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Fix off-by-one error in validation within GetOffsetAtPosition #1669

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Jan 24, 2022
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Fix off-by-one error in validation within GetOffsetAtPosition #1669

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2 changes: 1 addition & 1 deletion src/PowerShellEditorServices/Services/TextDocument/ScriptFile.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -411,7 +411,7 @@ public void ApplyChange(FileChange fileChange)
/// <returns>The zero-based offset for the given file position.</returns>
public int GetOffsetAtPosition(int lineNumber, int columnNumber)
{
Validate.IsWithinRange("lineNumber", lineNumber, 1, this.FileLines.Count);
Validate.IsWithinRange("lineNumber", lineNumber, 1, this.FileLines.Count + 1);
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Maybe this should just be a separate check for FileLines.Count == 0? I feel like the check is correct here, it just doesn't account for empty? Maybe it should be Math.Max(this.FileLines.Count, 1)?

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The use of IsWithinRange does not work well with 1-indexed lists that could be empty. I agree this looks weird, but it's what's done here too:

PowerShellEditorServices/src/PowerShellEditorServices/Services/TextDocument/ScriptFile.cs

Lines 230 to 237 in 149f5ac

public string GetLine(int lineNumber)
{
Validate.IsWithinRange(
"lineNumber", lineNumber,
1, this.FileLines.Count + 1);
return this.FileLines[lineNumber - 1];
}

Validate.IsGreaterThan("columnNumber", columnNumber, 0);

int offset = 0;
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