sql: Fix for invalid value for parameter "TimeZone": "GMT-08:00" cock…

…roachdb#41776

Previously, the inputs like `GMT+5` would cause error.
Postgres supports inputs like this. So adding support for
these inputs was necessary.
sql: Added a check to convert the strings to offset.
timeutil: added a function to convert input to offset seconds.
Added unit tests. Added a regex to accept the inputs.

Release note (sql change): `SET TIME ZONE` now accepts inputs
mentioned in cockroachdb#41776. Now accepted time zone strings
* `GMT+5`
* `UTC-03:59:59`

pkg/sql/logictest/testdata/logic_test/timestamp

@@ -192,3 +192,14 @@ query R
 SELECT extract(timezone FROM '2001-01-01 13:00:00+01:15'::timestamptz)
 ----
 10800
+
+
+# Test timezone() 
+
+statement ok
+SET TIME ZONE 'GMT+1';
+
+query T
+SELECT '2001-01-01 00:00:00'::TIMESTAMP::TIMESTAMPTZ
+----
+2001-01-01 00:00:00 +0100 +0100

pkg/sql/set_var.go

@@ -222,8 +222,12 @@ func timeZoneVarGetStringVal(
 			if err1 != nil {
 				loc, err1 = timeutil.LoadLocation(strings.ToTitle(location))
 				if err1 != nil {
-					return "", wrapSetVarError("timezone", values[0].String(),
-						"cannot find time zone %q: %v", location, err)
+					var ok bool
+					offset, ok = timeutil.TimeZoneOffsetStringConversion(location)
+					if !ok {
+						return "", wrapSetVarError("timezone", values[0].String(),
+							"cannot find time zone %q: %v", location, err)
+					}
 				}
 			}
 		}

pkg/util/timeutil/time_zone_util.go

@@ -12,12 +12,17 @@ package timeutil
 
 import (
 	"fmt"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
 )
 
 const fixedOffsetPrefix string = "fixed offset:"
+const pattern = `(?i)(GMT|UTC)([+-])(\d{1,3}(:[0-5]\d){0,2})\b$`
+const bound = 167*60*60 + 59*60
+
+var re = regexp.MustCompile(pattern)
 
 // FixedOffsetTimeZoneToLocation creates a time.Location with a set offset and
 // with a name that can be marshaled by crdb between nodes.
@@ -68,3 +73,44 @@ func ParseFixedOffsetTimeZone(location string) (offset int, origRepr string, suc
 	}
 	return offset, strings.TrimSuffix(strings.TrimPrefix(origRepr, "("), ")"), true
 }
+
+// TimeZoneOffsetStringConversion converts a time string to offset seconds
+// Supported time zone strings :- GMT/UTC±[00:00:00 - 15:59:59], GMT/UTC±[0-16]
+// Unsupported time zone strings :- GMT/UTC±16:00 to upper, GMT/UTC±6.5
+// (case insensitive)
+func TimeZoneOffsetStringConversion(s string) (offset int64, ok bool) {
+	if !(re.MatchString(s)) {
+		return 0, false
+	}
+	prefix := string(re.FindStringSubmatch(s)[0][3])
+	timeString := string(re.FindStringSubmatch(s)[3])
+
+	var (
+		hoursString   = "0"
+		minutesString = "0"
+		secondsString = "0"
+	)
+	if strings.Contains(timeString, ":") {
+		offsets := strings.Split(timeString, ":")
+		hoursString, minutesString = offsets[0], offsets[1]
+		if len(offsets) == 3 {
+			secondsString = offsets[2]
+		}
+	} else {
+		hoursString = timeString
+	}
+
+	hours, _ := strconv.ParseInt(hoursString, 10, 64)
+	minutes, _ := strconv.ParseInt(minutesString, 10, 64)
+	seconds, _ := strconv.ParseInt(secondsString, 10, 64)
+	offset = (hours * 60 * 60) + (minutes * 60) + seconds
+
+	if prefix == "-" {
+		offset *= -1
+	}
+
+	if offset > bound || offset < -bound {
+		return 0, false
+	}
+	return offset, true
+}

pkg/util/timeutil/time_zone_util_test.go

@@ -0,0 +1,45 @@
+// Copyright 2019 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package timeutil
+
+import "testing"
+
+func TestTimeZoneOffsetStringConversion(t *testing.T) {
+	testCases := []struct {
+		timezone   string
+		offsetSecs int64
+		ok         bool
+	}{
+		{`GMT+00:00`, 0, true},
+		{`UTC-1:00:00`, -3600, true},
+		{`UTC+15:59`, 57540, true},
+		{`GMT-15:59:59`, -57599, true},
+		{`GMT-06:59`, -25140, true},
+		{`GMT+167:59:00`, 604740, true},
+		{`GMT+5`, 18000, true},
+		{`GMT-16`, -57600, true},
+		{`GMT-15:59:5Z`, 0, false},
+		{`GMT+6:00:0`, 0, false},
+		{`GMT+6:`, 0, false},
+		{`GMT-6:00:`, 0, false},
+		{`GMT+168:00:00`, 0, false},
+		{`GMT+6:0:59`, 0, false},
+		{`GMT-170:00:59`, 0, false},
+	}
+
+	for i, testCase := range testCases {
+		offset, ok := TimeZoneOffsetStringConversion(testCase.timezone)
+		if offset != testCase.offsetSecs || ok != testCase.ok {
+			t.Errorf("%d: Expected offset: %d, success: %v for time %s, but got offset: %d, success: %v",
+				i, testCase.offsetSecs, testCase.ok, testCase.timezone, offset, ok)
+		}
+	}
+}