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[patch] Reject non-hex characters in Color.FromHex with ArgumentException #399

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Merged
matt-edmondson merged 1 commit into from
Oct 10, 2026
Merged

[patch] Reject non-hex characters in Color.FromHex with ArgumentException #399

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15 changes: 14 additions & 1 deletion Semantics.Color/Color.Conversions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@
/// <param name="hex">The hex color string.</param>
/// <returns>The linear-RGB color.</returns>
/// <exception cref="ArgumentNullException">Thrown when <paramref name="hex"/> is null.</exception>
/// <exception cref="ArgumentException">Thrown when <paramref name="hex"/> is not a recognised hex length.</exception>
/// <exception cref="ArgumentException">Thrown when <paramref name="hex"/> is not a recognised hex length, or contains a character that is not a hex digit.</exception>
public static Color FromHex(string hex)
{
Ensure.NotNull(hex);
Expand All @@ -62,6 +62,16 @@
throw new ArgumentException("Hex color must be #RGB, #RRGGBB, or #RRGGBBAA.", nameof(hex));
}

// Convert.ToByte(s, 16) accepts a leading '+' and throws FormatException for other bad
// characters, so every character is checked here and only hex digits reach it.
foreach (char c in h)

Check warning on line 67 in Semantics.Color/Color.Conversions.cs

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SonarQubeCloud / SonarCloud Code Analysis

Loops should be simplified using the "Where" LINQ method 


See more on https://sonarcloud.io/project/issues?id=ktsu-dev_Semantics&issues=AaEcLJJ5Q8RC0l5igvfB&open=AaEcLJJ5Q8RC0l5igvfB&pullRequest=399
{
if (!IsHexDigit(c))
{
throw new ArgumentException($"Hex color contains '{c}', which is not a hex digit.", nameof(hex));
}
}

byte r = ParseByte(h, 0);
byte g = ParseByte(h, 2);
byte b = ParseByte(h, 4);
Expand Down Expand Up @@ -99,6 +109,9 @@
private static byte ParseByte(string hex, int index) =>
Convert.ToByte(hex.Substring(index, 2), 16);

private static bool IsHexDigit(char c) =>
c is (>= '0' and <= '9') or (>= 'A' and <= 'F') or (>= 'a' and <= 'f');

/// <summary>Converts this linear color to <see cref="Oklab"/>.</summary>
/// <returns>The Oklab equivalent.</returns>
public Oklab ToOklab() => Oklab.FromColor(this);
Expand Down
23 changes: 23 additions & 0 deletions Semantics.Test/Colors/HexConversionTests.cs
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Expand Up @@ -58,4 +58,27 @@ public void ToHex_EmitsAlphaWhenNotOpaque()
[TestMethod]
public void FromHex_InvalidLength_Throws() =>
Assert.ThrowsExactly<ArgumentException>(() => Color.FromHex("#12345"));

[TestMethod]
[DataRow("#+F+F+F")]
[DataRow("+F+F+F")]
[DataRow("#00+F00")]
[DataRow("#GGGGGG")]
[DataRow("#0x0x0x")]
[DataRow("#-1-1-1")]
[DataRow("#12345G")]
[DataRow("#FFFFFF+F")]
[DataRow("#F F")]
[DataRow("#G00")]
public void FromHex_NonHexCharacter_ThrowsArgumentException(string hex) =>
Assert.ThrowsExactly<ArgumentException>(() => Color.FromHex(hex));

[TestMethod]
[DataRow("#abc", "#AABBCC")]
[DataRow("#ABC", "#AABBCC")]
[DataRow("#3a7bd5", "#3A7BD5")]
[DataRow("3A7BD5", "#3A7BD5")]
[DataRow("#3a7bd580", "#3A7BD580")]
public void FromHex_ValidDigitsInEitherCase_RoundTrip(string hex, string expected) =>
Assert.AreEqual(expected, Color.FromHex(hex).ToHex());
}
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