[PATCH 1/2] apply: check date of potential epoch timestamps first

René Scharfe· Aug 25, 2017, 19:04 UTC · lore

has_epoch_timestamp() looks for time stamps that amount to either 1969-12-31 24:00 or 1970-01-01 00:00 after applying the time zone offset. Move the check for these two dates up, set the expected hour based on which one is found, or exit early if none of them are present, thus avoiding to engage the regex machinery for newer dates.

This also gets rid of two magic string length constants.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
 apply.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

Show changes to apply.c +17 −16

diff --git a/apply.c b/apply.c
index 956f56a927..e14077eaee 100644
--- a/apply.c
+++ b/apply.c
@@ -819,8 +819,7 @@ static int has_epoch_timestamp(const char *nameline)
 	const char *timestamp = NULL, *cp, *colon;
 	static regex_t *stamp;
 	regmatch_t m[10];
-	int zoneoffset;
-	int hourminute;
+	int zoneoffset, epoch_hour, hour, minute;
 	int status;
 
 	for (cp = nameline; *cp != '\n'; cp++) {
@@ -829,6 +828,18 @@ static int has_epoch_timestamp(const char *nameline)
 	}
 	if (!timestamp)
 		return 0;
+
+	/*
+	 * YYYY-MM-DD hh:mm:ss must be from either 1969-12-31
+	 * (west of GMT) or 1970-01-01 (east of GMT)
+	 */
+	if (starts_with(timestamp, "1969-12-31"))
+		epoch_hour = 24;
+	else if (starts_with(timestamp, "1970-01-01"))
+		epoch_hour = 0;
+	else
+		return 0;
+
 	if (!stamp) {
 		stamp = xmalloc(sizeof(*stamp));
 		if (regcomp(stamp, stamp_regexp, REG_EXTENDED)) {
@@ -846,6 +857,9 @@ static int has_epoch_timestamp(const char *nameline)
 		return 0;
 	}
 
+	hour = strtol(timestamp + 11, NULL, 10);
+	minute = strtol(timestamp + 14, NULL, 10);
+
 	zoneoffset = strtol(timestamp + m[3].rm_so + 1, (char **) &colon, 10);
 	if (*colon == ':')
 		zoneoffset = zoneoffset * 60 + strtol(colon + 1, NULL, 10);
@@ -854,20 +868,7 @@ static int has_epoch_timestamp(const char *nameline)
 	if (timestamp[m[3].rm_so] == '-')
 		zoneoffset = -zoneoffset;
 
-	/*
-	 * YYYY-MM-DD hh:mm:ss must be from either 1969-12-31
-	 * (west of GMT) or 1970-01-01 (east of GMT)
-	 */
-	if ((zoneoffset < 0 && memcmp(timestamp, "1969-12-31", 10)) ||
-	    (0 <= zoneoffset && memcmp(timestamp, "1970-01-01", 10)))
-		return 0;
-
-	hourminute = (strtol(timestamp + 11, NULL, 10) * 60 +
-		      strtol(timestamp + 14, NULL, 10) -
-		      zoneoffset);
-
-	return ((zoneoffset < 0 && hourminute == 1440) ||
-		(0 <= zoneoffset && !hourminute));
+	return hour * 60 + minute - zoneoffset == epoch_hour * 60;
 }
 
 /*

-- 
2.14.1

René Scharfe· Aug 25, 2017, 19:06 UTC · re: René Scharfe · lore

[PATCH 2/2] apply: remove epoch date from regex

We check the date of epoch timestamp candidates already with starts_with(). Move beyond that part using skip_prefix() instead of checking it again using a regular expression. Also group the minutes part, so that we can access them using a substring match instead of using a magic number.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
 apply.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

Show changes to apply.c +5 −7

diff --git a/apply.c b/apply.c
index e14077eaee..9c70b4040a 100644
--- a/apply.c
+++ b/apply.c
@@ -811,9 +811,7 @@ static int has_epoch_timestamp(const char *nameline)
 	 * 1970-01-01, and the seconds part must be "00".
 	 */
 	const char stamp_regexp[] =
-		"^(1969-12-31|1970-01-01)"
-		" "
-		"[0-2][0-9]:[0-5][0-9]:00(\\.0+)?"
+		"^[0-2][0-9]:([0-5][0-9]):00(\\.0+)?"
 		" "
 		"([-+][0-2][0-9]:?[0-5][0-9])\n";
 	const char *timestamp = NULL, *cp, *colon;
@@ -833,9 +831,9 @@ static int has_epoch_timestamp(const char *nameline)
 	 * YYYY-MM-DD hh:mm:ss must be from either 1969-12-31
 	 * (west of GMT) or 1970-01-01 (east of GMT)
 	 */
-	if (starts_with(timestamp, "1969-12-31"))
+	if (skip_prefix(timestamp, "1969-12-31 ", &timestamp))
 		epoch_hour = 24;
-	else if (starts_with(timestamp, "1970-01-01"))
+	else if (skip_prefix(timestamp, "1970-01-01 ", &timestamp))
 		epoch_hour = 0;
 	else
 		return 0;
@@ -857,8 +855,8 @@ static int has_epoch_timestamp(const char *nameline)
 		return 0;
 	}
 
-	hour = strtol(timestamp + 11, NULL, 10);
-	minute = strtol(timestamp + 14, NULL, 10);
+	hour = strtol(timestamp, NULL, 10);
+	minute = strtol(timestamp + m[1].rm_so, NULL, 10);
 
 	zoneoffset = strtol(timestamp + m[3].rm_so + 1, (char **) &colon, 10);
 	if (*colon == ':')

-- 
2.14.1

patch, 2 partsapply: check date of potential epoch timestamps first