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Python: Fix isSequence() and isMapping()

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This commit is contained in:
Rasmus Wriedt Larsen
2020-06-09 12:00:29 +02:00
parent 846101d295
commit bacd491875
2 changed files with 32 additions and 15 deletions
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33
python/ql/src/semmle/python/objects/ObjectAPI.qll
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@@ -517,7 +517,14 @@ class ClassValue extends Value {
/** Holds if this class is a container(). That is, does it have a __getitem__ method. */
predicate isContainer() { exists(this.lookup("__getitem__")) }
/** Holds if this class is probably a sequence. */
/**
* Holds if this class is a sequence. Mutually exclusive with `isMapping()`.
*
* Following the definition from
* https://docs.python.org/3/glossary.html#term-sequence.
* We don't look at the keys accepted by `__getitem__, but default to treating a class
* as a sequence (so might treat some mappings as sequences).
*/
predicate isSequence() {
/*
* To determine whether something is a sequence or a mapping is not entirely clear,
@@ -538,16 +545,26 @@ class ClassValue extends Value {
or
major_version() = 3 and this.getASuperType() = Value::named("collections.abc.Sequence")
or
/* Does it have an index or __reversed__ method? */
this.isContainer() and
(
this.hasAttribute("index") or
this.hasAttribute("__reversed__")
)
this.hasAttribute("__getitem__") and
this.hasAttribute("__len__") and
not this.getASuperType() = ClassValue::dict() and
not this.getASuperType() = Value::named("collections.Mapping") and
not this.getASuperType() = Value::named("collections.abc.Mapping")
}
/** Holds if this class is a mapping. */
/**
* Holds if this class is a mapping. Mutually exclusive with `isSequence()`.
*
* Although a class will satisfy the requirement by the definition in
* https://docs.python.org/3.8/glossary.html#term-mapping, we don't look at the keys
* accepted by `__getitem__, but default to treating a class as a sequence (so might
* treat some mappings as sequences).
*/
predicate isMapping() {
major_version() = 2 and this.getASuperType() = Value::named("collections.Mapping")
or
major_version() = 3 and this.getASuperType() = Value::named("collections.abc.Mapping")
or
this.hasAttribute("__getitem__") and
not this.isSequence()
}

14
python/ql/test/library-tests/PointsTo/class_properties/ClassValues.expected
View File

@@ -1,13 +1,13 @@
| mapping | class MySequenceImpl |
| mapping | builtin-class collections.OrderedDict |
| mapping | builtin-class collections.defaultdict |
| mapping | builtin-class dict |
| mapping | class MyDictSubclass |
| mapping | class MyMappingABC |
| mapping | class OrderedDict |
| neither sequence nor mapping | builtin-class set |
| sequence | builtin-class bytes |
| sequence | builtin-class collections.OrderedDict |
| sequence | builtin-class collections.defaultdict |
| sequence | builtin-class dict |
| sequence | builtin-class list |
| sequence | builtin-class str |
| sequence | builtin-class tuple |
| sequence | class MyDictSubclass |
| sequence | class MyMappingABC |
| sequence | class MySequenceABC |
| sequence | class OrderedDict |
| sequence | class MySequenceImpl |