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Merge pull request #613 from filipnavara/head-in-packed-refs
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Fix resolving HEAD reference if it's a packed ref
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@AArnott
AArnott authored Jun 12, 2021
2 parents 07964f8 + 311f477 commit 1902982
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Showing 3 changed files with 75 additions and 53 deletions.
19 changes: 19 additions & 0 deletions src/NerdBank.GitVersioning.Tests/GitContextTests.cs
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Original file line number Diff line number Diff line change
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);
}
}
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109 changes: 56 additions & 53 deletions src/NerdBank.GitVersioning/ManagedGit/GitRepository.cs
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Original file line number Diff line number Diff line change
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

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