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Merge pull request #3039 from BekaValentine/python-objectapi-to-valueapi-returnvalueignored

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Python: ObjectAPI to ValueAPI: ReturnValueIgnored
This commit is contained in:
Taus
2020-04-02 11:42:01 +02:00
committed by GitHub
parent 32cf0f14dc cc53b15a5d
commit d540bf6ce5
3 changed files with 18 additions and 8 deletions
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17
python/ql/src/Functions/ReturnValueIgnored.ql
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@@ -15,17 +15,18 @@
*/
import python
import semmle.python.objects.Callables
predicate meaningful_return_value(Expr val) {
val instanceof Name
or
val instanceof BooleanLiteral
or
exists(FunctionObject callee |
exists(FunctionValue callee |
val = callee.getACall().getNode() and returns_meaningful_value(callee)
)
or
not exists(FunctionObject callee | val = callee.getACall().getNode()) and not val instanceof Name
not exists(FunctionValue callee | val = callee.getACall().getNode()) and not val instanceof Name
}
/* Value is used before returning, and thus its value is not lost if ignored */
@@ -35,10 +36,10 @@ predicate used_value(Expr val) {
)
}
predicate returns_meaningful_value(FunctionObject f) {
not exists(f.getFunction().getFallthroughNode()) and
predicate returns_meaningful_value(FunctionValue f) {
not exists(f.getScope().getFallthroughNode()) and
(
exists(Return ret, Expr val | ret.getScope() = f.getFunction() and val = ret.getValue() |
exists(Return ret, Expr val | ret.getScope() = f.getScope() and val = ret.getValue() |
meaningful_return_value(val) and
not used_value(val)
)
@@ -48,7 +49,9 @@ predicate returns_meaningful_value(FunctionObject f) {
* Ignore __import__ as it is often called purely for side effects
*/
f.isC() and f.getAnInferredReturnType() != theNoneType() and not f.getName() = "__import__"
f.isBuiltin() and
f.getAnInferredReturnType() != ClassValue::nonetype() and
not f.getName() = "__import__"
)
}
@@ -61,7 +64,7 @@ predicate wrapped_in_try_except(ExprStmt call) {
)
}
from ExprStmt call, FunctionObject callee, float percentage_used, int total
from ExprStmt call, FunctionValue callee, float percentage_used, int total
where
call.getValue() = callee.getACall().getNode() and
returns_meaningful_value(callee) and

7
python/ql/src/semmle/python/objects/ObjectAPI.qll
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@@ -581,6 +581,13 @@ abstract class FunctionValue extends CallableValue {
exists(Expr expr, AstNode origin | expr.pointsTo(this, origin) | not origin instanceof Lambda)
)
}
/** Gets a class that this function may return */
ClassValue getAnInferredReturnType() {
result = TBuiltinClassObject(this.(BuiltinFunctionObjectInternal).getReturnType())
or
result = TBuiltinClassObject(this.(BuiltinMethodObjectInternal).getReturnType())
}
}
/** Class representing Python functions */

2
python/ql/test/query-tests/Functions/return_values/ReturnValueIgnored.expected
View File

@@ -1,3 +1,3 @@
| functions_test.py:159:5:159:9 | ExprStmt | Call discards return value of function $@. The result is used in 80% of calls. | functions_test.py:12:1:12:11 | Function ok2 | ok2 |
| functions_test.py:160:5:160:9 | ExprStmt | Call discards return value of function $@. The result is used in 80% of calls. | functions_test.py:36:1:36:11 | Function ok4 | ok4 |
| functions_test.py:161:5:161:17 | ExprStmt | Call discards return value of function $@. The result is used in 80% of calls. | file://:Compiled Code:0:0:0:0 | Builtin-function sorted | sorted |
| functions_test.py:161:5:161:17 | ExprStmt | Call discards return value of function $@. The result is used in 80% of calls. | file://:0:0:0:0 | Builtin-function sorted | sorted |