// Based on dvmResolveClass. static void preloadDexCachesResolveType(DvmDex* pDvmDex, uint32_t typeIdx) { ClassObject* clazz = dvmDexGetResolvedClass(pDvmDex, typeIdx); if (clazz != NULL) { return; } const DexFile* pDexFile = pDvmDex->pDexFile; const char* className = dexStringByTypeIdx(pDexFile, typeIdx); if (className[0] != '\0' && className[1] == '\0') { /* primitive type */ clazz = dvmFindPrimitiveClass(className[0]); } else { clazz = dvmLookupClass(className, NULL, true); } if (clazz == NULL) { return; } // Skip uninitialized classes because filled cache entry implies it is initialized. if (!dvmIsClassInitialized(clazz)) { // ALOGI("VMRuntime.preloadDexCaches uninitialized clazz=%s", className); return; } // ALOGI("VMRuntime.preloadDexCaches found clazz=%s", className); dvmDexSetResolvedClass(pDvmDex, typeIdx, clazz); }
/* * Find the class corresponding to "classIdx", which maps to a class name * string. It might be in the same DEX file as "referrer", in a different * DEX file, generated by a class loader, or generated by the VM (e.g. * array classes). * * Because the DexTypeId is associated with the referring class' DEX file, * we may have to resolve the same class more than once if it's referred * to from classes in multiple DEX files. This is a necessary property for * DEX files associated with different class loaders. * * We cache a copy of the lookup in the DexFile's "resolved class" table, * so future references to "classIdx" are faster. * * Note that "referrer" may be in the process of being linked. * * Traditional VMs might do access checks here, but in Dalvik the class * "constant pool" is shared between all classes in the DEX file. We rely * on the verifier to do the checks for us. * * Does not initialize the class. * * "fromUnverifiedConstant" should only be set if this call is the direct * result of executing a "const-class" or "instance-of" instruction, which * use class constants not resolved by the bytecode verifier. * * Returns NULL with an exception raised on failure. */ ClassObject* dvmResolveClass(const ClassObject* referrer, u4 classIdx, bool fromUnverifiedConstant) { DvmDex* pDvmDex = referrer->pDvmDex; ClassObject* resClass; const char* className; /* * Check the table first -- this gets called from the other "resolve" * methods. */ resClass = dvmDexGetResolvedClass(pDvmDex, classIdx); if (resClass != NULL) return resClass; LOGVV("--- resolving class %u (referrer=%s cl=%p)\n", classIdx, referrer->descriptor, referrer->classLoader); /* * Class hasn't been loaded yet, or is in the process of being loaded * and initialized now. Try to get a copy. If we find one, put the * pointer in the DexTypeId. There isn't a race condition here -- * 32-bit writes are guaranteed atomic on all target platforms. Worst * case we have two threads storing the same value. * * If this is an array class, we'll generate it here. */ className = dexStringByTypeIdx(pDvmDex->pDexFile, classIdx); if (className[0] != '\0' && className[1] == '\0') { /* primitive type */ resClass = dvmFindPrimitiveClass(className[0]); } else { resClass = dvmFindClassNoInit(className, referrer->classLoader); } if (resClass != NULL) { /* * If the referrer was pre-verified, the resolved class must come * from the same DEX or from a bootstrap class. The pre-verifier * makes assumptions that could be invalidated by a wacky class * loader. (See the notes at the top of oo/Class.c.) * * The verifier does *not* fail a class for using a const-class * or instance-of instruction referring to an unresolveable class, * because the result of the instruction is simply a Class object * or boolean -- there's no need to resolve the class object during * verification. Instance field and virtual method accesses can * break dangerously if we get the wrong class, but const-class and * instance-of are only interesting at execution time. So, if we * we got here as part of executing one of the "unverified class" * instructions, we skip the additional check. * * Ditto for class references from annotations and exception * handler lists. */ if (!fromUnverifiedConstant && IS_CLASS_FLAG_SET(referrer, CLASS_ISPREVERIFIED)) { ClassObject* resClassCheck = resClass; if (dvmIsArrayClass(resClassCheck)) resClassCheck = resClassCheck->elementClass; if (referrer->pDvmDex != resClassCheck->pDvmDex && resClassCheck->classLoader != NULL) { LOGW("Class resolved by unexpected DEX:" " %s(%p):%p ref [%s] %s(%p):%p\n", referrer->descriptor, referrer->classLoader, referrer->pDvmDex, resClass->descriptor, resClassCheck->descriptor, resClassCheck->classLoader, resClassCheck->pDvmDex); LOGW("(%s had used a different %s during pre-verification)\n", referrer->descriptor, resClass->descriptor); dvmThrowException("Ljava/lang/IllegalAccessError;", "Class ref in pre-verified class resolved to unexpected " "implementation"); return NULL; } } LOGVV("##### +ResolveClass(%s): referrer=%s dex=%p ldr=%p ref=%d\n", resClass->descriptor, referrer->descriptor, referrer->pDvmDex, referrer->classLoader, classIdx); /* * Add what we found to the list so we can skip the class search * next time through. * * TODO: should we be doing this when fromUnverifiedConstant==true? * (see comments at top of oo/Class.c) */ dvmDexSetResolvedClass(pDvmDex, classIdx, resClass); } else { /* not found, exception should be raised */ LOGVV("Class not found: %s\n", dexStringByTypeIdx(pDvmDex->pDexFile, classIdx)); assert(dvmCheckException(dvmThreadSelf())); } return resClass; }
/* * Alternate version of dvmResolveClass for use with verification and * optimization. Performs access checks on every resolve, and refuses * to acknowledge the existence of classes defined in more than one DEX * file. * * Exceptions caused by failures are cleared before returning. * * On failure, returns NULL, and sets *pFailure if pFailure is not NULL. */ ClassObject* dvmOptResolveClass(ClassObject* referrer, u4 classIdx, VerifyError* pFailure) { DvmDex* pDvmDex = referrer->pDvmDex; ClassObject* resClass; /* * Check the table first. If not there, do the lookup by name. */ resClass = dvmDexGetResolvedClass(pDvmDex, classIdx); if (resClass == NULL) { const char* className = dexStringByTypeIdx(pDvmDex->pDexFile, classIdx); if (className[0] != '\0' && className[1] == '\0') { /* primitive type */ resClass = dvmFindPrimitiveClass(className[0]); } else { resClass = dvmFindClassNoInit(className, referrer->classLoader); } if (resClass == NULL) { /* not found, exception should be raised */ ALOGV("DexOpt: class %d (%s) not found", classIdx, dexStringByTypeIdx(pDvmDex->pDexFile, classIdx)); if (pFailure != NULL) { /* dig through the wrappers to find the original failure */ Object* excep = dvmGetException(dvmThreadSelf()); while (true) { Object* cause = dvmGetExceptionCause(excep); if (cause == NULL) break; excep = cause; } if (strcmp(excep->clazz->descriptor, "Ljava/lang/IncompatibleClassChangeError;") == 0) { *pFailure = VERIFY_ERROR_CLASS_CHANGE; } else { *pFailure = VERIFY_ERROR_NO_CLASS; } } dvmClearOptException(dvmThreadSelf()); return NULL; } /* * Add it to the resolved table so we're faster on the next lookup. */ dvmDexSetResolvedClass(pDvmDex, classIdx, resClass); } /* multiple definitions? */ if (IS_CLASS_FLAG_SET(resClass, CLASS_MULTIPLE_DEFS)) { ALOGI("DexOpt: not resolving ambiguous class '%s'", resClass->descriptor); if (pFailure != NULL) *pFailure = VERIFY_ERROR_NO_CLASS; return NULL; } /* access allowed? */ tweakLoader(referrer, resClass); bool allowed = dvmCheckClassAccess(referrer, resClass); untweakLoader(referrer, resClass); if (!allowed) { ALOGW("DexOpt: resolve class illegal access: %s -> %s", referrer->descriptor, resClass->descriptor); if (pFailure != NULL) *pFailure = VERIFY_ERROR_ACCESS_CLASS; return NULL; } return resClass; }