-
Notifications
You must be signed in to change notification settings - Fork 1.9k
Expand file tree
/
Copy pathFlow.qll
More file actions
1242 lines (1047 loc) · 41.3 KB
/
Flow.qll
File metadata and controls
1242 lines (1047 loc) · 41.3 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
overlay[local]
module;
import python
private import semmle.python.internal.CachedStages
private import codeql.controlflow.BasicBlock as BB
/*
* Note about matching parent and child nodes and CFG splitting:
*
* As a result of CFG splitting a single AST node may have multiple CFG nodes.
* Therefore, when matching CFG nodes to children, we need to make sure that
* we don't match the child of one CFG node to the wrong parent.
* We do this by checking dominance. If the CFG node for the parent precedes that of
* the child, then he child node matches the parent node if it is dominated by it.
* Vice versa for child nodes that precede the parent.
*/
private predicate augstore(ControlFlowNode load, ControlFlowNode store) {
exists(Expr load_store | exists(AugAssign aa | aa.getTarget() = load_store) |
toAst(load) = load_store and
toAst(store) = load_store and
load.strictlyDominates(store)
)
}
/** A non-dispatched getNode() to avoid negative recursion issues */
private AstNode toAst(ControlFlowNode n) { py_flow_bb_node(n, result, _, _) }
/**
* A control flow node. Control flow nodes have a many-to-one relation with syntactic nodes,
* although most syntactic nodes have only one corresponding control flow node.
* Edges between control flow nodes include exceptional as well as normal control flow.
*/
class ControlFlowNode extends @py_flow_node {
/** Whether this control flow node is a load (including those in augmented assignments) */
predicate isLoad() {
exists(Expr e | e = toAst(this) | py_expr_contexts(_, 3, e) and not augstore(_, this))
}
/** Whether this control flow node is a store (including those in augmented assignments) */
predicate isStore() {
exists(Expr e | e = toAst(this) | py_expr_contexts(_, 5, e) or augstore(_, this))
}
/** Whether this control flow node is a delete */
predicate isDelete() { exists(Expr e | e = toAst(this) | py_expr_contexts(_, 2, e)) }
/** Whether this control flow node is a parameter */
predicate isParameter() { exists(Expr e | e = toAst(this) | py_expr_contexts(_, 4, e)) }
/** Whether this control flow node is a store in an augmented assignment */
predicate isAugStore() { augstore(_, this) }
/** Whether this control flow node is a load in an augmented assignment */
predicate isAugLoad() { augstore(this, _) }
/** Whether this flow node corresponds to a literal */
predicate isLiteral() {
toAst(this) instanceof Bytes
or
toAst(this) instanceof Dict
or
toAst(this) instanceof DictComp
or
toAst(this) instanceof Set
or
toAst(this) instanceof SetComp
or
toAst(this) instanceof Ellipsis
or
toAst(this) instanceof GeneratorExp
or
toAst(this) instanceof Lambda
or
toAst(this) instanceof ListComp
or
toAst(this) instanceof List
or
toAst(this) instanceof Num
or
toAst(this) instanceof Tuple
or
toAst(this) instanceof Unicode
or
toAst(this) instanceof NameConstant
}
/** Whether this flow node corresponds to an attribute expression */
predicate isAttribute() { toAst(this) instanceof Attribute }
/** Whether this flow node corresponds to an subscript expression */
predicate isSubscript() { toAst(this) instanceof Subscript }
/** Whether this flow node corresponds to an import member */
predicate isImportMember() { toAst(this) instanceof ImportMember }
/** Whether this flow node corresponds to a call */
predicate isCall() { toAst(this) instanceof Call }
/** Whether this flow node is the first in a module */
predicate isModuleEntry() { this.isEntryNode() and toAst(this) instanceof Module }
/** Whether this flow node corresponds to an import */
predicate isImport() { toAst(this) instanceof ImportExpr }
/** Whether this flow node corresponds to a conditional expression */
predicate isIfExp() { toAst(this) instanceof IfExp }
/** Whether this flow node corresponds to a function definition expression */
predicate isFunction() { toAst(this) instanceof FunctionExpr }
/** Whether this flow node corresponds to a class definition expression */
predicate isClass() { toAst(this) instanceof ClassExpr }
/** Gets a predecessor of this flow node */
ControlFlowNode getAPredecessor() { this = result.getASuccessor() }
/** Gets a successor of this flow node */
ControlFlowNode getASuccessor() { py_successors(this, result) }
/** Gets the immediate dominator of this flow node */
ControlFlowNode getImmediateDominator() { py_idoms(this, result) }
/** Gets the syntactic element corresponding to this flow node */
AstNode getNode() { py_flow_bb_node(this, result, _, _) }
/** Gets a textual representation of this element. */
cached
string toString() {
Stages::AST::ref() and
// Since modules can have ambigous names, entry nodes can too, if we do not collate them.
exists(Scope s | s.getEntryNode() = this |
result = "Entry node for " + concat( | | s.toString(), ",")
)
or
exists(Scope s | s.getANormalExit() = this | result = "Exit node for " + s.toString())
or
not exists(Scope s | s.getEntryNode() = this or s.getANormalExit() = this) and
result = "ControlFlowNode for " + this.getNode().toString()
}
/** Gets the location of this ControlFlowNode */
Location getLocation() { result = this.getNode().getLocation() }
/** Whether this flow node is the first in its scope */
predicate isEntryNode() { py_scope_flow(this, _, -1) }
/** Gets the basic block containing this flow node */
BasicBlock getBasicBlock() { result.contains(this) }
/** Gets the scope containing this flow node */
cached
Scope getScope() {
Stages::AST::ref() and
if this.getNode() instanceof Scope
then
/* Entry or exit node */
result = this.getNode()
else result = this.getNode().getScope()
}
/** Gets the enclosing module */
Module getEnclosingModule() { result = this.getScope().getEnclosingModule() }
/** Gets a successor for this node if the relevant condition is True. */
ControlFlowNode getATrueSuccessor() {
result = this.getASuccessor() and
py_true_successors(this, result)
}
/** Gets a successor for this node if the relevant condition is False. */
ControlFlowNode getAFalseSuccessor() {
result = this.getASuccessor() and
py_false_successors(this, result)
}
/** Gets a successor for this node if an exception is raised. */
ControlFlowNode getAnExceptionalSuccessor() {
result = this.getASuccessor() and
py_exception_successors(this, result)
}
/** Gets a successor for this node if no exception is raised. */
ControlFlowNode getANormalSuccessor() {
result = this.getASuccessor() and
not py_exception_successors(this, result)
}
/** Whether the scope may be exited as a result of this node raising an exception */
predicate isExceptionalExit(Scope s) { py_scope_flow(this, s, 1) }
/** Whether this node is a normal (non-exceptional) exit */
predicate isNormalExit() { py_scope_flow(this, _, 0) or py_scope_flow(this, _, 2) }
/** Whether this strictly dominates other. */
overlay[caller]
pragma[inline]
predicate strictlyDominates(ControlFlowNode other) {
// This predicate is gigantic, so it must be inlined.
// About 1.4 billion tuples for OpenStack Cinder.
this.getBasicBlock().strictlyDominates(other.getBasicBlock())
or
exists(BasicBlock b, int i, int j | this = b.getNode(i) and other = b.getNode(j) and i < j)
}
/**
* Whether this dominates other.
* Note that all nodes dominate themselves.
*/
overlay[caller]
pragma[inline]
predicate dominates(ControlFlowNode other) {
// This predicate is gigantic, so it must be inlined.
this.getBasicBlock().strictlyDominates(other.getBasicBlock())
or
exists(BasicBlock b, int i, int j | this = b.getNode(i) and other = b.getNode(j) and i <= j)
}
/** Whether this strictly reaches other. */
overlay[caller]
pragma[inline]
predicate strictlyReaches(ControlFlowNode other) {
// This predicate is gigantic, even larger than strictlyDominates,
// so it must be inlined.
this.getBasicBlock().strictlyReaches(other.getBasicBlock())
or
exists(BasicBlock b, int i, int j | this = b.getNode(i) and other = b.getNode(j) and i < j)
}
/** Holds if this CFG node is a branch */
predicate isBranch() { py_true_successors(this, _) or py_false_successors(this, _) }
ControlFlowNode getAChild() { result = this.getExprChild(this.getBasicBlock()) }
/* join-ordering helper for `getAChild() */
pragma[noinline]
private ControlFlowNode getExprChild(BasicBlock dom) {
this.getNode().(Expr).getAChildNode() = result.getNode() and
result.getBasicBlock().dominates(dom) and
not this instanceof UnaryExprNode
}
}
/*
* This class exists to provide an implementation over ControlFlowNode.getNode()
* that subsumes all the others in an way that's obvious to the optimiser.
* This avoids wasting time on the trivial overrides on the ControlFlowNode subclasses.
*/
private class AnyNode extends ControlFlowNode {
override AstNode getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a call expression, such as `func(...)` */
class CallNode extends ControlFlowNode {
CallNode() { toAst(this) instanceof Call }
/** Gets the flow node corresponding to the function expression for the call corresponding to this flow node */
ControlFlowNode getFunction() {
exists(Call c |
this.getNode() = c and
c.getFunc() = result.getNode() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** Gets the flow node corresponding to the n'th positional argument of the call corresponding to this flow node */
ControlFlowNode getArg(int n) {
exists(Call c |
this.getNode() = c and
c.getArg(n) = result.getNode() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** Gets the flow node corresponding to the named argument of the call corresponding to this flow node */
ControlFlowNode getArgByName(string name) {
exists(Call c, Keyword k |
this.getNode() = c and
k = c.getANamedArg() and
k.getValue() = result.getNode() and
k.getArg() = name and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** Gets the flow node corresponding to an argument of the call corresponding to this flow node */
ControlFlowNode getAnArg() {
result = this.getArg(_)
or
result = this.getArgByName(_)
}
override Call getNode() { result = super.getNode() }
predicate isDecoratorCall() {
this.isClassDecoratorCall()
or
this.isFunctionDecoratorCall()
}
predicate isClassDecoratorCall() {
exists(ClassExpr cls | this.getNode() = cls.getADecoratorCall())
}
predicate isFunctionDecoratorCall() {
exists(FunctionExpr func | this.getNode() = func.getADecoratorCall())
}
/** Gets the first tuple (*) argument of this call, if any. */
ControlFlowNode getStarArg() {
result.getNode() = this.getNode().getStarArg() and
result.getBasicBlock().dominates(this.getBasicBlock())
}
/** Gets a dictionary (**) argument of this call, if any. */
ControlFlowNode getKwargs() {
result.getNode() = this.getNode().getKwargs() and
result.getBasicBlock().dominates(this.getBasicBlock())
}
}
/** A control flow corresponding to an attribute expression, such as `value.attr` */
class AttrNode extends ControlFlowNode {
AttrNode() { toAst(this) instanceof Attribute }
/** Gets the flow node corresponding to the object of the attribute expression corresponding to this flow node */
ControlFlowNode getObject() {
exists(Attribute a |
this.getNode() = a and
a.getObject() = result.getNode() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/**
* Gets the flow node corresponding to the object of the attribute expression corresponding to this flow node,
* with the matching name
*/
ControlFlowNode getObject(string name) {
exists(Attribute a |
this.getNode() = a and
a.getObject() = result.getNode() and
a.getName() = name and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** Gets the attribute name of the attribute expression corresponding to this flow node */
string getName() { exists(Attribute a | this.getNode() = a and a.getName() = result) }
override Attribute getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a `from ... import ...` expression */
class ImportMemberNode extends ControlFlowNode {
ImportMemberNode() { toAst(this) instanceof ImportMember }
/**
* Gets the flow node corresponding to the module in the import-member expression corresponding to this flow node,
* with the matching name
*/
ControlFlowNode getModule(string name) {
exists(ImportMember i | this.getNode() = i and i.getModule() = result.getNode() |
i.getName() = name and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
override ImportMember getNode() { result = super.getNode() }
}
/** A control flow node corresponding to an artificial expression representing an import */
class ImportExprNode extends ControlFlowNode {
ImportExprNode() { toAst(this) instanceof ImportExpr }
override ImportExpr getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a `from ... import *` statement */
class ImportStarNode extends ControlFlowNode {
ImportStarNode() { toAst(this) instanceof ImportStar }
/** Gets the flow node corresponding to the module in the import-star corresponding to this flow node */
ControlFlowNode getModule() {
exists(ImportStar i | this.getNode() = i and i.getModuleExpr() = result.getNode() |
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
override ImportStar getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a subscript expression, such as `value[slice]` */
class SubscriptNode extends ControlFlowNode {
SubscriptNode() { toAst(this) instanceof Subscript }
/** flow node corresponding to the value of the sequence in a subscript operation */
ControlFlowNode getObject() {
exists(Subscript s |
this.getNode() = s and
s.getObject() = result.getNode() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** flow node corresponding to the index in a subscript operation */
ControlFlowNode getIndex() {
exists(Subscript s |
this.getNode() = s and
s.getIndex() = result.getNode() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
override Subscript getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a comparison operation, such as `x<y` */
class CompareNode extends ControlFlowNode {
CompareNode() { toAst(this) instanceof Compare }
/** Whether left and right are a pair of operands for this comparison */
predicate operands(ControlFlowNode left, Cmpop op, ControlFlowNode right) {
exists(Compare c, Expr eleft, Expr eright |
this.getNode() = c and left.getNode() = eleft and right.getNode() = eright
|
eleft = c.getLeft() and eright = c.getComparator(0) and op = c.getOp(0)
or
exists(int i |
eleft = c.getComparator(i - 1) and eright = c.getComparator(i) and op = c.getOp(i)
)
) and
left.getBasicBlock().dominates(this.getBasicBlock()) and
right.getBasicBlock().dominates(this.getBasicBlock())
}
override Compare getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a conditional expression such as, `body if test else orelse` */
class IfExprNode extends ControlFlowNode {
IfExprNode() { toAst(this) instanceof IfExp }
/** flow node corresponding to one of the operands of an if-expression */
ControlFlowNode getAnOperand() { result = this.getAPredecessor() }
override IfExp getNode() { result = super.getNode() }
}
/** A control flow node corresponding to an assignment expression such as `lhs := rhs`. */
class AssignmentExprNode extends ControlFlowNode {
AssignmentExprNode() { toAst(this) instanceof AssignExpr }
/** Gets the flow node corresponding to the left-hand side of the assignment expression */
ControlFlowNode getTarget() {
exists(AssignExpr a |
this.getNode() = a and
a.getTarget() = result.getNode() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** Gets the flow node corresponding to the right-hand side of the assignment expression */
ControlFlowNode getValue() {
exists(AssignExpr a |
this.getNode() = a and
a.getValue() = result.getNode() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
override AssignExpr getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a binary expression, such as `x + y` */
class BinaryExprNode extends ControlFlowNode {
BinaryExprNode() { toAst(this) instanceof BinaryExpr }
/** flow node corresponding to one of the operands of a binary expression */
ControlFlowNode getAnOperand() { result = this.getLeft() or result = this.getRight() }
override BinaryExpr getNode() { result = super.getNode() }
ControlFlowNode getLeft() {
exists(BinaryExpr b |
this.getNode() = b and
result.getNode() = b.getLeft() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
ControlFlowNode getRight() {
exists(BinaryExpr b |
this.getNode() = b and
result.getNode() = b.getRight() and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** Gets the operator of this binary expression node. */
Operator getOp() { result = this.getNode().getOp() }
/** Whether left and right are a pair of operands for this binary expression */
predicate operands(ControlFlowNode left, Operator op, ControlFlowNode right) {
exists(BinaryExpr b, Expr eleft, Expr eright |
this.getNode() = b and left.getNode() = eleft and right.getNode() = eright
|
eleft = b.getLeft() and eright = b.getRight() and op = b.getOp()
) and
left.getBasicBlock().dominates(this.getBasicBlock()) and
right.getBasicBlock().dominates(this.getBasicBlock())
}
}
/** A control flow node corresponding to a boolean shortcut (and/or) operation */
class BoolExprNode extends ControlFlowNode {
BoolExprNode() { toAst(this) instanceof BoolExpr }
/** flow node corresponding to one of the operands of a boolean expression */
ControlFlowNode getAnOperand() {
exists(BoolExpr b | this.getNode() = b and result.getNode() = b.getAValue()) and
this.getBasicBlock().dominates(result.getBasicBlock())
}
override BoolExpr getNode() { result = super.getNode() }
}
/** A control flow node corresponding to a unary expression: (`+x`), (`-x`) or (`~x`) */
class UnaryExprNode extends ControlFlowNode {
UnaryExprNode() { toAst(this) instanceof UnaryExpr }
/**
* Gets flow node corresponding to the operand of a unary expression.
* Note that this might not be the flow node for the AST operand.
* In `not (a or b)` the AST operand is `(a or b)`, but as `a or b` is
* a short-circuiting operation, there will be two `not` CFG nodes, one will
* have `a` or `b` as it operand, the other will have just `b`.
*/
ControlFlowNode getOperand() { result = this.getAPredecessor() }
override UnaryExpr getNode() { result = super.getNode() }
override ControlFlowNode getAChild() { result = this.getAPredecessor() }
}
/**
* A control flow node corresponding to a definition, that is a control flow node
* where a value is assigned to this node.
* Includes control flow nodes for the targets of assignments, simple or augmented,
* and nodes implicitly assigned in class and function definitions and imports.
*/
class DefinitionNode extends ControlFlowNode {
cached
DefinitionNode() {
Stages::AST::ref() and
exists(Assign a | a.getATarget().getAFlowNode() = this)
or
exists(AssignExpr a | a.getTarget().getAFlowNode() = this)
or
exists(AnnAssign a | a.getTarget().getAFlowNode() = this and exists(a.getValue()))
or
exists(Alias a | a.getAsname().getAFlowNode() = this)
or
augstore(_, this)
or
// `x, y = 1, 2` where LHS is a combination of list or tuples
exists(Assign a | list_or_tuple_nested_element(a.getATarget()).getAFlowNode() = this)
or
exists(For for | for.getTarget().getAFlowNode() = this)
or
exists(Parameter param | this = param.asName().getAFlowNode() and exists(param.getDefault()))
}
/** flow node corresponding to the value assigned for the definition corresponding to this flow node */
ControlFlowNode getValue() {
result = assigned_value(this.getNode()).getAFlowNode() and
(
result.getBasicBlock().dominates(this.getBasicBlock())
or
result.isImport()
or
// since the default value for a parameter is evaluated in the same basic block as
// the function definition, but the parameter belongs to the basic block of the function,
// there is no dominance relationship between the two.
exists(Parameter param | this = param.asName().getAFlowNode())
)
}
}
private Expr list_or_tuple_nested_element(Expr list_or_tuple) {
exists(Expr elt |
elt = list_or_tuple.(Tuple).getAnElt()
or
elt = list_or_tuple.(List).getAnElt()
|
result = elt
or
result = list_or_tuple_nested_element(elt)
)
}
/**
* A control flow node corresponding to a deletion statement, such as `del x`.
* There can be multiple `DeletionNode`s for each `Delete` such that each
* target has own `DeletionNode`. The CFG for `del a, x.y` looks like:
* `NameNode('a') -> DeletionNode -> NameNode('b') -> AttrNode('y') -> DeletionNode`.
*/
class DeletionNode extends ControlFlowNode {
DeletionNode() { toAst(this) instanceof Delete }
/** Gets the unique target of this deletion node. */
ControlFlowNode getTarget() { result.getASuccessor() = this }
}
/** A control flow node corresponding to a sequence (tuple or list) literal */
abstract class SequenceNode extends ControlFlowNode {
SequenceNode() {
toAst(this) instanceof Tuple
or
toAst(this) instanceof List
}
/** Gets the control flow node for an element of this sequence */
ControlFlowNode getAnElement() { result = this.getElement(_) }
/** Gets the control flow node for the nth element of this sequence */
cached
abstract ControlFlowNode getElement(int n);
}
/** A control flow node corresponding to a tuple expression such as `( 1, 3, 5, 7, 9 )` */
class TupleNode extends SequenceNode {
TupleNode() { toAst(this) instanceof Tuple }
override ControlFlowNode getElement(int n) {
Stages::AST::ref() and
exists(Tuple t | this.getNode() = t and result.getNode() = t.getElt(n)) and
(
result.getBasicBlock().dominates(this.getBasicBlock())
or
this.getBasicBlock().dominates(result.getBasicBlock())
)
}
}
/** A control flow node corresponding to a list expression, such as `[ 1, 3, 5, 7, 9 ]` */
class ListNode extends SequenceNode {
ListNode() { toAst(this) instanceof List }
override ControlFlowNode getElement(int n) {
exists(List l | this.getNode() = l and result.getNode() = l.getElt(n)) and
(
result.getBasicBlock().dominates(this.getBasicBlock())
or
this.getBasicBlock().dominates(result.getBasicBlock())
)
}
}
/** A control flow node corresponding to a set expression, such as `{ 1, 3, 5, 7, 9 }` */
class SetNode extends ControlFlowNode {
SetNode() { toAst(this) instanceof Set }
ControlFlowNode getAnElement() {
exists(Set s | this.getNode() = s and result.getNode() = s.getElt(_)) and
(
result.getBasicBlock().dominates(this.getBasicBlock())
or
this.getBasicBlock().dominates(result.getBasicBlock())
)
}
}
/** A control flow node corresponding to a dictionary literal, such as `{ 'a': 1, 'b': 2 }` */
class DictNode extends ControlFlowNode {
DictNode() { toAst(this) instanceof Dict }
/**
* Gets a key of this dictionary literal node, for those items that have keys
* E.g, in {'a':1, **b} this returns only 'a'
*/
ControlFlowNode getAKey() {
exists(Dict d | this.getNode() = d and result.getNode() = d.getAKey()) and
result.getBasicBlock().dominates(this.getBasicBlock())
}
/** Gets a value of this dictionary literal node */
ControlFlowNode getAValue() {
exists(Dict d | this.getNode() = d and result.getNode() = d.getAValue()) and
result.getBasicBlock().dominates(this.getBasicBlock())
}
}
/**
* A control flow node corresponding to an iterable literal. Currently does not include
* dictionaries, use `DictNode` directly instead.
*/
class IterableNode extends ControlFlowNode {
IterableNode() {
this instanceof SequenceNode
or
this instanceof SetNode
}
/** Gets the control flow node for an element of this iterable. */
ControlFlowNode getAnElement() {
result = this.(SequenceNode).getAnElement()
or
result = this.(SetNode).getAnElement()
}
}
private AstNode assigned_value(Expr lhs) {
/* lhs = result */
exists(Assign a | a.getATarget() = lhs and result = a.getValue())
or
/* lhs := result */
exists(AssignExpr a | a.getTarget() = lhs and result = a.getValue())
or
/* lhs : annotation = result */
exists(AnnAssign a | a.getTarget() = lhs and result = a.getValue())
or
/* import result as lhs */
exists(Alias a | a.getAsname() = lhs and result = a.getValue())
or
/* lhs += x => result = (lhs + x) */
exists(AugAssign a, BinaryExpr b | b = a.getOperation() and result = b and lhs = b.getLeft())
or
/*
* ..., lhs, ... = ..., result, ...
* or
* ..., (..., lhs, ...), ... = ..., (..., result, ...), ...
*/
exists(Assign a | nested_sequence_assign(a.getATarget(), a.getValue(), lhs, result))
or
/* for lhs in seq: => `result` is the `for` node, representing the `iter(next(seq))` operation. */
result.(For).getTarget() = lhs
or
exists(Parameter param | lhs = param.asName() and result = param.getDefault())
}
predicate nested_sequence_assign(
Expr left_parent, Expr right_parent, Expr left_result, Expr right_result
) {
exists(Assign a |
a.getATarget().getASubExpression*() = left_parent and
a.getValue().getASubExpression*() = right_parent
) and
exists(int i, Expr left_elem, Expr right_elem |
(
left_elem = left_parent.(Tuple).getElt(i)
or
left_elem = left_parent.(List).getElt(i)
) and
(
right_elem = right_parent.(Tuple).getElt(i)
or
right_elem = right_parent.(List).getElt(i)
)
|
left_result = left_elem and right_result = right_elem
or
nested_sequence_assign(left_elem, right_elem, left_result, right_result)
)
}
/** A flow node for a `for` statement. */
class ForNode extends ControlFlowNode {
ForNode() { toAst(this) instanceof For }
override For getNode() { result = super.getNode() }
/** Holds if this `for` statement causes iteration over `sequence` storing each step of the iteration in `target` */
predicate iterates(ControlFlowNode target, ControlFlowNode sequence) {
sequence = this.getSequence() and
target = this.possibleTarget() and
not target = this.unrolledSuffix().possibleTarget()
}
/** Gets the sequence node for this `for` statement. */
ControlFlowNode getSequence() {
exists(For for |
toAst(this) = for and
for.getIter() = result.getNode()
|
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
/** A possible `target` for this `for` statement, not accounting for loop unrolling */
private ControlFlowNode possibleTarget() {
exists(For for |
toAst(this) = for and
for.getTarget() = result.getNode() and
this.getBasicBlock().dominates(result.getBasicBlock())
)
}
/** The unrolled `for` statement node matching this one */
private ForNode unrolledSuffix() {
not this = result and
toAst(this) = toAst(result) and
this.getBasicBlock().dominates(result.getBasicBlock())
}
}
/** A flow node for a `raise` statement */
class RaiseStmtNode extends ControlFlowNode {
RaiseStmtNode() { toAst(this) instanceof Raise }
/** Gets the control flow node for the exception raised by this raise statement */
ControlFlowNode getException() {
exists(Raise r |
r = toAst(this) and
r.getException() = toAst(result) and
result.getBasicBlock().dominates(this.getBasicBlock())
)
}
}
/**
* A control flow node corresponding to a (plain variable) name expression, such as `var`.
* `None`, `True` and `False` are excluded.
*/
class NameNode extends ControlFlowNode {
NameNode() {
exists(Name n | py_flow_bb_node(this, n, _, _))
or
exists(PlaceHolder p | py_flow_bb_node(this, p, _, _))
}
/** Whether this flow node defines the variable `v`. */
predicate defines(Variable v) {
exists(Name d | this.getNode() = d and d.defines(v)) and
not this.isLoad()
}
/** Whether this flow node deletes the variable `v`. */
predicate deletes(Variable v) { exists(Name d | this.getNode() = d and d.deletes(v)) }
/** Whether this flow node uses the variable `v`. */
predicate uses(Variable v) {
this.isLoad() and
exists(Name u | this.getNode() = u and u.uses(v))
or
exists(PlaceHolder u |
this.getNode() = u and u.getVariable() = v and u.getCtx() instanceof Load
)
or
Scopes::use_of_global_variable(this, v.getScope(), v.getId())
}
string getId() {
result = this.getNode().(Name).getId()
or
result = this.getNode().(PlaceHolder).getId()
}
/** Whether this is a use of a local variable. */
predicate isLocal() { Scopes::local(this) }
/** Whether this is a use of a non-local variable. */
predicate isNonLocal() { Scopes::non_local(this) }
/** Whether this is a use of a global (including builtin) variable. */
predicate isGlobal() { Scopes::use_of_global_variable(this, _, _) }
predicate isSelf() { exists(SsaVariable selfvar | selfvar.isSelf() and selfvar.getAUse() = this) }
}
/** A control flow node corresponding to a named constant, one of `None`, `True` or `False`. */
class NameConstantNode extends NameNode {
NameConstantNode() { exists(NameConstant n | py_flow_bb_node(this, n, _, _)) }
/*
* We ought to override uses as well, but that has
* a serious performance impact.
* deprecated predicate uses(Variable v) { none() }
*/
}
/** A control flow node corresponding to a starred expression, `*a`. */
class StarredNode extends ControlFlowNode {
StarredNode() { toAst(this) instanceof Starred }
ControlFlowNode getValue() { toAst(result) = toAst(this).(Starred).getValue() }
}
/** The ControlFlowNode for an 'except' statement. */
class ExceptFlowNode extends ControlFlowNode {
ExceptFlowNode() { this.getNode() instanceof ExceptStmt }
/**
* Gets the type handled by this exception handler.
* `ExceptionType` in `except ExceptionType as e:`
*/
ControlFlowNode getType() {
exists(ExceptStmt ex |
this.getBasicBlock().dominates(result.getBasicBlock()) and
ex = this.getNode() and
result = ex.getType().getAFlowNode()
)
}
/**
* Gets the name assigned to the handled exception, if any.
* `e` in `except ExceptionType as e:`
*/
ControlFlowNode getName() {
exists(ExceptStmt ex |
this.getBasicBlock().dominates(result.getBasicBlock()) and
ex = this.getNode() and
result = ex.getName().getAFlowNode()
)
}
}
/** The ControlFlowNode for an 'except*' statement. */
class ExceptGroupFlowNode extends ControlFlowNode {
ExceptGroupFlowNode() { this.getNode() instanceof ExceptGroupStmt }
/**
* Gets the type handled by this exception handler.
* `ExceptionType` in `except* ExceptionType as e:`
*/
ControlFlowNode getType() {
this.getBasicBlock().dominates(result.getBasicBlock()) and
result = this.getNode().(ExceptGroupStmt).getType().getAFlowNode()
}
/**
* Gets the name assigned to the handled exception, if any.
* `e` in `except* ExceptionType as e:`
*/
ControlFlowNode getName() {
this.getBasicBlock().dominates(result.getBasicBlock()) and
result = this.getNode().(ExceptGroupStmt).getName().getAFlowNode()
}
}
private module Scopes {
private predicate fast_local(NameNode n) {
exists(FastLocalVariable v |
n.uses(v) and
v.getScope() = n.getScope()
)
}
predicate local(NameNode n) {
fast_local(n)
or
exists(SsaVariable var |
var.getAUse() = n and
n.getScope() instanceof Class and
exists(var.getDefinition())
)
}
predicate non_local(NameNode n) {
exists(FastLocalVariable flv |
flv.getALoad() = n.getNode() and
not flv.getScope() = n.getScope()
)
}
// magic is fine, but we get questionable join-ordering of it
pragma[nomagic]
predicate use_of_global_variable(NameNode n, Module scope, string name) {
n.isLoad() and
not non_local(n) and
not exists(SsaVariable var | var.getAUse() = n |
var.getVariable() instanceof FastLocalVariable
or
n.getScope() instanceof Class and
not maybe_undefined(var)
) and
name = n.getId() and
scope = n.getEnclosingModule()
}
private predicate maybe_undefined(SsaVariable var) {
not exists(var.getDefinition()) and not py_ssa_phi(var, _)
or
var.getDefinition().isDelete()
or
maybe_undefined(var.getAPhiInput())
or
exists(BasicBlock incoming |
exists(var.getAPhiInput()) and
incoming.getASuccessor() = var.getDefinition().getBasicBlock() and
not var.getAPhiInput().getDefinition().getBasicBlock().dominates(incoming)
)
}
}
/** A basic block (ignoring exceptional flow edges to scope exit) */
class BasicBlock extends @py_flow_node {