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Add missing regex position check after BOL optimization #66216

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Merged
stephentoub merged 2 commits into from
Mar 7, 2022
+62 −1
Merged

Add missing regex position check after BOL optimization #66216

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cd7c376
Add missing regex position check after BOL optimization
stephentoub Mar 4, 2022
4c7e642
Address PR feedback
stephentoub Mar 6, 2022
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11 changes: 11 additions & 0 deletions src/libraries/System.Text.RegularExpressions/gen/RegexGenerator.Emitter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -535,6 +535,17 @@ bool EmitAnchors()
Goto(NoStartingPositionFound);
}
writer.WriteLine("pos = newlinePos + pos + 1;");

// We've updated the position. Make sure there's still enough room in the input for a possible match.
using (EmitBlock(writer, minRequiredLength switch
{
0 => "if (pos > inputSpan.Length)",
1 => "if (pos >= inputSpan.Length)",
_ => $"if (pos > inputSpan.Length - {minRequiredLength})"
}))
{
Goto(NoStartingPositionFound);
}
}
writer.WriteLine();
break;
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12 changes: 12 additions & 0 deletions ...raries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexCompiler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -622,6 +622,18 @@ bool GenerateAnchors()
Ldc(1);
Add();
Stloc(pos);

// We've updated the position. Make sure there's still enough room in the input for a possible match.
// if (pos > inputSpan.Length - minRequiredLength) returnFalse;
Ldloca(inputSpan);
Call(s_spanGetLengthMethod);
if (minRequiredLength != 0)
{
Ldc(minRequiredLength);
Sub();
}
Ldloc(pos);
BltFar(returnFalse);
}

MarkLabel(label);
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6 changes: 6 additions & 0 deletions ...stem.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexFindOptimizations.cs
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Expand Up @@ -281,7 +281,13 @@ public bool TryFindNextStartingPosition(ReadOnlySpan<char> textSpan, ref int pos
return false;
}

// We've updated the position. Make sure there's still enough room in the input for a possible match.
pos = newline + 1 + pos;
if (pos > textSpan.Length - MinRequiredLength)
{
pos = textSpan.Length;
return false;
}
}
}

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34 changes: 33 additions & 1 deletion ...aries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.MultipleMatches.Tests.cs
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Expand Up @@ -176,7 +176,7 @@ public static IEnumerable<object[]> Matches_TestData()
}
};

// Using ^ with multiline
// Using ^ and $ with multiline
yield return new object[]
{
engine,
Expand Down Expand Up @@ -244,6 +244,38 @@ public static IEnumerable<object[]> Matches_TestData()
}
};

yield return new object[]
{
engine,
@"^[^a]a", "bar\n", RegexOptions.Multiline,
new[]
{
new CaptureData("ba", 0, 2)
}
};

yield return new object[]
{
engine,
@"^[^a]a", "car\nbar\n", RegexOptions.Multiline,
new[]
{
new CaptureData("ca", 0, 2),
new CaptureData("ba", 4, 2)
}
};

yield return new object[]
{
engine,
@"[0-9]cat$", "1cat\n2cat", RegexOptions.Multiline,
new[]
{
new CaptureData("1cat", 0, 4),
new CaptureData("2cat", 5, 4)
}
};

if (!PlatformDetection.IsNetFramework)
{
// .NET Framework missing fix in https://github.com/dotnet/runtime/pull/1075
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