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Simplify handling of wrapper classes and exception flow + improve qldoc and annotate tests.

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This commit is contained in:
Joe Farebrother
2025-03-20 09:52:56 +00:00
parent f8a0b1c5f9
commit b2acfbcf87
5 changed files with 38 additions and 34 deletions
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45
python/ql/src/Resources/FileNotAlwaysClosedQuery.qll
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@@ -24,17 +24,10 @@ private DataFlow::TypeTrackingNode fileOpenInstance(DataFlow::TypeTracker t) {
/** A call that returns an instance of an open file object. */
class FileOpen extends DataFlow::CallCfgNode {
FileOpen() { fileOpenInstance(DataFlow::TypeTracker::end()).flowsTo(this) }
/** Gets the local source of this file object, through any wrapper calls. */
FileOpen getLocalSource() {
if this instanceof FileWrapperCall
then result = this.(FileWrapperCall).getWrapped().getLocalSource()
else result = this
}
}
/** A call that may wrap a file object in a wrapper class or `os.fdopen`. */
class FileWrapperCall extends FileOpenSource, DataFlow::CallCfgNode {
class FileWrapperCall extends DataFlow::CallCfgNode {
FileOpen wrapped;
FileWrapperCall() {
@@ -53,14 +46,11 @@ class FileWrapperCall extends FileOpenSource, DataFlow::CallCfgNode {
abstract class FileClose extends DataFlow::CfgNode {
/** Holds if this file close will occur if an exception is thrown at `e`. */
predicate guardsExceptions(Expr e) {
exists(Try try |
e = try.getAStmt().getAChildNode*() and
(
this.asExpr() = try.getAHandler().getAChildNode*()
or
this.asExpr() = try.getAFinalstmt().getAChildNode*()
)
)
this.asCfgNode() =
DataFlow::exprNode(e).asCfgNode().getAnExceptionalSuccessor().getASuccessor*()
or
// the expression is after the close call
DataFlow::exprNode(e).asCfgNode() = this.asCfgNode().getASuccessor*()
}
}
@@ -95,8 +85,20 @@ private predicate mayRaiseWithFile(DataFlow::CfgNode node) {
not node instanceof FileClose
}
/** Holds if data flows from `nodeFrom` to `nodeTo` in one step that also includes file wrapper classes. */
private predicate fileLocalFlowStep(DataFlow::Node nodeFrom, DataFlow::Node nodeTo) {
DataFlow::localFlowStep(nodeFrom, nodeTo)
or
exists(FileWrapperCall fw | nodeFrom = fw.getWrapped() and nodeTo = fw)
}
/** Holds if data flows from `source` to `sink`, including file wrapper classes. */
private predicate fileLocalFlow(DataFlow::Node source, DataFlow::Node sink) {
fileLocalFlowStep*(source, sink)
}
/** Holds if the file opened at `fo` is closed. */
predicate fileIsClosed(FileOpen fo) { exists(FileClose fc | DataFlow::localFlow(fo, fc)) }
predicate fileIsClosed(FileOpen fo) { exists(FileClose fc | fileLocalFlow(fo, fc)) }
/** Holds if the file opened at `fo` is returned to the caller. This makes the caller responsible for closing the file. */
predicate fileIsReturned(FileOpen fo) {
@@ -108,27 +110,26 @@ predicate fileIsReturned(FileOpen fo) {
or
retVal = ret.getValue().(Tuple).getAnElt()
) and
DataFlow::localFlow(fo, DataFlow::exprNode(retVal))
fileLocalFlow(fo, DataFlow::exprNode(retVal))
)
}
/** Holds if the file opened at `fo` is stored in a field. We assume that another method is then responsible for closing the file. */
predicate fileIsStoredInField(FileOpen fo) {
exists(DataFlow::AttrWrite aw | DataFlow::localFlow(fo, aw.getValue()))
exists(DataFlow::AttrWrite aw | fileLocalFlow(fo, aw.getValue()))
}
/** Holds if the file opened at `fo` is not closed, and is expected to be closed. */
predicate fileNotClosed(FileOpen fo) {
not fileIsClosed(fo) and
not fileIsReturned(fo) and
not fileIsStoredInField(fo) and
not exists(FileWrapperCall fwc | fo = fwc.getWrapped())
not fileIsStoredInField(fo)
}
predicate fileMayNotBeClosedOnException(FileOpen fo, DataFlow::Node raises) {
fileIsClosed(fo) and
mayRaiseWithFile(raises) and
DataFlow::localFlow(fo, raises) and
fileLocalFlow(fo, raises) and
not exists(FileClose fc |
DataFlow::localFlow(fo, fc) and
fc.guardsExceptions(raises.asExpr())