time: accept anything between -23 and 23 as offset namezone name

time.Parse currently rejects numeric timezones names with UTC offsets
bigger than +12, but this is incorrect: there's a +13 timezone and a
+14 timezone:

  $ zdump Pacific/Kiritimati
  Pacific/Kiritimati  Mon Jun 25 02:15:03 2018 +14

For convenience, this cl changes the ranges of accepted offsets from
-14..+12 to -23..+23 (zero still excluded), i.e. every possible offset
that makes sense. We don't validate three-letter abbreviations for the
timezones names, so there's no need to be too strict on numeric names.

This change also fixes a bug in the parseTimeZone, that is currently
unconditionally returning true (i.e. valid timezone), without checking
the value returned by parseSignedOffset.

This fixes 5 of 17 time.Parse() failures listed in Issue #26032.

Updates #26032

Change-Id: I2f08ca9aa41ea4c6149ed35ed2dd8f23eeb42bff
Reviewed-on: https://go-review.googlesource.com/120558
Reviewed-by: Rob Pike <r@golang.org>

diff --git a/src/time/format.go b/src/time/format.go
index 237f28738b5d2ac764586d47fd5b9579f4eb4a10..f9cdbab3b8f31cc9f710d4634cdf63e0ade6b97e 100644 (file)
--- a/src/time/format.go
+++ b/src/time/format.go
@@ -1120,7 +1120,8 @@ func parseTimeZone(value string) (length int, ok bool) {
        // Special Case 3: Some time zones are not named, but have +/-00 format
        if value[0] == '+' || value[0] == '-' {
                length = parseSignedOffset(value)
-               return length, true
+               ok := length > 0 // parseSignedOffset returns 0 in case of bad input
+               return length, ok
        }
        // How many upper-case letters are there? Need at least three, at most five.
        var nUpper int
@@ -1152,7 +1153,7 @@ func parseTimeZone(value string) (length int, ok bool) {
 
 // parseGMT parses a GMT time zone. The input string is known to start "GMT".
 // The function checks whether that is followed by a sign and a number in the
-// range -14 through 12 excluding zero.
+// range -23 through +23 excluding zero.
 func parseGMT(value string) int {
        value = value[3:]
        if len(value) == 0 {
@@ -1163,7 +1164,7 @@ func parseGMT(value string) int {
 }
 
 // parseSignedOffset parses a signed timezone offset (e.g. "+03" or "-04").
-// The function checks for a signed number in the range -14 through +12 excluding zero.
+// The function checks for a signed number in the range -23 through +23 excluding zero.
 // Returns length of the found offset string or 0 otherwise
 func parseSignedOffset(value string) int {
        sign := value[0]
@@ -1177,7 +1178,7 @@ func parseSignedOffset(value string) int {
        if sign == '-' {
                x = -x
        }
-       if x == 0 || x < -14 || 12 < x {
+       if x == 0 || x < -23 || 23 < x {
                return 0
        }
        return len(value) - len(rem)

diff --git a/src/time/format_test.go b/src/time/format_test.go
index 68a4d3ddb0e8992d5d567c60cfe539feddcafc7a..c3552f4161361f5565d999d7fed53c88fcbbcf8b 100644 (file)
--- a/src/time/format_test.go
+++ b/src/time/format_test.go
@@ -427,8 +427,18 @@ var parseTimeZoneTests = []ParseTimeZoneTest{
        {"ESASTT hi", 0, false}, // run of upper-case letters too long.
        {"ESATY hi", 0, false},  // five letters must end in T.
        {"WITA hi", 4, true},    // Issue #18251
-       {"+03 hi", 3, true},     // Issue #24071
-       {"-04 hi", 3, true},     // Issue #24071
+       // Issue #24071
+       {"+03 hi", 3, true},
+       {"-04 hi", 3, true},
+       // Issue #26032
+       {"-11", 3, true},
+       {"-12", 3, true},
+       {"-23", 3, true},
+       {"-24", 0, false},
+       {"+13", 3, true},
+       {"+14", 3, true},
+       {"+23", 3, true},
+       {"+24", 0, false},
 }
 
 func TestParseTimeZone(t *testing.T) {