Skip to content

Fix BSTR.ToString() to not throw when the pointer is null #725

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 13, 2022
Merged

Fix BSTR.ToString() to not throw when the pointer is null #725

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
21 changes: 13 additions & 8 deletions src/Microsoft.Windows.CsWin32/Generator.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4325,16 +4325,21 @@ private IEnumerable<MemberDeclarationSyntax> CreateAdditionalTypeDefBSTRMembers(
{
ExpressionSyntax thisValue = MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, ThisExpression(), IdentifierName("Value"));

// public override string ToString() => Marshal.PtrToStringBSTR(new IntPtr(this.Value));
// Marshal.PtrToStringBSTR(new IntPtr(this.Value))
InvocationExpressionSyntax ptrToStringBstr = InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
IdentifierName(nameof(Marshal)),
IdentifierName(nameof(Marshal.PtrToStringBSTR))))
.WithArgumentList(ArgumentList(SingletonSeparatedList(Argument(ObjectCreationExpression(IntPtrTypeSyntax).WithArgumentList(ArgumentList(SingletonSeparatedList(Argument(thisValue))))))));

// this.Value != null
ExpressionSyntax valueIsNotNull = BinaryExpression(SyntaxKind.NotEqualsExpression, thisValue, LiteralExpression(SyntaxKind.NullLiteralExpression));

// public override string ToString() => this.Value != null ? Marshal.PtrToStringBSTR(new IntPtr(this.Value)) : null;
yield return MethodDeclaration(PredefinedType(TokenWithSpace(SyntaxKind.StringKeyword)), Identifier(nameof(this.ToString)))
.AddModifiers(TokenWithSpace(SyntaxKind.PublicKeyword), TokenWithSpace(SyntaxKind.OverrideKeyword))
.WithExpressionBody(ArrowExpressionClause(
InvocationExpression(
MemberAccessExpression(
SyntaxKind.SimpleMemberAccessExpression,
IdentifierName(nameof(Marshal)),
IdentifierName(nameof(Marshal.PtrToStringBSTR))))
.WithArgumentList(ArgumentList(SingletonSeparatedList(Argument(ObjectCreationExpression(IntPtrTypeSyntax).WithArgumentList(ArgumentList(SingletonSeparatedList(Argument(thisValue))))))))))
.WithExpressionBody(ArrowExpressionClause(ConditionalExpression(valueIsNotNull, ptrToStringBstr, LiteralExpression(SyntaxKind.NullLiteralExpression))))
.WithSemicolonToken(SemicolonWithLineFeed);

if (this.canUseSpan)
Expand Down
7 changes: 7 additions & 0 deletions test/GenerationSandbox.Tests/BasicTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,13 @@ public void BSTR_ToString()
}
}

[Fact]
public void BSTR_ToString_Null()
{
BSTR bstr = default;
Assert.Null(bstr.ToString());
}

[Fact]
public unsafe void BSTR_ImplicitConversionTo_ReadOnlySpan()
{
Expand Down