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Python: Add cursor::instance for PEP249

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For Peewee modeling I want to be able to define new cursor instances
just like I can do for connections.
This commit is contained in:
Rasmus Wriedt Larsen
2021-06-25 17:29:32 +02:00
parent 6be0db2c22
commit d8db83d081
1 changed files with 39 additions and 3 deletions
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42
python/ql/src/semmle/python/frameworks/internal/PEP249Impl.qll
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@@ -79,6 +79,31 @@ module PEP249 {
* See https://www.python.org/dev/peps/pep-0249/#cursor.
*/
module cursor {
/**
* A source of database cursors (following PEP 249), extend this class to model new instances.
*
* This can include instantiations of the class, return values from function
* calls, or a special parameter that will be set when functions are called by external
* libraries.
*
* Use the predicate `Connection::instance()` to get references database cursors (following PEP 249).
*
* Extend this class if the module implementing PEP 249 offers more direct ways to obtain
* a connection than going through `connect`.
*/
abstract class InstanceSource extends DataFlow::LocalSourceNode { }
/** Gets a reference to a database cursor. */
private DataFlow::LocalSourceNode instance(DataFlow::TypeTracker t) {
t.start() and
result instanceof InstanceSource
or
exists(DataFlow::TypeTracker t2 | result = instance(t2).track(t2, t))
}
/** Gets a reference to a database cursor. */
DataFlow::Node instance() { instance(DataFlow::TypeTracker::end()).flowsTo(result) }
/** Gets a reference to the `cursor` method on a database connection. */
private DataFlow::LocalSourceNode methodRef(DataFlow::TypeTracker t) {
t.startInAttr("cursor") and
@@ -90,6 +115,11 @@ module PEP249 {
/** Gets a reference to the `cursor` method on a database connection. */
DataFlow::Node methodRef() { methodRef(DataFlow::TypeTracker::end()).flowsTo(result) }
/** A call to the `cursor` method on a database connection */
private class CursorCall extends InstanceSource, DataFlow::CallCfgNode {
CursorCall() { this.getFunction() = methodRef() }
}
/** Gets a reference to a result of calling the `cursor` method on a database connection. */
private DataFlow::LocalSourceNode methodResult(DataFlow::TypeTracker t) {
t.start() and
@@ -98,8 +128,14 @@ module PEP249 {
exists(DataFlow::TypeTracker t2 | result = methodResult(t2).track(t2, t))
}
/** Gets a reference to a result of calling the `cursor` method on a database connection. */
DataFlow::Node methodResult() { methodResult(DataFlow::TypeTracker::end()).flowsTo(result) }
/**
* DEPRECATED: Use `Cursor::instance()` to get references to database cursors instead.
*
* Gets a reference to a result of calling the `cursor` method on a database connection.
*/
deprecated DataFlow::Node methodResult() {
methodResult(DataFlow::TypeTracker::end()).flowsTo(result)
}
}
/**
@@ -112,7 +148,7 @@ module PEP249 {
*/
private DataFlow::LocalSourceNode execute(DataFlow::TypeTracker t) {
t.startInAttr("execute") and
result in [cursor::methodResult(), Connection::instance()]
result in [cursor::instance(), Connection::instance()]
or
exists(DataFlow::TypeTracker t2 | result = execute(t2).track(t2, t))
}