Preserve runtime object identity and declaring-class scope in inherited method calls

engine/vm.c

@@ -1391,6 +1391,19 @@ static ph7_value *VmNewOperandStack(
 /* Forward declaration */
 static sxi32 VmRegisterSpecialFunction(ph7_vm *pVm);
 static int VmClassMemberAccess(ph7_vm *pVm, ph7_class *pClass, sxi32 iProtection);
+/* Exception frames retain the enclosing method's lexical scope. */
+static ph7_class *VmMethodClass(ph7_vm *pVm) {
+	VmFrame *pFrame = pVm->pFrame;
+	ph7_vm_func *pVmFunc;
+	while(pFrame->pParent && (pFrame->iFlags & (VM_FRAME_EXCEPTION | VM_FRAME_CATCH | VM_FRAME_FINALLY))) {
+		pFrame = pFrame->pParent;
+	}
+	pVmFunc = (ph7_vm_func *)pFrame->pUserData;
+	if(pVmFunc == 0 || (pVmFunc->iFlags & VM_FUNC_CLASS_METHOD) == 0) {
+		return 0;
+	}
+	return (ph7_class *)pVmFunc->pUserData;
+}
 /*
  * Prepare the Virtual Machine for byte-code execution.
  * This routine gets called by the PH7 engine after
@@ -4451,12 +4464,17 @@ static sxi32 VmByteCodeExec(
 							if(!pNos->x.pOther) {
 								PH7_VmThrowError(&(*pVm), PH7_CTX_ERR, "Call to non-instantiated object '$%z'", &sName);
 							}
-							ph7_class *pClass, *pDerived;
+							ph7_class *pClass, *pDerived, *pScope;
 							/* Class already instantiated */
 							pThis = (ph7_class_instance *)pNos->x.pOther;
 							/* Point to the instantiated class */
 							pClass = pThis->pClass;
+							pScope = VmMethodClass(pVm);
 							if(pNos->iFlags == MEMOBJ_PARENTOBJ) {
+								/* Parent lookup starts at the declaring class, not the receiver. */
+								if(pScope) {
+									pClass = pScope;
+								}
 								if(pClass->pBase == 0) {
 									PH7_VmThrowError(&(*pVm), PH7_CTX_ERR,
 													"Attempt to call parent class from non-inheritance instance of class '%z'", &pClass->sName);
@@ -4470,7 +4488,15 @@ static sxi32 VmByteCodeExec(
 								if(sName.nByte > 0) {
 									/* Extract the target method */
 									if(pNos->iFlags != MEMOBJ_PARENTOBJ) {
-										pMeth = PH7_ClassExtractMethod(pClass, sName.zString, sName.nByte);
+										if(pScope && VmInstanceOf(pClass, pScope)) {
+											pMeth = PH7_ClassExtractMethod(pScope, sName.zString, sName.nByte);
+											if(pMeth && (pMeth->iProtection != PH7_CLASS_PROT_PRIVATE || pMeth->sFunc.pClass != pScope)) {
+												pMeth = 0;
+											}
+										}
+										if(pMeth == 0) {
+											pMeth = PH7_ClassExtractMethod(pClass, sName.zString, sName.nByte);
+										}
 									}
 									if(pMeth == 0) {
 										/* Browse hashtable from the beginning */
@@ -4510,7 +4536,16 @@ static sxi32 VmByteCodeExec(
 								if(sName.nByte > 0) {
 									/* Extract the target attribute */
 									if(pNos->iFlags != MEMOBJ_PARENTOBJ) {
-										pAttr = PH7_ClassExtractAttribute(pClass, sName.zString, sName.nByte);
+										/* Private fields belong to their declaring class, even on a derived object. */
+										if(pScope && VmInstanceOf(pClass, pScope)) {
+											pAttr = PH7_ClassExtractAttribute(pScope, sName.zString, sName.nByte);
+											if(pAttr && pAttr->iProtection != PH7_CLASS_PROT_PRIVATE) {
+												pAttr = 0;
+											}
+										}
+										if(pAttr == 0) {
+											pAttr = PH7_ClassExtractAttribute(pClass, sName.zString, sName.nByte);
+										}
 									}
 									if(pAttr == 0) {
 										/* Browse hashtable from the beginning */
@@ -4903,7 +4938,6 @@ static sxi32 VmByteCodeExec(
 					if(pEntry) {
 						ph7_vm_func_arg *aFormalArg;
 						ph7_class_instance *pThis;
-						ph7_class *pClass;
 						ph7_value *pFrameStack;
 						ph7_vm_func *pVmFunc;
 						ph7_class *pSelf;
@@ -4915,7 +4949,6 @@ static sxi32 VmByteCodeExec(
 						pVmFunc = (ph7_vm_func *)pEntry->pUserData;
 						pThis = 0;
 						pSelf = 0;
-						pClass = 0;
 						if(pVmFunc->iFlags & VM_FUNC_CLASS_METHOD) {
 							/* Class method call */
 							ph7_value *pTarget = &pTos[-1];
@@ -4925,9 +4958,7 @@ static sxi32 VmByteCodeExec(
 									/* Instance already loaded */
 									pThis = (ph7_class_instance *)pTarget->x.pOther;
 									pThis->iRef += 2;
-									pClass = pThis->pClass;
+									pSelf = pVmFunc->pClass;
-									pThis->pClass = pVmFunc->pClass;
-									pSelf = pThis->pClass;
 								}
 								if(pSelf == 0) {
 									if((pTarget->nType & MEMOBJ_STRING) && SyBlobLength(&pTarget->sBlob) > 0) {
@@ -4957,6 +4988,9 @@ static sxi32 VmByteCodeExec(
 						if(pInstr->iP2 == 0) {
 							pVmFunc = VmOverload(&(*pVm), pVmFunc, pArg, (int)(pTos - pArg));
 						}
+						if(pThis && (pVmFunc->iFlags & VM_FUNC_CLASS_METHOD)) {
+							pSelf = pVmFunc->pClass;
+						}
 						/* Extract the formal argument set */
 						aFormalArg = (ph7_vm_func_arg *)SySetBasePtr(&pVmFunc->aArgs);
 						/* Create a new VM frame  */
@@ -5256,10 +5290,6 @@ static sxi32 VmByteCodeExec(
 						SyMemBackendFree(&pVm->sAllocator, pFrameStack);
 						/* Leave the frame */
 						VmLeaveFrame(&(*pVm));
-						if(pClass != 0 && pClass != pThis->pClass) {
-							/* Restore original class */
-							pThis->pClass = pClass;
-						}
 						if(rc == PH7_ABORT) {
 							/* Abort processing immediately */
 							goto Abort;
@@ -6209,26 +6239,19 @@ static int VmClassMemberAccess(
 	sxi32 iProtection          /* Attribute protection level [i.e: public,protected or private] */
 ) {
 	if(iProtection != PH7_CLASS_PROT_PUBLIC) {
-		VmFrame *pFrame = pVm->pFrame;
+		ph7_class *pScope = VmMethodClass(pVm);
-		ph7_vm_func *pVmFunc;
+		if(pScope == 0) {
-		while(pFrame->pParent && (pFrame->iFlags & (VM_FRAME_EXCEPTION | VM_FRAME_CATCH | VM_FRAME_FINALLY))) {
-			/* Safely ignore the exception frame */
-			pFrame = pFrame->pParent;
-		}
-		pVmFunc = (ph7_vm_func *)pFrame->pUserData;
-		if(pVmFunc == 0 || (pVmFunc->iFlags & VM_FUNC_CLASS_METHOD) == 0) {
 			return 0; /* Access is forbidden */
 		}
 		if(iProtection == PH7_CLASS_PROT_PRIVATE) {
 			/* Must be the same instance */
-			if((ph7_class *)pVmFunc->pUserData != pClass) {
+			if(pScope != pClass) {
 				return 0; /* Access is forbidden */
 			}
 		} else {
 			/* Protected */
-			ph7_class *pBase = (ph7_class *)pVmFunc->pUserData;
 			/* Must be a derived class */
-			if(!VmInstanceOf(pBase, pClass)) {
+			if(!VmInstanceOf(pScope, pClass)) {
 				return 0; /* Access is forbidden */
 			}
 		}