kdump -E for time elapsed since the beginning of trace

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

I'd like to add kdump -E option to print timestamps as time elapsed
since the beginning of trace.  The option name is from FreeBSD.  While
here, the patch makes it possible to use a combination of -T -E and -R
options to print timestamps in several formats.  The idea is also from
FreeBSD.

Trivial patch to the man page is not included.

Any objections or comments?

-uwe

--- kdump.c.~1.125.~	2016-09-13 04:50:59.000000000 +0300
+++ kdump.c	2017-09-07 04:52:44.488100929 +0300
@@ -72,6 +72,11 @@
 
 #include <sys/syscall.h>
 
+#define TIMESTAMP_NONE		0x0
+#define TIMESTAMP_ABSOLUTE	0x1
+#define TIMESTAMP_ELAPSED	0x2
+#define TIMESTAMP_RELATIVE	0x4
+
 static int timestamp, decimal, plain, tail, maxdata = -1, numeric;
 static int word_size = 0;
 static pid_t do_pid = -1;
@@ -162,9 +167,14 @@
 		}
 		return 0;
 	}
-		
-	while ((ch = getopt(argc, argv, "e:f:dlm:Nnp:RTt:xX:")) != -1) {
+
+	timestamp = TIMESTAMP_NONE;
+
+	while ((ch = getopt(argc, argv, "Ee:f:dlm:Nnp:RTt:xX:")) != -1) {
 		switch (ch) {
+		case 'E':
+			timestamp |= TIMESTAMP_ELAPSED;
+			break;
 		case 'e':
 			emul_name = strdup(optarg); /* it's safer to copy it */
 			break;
@@ -194,10 +204,10 @@
 			plain++;
 			break;
 		case 'R':
-			timestamp = 2;	/* relative timestamp */
+			timestamp |= TIMESTAMP_RELATIVE;
 			break;
 		case 'T':
-			timestamp = 1;
+			timestamp |= TIMESTAMP_ABSOLUTE;
 			break;
 		case 't':
 			trset = 1;
@@ -333,7 +343,7 @@
 		struct timeval tv;
 		struct timespec ts;
 	};
-	static union holdtime prevtime;
+	static union holdtime starttime, prevtime;
 	union holdtime temp;
 	int col;
 
@@ -388,8 +398,78 @@
 		col += printf("%6d ", kth->ktr_lid);
 	col += printf("%-8.*s ", MAXCOMLEN, kth->ktr_comm);
 	if (timestamp) {
-		(void)&prevtime;
-		if (timestamp == 2) {
+		if (timestamp & TIMESTAMP_ABSOLUTE) {
+			switch (kth->ktr_version) {
+			case KTRFAC_VERSION(KTRFACv0):
+				temp.tv.tv_sec = kth->ktr_otv.tv_sec;
+				temp.tv.tv_usec = kth->ktr_otv.tv_usec;
+				break;
+			case KTRFAC_VERSION(KTRFACv1):
+				temp.ts.tv_sec = kth->ktr_ots.tv_sec;
+				temp.ts.tv_nsec = kth->ktr_ots.tv_nsec;
+				break;
+			case KTRFAC_VERSION(KTRFACv2):
+				temp.ts.tv_sec = kth->ktr_ts.tv_sec;
+				temp.ts.tv_nsec = kth->ktr_ts.tv_nsec;
+				break;
+			default:
+				goto badversion;
+			}
+
+			if (kth->ktr_version == KTRFACv0)
+				col += printf("%lld.%06ld ",
+					      (long long)temp.tv.tv_sec,
+					      (long)temp.tv.tv_usec);
+			else
+				col += printf("%lld.%09ld ",
+					      (long long)temp.ts.tv_sec,
+					      (long)temp.ts.tv_nsec);
+		}
+
+		if (timestamp & TIMESTAMP_ELAPSED) {
+			switch (kth->ktr_version) {
+			case KTRFAC_VERSION(KTRFACv0):
+				if (starttime.tv.tv_sec == 0) {
+					starttime.tv.tv_sec = kth->ktr_otv.tv_sec;
+					starttime.tv.tv_usec = kth->ktr_otv.tv_usec;
+					temp.tv.tv_sec = temp.tv.tv_usec = 0;
+				} else
+					timersub(&kth->ktr_otv,
+					    &starttime.tv, &temp.tv);
+				break;
+			case KTRFAC_VERSION(KTRFACv1):
+				if (starttime.ts.tv_sec == 0) {
+					starttime.ts.tv_sec = kth->ktr_ots.tv_sec;
+					starttime.ts.tv_nsec = kth->ktr_ots.tv_nsec;
+					temp.ts.tv_sec = temp.ts.tv_nsec = 0;
+				} else
+					timespecsub(&kth->ktr_ots,
+					    &starttime.ts, &temp.ts);
+				break;
+			case KTRFAC_VERSION(KTRFACv2):
+				if (starttime.ts.tv_sec == 0) {
+					starttime.ts.tv_sec = kth->ktr_ts.tv_sec;
+					starttime.ts.tv_nsec = kth->ktr_ts.tv_nsec;
+					temp.ts.tv_sec = temp.ts.tv_nsec = 0;
+				} else
+					timespecsub(&kth->ktr_ts,
+					    &starttime.ts, &temp.ts);
+				break;
+			default:
+				goto badversion;
+			}
+
+			if (kth->ktr_version == KTRFACv0)
+				col += printf("%lld.%06ld ",
+					      (long long)temp.tv.tv_sec,
+					      (long)temp.tv.tv_usec);
+			else
+				col += printf("%lld.%09ld ",
+					      (long long)temp.ts.tv_sec,
+					      (long)temp.ts.tv_nsec);
+		}
+
+		if (timestamp & TIMESTAMP_RELATIVE) {
 			switch (kth->ktr_version) {
 			case KTRFAC_VERSION(KTRFACv0):
 				if (prevtime.tv.tv_sec == 0)
@@ -421,35 +501,23 @@
 			default:
 				goto badversion;
 			}
-		} else {
-			switch (kth->ktr_version) {
-			case KTRFAC_VERSION(KTRFACv0):
-				temp.tv.tv_sec = kth->ktr_otv.tv_sec;
-				temp.tv.tv_usec = kth->ktr_otv.tv_usec;
-				break;
-			case KTRFAC_VERSION(KTRFACv1):
-				temp.ts.tv_sec = kth->ktr_ots.tv_sec;
-				temp.ts.tv_nsec = kth->ktr_ots.tv_nsec;
-				break;
-			case KTRFAC_VERSION(KTRFACv2):
-				temp.ts.tv_sec = kth->ktr_ts.tv_sec;
-				temp.ts.tv_nsec = kth->ktr_ts.tv_nsec;
-				break;
-			default:
-			badversion:
-				err(1, "Unsupported ktrace version %x",
-				    kth->ktr_version);
-			}
+
+			if (kth->ktr_version == KTRFACv0)
+				col += printf("%lld.%06ld ",
+					      (long long)temp.tv.tv_sec,
+					      (long)temp.tv.tv_usec);
+			else
+				col += printf("%lld.%09ld ",
+					      (long long)temp.ts.tv_sec,
+					      (long)temp.ts.tv_nsec);
 		}
-		if (kth->ktr_version == KTRFACv0)
-			col += printf("%lld.%06ld ",
-			    (long long)temp.tv.tv_sec, (long)temp.tv.tv_usec);
-		else
-			col += printf("%lld.%09ld ",
-			    (long long)temp.ts.tv_sec, (long)temp.ts.tv_nsec);
 	}
 	col += printf("%-4s  ", type);
 	return col;
+
+badversion:
+	err(1, "Unsupported ktrace version %x", kth->ktr_version);
+	/* NOTREACHED */
 }
 
 static void