Filter fatal exceptions from Task.FromException in async paths

[cheenamalhotra]

Summary

Multiple sites in SqlBulkCopy, SqlDataReader.InvokeAsyncCall, SqlCommand.Reader, and SqlCommand.Xml catch Exception broadly and wrap it in Task.FromException<T>() or TrySetException() without filtering fatal exceptions. This means OutOfMemoryException, StackOverflowException, ThreadAbortException, etc. get silently captured into faulted Tasks instead of propagating synchronously.

Changes

File	Fix
SqlBulkCopy.cs	Added when (ADP.IsCatchableExceptionType(ex)) filter to 8 catch blocks that wrap exceptions into Task.FromException or TrySetException
SqlDataReader.cs (InvokeAsyncCall)	Added when (ADP.IsCatchableExceptionType(ex)) exception filter
SqlCommand.Reader.cs	Added when (ADP.IsCatchableExceptionType(e)) exception filter
SqlCommand.Xml.cs	Added when (ADP.IsCatchableExceptionType(e)) exception filter

Precedent

This matches the existing pattern already used in SqlDataReader at multiple other sites (e.g., ReadNextAsync, IsDBNullAsync, GetFieldValueAsync):

catch (Exception ex) when (ADP.IsCatchableExceptionType(ex))
{
    return Task.FromException<bool>(ex);
}

What was NOT changed

Sites in task continuations / callbacks (TdsParserStateObject SNI callbacks, AsyncHelper continuations, SqlCommand retry continuations) were intentionally left unchanged. In those contexts, rethrowing would crash the unobserved-task handler or the thread-pool thread; the TrySetException call is the correct behavior since the exception originated asynchronously.

Similarly, sites in SqlSequentialTextReader and SqlSequentialStream that call TrySetException and then rethrow were left unchanged — the fatal exception already propagates.

Testing

• Build verified on net8.0 (0 warnings, 0 errors)
• No new tests needed — this is a defensive guard that only affects behavior under fatal runtime conditions

[Copilot]

Pull request overview

This PR hardens async error-handling paths in Microsoft.Data.SqlClient by ensuring “fatal” exceptions (e.g., OutOfMemoryException, ThreadAbortException, etc.) are not silently converted into faulted Tasks via Task.FromException, aligning behavior with existing ADP.IsCatchableExceptionType patterns in the codebase.

Changes:

• Add an exception filter to SqlDataReader.InvokeAsyncCall to avoid wrapping non-catchable exceptions via Task.FromException<T>.
• Add an ADP.IsCatchableExceptionType guard in SqlBulkCopy before returning Task.FromException<bool>(ex) for async bulk copy.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlDataReader.cs	Adds an exception filter around Task.FromException<T>(ex) in InvokeAsyncCall.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlBulkCopy.cs	Adds a catchability guard before returning Task.FromException<bool>(ex) in the async bulk copy path.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

[codecov]

Codecov Report

❌ Patch coverage is 64.28571% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.06%. Comparing base (fdebcd2) to head (33de935).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...Client/src/Microsoft/Data/SqlClient/SqlBulkCopy.cs	72.72%	3 Missing ⚠️
.../src/Microsoft/Data/SqlClient/SqlCommand.Reader.cs	0.00%	1 Missing ⚠️
...ent/src/Microsoft/Data/SqlClient/SqlCommand.Xml.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4437      +/-   ##
==========================================
- Coverage   65.83%   64.06%   -1.78%     
==========================================
  Files         287      282       -5     
  Lines       43763    66661   +22898     
==========================================
+ Hits        28812    42704   +13892     
- Misses      14951    23957    +9006     

Flag	Coverage Δ
CI-SqlClient	?
PR-SqlClient-Project	64.06% <64.28%> (?)

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