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Fix resolving HEAD reference if it's a packed ref #613

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merged 6 commits into from Jun 12, 2021
Merged

Fix resolving HEAD reference if it's a packed ref #613

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e9b28de
Add repro test for #602
AArnott Jun 12, 2021
47d7f46
Fix resolving HEAD reference if it's a packed ref
filipnavara Jun 11, 2021
ea9517b
Tweak GitRepository.Lookup error handling
filipnavara Jun 11, 2021
35a11f5
Fix flipped condition
filipnavara Jun 11, 2021
4d8ecca
Hopefully fix worktree support
filipnavara Jun 11, 2021
311f477
Touch-up on perf and add a test
AArnott Jun 12, 2021
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19 changes: 19 additions & 0 deletions src/NerdBank.GitVersioning.Tests/GitContextTests.cs
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Expand Up @@ -162,4 +162,23 @@ public void SelectDirectory_SubDir()
Assert.Equal("sub", this.Context.RepoRelativeProjectDirectory);
Assert.Equal(absolutePath, this.Context.AbsoluteProjectDirectory);
}

[Fact]
public void GetVersion_PackedHead()
{
using var expandedRepo = TestUtilities.ExtractRepoArchive("PackedHeadRef");
this.Context = this.CreateGitContext(Path.Combine(expandedRepo.RepoPath));
var oracle = new VersionOracle(this.Context);
Assert.Equal("1.0.1", oracle.SimpleVersion.ToString());
this.Context.TrySelectCommit("HEAD");
Assert.Equal("1.0.1", oracle.SimpleVersion.ToString());
}

[Fact]
public void HeadCanonicalName_PackedHead()
{
using var expandedRepo = TestUtilities.ExtractRepoArchive("PackedHeadRef");
this.Context = this.CreateGitContext(Path.Combine(expandedRepo.RepoPath));
Assert.Equal("refs/heads/main", this.Context.HeadCanonicalName);
}
}
Binary file added src/NerdBank.GitVersioning.Tests/repos/PackedHeadRef.zip
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109 changes: 56 additions & 53 deletions src/NerdBank.GitVersioning/ManagedGit/GitRepository.cs
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Expand Up @@ -8,6 +8,7 @@
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using Validation;

namespace Nerdbank.GitVersioning.ManagedGit
{
Expand Down Expand Up @@ -222,9 +223,7 @@ public object GetHeadAsReferenceOrSha()
/// </returns>
public GitObjectId GetHeadCommitSha()
{
var reference = this.GetHeadAsReferenceOrSha();
var objectId = this.ResolveReference(reference);
return objectId;
return this.Lookup("HEAD") ?? GitObjectId.Empty;
}

/// <summary>
Expand Down Expand Up @@ -280,16 +279,25 @@ public GitCommit GetCommit(GitObjectId sha, bool readAuthor = false)
/// <returns>The object ID referenced by <paramref name="objectish"/> if found; otherwise <see langword="null"/>.</returns>
public GitObjectId? Lookup(string objectish)
{
bool skipObjectIdLookup = false;

if (objectish == "HEAD")
{
return this.GetHeadCommitSha();
var reference = this.GetHeadAsReferenceOrSha();
if (reference is GitObjectId headObjectId)
{
return headObjectId;
}

objectish = (string)reference;
}

var possibleLooseFileMatches = new List<string>();
if (objectish.StartsWith("refs/", StringComparison.Ordinal))
{
// Match on loose ref files by their canonical name.
possibleLooseFileMatches.Add(Path.Combine(this.GitDirectory, objectish));
possibleLooseFileMatches.Add(Path.Combine(this.CommonDirectory, objectish));
skipObjectIdLookup = true;
}
else
{
Expand Down Expand Up @@ -341,6 +349,11 @@ public GitCommit GetCommit(GitObjectId sha, bool readAuthor = false)
}
}

if (skipObjectIdLookup)
{
return null;
}

if (objectish.Length == 40)
{
return GitObjectId.Parse(objectish);
Expand Down Expand Up @@ -372,25 +385,30 @@ public GitCommit GetCommit(GitObjectId sha, bool readAuthor = false)
objectish += "0";
}

var hex = ConvertHexStringToByteArray(objectish);

foreach (var pack in this.packs.Value.Span)
if (objectish.Length <= 40 && objectish.Length % 2 == 0)
{
var objectId = pack.Lookup(hex, endsWithHalfByte);

// It's possible for the same object to be present in both the object database and the pack files,
// or in multiple pack files.
if (objectId != null && !possibleObjectIds.Contains(objectId.Value))
Span<byte> decodedHex = stackalloc byte[objectish.Length / 2];
if (TryConvertHexStringToByteArray(objectish, decodedHex))
{
if (possibleObjectIds.Count > 0)
{
// If objectish already resolved to at least one object which is different from the current
// object id, objectish is not well-defined; so stop resolving and return null instead.
return null;
}
else
foreach (var pack in this.packs.Value.Span)
{
possibleObjectIds.Add(objectId.Value);
var objectId = pack.Lookup(decodedHex, endsWithHalfByte);

// It's possible for the same object to be present in both the object database and the pack files,
// or in multiple pack files.
if (objectId != null && !possibleObjectIds.Contains(objectId.Value))
{
if (possibleObjectIds.Count > 0)
{
// If objectish already resolved to at least one object which is different from the current
// object id, objectish is not well-defined; so stop resolving and return null instead.
return null;
}
else
{
possibleObjectIds.Add(objectId.Value);
}
}
}
}
}
Expand Down Expand Up @@ -610,33 +628,6 @@ private bool TryGetObjectByPath(GitObjectId sha, string objectType, [NotNullWhen
return true;
}

private GitObjectId ResolveReference(object reference)
{
if (reference is string)
{
if (!FileHelpers.TryOpen(Path.Combine(this.CommonDirectory, (string)reference), out FileStream? stream))
{
return GitObjectId.Empty;
}

using (stream)
{
Span<byte> objectId = stackalloc byte[40];
stream!.Read(objectId);

return GitObjectId.ParseHex(objectId);
}
}
else if (reference is GitObjectId)
{
return (GitObjectId)reference;
}
else
{
throw new GitException();
}
}

private ReadOnlyMemory<GitPack> LoadPacks()
{
var packDirectory = Path.Combine(this.ObjectDirectory, "pack/");
Expand Down Expand Up @@ -687,22 +678,34 @@ private static string TrimEndingDirectorySeparator(string path)
#endif
}

private static byte[] ConvertHexStringToByteArray(string hexString)
private static bool TryConvertHexStringToByteArray(string hexString, Span<byte> data)
{
// https://stackoverflow.com/questions/321370/how-can-i-convert-a-hex-string-to-a-byte-array
if (hexString.Length % 2 != 0)
{
throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, "The binary key cannot have an odd number of digits: {0}", hexString));
data = null;
return false;
}

byte[] data = new byte[hexString.Length / 2];
Requires.Argument(data.Length == hexString.Length / 2, nameof(data), "Length must be exactly half that of " + nameof(hexString) + ".");
for (int index = 0; index < data.Length; index++)
{
#if NETCOREAPP3_1_OR_GREATER
ReadOnlySpan<char> byteValue = hexString.AsSpan(index * 2, 2);
if (!byte.TryParse(byteValue, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out data[index]))
{
return false;
}
#else
string byteValue = hexString.Substring(index * 2, 2);
data[index] = byte.Parse(byteValue, NumberStyles.HexNumber, CultureInfo.InvariantCulture);
if (!byte.TryParse(byteValue, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out data[index]))
{
return false;
}
#endif
}

return data;
return true;
}

/// <summary>
Expand Down