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PS: Fixup CFG after the introduction of variables into the AST.

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Mathias Vorreiter Pedersen
2024-09-12 17:34:09 +01:00
parent 810978d3ab
commit 9107075f41
1 changed files with 22 additions and 25 deletions
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47
powershell/ql/lib/semmle/code/powershell/controlflow/internal/ControlFlowGraphImpl.qll
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@@ -76,23 +76,10 @@ predicate succExit(CfgScope scope, Ast last, Completion c) { scope.exit(last, c)
/** Defines the CFG by dispatch on the various AST types. */
module Trees {
class NonDefaultParameterTree extends LeafTree instanceof Parameter {
NonDefaultParameterTree() { not exists(super.getDefaultValue()) }
}
class DefaultParameterTree extends StandardPostOrderTree instanceof Parameter {
DefaultParameterTree() { exists(super.getDefaultValue()) }
override AstNode getChildNode(int i) {
i = 0 and
result = super.getDefaultValue()
}
final override predicate propagatesAbnormal(AstNode child) { child = super.getDefaultValue() }
}
class ParameterBlockTree extends StandardPostOrderTree instanceof ParamBlock {
override AstNode getChildNode(int i) { result = super.getParameter(i) }
override AstNode getChildNode(int i) {
exists(Parameter p | p = super.getParameter(i) | result = p.getDefaultValue())
}
}
abstract class ScriptBlockTree extends ControlFlowTree instanceof ScriptBlock {
@@ -185,21 +172,31 @@ module Trees {
FunctionScriptBlockTree() { func.getBody() = this }
AstNode getParameter(int i) { result = func.getFunctionParameter(i) }
Expr getDefaultValue(int i) {
exists(Parameter p |
p =
rank[i + 1](Parameter cand, int j |
cand.hasDefaultValue() and j = cand.getIndex()
|
cand order by j
) and
result = p.getDefaultValue()
)
}
int getNumberOfParameters() { result = func.getNumberOfFunctionParameters() }
int getNumberOfDefaultValues() { result = count(int i | exists(this.getDefaultValue(i))) }
override predicate succ(AstNode pred, AstNode succ, Completion c) {
// Step to the first parameter
pred = this and
first(this.getParameter(0), succ) and
first(this.getDefaultValue(0), succ) and
completionIsSimple(c)
or
// Step to the next parameter
exists(int i |
last(this.getParameter(i), pred, c) and
last(this.getDefaultValue(i), pred, c) and
completionIsNormal(c) and
first(this.getParameter(i + 1), succ)
first(this.getDefaultValue(i + 1), succ)
)
or
// Body steps
@@ -208,12 +205,12 @@ module Trees {
final override predicate succEntry(AstNode n, Completion c) {
// If there are no paramters we enter the body directly
not exists(this.getParameter(0)) and
not exists(this.getDefaultValue(_)) and
n = this and
completionIsSimple(c)
or
// Once we are done with the last parameter we enter the body
last(this.getParameter(this.getNumberOfParameters() - 1), n, c) and
last(this.getDefaultValue(this.getNumberOfDefaultValues() - 1), n, c) and
completionIsNormal(c)
}
}
@@ -380,11 +377,11 @@ module Trees {
or
// Emptiness test to variable declaration
pred = this and
first(super.getVariable(), succ) and
first(super.getVarAccess(), succ) and
completionIsSimple(c)
or
// Variable declaration to body
last(super.getVariable(), succ, c) and
last(super.getVarAccess(), succ, c) and
completionIsNormal(c) and
first(this.getBody(), succ)
or