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Microsoft ODBC Specification
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SQLCancel closing cursor during 'interrupted' SQLFetch/SQLFetchScroll #61

Closed matthew-wozniczka closed 7 years ago

matthew-wozniczka commented 7 years ago

Section 3.6 (Getting Data during Fetch) says that

Calling SQLCancel cancels the fetch operation and closes the cursor.

[after SQLFetch/SQLFetchScroll return SQL_DATA_AVAILABLE] (and presumably the same for SQL_METADATA_CHANGED/SQL_MORE_DATA).

Because SQLCancel does both synchronous and asynchronous cancellation, this behavior can cause a race condition: an application attempting an asynchronous cancellation of a call to SQLFetch/SQLFetchScroll may unintentionally end up doing a synchronous cancellation if that call happens to return 'too early', and thus unintentionally close the cursor.

Instead, perhaps we could allow SQLCloseCursor/SQLFreeStmt(SQL_CLOSE) to fulfill that purpose?

mikepizzo commented 7 years ago

Update spec to use SQLCloseCursor/SQLFreeStmt(SQL_CLOSE) for this.