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JS: fix FPs in UselessConditional

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Asger F
2018-12-13 15:26:36 +00:00
parent a4b3b1e8c8
commit ae4b55de9a
3 changed files with 22 additions and 5 deletions
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21
javascript/ql/src/Statements/UselessConditional.ql
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@@ -109,15 +109,26 @@ predicate whitelist(Expr e) {
/**
* Holds if `e` is part of a conditional node `cond` that evaluates
* `e` and checks its value for truthiness.
* `e` and checks its value for truthiness, and the return value of `e`
* is not used for anything other than this truthiness check.
*/
predicate isConditional(ASTNode cond, Expr e) {
predicate isExplicitConditional(ASTNode cond, Expr e) {
e = cond.(IfStmt).getCondition() or
e = cond.(LoopStmt).getTest() or
e = cond.(ConditionalExpr).getCondition() or
e = cond.(LogicalBinaryExpr).getLeftOperand() or
// Include `z` in `if (x && z)`.
isConditional(_, cond) and e = cond.(Expr).getUnderlyingValue().(LogicalBinaryExpr).getRightOperand()
isExplicitConditional(_, cond) and e = cond.(Expr).getUnderlyingValue().(LogicalBinaryExpr).getAnOperand()
}
/**
* Holds if `e` is part of a conditional node `cond` that evaluates
* `e` and checks its value for truthiness.
*
* The return value of `e` may have other uses besides the truthiness check,
* but if the truthiness check is always goes one way, it still indicates an error.
*/
predicate isConditional(ASTNode cond, Expr e) {
isExplicitConditional(cond, e) or
e = cond.(LogicalBinaryExpr).getLeftOperand()
}
from ASTNode cond, DataFlow::AnalyzedNode op, boolean cv, ASTNode sel, string msg