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package io.joern.pysrc2cpg
import io.joern.pysrc2cpg.ContextStack.transferLineColInfo
import io.joern.pysrc2cpg.memop._
import io.shiftleft.codepropertygraph.generated.nodes
import io.shiftleft.codepropertygraph.generated.nodes._
import org.slf4j.LoggerFactory
import scala.collection.mutable
object ContextStack {
private val logger = LoggerFactory.getLogger(getClass)
def transferLineColInfo(src: NewIdentifier, tgt: NewLocal): Unit = {
src.lineNumber match {
// If there are multiple occurrences and the local is already set, ignore later updates
case Some(srcLineNo) if tgt.lineNumber.isEmpty || !tgt.lineNumber.exists(_ < srcLineNo) =>
tgt.lineNumber(src.lineNumber)
tgt.columnNumber(src.columnNumber)
case _ =>
}
}
}
class ContextStack {
import ContextStack.logger
private trait Context {
val astParent: nodes.NewNode
val order: AutoIncIndex
val variables: mutable.Map[String, nodes.NewNode]
var lambdaCounter: Int
}
private class MethodContext(
val scopeName: Option[String],
val astParent: nodes.NewNode,
val order: AutoIncIndex,
val isClassBodyMethod: Boolean = false,
val methodBlockNode: Option[nodes.NewBlock] = None,
val methodRefNode: Option[nodes.NewMethodRef] = None,
val variables: mutable.Map[String, nodes.NewNode] = mutable.Map.empty,
val globalVariables: mutable.Set[String] = mutable.Set.empty,
val nonLocalVariables: mutable.Set[String] = mutable.Set.empty,
var lambdaCounter: Int = 0
) extends Context {}
private class ClassContext(
val scopeName: Option[String],
val astParent: nodes.NewNode,
val order: AutoIncIndex,
val variables: mutable.Map[String, nodes.NewNode] = mutable.Map.empty,
var lambdaCounter: Int = 0
) extends Context {}
// Used to represent comprehension variable and exception
// handler context.
// E.g.: [x for x in y] creates an extra context with a
// local variable x which is different from a possible x
// in the surrounding method context. The same applies
// to x in:
// try:
// pass
// except e as x:
// pass
private class SpecialBlockContext(
val astParent: nodes.NewNode,
val order: AutoIncIndex,
val variables: mutable.Map[String, nodes.NewNode] = mutable.Map.empty,
var lambdaCounter: Int = 0
) extends Context {}
private case class VariableReference(
identifier: nodes.NewIdentifier,
memOp: MemoryOperation,
// Context stack as it was when VariableReference
// was created. Context objects are and need to
// shared between different VariableReference
// instances because the changes in the variable
// maps need to be in sync.
stack: List[Context]
)
private var stack = List[Context]()
private val variableReferences = mutable.ArrayBuffer.empty[VariableReference]
private var moduleMethodContext = Option.empty[MethodContext]
private var fileNamespaceBlock = Option.empty[nodes.NewNamespaceBlock]
private val fileNamespaceBlockOrder = new AutoIncIndex(1)
private def push(context: Context): Unit = {
stack = context :: stack
}
def pushMethod(
scopeName: Option[String],
methodNode: nodes.NewMethod,
methodBlockNode: nodes.NewBlock,
methodRefNode: Option[nodes.NewMethodRef]
): Unit = {
val isClassBodyMethod = stack.headOption.exists(_.isInstanceOf[ClassContext])
val methodContext =
new MethodContext(
scopeName,
methodNode,
new AutoIncIndex(1),
isClassBodyMethod,
Some(methodBlockNode),
methodRefNode
)
if (moduleMethodContext.isEmpty) {
moduleMethodContext = Some(methodContext)
}
push(methodContext)
}
def pushClass(scopeName: Option[String], classNode: nodes.NewTypeDecl): Unit = {
push(new ClassContext(scopeName, classNode, new AutoIncIndex(1)))
}
def pushSpecialContext(): Unit = {
val methodContext = findEnclosingMethodContext(stack)
push(new SpecialBlockContext(methodContext.astParent, methodContext.order))
}
def pop(): Unit = {
stack = stack.tail
}
def setFileNamespaceBlock(namespaceBlock: nodes.NewNamespaceBlock): Unit = {
fileNamespaceBlock = Some(namespaceBlock)
}
def addVariableReference(identifier: nodes.NewIdentifier, memOp: MemoryOperation): Unit = {
variableReferences.append(VariableReference(identifier, memOp, stack))
}
def getAndIncLambdaCounter(): Int = {
val result = stack.head.lambdaCounter
stack.head.lambdaCounter += 1
result
}
private def findEnclosingMethodContext(contextStack: List[Context]): MethodContext = {
contextStack.find(_.isInstanceOf[MethodContext]).get.asInstanceOf[MethodContext]
}
def findEnclosingTypeDecl(): Option[NewNode] = {
stack.find(_.isInstanceOf[ClassContext]) match {
case Some(classContext: ClassContext) =>
Some(classContext.astParent)
case _ => None
}
}
def createIdentifierLinks(
createLocal: (String, Option[String]) => nodes.NewLocal,
createClosureBinding: (String, String) => nodes.NewClosureBinding,
createAstEdge: (nodes.NewNode, nodes.NewNode, Int) => Unit,
createRefEdge: (nodes.NewNode, nodes.NewNode) => Unit,
createCaptureEdge: (nodes.NewNode, nodes.NewNode) => Unit
): Unit = {
// Before we do any linking, we iterate over all variable references and
// create a variable in the module method context for each global variable
// with a store operation on it.
// This is necessary because there might be load/delete operations
// referencing the global variable which are syntactically before the store
// operations.
variableReferences.foreach { case VariableReference(identifier, memOp, contextStack) =>
val name = identifier.name
if (
memOp == Store &&
findEnclosingMethodContext(contextStack).globalVariables.contains(name) &&
!moduleMethodContext.get.variables.contains(name)
) {
val localNode = createLocal(name, None)
transferLineColInfo(identifier, localNode)
createAstEdge(localNode, moduleMethodContext.get.methodBlockNode.get, moduleMethodContext.get.order.getAndInc)
moduleMethodContext.get.variables.put(name, localNode)
}
}
// Variable references processing needs to be ordered by context depth in
// order to make sure that variables captured into deeper nested contexts
// are already created.
val sortedVariableRefs = variableReferences.sortBy(_.stack.size)
sortedVariableRefs.foreach { case VariableReference(identifier, memOp, contextStack) =>
val name = identifier.name
// Store and delete operations look up variable only in method scope.
// Load operations also look up captured or global variables.
// If a store and load/del happens in the same context, the store must
// come first. Otherwise it is not valid Python, which we assume here.
if (memOp == Load) {
linkLocalOrCapturing(
createLocal,
createClosureBinding,
createAstEdge,
createRefEdge,
createCaptureEdge,
identifier,
name,
contextStack
)
} else {
val enclosingMethodContext = findEnclosingMethodContext(contextStack)
if (
enclosingMethodContext.globalVariables.contains(name) ||
enclosingMethodContext.nonLocalVariables.contains(name)
) {
linkLocalOrCapturing(
createLocal,
createClosureBinding,
createAstEdge,
createRefEdge,
createCaptureEdge,
identifier,
name,
contextStack
)
} else if (memOp == Store) {
var variableNode = lookupVariableInMethod(name, contextStack)
if (variableNode.isEmpty) {
val localNode = createLocal(name, None)
transferLineColInfo(identifier, localNode)
val enclosingMethodContext = findEnclosingMethodContext(contextStack)
createAstEdge(localNode, enclosingMethodContext.methodBlockNode.get, enclosingMethodContext.order.getAndInc)
enclosingMethodContext.variables.put(name, localNode)
variableNode = Some(localNode)
}
createRefEdge(variableNode.get, identifier)
} else if (memOp == Del) {
val variableNode = lookupVariableInMethod(name, contextStack)
variableNode match {
case Some(variableNode) =>
createRefEdge(variableNode, identifier)
case None =>
logger.warn("Unable to link identifier. Resulting CPG will have invalid format.")
}
}
}
}
}
/** Assignments to variables on the module-level may be exported to other modules and behave as inter-procedurally
* global variables.
* @param lhs
* the LHS node of an assignment
*/
def considerAsGlobalVariable(lhs: NewNode): Unit = {
lhs match {
case n: NewIdentifier if findEnclosingMethodContext(stack).scopeName.contains("") =>
addGlobalVariable(n.name)
case _ =>
}
}
/** For module-methods, the variables of this method can be imported into other modules which resembles behaviour much
* like fields/members. This inter-procedural accessibility should be marked via the module's type decl node.
*/
def createMemberLinks(moduleTypeDecl: NewTypeDecl, astEdgeLinker: (NewNode, NewNode, Int) => Unit): Unit = {
val globalVarsForEnclMethod = findEnclosingMethodContext(stack).globalVariables
variableReferences
.map(_.identifier)
.filter(i => globalVarsForEnclMethod.contains(i.name))
.sortBy(i => (i.lineNumber, i.columnNumber))
.distinctBy(_.name)
.map(i =>
NewMember()
.name(i.name)
.typeFullName(Constants.ANY)
.dynamicTypeHintFullName(i.dynamicTypeHintFullName)
.lineNumber(i.lineNumber)
.columnNumber(i.columnNumber)
.code(i.name)
)
.zipWithIndex
.foreach { case (m, idx) => astEdgeLinker(m, moduleTypeDecl, idx + 1) }
}
private def linkLocalOrCapturing(
createLocal: (String, Option[String]) => NewLocal,
createClosureBinding: (String, String) => NewClosureBinding,
createAstEdge: (NewNode, NewNode, Int) => Unit,
createRefEdge: (NewNode, NewNode) => Unit,
createCaptureEdge: (NewNode, NewNode) => Unit,
identifier: NewIdentifier,
name: String,
contextStack: List[Context]
): Unit = {
var identifierOrClosureBindingToLink: nodes.NewNode = identifier
val stackIt = contextStack.iterator
var contextHasVariable = false
val startContext = contextStack.head
while (stackIt.hasNext && !contextHasVariable) {
val context = stackIt.next()
context match {
case methodContext: MethodContext =>
// Context is only relevant for linking if it is not a class body methods context
// or the identifier/reference itself is from the class body method context.
if (!methodContext.isClassBodyMethod || methodContext == startContext) {
contextHasVariable = context.variables.contains(name)
val closureBindingId =
methodContext.astParent.asInstanceOf[NewMethod].fullName + ":" + name
if (!contextHasVariable) {
if (context != moduleMethodContext.get) {
val localNode = createLocal(name, Some(closureBindingId))
transferLineColInfo(identifier, localNode)
createAstEdge(localNode, methodContext.methodBlockNode.get, methodContext.order.getAndInc)
methodContext.variables.put(name, localNode)
} else {
// When we could not even find a matching variable in the module context we get
// here and create a local so that we can link something and fullfil the CPG
// format requirements.
// For example this happens when there are wildcard imports directly into the
// modules namespace.
val localNode = createLocal(name, None)
transferLineColInfo(identifier, localNode)
createAstEdge(localNode, methodContext.methodBlockNode.get, methodContext.order.getAndInc)
methodContext.variables.put(name, localNode)
}
}
val localNodeInContext = methodContext.variables(name)
createRefEdge(localNodeInContext, identifierOrClosureBindingToLink)
if (!contextHasVariable && context != moduleMethodContext.get) {
identifierOrClosureBindingToLink = createClosureBinding(closureBindingId, name)
createCaptureEdge(identifierOrClosureBindingToLink, methodContext.methodRefNode.get)
}
}
case specialBlockContext: SpecialBlockContext =>
contextHasVariable = context.variables.contains(name)
if (contextHasVariable) {
val localNodeInContext = specialBlockContext.variables(name)
createRefEdge(localNodeInContext, identifierOrClosureBindingToLink)
}
case _: ClassContext =>
assert(context.variables.isEmpty)
// Class context is not relevant for variable linking.
// The context relevant for this is the class method body context.
}
}
}
private def lookupVariableInMethod(name: String, stack: List[Context]): Option[nodes.NewNode] = {
var variableNode = Option.empty[nodes.NewNode]
val stackIt = stack.iterator
var lastContextWasMethod = false
while (stackIt.hasNext && variableNode.isEmpty && !lastContextWasMethod) {
val context = stackIt.next()
variableNode = context.variables.get(name)
lastContextWasMethod = context.isInstanceOf[MethodContext]
}
variableNode
}
def addParameter(parameter: nodes.NewMethodParameterIn): Unit = {
assert(stack.head.isInstanceOf[MethodContext])
stack.head.variables.put(parameter.name, parameter)
}
def addSpecialVariable(local: nodes.NewLocal): Unit = {
assert(stack.head.isInstanceOf[SpecialBlockContext])
stack.head.variables.put(local.name, local)
}
def addGlobalVariable(name: String): Unit = {
findEnclosingMethodContext(stack).globalVariables.add(name)
}
def addNonLocalVariable(name: String): Unit = {
findEnclosingMethodContext(stack).nonLocalVariables.add(name)
}
// Together with the file name this is used to compute full names.
def qualName: String = {
stack
.flatMap {
case methodContext: MethodContext =>
methodContext.scopeName
case specialBlockContext: SpecialBlockContext =>
None
case classContext: ClassContext =>
classContext.scopeName
}
.reverse
.mkString(".")
}
def astParent: nodes.NewNode = {
stack match {
case head :: _ =>
head.astParent
case Nil =>
fileNamespaceBlock.get
}
}
def order: AutoIncIndex = {
stack match {
case head :: _ =>
head.order
case Nil =>
fileNamespaceBlockOrder
}
}
def isClassContext: Boolean = {
stack.nonEmpty && (stack.head match {
case methodContext: MethodContext if methodContext.isClassBodyMethod => true
case _ => false
})
}
}
