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Python: Improve performance of FileNotClosed query by using an explicit fastTC #19411

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joefarebrother merged 1 commit into from
Apr 30, 2025
Merged

Python: Improve performance of FileNotClosed query by using an explicit fastTC #19411

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19 changes: 17 additions & 2 deletions python/ql/src/Resources/FileNotAlwaysClosedQuery.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -52,14 +52,29 @@ class FileWrapperCall extends DataFlow::CallCfgNode {
abstract class FileClose extends DataFlow::CfgNode {
/** Holds if this file close will occur if an exception is thrown at `raises`. */
predicate guardsExceptions(DataFlow::CfgNode raises) {
this.asCfgNode() = raises.asCfgNode().getAnExceptionalSuccessor().getASuccessor*()
cfgGetASuccessorStar(raises.asCfgNode().getAnExceptionalSuccessor(), this.asCfgNode())
or
// The expression is after the close call.
// This also covers the body of a `with` statement.
raises.asCfgNode() = this.asCfgNode().getASuccessor*()
cfgGetASuccessorStar(this.asCfgNode(), raises.asCfgNode())
}
}

private predicate cfgGetASuccessor(ControlFlowNode src, ControlFlowNode sink) {
sink = src.getASuccessor()
}

pragma[inline]
private predicate cfgGetASuccessorPlus(ControlFlowNode src, ControlFlowNode sink) =
fastTC(cfgGetASuccessor/2)(src, sink)

pragma[inline]
private predicate cfgGetASuccessorStar(ControlFlowNode src, ControlFlowNode sink) {
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Copilot AI Apr 29, 2025

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[nitpick] It may be helpful to add documentation clarifying the base condition 'src = sink' in cfgGetASuccessorStar to outline its role in implementing the transitive closure.

Suggested change
private predicate cfgGetASuccessorStar(ControlFlowNode src, ControlFlowNode sink) {
private predicate cfgGetASuccessorStar(ControlFlowNode src, ControlFlowNode sink) {
// Base condition: A node is always reachable from itself, ensuring reflexivity.

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src = sink
or
cfgGetASuccessorPlus(src, sink)
}

/** A call to the `.close()` method of a file object. */
class FileCloseCall extends FileClose {
FileCloseCall() { exists(DataFlow::MethodCallNode mc | mc.calls(this, "close")) }
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