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Address review comments

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This commit is contained in:
Owen Mansel-Chan
2021-03-22 14:25:09 +00:00
parent a5293fa835
commit 00aac808d2
3 changed files with 17 additions and 10 deletions
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8
ql/src/semmle/go/Expr.qll
View File

@@ -595,10 +595,10 @@ class SelectorExpr extends @selectorexpr, Expr {
/**
* A selector expression that refers to a promoted field. These selectors may implicitly
* address an embedded struct of their base type (e.g. the selector `x.field` may implicitly
* address `x.Embedded.field`). Note they may also explicitly address `field`; being a
* `PromotedFieldSelector` only indicates the addressed field may be promoted, not that it
* is promoted in this particular context.
* address an embedded struct of their base type - for example, the selector `x.field` may
* implicitly address `x.Embedded.field`). Note they may also explicitly address `field`;
* being a `PromotedFieldSelector` only indicates the addressed field may be promoted, not
* that it is promoted in this particular context.
*/
class PromotedFieldSelector extends SelectorExpr {
PromotedFieldSelector() { this.refersTo(any(PromotedField f)) }

9
ql/src/semmle/go/controlflow/ControlFlowGraphImpl.qll
View File

@@ -48,6 +48,13 @@ private predicate isCond(Expr e) {
e = any(ParenExpr par | isCond(par)).getExpr()
}
/**
* Holds if `e` implicitly reads the embedded field `implicitField`.
*
* The `index` is the distance from the promoted field. For example, if `A` contains an embedded
* field `B`, `B` contains an embedded field `C` and `C` contains the non-embedded field `x`.
* Then `a.x` implicitly reads `C` with index 1 and `B` with index 2.
*/
private predicate implicitFieldSelection(PromotedFieldSelector e, int index, Field implicitField) {
exists(StructType baseType, PromotedField child, int implicitFieldDepth |
baseType = e.getSelectedStructType() and
@@ -326,7 +333,7 @@ newtype TControlFlowNode =
* If that field has a pointer type then this control-flow node also
* represents an implicit dereference of it.
*/
MkImplicitFieldSelection(SelectorExpr e, int i, Field implicitField) {
MkImplicitFieldSelection(PromotedFieldSelector e, int i, Field implicitField) {
implicitFieldSelection(e, i, implicitField)
} or
/**

10
ql/src/semmle/go/controlflow/IR.qll
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@@ -243,8 +243,8 @@ module IR {
* and implicit field reads into account.
*
* For a selector expression `b.f`, this could be the implicit dereference `*b`, or the implicit
* field access `b.Embedded.f` if the field `f` is promoted from an embedded type `Embedded`, or
* a combination of both, or simply `b` if neither case applies.
* field access `b.Embedded` if the field `f` is promoted from an embedded type `Embedded`, or a
* combination of both `*(b.Embedded)`, or simply `b` if neither case applies.
*/
private Instruction selectorBase(Expr e) {
exists(ImplicitFieldReadInstruction fri | fri.getSelectorExpr() = e and fri.getIndex() = 1 |
@@ -305,7 +305,7 @@ module IR {
FieldReadInstruction() {
e = this.(EvalInstruction).getExpr() and
index = 0 and
field.getAReference() = this.(EvalInstruction).getExpr().(SelectorExpr).getSelector()
field.getAReference() = e.getSelector()
or
e = this.(ImplicitFieldReadInstruction).getSelectorExpr() and
index = this.(ImplicitFieldReadInstruction).getIndex() and
@@ -348,8 +348,8 @@ module IR {
* An IR instruction for an implicit field read as part of reading a
* promoted field.
*
* If that field has a pointer type then this instruction also represents an
* implicit dereference of it.
* If the field that is being implicitly read has a pointer type then this
* instruction represents an implicit dereference of it.
*/
class ImplicitFieldReadInstruction extends Instruction, MkImplicitFieldSelection {
SelectorExpr e;