From: Dave Hart <hart@ntp.org>
Date: Wed, 26 Jan 2011 16:50:03 +0000 (+0000)
Subject: Fix off-by-one bug in format_time_fraction() introduced by hart@ntp.org.
X-Git-Tag: NTP_4_2_7P126~2^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dc9cf4e5a72d8ac99433950847be4e9ebf3d413c;p=thirdparty%2Fntp.git

Fix off-by-one bug in format_time_fraction() introduced by hart@ntp.org.
Remove abs(prec) <= 9 requirement from format_time_fraction().
Add more time{spec|val}_tostr() tests.

bk: 4d4050bbhFJeWxtWxx9_y5W7N_xN3A
---

diff --git a/include/timetoa.h b/include/timetoa.h
index e766d1300..686928ab4 100644
--- a/include/timetoa.h
+++ b/include/timetoa.h
@@ -65,12 +65,10 @@ typedef unsigned long long u_time;
  *
  * secs - integral seconds of time stamp
  * frac - fractional units
- * prec - log10 of units per second (3=miliseconds, 6=microseconds,..)
+ * prec - log10 of units per second (3=milliseconds, 6=microseconds,..)
  *	  or in other words: the number decimal digits required.
- *	  If prec is < 0, abs(prec) is taken and for the precision
- *	  and 'secs' is treated as an unsigned value.
- *
- * abs(prec) must be in [1 .. 9], or only the seconds are formatted.
+ *	  If prec is < 0, abs(prec) is taken for the precision and secs
+ *	  is treated as an unsigned value.
  *
  * The function will eventually normalise the fraction and adjust the
  * seconds accordingly.
diff --git a/libntp/timetoa.c b/libntp/timetoa.c
index bcacf095d..2f0a7daa3 100644
--- a/libntp/timetoa.c
+++ b/libntp/timetoa.c
@@ -20,9 +20,11 @@
 
 #include "config.h"
 
+#include <math.h>
 #include <stdio.h>
 
 #include "timetoa.h"
+#include "ntp_assert.h"
 #include "lib_strbuf.h"
 
 /*
@@ -49,19 +51,16 @@ format_time_fraction(
 	int	prec
 	)
 {
-	static const long limit[10] = {
-		1,
-		10, 100, 1000,
-		10000, 100000, 1000000,
-		10000000, 100000000, 1000000000
-	};
-
 	char *		cp;
 	u_time		ttmp;	/* unsigned storage for seconds */
+	int		i;
+	long		fraclimit;
 	int		notneg;	/* flag for non-negative value	*/
 	const char *	fmt;
 	ldiv_t		qr;
 
+	DEBUG_REQUIRE(prec != 0);
+
 	LIB_GETBUF(cp);
 	ttmp = (u_time)secs;
 	fmt = "-%" UTIME_FORMAT ".%0*ld";
@@ -69,43 +68,36 @@ format_time_fraction(
 	/* check if we need signed or unsigned mode */
 	notneg = (prec < 0);
 	prec = abs(prec);
-	if (prec <= 0 || prec > COUNTOF(limit)) {
-		if (notneg)
-			fmt = "%" UTIME_FORMAT;
-		else
-			fmt = "%" TIME_FORMAT;
-		snprintf(cp, LIB_BUFLENGTH, fmt, secs);
-
-		return cp;
-	}
+	/* fraclimit = (long)pow(10, prec); */
+	for (fraclimit = 10, i = 1; i < prec; i++)
+		fraclimit *= 10;
+	DEBUG_INSIST(fraclimit > 0);
 
 	/*
 	 * Since conversion to string uses lots of divisions anyway,
 	 * there's no big extra penalty for normalisation. We do it for
 	 * consistency.
 	 */
-	if (frac < 0 || frac >= limit[prec]) {
-		qr = ldiv(frac, limit[prec]);
+	if (frac < 0 || frac >= fraclimit) {
+		qr = ldiv(frac, fraclimit);
 		if (qr.rem < 0) {
 			qr.quot--;
-			qr.rem += limit[prec];
+			qr.rem += fraclimit;
 		}
 		ttmp += (time_t)qr.quot;
 		frac = qr.rem;
 	}
 
-	/*
-	 * Get the absolute value of the time stamp.
-	 */
+	/* Get the absolute value of the time stamp. */
 	notneg = notneg || ((time_t)ttmp >= 0);
-	if (!notneg) {
+	if (notneg) {
+		fmt++; /* skip sign char in format string */
+	} else {
 		ttmp = ~ttmp;
 		if (frac != 0)
-			frac = limit[prec] - frac;
+			frac = fraclimit - frac;
 		else
 			ttmp += 1;
-	} else {
-		fmt++; /* skip sign char in format string */
 	}
 
 	/* finally format the data and return the result */
diff --git a/tests/libntp/tspecops.cpp b/tests/libntp/tspecops.cpp
index 9a57b4550..008349298 100644
--- a/tests/libntp/tspecops.cpp
+++ b/tests/libntp/tspecops.cpp
@@ -347,8 +347,10 @@ TEST_F(timespecTest, ToString) {
 		{ 2, 0,	 "2.000000000" },
 		{-2, 0, "-2.000000000" },
 		{ 0, 1,	 "0.000000001" },
+		{ 0,-1,	"-0.000000001" },
 		{ 1,-1,	 "0.999999999" },
-		{-1, 1, "-0.999999999" }
+		{-1, 1, "-0.999999999" },
+		{-1,-1, "-1.000000001" },
 	};
 	for (int i = 0; i < COUNTOF(data); i++) {
 		TSPEC a(data[i].sec, data[i].nsec);
diff --git a/tests/libntp/tvalops.cpp b/tests/libntp/tvalops.cpp
index 4ca17cd6b..cb43123af 100644
--- a/tests/libntp/tvalops.cpp
+++ b/tests/libntp/tvalops.cpp
@@ -382,8 +382,10 @@ TEST_F(timevalTest, ToString) {
 		{ 2, 0,	 "2.000000" },
 		{-2, 0, "-2.000000" },
 		{ 0, 1,	 "0.000001" },
+		{ 0,-1,	"-0.000001" },
 		{ 1,-1,	 "0.999999" },
-		{-1, 1, "-0.999999" }
+		{-1, 1, "-0.999999" },
+		{-1,-1, "-1.000001" },
 	};
 	for (int i = 0; i < COUNTOF(data); ++i) {
 		timeval_wrap a(data[i].sec, data[i].usec);