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Android remove backward timezones #64028

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Merged
steveisok merged 13 commits into from
Jan 24, 2022
Merged

Android remove backward timezones #64028

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e08f971
[libraries][Android] Filter out backward timezone IDs using tzlookup …
mdh1418 Jan 19, 2022
7258e39
[tests] Add TimeZoneInfo Test to detect Backward TimeZones
mdh1418 Jan 20, 2022
3c86169
Address feedback
mdh1418 Jan 20, 2022
9f6adce
Address more feedback
mdh1418 Jan 20, 2022
602201f
[libraries][Android] Add isBackwards in lieu of removing timezone ids
mdh1418 Jan 20, 2022
86a56b8
Remove unneeded strings.resx additions
mdh1418 Jan 21, 2022
ec59f25
Temporarily show timezone displayNames in NoBackwardTimeZones
mdh1418 Jan 21, 2022
9da4754
Figure out backwards IDs on linux and maybe windows
mdh1418 Jan 21, 2022
2a96703
[libraries] ActiveIssue NoBackwardTimeZones for Linux Arm64
mdh1418 Jan 21, 2022
559df41
Cleanup
mdh1418 Jan 21, 2022
09e71d2
Skip test with TestPlatforms instead
mdh1418 Jan 21, 2022
b3b4845
Optimize further by not allocating a list for GetTimeZoneIDs
mdh1418 Jan 24, 2022
a65bc46
Fix indexing
mdh1418 Jan 24, 2022
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92 changes: 83 additions & 9 deletions src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.Android.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,7 @@ private sealed class AndroidTzData
private string[] _ids;
private int[] _byteOffsets;
private int[] _lengths;
private bool[] _isBackwards;
private string _tzFileDir;
private string _tzFilePath;

Expand Down Expand Up @@ -230,7 +231,7 @@ public AndroidTzData()
foreach (var tzFileDir in tzFileDirList)
{
string tzFilePath = Path.Combine(tzFileDir, TimeZoneFileName);
if (LoadData(tzFilePath))
if (LoadData(tzFileDir, tzFilePath))
{
_tzFileDir = tzFileDir;
_tzFilePath = tzFilePath;
Expand All @@ -241,10 +242,62 @@ public AndroidTzData()
throw new TimeZoneNotFoundException(SR.TimeZoneNotFound_ValidTimeZoneFileMissing);
}

// On some versions of Android, the tzdata file may still contain backward timezone ids.
// We attempt to use tzlookup.xml, which is available on some versions of Android to help
// validate non-backward timezone ids
// tzlookup.xml is an autogenerated file that contains timezone ids in this form:
//
// <timezones ianaversion="2019b">
// <countryzones>
// <country code="au" default="Australia/Sydney" everutc="n">
// <id alts="Australia/ACT,Australia/Canberra,Australia/NSW">Australia/Sydney</id>
// ...
// ...
// <id>Australia/Eucla</id>
// </country>
// <country ...>
// ...
// ...
// ...
// </country>
// </countryzones>
// </timezones>
//
// Once the timezone cache is populated with the IDs, we reference tzlookup id tags
// to determine if an id is backwards and label it as such if they are.
private void FilterBackwardIDs(string tzFileDir, out HashSet<string> tzLookupIDs)
{
tzLookupIDs = new HashSet<string>();
try
{
using (StreamReader sr = File.OpenText(Path.Combine(tzFileDir, "tzlookup.xml")))
{
string? tzLookupLine;
while (sr.Peek() >= 0)
{
if (!(tzLookupLine = sr.ReadLine())!.AsSpan().TrimStart().StartsWith("<id", StringComparison.Ordinal))
continue;

int idStart = tzLookupLine!.IndexOf('>') + 1;
int idLength = tzLookupLine.LastIndexOf("</", StringComparison.Ordinal) - idStart;
if (idStart <= 0 || idLength < 0)
{
// Either the start tag <id ... > or the end tag </id> are not found
continue;
}
string id = tzLookupLine.Substring(idStart, idLength);
tzLookupIDs.Add(id);
}
}
}
catch {}
}

[MemberNotNullWhen(true, nameof(_ids))]
[MemberNotNullWhen(true, nameof(_byteOffsets))]
[MemberNotNullWhen(true, nameof(_lengths))]
private bool LoadData(string path)
[MemberNotNullWhen(true, nameof(_isBackwards))]
private bool LoadData(string tzFileDir, string path)
{
if (!File.Exists(path))
{
Expand All @@ -254,7 +307,7 @@ private bool LoadData(string path)
{
using (FileStream fs = File.OpenRead(path))
{
LoadTzFile(fs);
LoadTzFile(tzFileDir, fs);
}
return true;
}
Expand All @@ -266,15 +319,16 @@ private bool LoadData(string path)
[MemberNotNull(nameof(_ids))]
[MemberNotNull(nameof(_byteOffsets))]
[MemberNotNull(nameof(_lengths))]
private void LoadTzFile(Stream fs)
[MemberNotNull(nameof(_isBackwards))]
private void LoadTzFile(string tzFileDir, Stream fs)
{
const int HeaderSize = 24;
Span<byte> buffer = stackalloc byte[HeaderSize];

ReadTzDataIntoBuffer(fs, 0, buffer);

LoadHeader(buffer, out int indexOffset, out int dataOffset);
ReadIndex(fs, indexOffset, dataOffset);
ReadIndex(tzFileDir, fs, indexOffset, dataOffset);
}

private void LoadHeader(Span<byte> buffer, out int indexOffset, out int dataOffset)
Expand Down Expand Up @@ -303,23 +357,25 @@ private void LoadHeader(Span<byte> buffer, out int indexOffset, out int dataOffs
[MemberNotNull(nameof(_ids))]
[MemberNotNull(nameof(_byteOffsets))]
[MemberNotNull(nameof(_lengths))]
private void ReadIndex(Stream fs, int indexOffset, int dataOffset)
[MemberNotNull(nameof(_isBackwards))]
private void ReadIndex(string tzFileDir, Stream fs, int indexOffset, int dataOffset)
{
int indexSize = dataOffset - indexOffset;
const int entrySize = 52; // Data entry size
int entryCount = indexSize / entrySize;

_byteOffsets = new int[entryCount];
_ids = new string[entryCount];
_lengths = new int[entryCount];

_isBackwards = new bool[entryCount];
FilterBackwardIDs(tzFileDir, out HashSet<string> tzLookupIDs);
for (int i = 0; i < entryCount; ++i)
{
LoadEntryAt(fs, indexOffset + (entrySize*i), out string id, out int byteOffset, out int length);

_byteOffsets[i] = byteOffset + dataOffset;
_ids[i] = id;
_lengths[i] = length;
_isBackwards[i] = !tzLookupIDs.Contains(id);

if (length < 24) // Header Size
{
Expand Down Expand Up @@ -372,7 +428,25 @@ private void LoadEntryAt(Stream fs, long position, out string id, out int byteOf

public string[] GetTimeZoneIds()
{
return _ids;
int numTimeZoneIDs = 0;
for (int i = 0; i < _ids.Length; i++)
{
if (!_isBackwards[i])
{
numTimeZoneIDs++;
}
}
string[] nonBackwardsTZIDs = new string[numTimeZoneIDs];
var index = 0;
for (int i = 0; i < _ids.Length; i++)
{
if (!_isBackwards[i])
{
nonBackwardsTZIDs[index] = _ids[i];
index++;
}
}
return nonBackwardsTZIDs;
}

public string GetTimeZoneDirectory()
Expand Down
14 changes: 14 additions & 0 deletions src/libraries/System.Runtime/tests/System/TimeZoneInfoTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2921,6 +2921,20 @@ public static void AdjustmentRuleBaseUtcOffsetDeltaTest()
Assert.Equal(new TimeSpan(2, 0, 0), customTimeZone.GetUtcOffset(new DateTime(2021, 3, 10, 2, 0, 0)));
}

[Fact]
[ActiveIssue("https://github.com/dotnet/runtime/issues/64111", TestPlatforms.Linux)]
public static void NoBackwardTimeZones()
{
ReadOnlyCollection<TimeZoneInfo> tzCollection = TimeZoneInfo.GetSystemTimeZones();
HashSet<String> tzDisplayNames = new HashSet<String>();

foreach (TimeZoneInfo timezone in tzCollection)
{
tzDisplayNames.Add(timezone.DisplayName);
}
Assert.Equal(tzCollection.Count, tzDisplayNames.Count);
}

private static bool IsEnglishUILanguage => CultureInfo.CurrentUICulture.Name.Length == 0 || CultureInfo.CurrentUICulture.TwoLetterISOLanguageName == "en";

private static bool IsEnglishUILanguageAndRemoteExecutorSupported => IsEnglishUILanguage && RemoteExecutor.IsSupported;
Expand Down