libs/binder/ProcessState.cpp - platform/frameworks/native - Gitiles

 /*
  * Copyright (C) 2005 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "ProcessState"

 #include <binder/ProcessState.h>

 #include <binder/BpBinder.h>
 #include <binder/IPCThreadState.h>
 #include <binder/IServiceManager.h>
 #include <binder/Stability.h>
 #include <cutils/atomic.h>
 #include <utils/Log.h>
 #include <utils/String8.h>
 #include <utils/threads.h>

 #include <private/binder/binder_module.h>
 #include "Static.h"

 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>

 #define BINDER_VM_SIZE ((1 * 1024 * 1024) - sysconf(_SC_PAGE_SIZE) * 2)
 #define DEFAULT_MAX_BINDER_THREADS 15

 #ifdef __ANDROID_VNDK__
 const char* kDefaultDriver = "/dev/vndbinder";
 #else
 const char* kDefaultDriver = "/dev/binder";
 #endif

 // -------------------------------------------------------------------------

 namespace android {

 class PoolThread : public Thread
 {
 public:
     explicit PoolThread(bool isMain)
         : mIsMain(isMain)
     {
     }

 protected:
     virtual bool threadLoop()
     {
         IPCThreadState::self()->joinThreadPool(mIsMain);
         return false;
     }

     const bool mIsMain;
 };

 sp<ProcessState> ProcessState::self()
 {
     Mutex::Autolock _l(gProcessMutex);
     if (gProcess != nullptr) {
         return gProcess;
     }
     gProcess = new ProcessState(kDefaultDriver);
     return gProcess;
 }

 sp<ProcessState> ProcessState::initWithDriver(const char* driver)
 {
     Mutex::Autolock _l(gProcessMutex);
     if (gProcess != nullptr) {
         // Allow for initWithDriver to be called repeatedly with the same
         // driver.
         if (!strcmp(gProcess->getDriverName().c_str(), driver)) {
             return gProcess;
         }
         LOG_ALWAYS_FATAL("ProcessState was already initialized.");
     }

     if (access(driver, R_OK) == -1) {
         ALOGE("Binder driver %s is unavailable. Using /dev/binder instead.", driver);
         driver = "/dev/binder";
     }

     gProcess = new ProcessState(driver);
     return gProcess;
 }

 sp<ProcessState> ProcessState::selfOrNull()
 {
     Mutex::Autolock _l(gProcessMutex);
     return gProcess;
 }

 sp<IBinder> ProcessState::getContextObject(const sp<IBinder>& /*caller*/)
 {
     sp<IBinder> context = getStrongProxyForHandle(0);

     // The root object is special since we get it directly from the driver, it is never
     // written by Parcell::writeStrongBinder.
     internal::Stability::tryMarkCompilationUnit(context.get());

     return context;
 }

 void ProcessState::startThreadPool()
 {
     AutoMutex _l(mLock);
     if (!mThreadPoolStarted) {
         mThreadPoolStarted = true;
         spawnPooledThread(true);
     }
 }

 bool ProcessState::becomeContextManager(context_check_func checkFunc, void* userData)
 {
     AutoMutex _l(mLock);
     mBinderContextCheckFunc = checkFunc;
     mBinderContextUserData = userData;

     flat_binder_object obj {
         .flags = FLAT_BINDER_FLAG_TXN_SECURITY_CTX,
     };

     int result = ioctl(mDriverFD, BINDER_SET_CONTEXT_MGR_EXT, &obj);

     // fallback to original method
     if (result != 0) {
         android_errorWriteLog(0x534e4554, "121035042");

         int dummy = 0;
         result = ioctl(mDriverFD, BINDER_SET_CONTEXT_MGR, &dummy);
     }

     if (result == -1) {
         mBinderContextCheckFunc = nullptr;
         mBinderContextUserData = nullptr;
         ALOGE("Binder ioctl to become context manager failed: %s\n", strerror(errno));
     }

     return result == 0;
 }

 // Get references to userspace objects held by the kernel binder driver
 // Writes up to count elements into buf, and returns the total number
 // of references the kernel has, which may be larger than count.
 // buf may be NULL if count is 0.  The pointers returned by this method
 // should only be used for debugging and not dereferenced, they may
 // already be invalid.
 ssize_t ProcessState::getKernelReferences(size_t buf_count, uintptr_t* buf)
 {
     binder_node_debug_info info = {};

     uintptr_t* end = buf ? buf + buf_count : nullptr;
     size_t count = 0;

     do {
         status_t result = ioctl(mDriverFD, BINDER_GET_NODE_DEBUG_INFO, &info);
         if (result < 0) {
             return -1;
         }
         if (info.ptr != 0) {
             if (buf && buf < end)
                 *buf++ = info.ptr;
             count++;
             if (buf && buf < end)
                 *buf++ = info.cookie;
             count++;
         }
     } while (info.ptr != 0);

     return count;
 }

 // Queries the driver for the current strong reference count of the node
 // that the handle points to. Can only be used by the servicemanager.
 //
 // Returns -1 in case of failure, otherwise the strong reference count.
 ssize_t ProcessState::getStrongRefCountForNodeByHandle(int32_t handle) {
     binder_node_info_for_ref info;
     memset(&info, 0, sizeof(binder_node_info_for_ref));

     info.handle = handle;

     status_t result = ioctl(mDriverFD, BINDER_GET_NODE_INFO_FOR_REF, &info);

     if (result != OK) {
         static bool logged = false;
         if (!logged) {
           ALOGW("Kernel does not support BINDER_GET_NODE_INFO_FOR_REF.");
           logged = true;
         }
         return -1;
     }

     return info.strong_count;
 }

 void ProcessState::setCallRestriction(CallRestriction restriction) {
     LOG_ALWAYS_FATAL_IF(IPCThreadState::selfOrNull() != nullptr,
         "Call restrictions must be set before the threadpool is started.");

     mCallRestriction = restriction;
 }

 ProcessState::handle_entry* ProcessState::lookupHandleLocked(int32_t handle)
 {
     const size_t N=mHandleToObject.size();
     if (N <= (size_t)handle) {
         handle_entry e;
         e.binder = nullptr;
         e.refs = nullptr;
         status_t err = mHandleToObject.insertAt(e, N, handle+1-N);
         if (err < NO_ERROR) return nullptr;
     }
     return &mHandleToObject.editItemAt(handle);
 }

 sp<IBinder> ProcessState::getStrongProxyForHandle(int32_t handle)
 {
     sp<IBinder> result;

     AutoMutex _l(mLock);

     handle_entry* e = lookupHandleLocked(handle);

     if (e != nullptr) {
         // We need to create a new BpBinder if there isn't currently one, OR we
         // are unable to acquire a weak reference on this current one.  The
         // attemptIncWeak() is safe because we know the BpBinder destructor will always
         // call expungeHandle(), which acquires the same lock we are holding now.
         // We need to do this because there is a race condition between someone
         // releasing a reference on this BpBinder, and a new reference on its handle
         // arriving from the driver.
         IBinder* b = e->binder;
         if (b == nullptr || !e->refs->attemptIncWeak(this)) {
             if (handle == 0) {
                 // Special case for context manager...
                 // The context manager is the only object for which we create
                 // a BpBinder proxy without already holding a reference.
                 // Perform a dummy transaction to ensure the context manager
                 // is registered before we create the first local reference
                 // to it (which will occur when creating the BpBinder).
                 // If a local reference is created for the BpBinder when the
                 // context manager is not present, the driver will fail to
                 // provide a reference to the context manager, but the
                 // driver API does not return status.
                 //
                 // Note that this is not race-free if the context manager
                 // dies while this code runs.
                 //
                 // TODO: add a driver API to wait for context manager, or
                 // stop special casing handle 0 for context manager and add
                 // a driver API to get a handle to the context manager with
                 // proper reference counting.

                 Parcel data;
                 status_t status = IPCThreadState::self()->transact(
                         0, IBinder::PING_TRANSACTION, data, nullptr, 0);
                 if (status == DEAD_OBJECT)
                    return nullptr;
             }

             b = BpBinder::create(handle);
             e->binder = b;
             if (b) e->refs = b->getWeakRefs();
             result = b;
         } else {
             // This little bit of nastyness is to allow us to add a primary
             // reference to the remote proxy when this team doesn't have one
             // but another team is sending the handle to us.
             result.force_set(b);
             e->refs->decWeak(this);
         }
     }

     return result;
 }

 void ProcessState::expungeHandle(int32_t handle, IBinder* binder)
 {
     AutoMutex _l(mLock);

     handle_entry* e = lookupHandleLocked(handle);

     // This handle may have already been replaced with a new BpBinder
     // (if someone failed the AttemptIncWeak() above); we don't want
     // to overwrite it.
     if (e && e->binder == binder) e->binder = nullptr;
 }

 String8 ProcessState::makeBinderThreadName() {
     int32_t s = android_atomic_add(1, &mThreadPoolSeq);
     pid_t pid = getpid();
     String8 name;
     name.appendFormat("Binder:%d_%X", pid, s);
     return name;
 }

 void ProcessState::spawnPooledThread(bool isMain)
 {
     if (mThreadPoolStarted) {
         String8 name = makeBinderThreadName();
         ALOGV("Spawning new pooled thread, name=%s\n", name.string());
         sp<Thread> t = new PoolThread(isMain);
         t->run(name.string());
     }
 }

 status_t ProcessState::setThreadPoolMaxThreadCount(size_t maxThreads) {
     status_t result = NO_ERROR;
     if (ioctl(mDriverFD, BINDER_SET_MAX_THREADS, &maxThreads) != -1) {
         mMaxThreads = maxThreads;
     } else {
         result = -errno;
         ALOGE("Binder ioctl to set max threads failed: %s", strerror(-result));
     }
     return result;
 }

 void ProcessState::giveThreadPoolName() {
     androidSetThreadName( makeBinderThreadName().string() );
 }

 String8 ProcessState::getDriverName() {
     return mDriverName;
 }

 static int open_driver(const char *driver)
 {
     int fd = open(driver, O_RDWR | O_CLOEXEC);
     if (fd >= 0) {
         int vers = 0;
         status_t result = ioctl(fd, BINDER_VERSION, &vers);
         if (result == -1) {
             ALOGE("Binder ioctl to obtain version failed: %s", strerror(errno));
             close(fd);
             fd = -1;
         }
         if (result != 0 || vers != BINDER_CURRENT_PROTOCOL_VERSION) {
           ALOGE("Binder driver protocol(%d) does not match user space protocol(%d)! ioctl() return value: %d",
                 vers, BINDER_CURRENT_PROTOCOL_VERSION, result);
             close(fd);
             fd = -1;
         }
         size_t maxThreads = DEFAULT_MAX_BINDER_THREADS;
         result = ioctl(fd, BINDER_SET_MAX_THREADS, &maxThreads);
         if (result == -1) {
             ALOGE("Binder ioctl to set max threads failed: %s", strerror(errno));
         }
     } else {
         ALOGW("Opening '%s' failed: %s\n", driver, strerror(errno));
     }
     return fd;
 }

 ProcessState::ProcessState(const char *driver)
     : mDriverName(String8(driver))
     , mDriverFD(open_driver(driver))
     , mVMStart(MAP_FAILED)
     , mThreadCountLock(PTHREAD_MUTEX_INITIALIZER)
     , mThreadCountDecrement(PTHREAD_COND_INITIALIZER)
     , mExecutingThreadsCount(0)
     , mMaxThreads(DEFAULT_MAX_BINDER_THREADS)
     , mStarvationStartTimeMs(0)
     , mBinderContextCheckFunc(nullptr)
     , mBinderContextUserData(nullptr)
     , mThreadPoolStarted(false)
     , mThreadPoolSeq(1)
     , mCallRestriction(CallRestriction::NONE)
 {

 // TODO(b/139016109): enforce in build system
 #if defined(__ANDROID_APEX__) && !defined(__ANDROID_APEX_COM_ANDROID_VNDK_CURRENT__)
     LOG_ALWAYS_FATAL("Cannot use libbinder in APEX (only system.img libbinder) since it is not stable.");
 #endif

     if (mDriverFD >= 0) {
         // mmap the binder, providing a chunk of virtual address space to receive transactions.
         mVMStart = mmap(nullptr, BINDER_VM_SIZE, PROT_READ, MAP_PRIVATE | MAP_NORESERVE, mDriverFD, 0);
         if (mVMStart == MAP_FAILED) {
             // *sigh*
             ALOGE("Using %s failed: unable to mmap transaction memory.\n", mDriverName.c_str());
             close(mDriverFD);
             mDriverFD = -1;
             mDriverName.clear();
         }
     }

     LOG_ALWAYS_FATAL_IF(mDriverFD < 0, "Binder driver '%s' could not be opened.  Terminating.", driver);
 }

 ProcessState::~ProcessState()
 {
     if (mDriverFD >= 0) {
         if (mVMStart != MAP_FAILED) {
             munmap(mVMStart, BINDER_VM_SIZE);
         }
         close(mDriverFD);
     }
     mDriverFD = -1;
 }

 } // namespace android
	/*
	* Copyright (C) 2005 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "ProcessState"

	#include <binder/ProcessState.h>

	#include <binder/BpBinder.h>
	#include <binder/IPCThreadState.h>
	#include <binder/IServiceManager.h>
	#include <binder/Stability.h>
	#include <cutils/atomic.h>
	#include <utils/Log.h>
	#include <utils/String8.h>
	#include <utils/threads.h>

	#include <private/binder/binder_module.h>
	#include "Static.h"

	#include <errno.h>
	#include <fcntl.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <sys/ioctl.h>
	#include <sys/mman.h>
	#include <sys/stat.h>
	#include <sys/types.h>

	#define BINDER_VM_SIZE ((1 * 1024 * 1024) - sysconf(_SC_PAGE_SIZE) * 2)
	#define DEFAULT_MAX_BINDER_THREADS 15

	#ifdef __ANDROID_VNDK__
	const char* kDefaultDriver = "/dev/vndbinder";
	#else
	const char* kDefaultDriver = "/dev/binder";
	#endif

	// -------------------------------------------------------------------------

	namespace android {

	class PoolThread : public Thread
	{
	public:
	explicit PoolThread(bool isMain)
	: mIsMain(isMain)
	{
	}

	protected:
	virtual bool threadLoop()
	{
	IPCThreadState::self()->joinThreadPool(mIsMain);
	return false;
	}

	const bool mIsMain;
	};

	sp<ProcessState> ProcessState::self()
	{
	Mutex::Autolock _l(gProcessMutex);
	if (gProcess != nullptr) {
	return gProcess;
	}
	gProcess = new ProcessState(kDefaultDriver);
	return gProcess;
	}

	sp<ProcessState> ProcessState::initWithDriver(const char* driver)
	{
	Mutex::Autolock _l(gProcessMutex);
	if (gProcess != nullptr) {
	// Allow for initWithDriver to be called repeatedly with the same
	// driver.
	if (!strcmp(gProcess->getDriverName().c_str(), driver)) {
	return gProcess;
	}
	LOG_ALWAYS_FATAL("ProcessState was already initialized.");
	}

	if (access(driver, R_OK) == -1) {
	ALOGE("Binder driver %s is unavailable. Using /dev/binder instead.", driver);
	driver = "/dev/binder";
	}

	gProcess = new ProcessState(driver);
	return gProcess;
	}

	sp<ProcessState> ProcessState::selfOrNull()
	{
	Mutex::Autolock _l(gProcessMutex);
	return gProcess;
	}

	sp<IBinder> ProcessState::getContextObject(const sp<IBinder>& /caller/)
	{
	sp<IBinder> context = getStrongProxyForHandle(0);

	// The root object is special since we get it directly from the driver, it is never
	// written by Parcell::writeStrongBinder.
	internal::Stability::tryMarkCompilationUnit(context.get());

	return context;
	}

	void ProcessState::startThreadPool()
	{
	AutoMutex _l(mLock);
	if (!mThreadPoolStarted) {
	mThreadPoolStarted = true;
	spawnPooledThread(true);
	}
	}

	bool ProcessState::becomeContextManager(context_check_func checkFunc, void* userData)
	{
	AutoMutex _l(mLock);
	mBinderContextCheckFunc = checkFunc;
	mBinderContextUserData = userData;

	flat_binder_object obj {
	.flags = FLAT_BINDER_FLAG_TXN_SECURITY_CTX,
	};

	int result = ioctl(mDriverFD, BINDER_SET_CONTEXT_MGR_EXT, &obj);

	// fallback to original method
	if (result != 0) {
	android_errorWriteLog(0x534e4554, "121035042");

	int dummy = 0;
	result = ioctl(mDriverFD, BINDER_SET_CONTEXT_MGR, &dummy);
	}

	if (result == -1) {
	mBinderContextCheckFunc = nullptr;
	mBinderContextUserData = nullptr;
	ALOGE("Binder ioctl to become context manager failed: %s\n", strerror(errno));
	}

	return result == 0;
	}

	// Get references to userspace objects held by the kernel binder driver
	// Writes up to count elements into buf, and returns the total number
	// of references the kernel has, which may be larger than count.
	// buf may be NULL if count is 0. The pointers returned by this method
	// should only be used for debugging and not dereferenced, they may
	// already be invalid.
	ssize_t ProcessState::getKernelReferences(size_t buf_count, uintptr_t* buf)
	{
	binder_node_debug_info info = {};

	uintptr_t* end = buf ? buf + buf_count : nullptr;
	size_t count = 0;

	do {
	status_t result = ioctl(mDriverFD, BINDER_GET_NODE_DEBUG_INFO, &info);
	if (result < 0) {
	return -1;
	}
	if (info.ptr != 0) {
	if (buf && buf < end)
	*buf++ = info.ptr;
	count++;
	if (buf && buf < end)
	*buf++ = info.cookie;
	count++;
	}
	} while (info.ptr != 0);

	return count;
	}

	// Queries the driver for the current strong reference count of the node
	// that the handle points to. Can only be used by the servicemanager.
	//
	// Returns -1 in case of failure, otherwise the strong reference count.
	ssize_t ProcessState::getStrongRefCountForNodeByHandle(int32_t handle) {
	binder_node_info_for_ref info;
	memset(&info, 0, sizeof(binder_node_info_for_ref));

	info.handle = handle;

	status_t result = ioctl(mDriverFD, BINDER_GET_NODE_INFO_FOR_REF, &info);

	if (result != OK) {
	static bool logged = false;
	if (!logged) {
	ALOGW("Kernel does not support BINDER_GET_NODE_INFO_FOR_REF.");
	logged = true;
	}
	return -1;
	}

	return info.strong_count;
	}

	void ProcessState::setCallRestriction(CallRestriction restriction) {
	LOG_ALWAYS_FATAL_IF(IPCThreadState::selfOrNull() != nullptr,
	"Call restrictions must be set before the threadpool is started.");

	mCallRestriction = restriction;
	}

	ProcessState::handle_entry* ProcessState::lookupHandleLocked(int32_t handle)
	{
	const size_t N=mHandleToObject.size();
	if (N <= (size_t)handle) {
	handle_entry e;
	e.binder = nullptr;
	e.refs = nullptr;
	status_t err = mHandleToObject.insertAt(e, N, handle+1-N);
	if (err < NO_ERROR) return nullptr;
	}
	return &mHandleToObject.editItemAt(handle);
	}

	sp<IBinder> ProcessState::getStrongProxyForHandle(int32_t handle)
	{
	sp<IBinder> result;

	AutoMutex _l(mLock);

	handle_entry* e = lookupHandleLocked(handle);

	if (e != nullptr) {
	// We need to create a new BpBinder if there isn't currently one, OR we
	// are unable to acquire a weak reference on this current one. The
	// attemptIncWeak() is safe because we know the BpBinder destructor will always
	// call expungeHandle(), which acquires the same lock we are holding now.
	// We need to do this because there is a race condition between someone
	// releasing a reference on this BpBinder, and a new reference on its handle
	// arriving from the driver.
	IBinder* b = e->binder;
	if (b == nullptr \|\| !e->refs->attemptIncWeak(this)) {
	if (handle == 0) {
	// Special case for context manager...
	// The context manager is the only object for which we create
	// a BpBinder proxy without already holding a reference.
	// Perform a dummy transaction to ensure the context manager
	// is registered before we create the first local reference
	// to it (which will occur when creating the BpBinder).
	// If a local reference is created for the BpBinder when the
	// context manager is not present, the driver will fail to
	// provide a reference to the context manager, but the
	// driver API does not return status.
	//
	// Note that this is not race-free if the context manager
	// dies while this code runs.
	//
	// TODO: add a driver API to wait for context manager, or
	// stop special casing handle 0 for context manager and add
	// a driver API to get a handle to the context manager with
	// proper reference counting.

	Parcel data;
	status_t status = IPCThreadState::self()->transact(
	0, IBinder::PING_TRANSACTION, data, nullptr, 0);
	if (status == DEAD_OBJECT)
	return nullptr;
	}

	b = BpBinder::create(handle);
	e->binder = b;
	if (b) e->refs = b->getWeakRefs();
	result = b;
	} else {
	// This little bit of nastyness is to allow us to add a primary
	// reference to the remote proxy when this team doesn't have one
	// but another team is sending the handle to us.
	result.force_set(b);
	e->refs->decWeak(this);
	}
	}

	return result;
	}

	void ProcessState::expungeHandle(int32_t handle, IBinder* binder)
	{
	AutoMutex _l(mLock);

	handle_entry* e = lookupHandleLocked(handle);

	// This handle may have already been replaced with a new BpBinder
	// (if someone failed the AttemptIncWeak() above); we don't want
	// to overwrite it.
	if (e && e->binder == binder) e->binder = nullptr;
	}

	String8 ProcessState::makeBinderThreadName() {
	int32_t s = android_atomic_add(1, &mThreadPoolSeq);
	pid_t pid = getpid();
	String8 name;
	name.appendFormat("Binder:%d_%X", pid, s);
	return name;
	}

	void ProcessState::spawnPooledThread(bool isMain)
	{
	if (mThreadPoolStarted) {
	String8 name = makeBinderThreadName();
	ALOGV("Spawning new pooled thread, name=%s\n", name.string());
	sp<Thread> t = new PoolThread(isMain);
	t->run(name.string());
	}
	}

	status_t ProcessState::setThreadPoolMaxThreadCount(size_t maxThreads) {
	status_t result = NO_ERROR;
	if (ioctl(mDriverFD, BINDER_SET_MAX_THREADS, &maxThreads) != -1) {
	mMaxThreads = maxThreads;
	} else {
	result = -errno;
	ALOGE("Binder ioctl to set max threads failed: %s", strerror(-result));
	}
	return result;
	}

	void ProcessState::giveThreadPoolName() {
	androidSetThreadName( makeBinderThreadName().string() );
	}

	String8 ProcessState::getDriverName() {
	return mDriverName;
	}

	static int open_driver(const char *driver)
	{
	int fd = open(driver, O_RDWR \| O_CLOEXEC);
	if (fd >= 0) {
	int vers = 0;
	status_t result = ioctl(fd, BINDER_VERSION, &vers);
	if (result == -1) {
	ALOGE("Binder ioctl to obtain version failed: %s", strerror(errno));
	close(fd);
	fd = -1;
	}
	if (result != 0 \|\| vers != BINDER_CURRENT_PROTOCOL_VERSION) {
	ALOGE("Binder driver protocol(%d) does not match user space protocol(%d)! ioctl() return value: %d",
	vers, BINDER_CURRENT_PROTOCOL_VERSION, result);
	close(fd);
	fd = -1;
	}
	size_t maxThreads = DEFAULT_MAX_BINDER_THREADS;
	result = ioctl(fd, BINDER_SET_MAX_THREADS, &maxThreads);
	if (result == -1) {
	ALOGE("Binder ioctl to set max threads failed: %s", strerror(errno));
	}
	} else {
	ALOGW("Opening '%s' failed: %s\n", driver, strerror(errno));
	}
	return fd;
	}

	ProcessState::ProcessState(const char *driver)
	: mDriverName(String8(driver))
	, mDriverFD(open_driver(driver))
	, mVMStart(MAP_FAILED)
	, mThreadCountLock(PTHREAD_MUTEX_INITIALIZER)
	, mThreadCountDecrement(PTHREAD_COND_INITIALIZER)
	, mExecutingThreadsCount(0)
	, mMaxThreads(DEFAULT_MAX_BINDER_THREADS)
	, mStarvationStartTimeMs(0)
	, mBinderContextCheckFunc(nullptr)
	, mBinderContextUserData(nullptr)
	, mThreadPoolStarted(false)
	, mThreadPoolSeq(1)
	, mCallRestriction(CallRestriction::NONE)
	{

	// TODO(b/139016109): enforce in build system
	#if defined(__ANDROID_APEX__) && !defined(__ANDROID_APEX_COM_ANDROID_VNDK_CURRENT__)
	LOG_ALWAYS_FATAL("Cannot use libbinder in APEX (only system.img libbinder) since it is not stable.");
	#endif

	if (mDriverFD >= 0) {
	// mmap the binder, providing a chunk of virtual address space to receive transactions.
	mVMStart = mmap(nullptr, BINDER_VM_SIZE, PROT_READ, MAP_PRIVATE \| MAP_NORESERVE, mDriverFD, 0);
	if (mVMStart == MAP_FAILED) {
	// sigh
	ALOGE("Using %s failed: unable to mmap transaction memory.\n", mDriverName.c_str());
	close(mDriverFD);
	mDriverFD = -1;
	mDriverName.clear();
	}
	}

	LOG_ALWAYS_FATAL_IF(mDriverFD < 0, "Binder driver '%s' could not be opened. Terminating.", driver);
	}

	ProcessState::~ProcessState()
	{
	if (mDriverFD >= 0) {
	if (mVMStart != MAP_FAILED) {
	munmap(mVMStart, BINDER_VM_SIZE);
	}
	close(mDriverFD);
	}
	mDriverFD = -1;
	}

	} // namespace android