System.Data.Odbc - SQLLEN does not handle -1

[TonyValenti]

Description

Hi .NET Team
When querying Filemaker Pro ODBC databases through .NET ODBC, we're running into some issues.
(This does not affect Java ODBC connectors)

Specifically, it seems that some fields represent their length as 0x00000000ffffffff (-1).

This is causing overflow errors in SQLLEN.cs when trying to parse the field at this code:

	public static implicit operator int(SQLLEN value)
	{
		return ((IntPtr)value._value).ToInt32();
	}

Instead of:

return ((IntPtr)value._value).ToInt32();

I think the code should be:

return (int)value.ToInt64();

Reproduction Steps

I can provide a sample database if contacted

Expected behavior

No Error occurs

Actual behavior

An overflow exception occurs.

Regression?

No response

Known Workarounds

I can wrap the access and return null if this happens.

Configuration

.NET 9.0 on Windows.

Other information

Java ODBC libraries are not affected by this issue.

[dotnet-policy-service]

Tagging subscribers to this area: @roji, @ajcvickers
See info in area-owners.md if you want to be subscribed.

[huoyaoyuan]

IntPtr.ToInt32() is checked. The new explicit cast operator is unchecked since C# 11, but only available on newer frameworks.

[TonyValenti]

Hi All - Some additional information.
This works fine with 32-bit EXEs but crashes on 64-bit EXEs. Here's why:
If you take a look at this line:

runtime/src/libraries/System.Data.Odbc/src/System/Data/Odbc/OdbcDataReader.cs

Line 589 in 1b5f930

info._dbtype = unchecked((ODBC32.SQL_TYPE)(int)GetColAttribute(i, ODBC32.SQL_DESC.CONCISE_TYPE, ODBC32.SQL_COLUMN.TYPE, ODBC32.HANDLER.THROW));

You'll see that the cast is happening inside of an unchecked operation. This is correct.
However, IntPtr.ToInt32() is checked and is throwing.

@huoyaoyuan - This is an important fix for us. Can you get a PR rolling?

[TonyValenti]

@huoyaoyuan -
Should this be moved out of untriaged?

[huoyaoyuan]

Should this be moved out of untriaged?

It should be done by the area owners of System.Data. The decision about the behavior is also up to the owners.

[TonyValenti]

@roji - Could you take a look at this one when you have a chance?

[SamMonoRT]

We will not get to this anytime soon. Adding to 10.0 milestone for tracking