From 3de2e556da09d7b08ffaca3513a7be606b290a86 Mon Sep 17 00:00:00 2001
From: Rishabh Thukral <rthukral@arista.com>
Date: Tue, 5 Dec 2023 11:53:33 -0800
Subject: [PATCH] dmesg: support for additional human readable timestamp

The dmesg logs have timestamps in seconds since boot format which can
be converted to other formats. However, there is no option to include
both the original timestamp as present in the buffer along with the
converted timestamp in the specified format.

This change updates the --time-format option in dmesg to enable the
user to specify it multiple times with different formats with each
input providing a timestamp format among the currently supported
choices. This enables seeing the dmesg logs in both seconds since boot
and human readable format simultaneously in each row of the log output.
The sequence of timestamp format follows the order
in which the user provides the desired formats.

Signed-off-by: Rishabh Thukral <rthukral@arista.com>
---
 sys-utils/dmesg.1.adoc |   4 +-
 sys-utils/dmesg.c      | 257 ++++++++++++++++++++++++++---------------
 2 files changed, 168 insertions(+), 93 deletions(-)

diff --git a/sys-utils/dmesg.1.adoc b/sys-utils/dmesg.1.adoc
index 156ee0896d..4314131495 100644
--- a/sys-utils/dmesg.1.adoc
+++ b/sys-utils/dmesg.1.adoc
@@ -136,9 +136,11 @@ Display record until the specified time. Supported is the subsecond granularity.
 Do not print kernel's timestamps.
 
 *--time-format* _format_::
-Print timestamps using the given _format_, which can be *ctime*, *reltime*, *delta* or *iso*. The first three formats are aliases of the time-format-specific options. The *iso* format is a *dmesg* implementation of the ISO-8601 timestamp format. The purpose of this format is to make the comparing of timestamps between two systems, and any other parsing, easy. The definition of the *iso* timestamp is: YYYY-MM-DD<T>HH:MM:SS,<microseconds><-+><timezone offset from UTC>.
++Print timestamps using the given _format_, which can be *ctime*, *reltime*, *delta*, *iso* or *raw*. The first three formats are aliases of the time-format-specific options. The *raw* format uses the default timestamp format showing seconds since boot. The *iso* format is a *dmesg* implementation of the ISO-8601 timestamp format. The purpose of this format is to make the comparing of timestamps between two systems, and any other parsing, easy. The definition of the *iso* timestamp is: YYYY-MM-DD<T>HH:MM:SS,<microseconds><-+><timezone offset from UTC>.
 +
 The *iso* format has the same issue as *ctime*: the time may be inaccurate when a system is suspended and resumed.
++
+*--time-format* may be used multiple times with different values for _format_ to output each specified format.
 
 *-u*, *--userspace*::
 Print userspace messages.
diff --git a/sys-utils/dmesg.c b/sys-utils/dmesg.c
index 77728b419d..d95318c53f 100644
--- a/sys-utils/dmesg.c
+++ b/sys-utils/dmesg.c
@@ -178,7 +178,8 @@ enum {
 	DMESG_TIMEFTM_TIME_DELTA,	/* [time <delta>] */
 	DMESG_TIMEFTM_ISO8601		/* 2013-06-13T22:11:00,123456+0100 */
 };
-#define is_timefmt(c, f) ((c)->time_fmt == (DMESG_TIMEFTM_ ##f))
+#define TOTAL_DMESG_TIMESTAMP_FORMATS_SUPPORTED 8
+#define DEFAULT_TIMESTAMP_FORMAT DMESG_TIMEFTM_TIME
 
 struct dmesg_control {
 	/* bit arrays -- see include/bitops.h */
@@ -216,7 +217,8 @@ struct dmesg_control {
 	char		*filename;
 	char		*mmap_buff;
 	size_t		pagesize;
-	unsigned int	time_fmt;	/* time format */
+	size_t		ntime_fmts;
+	unsigned int	time_fmts[2 * TOTAL_DMESG_TIMESTAMP_FORMATS_SUPPORTED];	/* time format */
 
 	struct ul_jsonwrt jfmt;		/* -J formatting */
 
@@ -335,7 +337,7 @@ static void __attribute__((__noreturn__)) usage(void)
 	fputs(_(" -T, --ctime                 show human-readable timestamp (may be inaccurate!)\n"), out);
 	fputs(_(" -t, --notime                don't show any timestamp with messages\n"), out);
 	fputs(_("     --time-format <format>  show timestamp using the given format:\n"
-		"                               [delta|reltime|ctime|notime|iso]\n"
+		"                               [delta|reltime|ctime|notime|iso|raw]\n"
 		"Suspending/resume will make ctime and iso timestamps inaccurate.\n"), out);
 	fputs(_("     --since <time>          display the lines since the specified time\n"), out);
 	fputs(_("     --until <time>          display the lines until the specified time\n"), out);
@@ -358,6 +360,53 @@ static void __attribute__((__noreturn__)) usage(void)
 	exit(EXIT_SUCCESS);
 }
 
+static void reset_time_fmts(struct dmesg_control *ctl)
+{
+	memset(ctl->time_fmts, 0,
+		TOTAL_DMESG_TIMESTAMP_FORMATS_SUPPORTED * sizeof(*(ctl->time_fmts)));
+	ctl->time_fmts[0] = DEFAULT_TIMESTAMP_FORMAT;
+}
+
+static int is_time_fmt_set(struct dmesg_control *ctl, unsigned int time_format)
+{
+	size_t i;
+
+	if (ctl->ntime_fmts == 0)
+		return time_format == DEFAULT_TIMESTAMP_FORMAT;
+
+	for (i = 0; i < ctl->ntime_fmts; i++)
+		if (ctl->time_fmts[i] == time_format)
+			return 1;
+	return 0;
+}
+
+static void include_time_fmt(struct dmesg_control *ctl, unsigned int time_format)
+{
+	if (ctl->ntime_fmts > 0 && is_time_fmt_set(ctl, time_format))
+		return;
+
+	if (ctl->ntime_fmts < TOTAL_DMESG_TIMESTAMP_FORMATS_SUPPORTED)
+		ctl->time_fmts[ctl->ntime_fmts++] = time_format;
+}
+
+static void exclude_time_fmt(struct dmesg_control *ctl, unsigned int time_format)
+{
+	size_t idx = 0;
+
+	while (idx < ctl->ntime_fmts && ctl->time_fmts[idx] != time_format)
+		idx++;
+
+	if (idx < ctl->ntime_fmts && ctl->time_fmts[idx] == time_format) {
+		while (idx + 1 < ctl->ntime_fmts) {
+			ctl->time_fmts[idx] = ctl->time_fmts[idx+1];
+			idx++;
+		}
+		ctl->ntime_fmts--;
+		if (ctl->ntime_fmts == 0)
+			reset_time_fmts(ctl);
+	}
+}
+
 /*
  * LEVEL     ::= <number> | <name>
  *  <number> ::= @len is set:  number in range <0..N>, where N < ARRAY_SIZE(level_names)
@@ -538,7 +587,6 @@ static const char *parse_kmsg_timestamp(const char *str0, struct timeval *tv)
 	return end + 1;	/* skip separator */
 }
 
-
 static double time_diff(struct timeval *a, struct timeval *b)
 {
 	return (a->tv_sec - b->tv_sec) + (a->tv_usec - b->tv_usec) / USEC_PER_SEC;
@@ -786,7 +834,7 @@ static int get_next_syslog_record(struct dmesg_control *ctl,
 		if (*begin == '[' && (*(begin + 1) == ' ' ||
 				      isdigit(*(begin + 1)))) {
 
-			if (!is_timefmt(ctl, NONE))
+			if (!is_time_fmt_set(ctl, DMESG_TIMEFTM_NONE))
 				begin = parse_syslog_timestamp(begin + 1, &rec->tv);
 			else
 				begin = skip_item(begin, end, "]");
@@ -961,10 +1009,13 @@ static void print_record(struct dmesg_control *ctl,
 	char buf[128];
 	char fpbuf[32] = "\0";
 	char tsbuf[64] = "\0";
+	char full_tsbuf[64*TOTAL_DMESG_TIMESTAMP_FORMATS_SUPPORTED] = "\0";
 	size_t mesg_size = rec->mesg_size;
 	int timebreak = 0;
 	char *mesg_copy = NULL;
 	const char *line = NULL;
+	double delta = record_count_delta(ctl, rec);
+	size_t format_iter = 0;
 
 	if (!accept_record(ctl, rec))
 		return;
@@ -989,7 +1040,7 @@ static void print_record(struct dmesg_control *ctl,
 	 * backward compatibility with syslog(2) buffers only
 	 */
 	if (ctl->raw) {
-		ctl->indent = snprintf(tsbuf, sizeof(tsbuf),
+		ctl->indent = snprintf(full_tsbuf, sizeof(full_tsbuf),
 				       "<%d>[%5ld.%06ld] ",
 				       LOG_RAW_FAC_PRI(rec->facility, rec->level),
 				       (long) rec->tv.tv_sec,
@@ -1004,64 +1055,71 @@ static void print_record(struct dmesg_control *ctl,
 			 level_names[rec->level].name);
 
 	/* Store the timestamp in a buffer */
-	switch (ctl->time_fmt) {
-		double delta;
-		struct tm cur;
-	case DMESG_TIMEFTM_NONE:
-		ctl->indent = 0;
-		break;
-	case DMESG_TIMEFTM_CTIME:
-		ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[%s] ",
-				      record_ctime(ctl, rec, buf, sizeof(buf)));
-		break;
-	case DMESG_TIMEFTM_CTIME_DELTA:
-		ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[%s <%12.06f>] ",
-				      record_ctime(ctl, rec, buf, sizeof(buf)),
-				      record_count_delta(ctl, rec));
-		break;
-	case DMESG_TIMEFTM_DELTA:
-		ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[<%12.06f>] ",
-				      record_count_delta(ctl, rec));
-		break;
-	case DMESG_TIMEFTM_RELTIME:
-		record_localtime(ctl, rec, &cur);
-		delta = record_count_delta(ctl, rec);
-		if (cur.tm_min != ctl->lasttm.tm_min ||
-		    cur.tm_hour != ctl->lasttm.tm_hour ||
-		    cur.tm_yday != ctl->lasttm.tm_yday) {
-			timebreak = 1;
+	for (format_iter = 0; format_iter < (ctl->ntime_fmts > 0 ? ctl->ntime_fmts : 1);
+		 format_iter++) {
+		switch (ctl->time_fmts[format_iter]) {
+			struct tm cur;
+		case DMESG_TIMEFTM_NONE:
+			ctl->indent = 0;
+			break;
+		case DMESG_TIMEFTM_CTIME:
 			ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[%s] ",
-					      short_ctime(&cur, buf,
-							  sizeof(buf)));
-		} else {
-			if (delta < 10)
-				ctl->indent = snprintf(tsbuf, sizeof(tsbuf),
-						"[  %+8.06f] ",  delta);
-			else
-				ctl->indent = snprintf(tsbuf, sizeof(tsbuf),
-						"[ %+9.06f] ", delta);
+						record_ctime(ctl, rec, buf, sizeof(buf)));
+			break;
+		case DMESG_TIMEFTM_CTIME_DELTA:
+			ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[%s <%12.06f>] ",
+						record_ctime(ctl, rec, buf, sizeof(buf)),
+						delta);
+			break;
+		case DMESG_TIMEFTM_DELTA:
+			ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[<%12.06f>] ",
+						delta);
+			break;
+		case DMESG_TIMEFTM_RELTIME:
+			record_localtime(ctl, rec, &cur);
+			if (cur.tm_min != ctl->lasttm.tm_min ||
+				cur.tm_hour != ctl->lasttm.tm_hour ||
+				cur.tm_yday != ctl->lasttm.tm_yday) {
+				timebreak = 1;
+				ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[%s] ",
+							short_ctime(&cur, buf,
+								sizeof(buf)));
+			} else {
+				if (delta < 10)
+					ctl->indent = snprintf(tsbuf, sizeof(tsbuf),
+							"[  %+8.06f] ",  delta);
+				else
+					ctl->indent = snprintf(tsbuf, sizeof(tsbuf),
+							"[ %+9.06f] ", delta);
+			}
+			ctl->lasttm = cur;
+			break;
+		case DMESG_TIMEFTM_TIME:
+			ctl->indent = snprintf(tsbuf, sizeof(tsbuf),
+						ctl->json ? "%5ld.%06ld" : "[%5ld.%06ld] ",
+						(long)rec->tv.tv_sec,
+						(long)rec->tv.tv_usec);
+			break;
+		case DMESG_TIMEFTM_TIME_DELTA:
+			ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[%5ld.%06ld <%12.06f>] ",
+						(long)rec->tv.tv_sec,
+						(long)rec->tv.tv_usec,
+						delta);
+			break;
+		case DMESG_TIMEFTM_ISO8601:
+			ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "%s ",
+						iso_8601_time(ctl, rec, buf,
+								sizeof(buf)));
+			break;
+		default:
+			abort();
 		}
-		ctl->lasttm = cur;
-		break;
-	case DMESG_TIMEFTM_TIME:
-		ctl->indent = snprintf(tsbuf, sizeof(tsbuf),
-				      ctl->json ? "%5ld.%06ld" : "[%5ld.%06ld] ",
-				      (long)rec->tv.tv_sec,
-				      (long)rec->tv.tv_usec);
-		break;
-	case DMESG_TIMEFTM_TIME_DELTA:
-		ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "[%5ld.%06ld <%12.06f>] ",
-				      (long)rec->tv.tv_sec,
-				      (long)rec->tv.tv_usec,
-				      record_count_delta(ctl, rec));
-		break;
-	case DMESG_TIMEFTM_ISO8601:
-		ctl->indent = snprintf(tsbuf, sizeof(tsbuf), "%s ",
-				      iso_8601_time(ctl, rec, buf,
-						    sizeof(buf)));
-		break;
-	default:
-		abort();
+
+		if (is_time_fmt_set(ctl, DMESG_TIMEFTM_NONE))
+			break;
+		else if (*tsbuf)
+			strcat(full_tsbuf, tsbuf);
+
 	}
 
 	ctl->indent += strlen(fpbuf);
@@ -1079,23 +1137,23 @@ full_output:
 	}
 
 	/* Output the timestamp buffer */
-	if (*tsbuf) {
+	if (*full_tsbuf) {
 		/* Colorize the timestamp */
 		if (ctl->color)
 			dmesg_enable_color(timebreak ? DMESG_COLOR_TIMEBREAK :
 						       DMESG_COLOR_TIME);
-		if (ctl->time_fmt != DMESG_TIMEFTM_RELTIME) {
+		if (!is_time_fmt_set(ctl, DMESG_TIMEFTM_RELTIME)) {
 			if (ctl->json)
-				ul_jsonwrt_value_raw(&ctl->jfmt, "time", tsbuf);
+				ul_jsonwrt_value_raw(&ctl->jfmt, "time", full_tsbuf);
 			else
-				fputs(tsbuf, stdout);
+				fputs(full_tsbuf, stdout);
 		} else {
 			/*
 			 * For relative timestamping, the first line's
 			 * timestamp is the offset and all other lines will
 			 * report an offset of 0.000000.
 			 */
-			fputs(!line ? tsbuf : "[  +0.000000] ", stdout);
+			fputs(!line ? full_tsbuf : "[  +0.000000] ", stdout);
 		}
 		if (ctl->color)
 			color_disable();
@@ -1276,7 +1334,7 @@ static int parse_kmsg_record(struct dmesg_control *ctl,
 		goto mesg;
 
 	/* C) timestamp */
-	if (is_timefmt(ctl, NONE))
+	if (is_time_fmt_set(ctl, DMESG_TIMEFTM_NONE))
 		p = skip_item(p, end, ",;");
 	else
 		p = parse_kmsg_timestamp(p, &rec->tv);
@@ -1402,6 +1460,8 @@ static int which_time_format(const char *s)
 		return DMESG_TIMEFTM_RELTIME;
 	if (!strcmp(s, "iso"))
 		return DMESG_TIMEFTM_ISO8601;
+	if (!strcmp(s, "raw"))
+		return DMESG_TIMEFTM_TIME;
 	errx(EXIT_FAILURE, _("unknown time format: %s"), s);
 }
 
@@ -1444,9 +1504,10 @@ int main(int argc, char *argv[])
 		.action = SYSLOG_ACTION_READ_ALL,
 		.method = DMESG_METHOD_KMSG,
 		.kmsg = -1,
-		.time_fmt = DMESG_TIMEFTM_TIME,
+		.ntime_fmts = 0,
 		.indent = 0,
 	};
+	ctl.time_fmts[0] = DEFAULT_TIMESTAMP_FORMAT;
 	int colormode = UL_COLORMODE_UNDEF;
 	enum {
 		OPT_TIME_FORMAT = CHAR_MAX + 1,
@@ -1533,7 +1594,7 @@ int main(int argc, char *argv[])
 			ctl.action = SYSLOG_ACTION_CONSOLE_ON;
 			break;
 		case 'e':
-			ctl.time_fmt = DMESG_TIMEFTM_RELTIME;
+			include_time_fmt(&ctl, DMESG_TIMEFTM_RELTIME);
 			break;
 		case 'F':
 			ctl.filename = optarg;
@@ -1550,7 +1611,7 @@ int main(int argc, char *argv[])
 				return EXIT_FAILURE;
 			break;
 		case 'H':
-			ctl.time_fmt = DMESG_TIMEFTM_RELTIME;
+			include_time_fmt(&ctl, DMESG_TIMEFTM_RELTIME);
 			colormode = UL_COLORMODE_AUTO;
 			ctl.pager = 1;
 			break;
@@ -1597,10 +1658,11 @@ int main(int argc, char *argv[])
 				ctl.bufsize = 4096;
 			break;
 		case 'T':
-			ctl.time_fmt = DMESG_TIMEFTM_CTIME;
+			include_time_fmt(&ctl, DMESG_TIMEFTM_CTIME);
 			break;
 		case 't':
-			ctl.time_fmt = DMESG_TIMEFTM_NONE;
+			reset_time_fmts(&ctl);
+			include_time_fmt(&ctl, DMESG_TIMEFTM_NONE);
 			break;
 		case 'u':
 			ctl.fltr_fac = 1;
@@ -1618,7 +1680,7 @@ int main(int argc, char *argv[])
 			ctl.decode = 1;
 			break;
 		case OPT_TIME_FORMAT:
-			ctl.time_fmt = which_time_format(optarg);
+			include_time_fmt(&ctl, which_time_format(optarg));
 			break;
 		case OPT_NOESC:
 			ctl.noesc = 1;
@@ -1650,7 +1712,8 @@ int main(int argc, char *argv[])
 	}
 
 	if (ctl.json) {
-		ctl.time_fmt = DMESG_TIMEFTM_TIME;
+		reset_time_fmts(&ctl);
+		ctl.ntime_fmts = 0;
 		delta = 0;
 		ctl.force_prefix = 0;
 		ctl.raw = 0;
@@ -1658,30 +1721,40 @@ int main(int argc, char *argv[])
 		nopager = 1;
 	}
 
-	if ((is_timefmt(&ctl, RELTIME) ||
-	     is_timefmt(&ctl, CTIME)   ||
-	     is_timefmt(&ctl, ISO8601)) ||
+	if ((is_time_fmt_set(&ctl, DMESG_TIMEFTM_RELTIME) ||
+	     is_time_fmt_set(&ctl, DMESG_TIMEFTM_CTIME)   ||
+	     is_time_fmt_set(&ctl, DMESG_TIMEFTM_ISO8601)) ||
 	     ctl.since ||
 	     ctl.until) {
 		if (dmesg_get_boot_time(&ctl.boot_time) != 0)
-			ctl.time_fmt = DMESG_TIMEFTM_NONE;
+			include_time_fmt(&ctl, DMESG_TIMEFTM_NONE);
 		else
 			ctl.suspended_time = dmesg_get_suspended_time();
 	}
 
-	if (delta) {
-		switch (ctl.time_fmt) {
-		case DMESG_TIMEFTM_CTIME:
-			ctl.time_fmt = DMESG_TIMEFTM_CTIME_DELTA;
-			break;
-		case DMESG_TIMEFTM_TIME:
-			ctl.time_fmt = DMESG_TIMEFTM_TIME_DELTA;
-			break;
-		case DMESG_TIMEFTM_ISO8601:
-			warnx(_("--show-delta is ignored when used together with iso8601 time format"));
-			break;
-		default:
-			ctl.time_fmt = DMESG_TIMEFTM_DELTA;
+	if (delta || is_time_fmt_set(&ctl, DMESG_TIMEFTM_DELTA)) {
+		if (is_time_fmt_set(&ctl, DMESG_TIMEFTM_TIME)) {
+			if (ctl.ntime_fmts == 0) {
+				ctl.time_fmts[ctl.ntime_fmts++] = DMESG_TIMEFTM_TIME_DELTA;
+			} else {
+				exclude_time_fmt(&ctl, DMESG_TIMEFTM_DELTA);
+				for (n = 0; (size_t) n < ctl.ntime_fmts; n++) {
+					if (ctl.time_fmts[n] == DMESG_TIMEFTM_TIME) {
+						ctl.time_fmts[n] = DMESG_TIMEFTM_TIME_DELTA;
+						break;
+					}
+				}
+			}
+		} else if (is_time_fmt_set(&ctl, DMESG_TIMEFTM_CTIME)) {
+			exclude_time_fmt(&ctl, DMESG_TIMEFTM_DELTA);
+			for (n = 0; (size_t) n < ctl.ntime_fmts; n++) {
+				if (ctl.time_fmts[n] == DMESG_TIMEFTM_CTIME) {
+					ctl.time_fmts[n] = DMESG_TIMEFTM_CTIME_DELTA;
+					break;
+				}
+			}
+		} else {
+			include_time_fmt(&ctl, DMESG_TIMEFTM_DELTA);
 		}
 	}
 
-- 
2.47.3