/NS_PER_Y; ns -= y*NS_PER_Y;
+		uint64_t d = ns/NS_PER_D; ns -= d*NS_PER_D;
+		uint64_t h = ns/NS_PER_H; ns -= h*NS_PER_H;
+		uint64_t m = ns/NS_PER_M; ns -= m*NS_PER_M;
+		uint64_t s = ns/NS_PER_S; ns -= s*NS_PER_S;
+		if (y)
+			self->buf_len += fmt_snprint(&self->buf[self->buf_len], sizeof(self->buf)-self->buf_len, y, "y");
+		if (y || d)
+			self->buf_len += fmt_snprint(&self->buf[self->buf_len], sizeof(self->buf)-self->buf_len, d, "d ");
+		if (y || d || h)
+			self->buf_len += fmt_snprint(&self->buf[self->buf_len], sizeof(self->buf)-self->buf_len, h, "h");
+		if (y || d || h || m)
+			self->buf_len += fmt_snprint(&self->buf[self->buf_len], sizeof(self->buf)-self->buf_len, m, "m");
+		self->buf_len += fmt_snprint(&self->buf[self->buf_len], sizeof(self->buf)-self->buf_len, s, ".", (rjust, 9, '0', ns), "s\n");
 	}
 
 	if (byte_offset > (uint64_t)self->buf_len)
diff --git a/cmd/sbc_harness/static/Documentation/harness_uptime_txt.txt b/cmd/sbc_harness/static/Documentation/harness_uptime_txt.txt
index 1ab86f7..09e9243 100644
--- a/cmd/sbc_harness/static/Documentation/harness_uptime_txt.txt
+++ b/cmd/sbc_harness/static/Documentation/harness_uptime_txt.txt
@@ -3,14 +3,24 @@ NAME
 
 DESCRIPTION
 	Reading this file gives a text string of the format
-	`sprintf("%uns\n", uptime_ns)` indicating the harness's uptime
-	in an integer number of nanoseconds.
+
+		{ns}ns
+		[[[[{y}y]{d}d ]{h}h]{m}m]{s.09}s
+
+	That is: the first line is simply the harness's uptime in an
+	integer number of nanoseconds; and the second line is this
+	same number in a more human-readable form; divided into
+	seconds, minutes, hours, days, and years.
 
 BUGS
-	Using nanoseconds gives the illusion of more precision than
-	there actually is; the harness' clock only has microsecond
-	resolution; the last 3 digits of the returned nanosecond count
-	will always be 0.
+	- Using nanoseconds gives the illusion of more precision than
+	  there actually is; the harness' clock only has microsecond
+	  resolution; the last 3 digits of the returned nanosecond
+	  count will always be 0.
+
+	- In the human-readable form, the days are always exactly
+	  60*60*24 seconds (leap seconds are ignored), and the years
+	  are always exactly 365 days (leap years are ignored).
 
 AUTHOR
 	Copyright (C) 2025  Luke T. Shumaker <lukeshu@lukeshu.com>