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Commit 8b802915 authored by Kalesh Singh's avatar Kalesh Singh
Browse files

libbinder_ndk: Add stability downgrade 

This can be used to allow registering a service with a VINTF interface
without requiring a manifest declaration.

This is useful for test services or in the case of a system proxy
service that implements the same interface as the vintf service.

Bug: 183154648
Bug: 177664629
Test: atest binderStabilityTest
Change-Id: Ibd8dad46945a339b77dca70484082fda06220ee3
parent 78a58c8a

libs/binder/Stability.cpp

+14 −2
Original line number Diff line number Diff line
@@ -38,18 +38,30 @@ Stability::Category Stability::Category::currentFromLevel(Level level) { 
    };

}



void Stability::forceDowngradeCompilationUnit(const sp<IBinder>& binder) {

void Stability::forceDowngradeToStability(const sp<IBinder>& binder, Level level) {

    // Downgrading a remote binder would require also copying the version from

    // the binder sent here. In practice though, we don't need to downgrade the

    // stability of a remote binder, since this would as an effect only restrict

    // what we can do to it.

    LOG_ALWAYS_FATAL_IF(!binder || !binder->localBinder(), "Can only downgrade local binder");



    auto stability = Category::currentFromLevel(getLocalLevel());

    auto stability = Category::currentFromLevel(level);

    status_t result = setRepr(binder.get(), stability.repr(), REPR_LOG | REPR_ALLOW_DOWNGRADE);

    LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");

}



void Stability::forceDowngradeToLocalStability(const sp<IBinder>& binder) {

    forceDowngradeToStability(binder, getLocalLevel());

}



void Stability::forceDowngradeToSystemStability(const sp<IBinder>& binder) {

    forceDowngradeToStability(binder, Level::SYSTEM);

}



void Stability::forceDowngradeToVendorStability(const sp<IBinder>& binder) {

    forceDowngradeToStability(binder, Level::VENDOR);

}



std::string Stability::Category::debugString() {

    return levelString(level) + " wire protocol version "

        + std::to_string(version);

libs/binder/include/binder/Stability.h

+30 −2
Original line number Diff line number Diff line
@@ -54,8 +54,33 @@ public: 
    // Given a binder interface at a certain stability, there may be some

    // requirements associated with that higher stability level. For instance, a

    // VINTF stability binder is required to be in the VINTF manifest. This API

    // can be called to use that same interface within a partition.

    static void forceDowngradeCompilationUnit(const sp<IBinder>& binder);

    // can be called to use that same interface within the local partition.

    static void forceDowngradeToLocalStability(const sp<IBinder>& binder);



    // WARNING: The only client of

    //      - forceDowngradeToSystemStability() and;

    //      - korceDowngradeToVendorStability()

    //  should be AIBinder_forceDowngradeToLocalStability().

    //

    // getLocalLevel() in libbinder returns Level::SYSTEM when called

    // from libbinder_ndk (even on vendor partition). So we explicitly provide

    // these methods for use by the NDK API:

    //      AIBinder_forceDowngradeToLocalStability().

    //

    // This allows correctly downgrading the binder's stability to either system/vendor,

    // depending on the partition.



    // Given a binder interface at a certain stability, there may be some

    // requirements associated with that higher stability level. For instance, a

    // VINTF stability binder is required to be in the VINTF manifest. This API

    // can be called to use that same interface within the vendor partition.

    static void forceDowngradeToVendorStability(const sp<IBinder>& binder);



    // Given a binder interface at a certain stability, there may be some

    // requirements associated with that higher stability level. For instance, a

    // VINTF stability binder is required to be in the VINTF manifest. This API

    // can be called to use that same interface within the system partition.

    static void forceDowngradeToSystemStability(const sp<IBinder>& binder);



    // WARNING: Below APIs are only ever expected to be called by auto-generated code.

    //     Instead of calling them, you should set the stability of a .aidl interface
@@ -146,6 +171,9 @@ private: 
    // returns the stability according to how this was built

    static Level getLocalLevel();



    // Downgrades binder stability to the specified level.

    static void forceDowngradeToStability(const sp<IBinder>& binder, Level level);



    enum {

      REPR_NONE = 0,

      REPR_LOG = 1,

libs/binder/ndk/include_platform/android/binder_stability.h

+24 −0
Original line number Diff line number Diff line
@@ -45,6 +45,18 @@ static inline void AIBinder_markCompilationUnitStability(AIBinder* binder) { 
    AIBinder_markVendorStability(binder);

}



/**

 * Given a binder interface at a certain stability, there may be some

 * requirements associated with that higher stability level. For instance, a

 * VINTF stability binder is required to be in the VINTF manifest. This API

 * can be called to use that same interface within the vendor partition.

 */

void AIBinder_forceDowngradeToVendorStability(AIBinder* binder);



static inline void AIBinder_forceDowngradeToLocalStability(AIBinder* binder) {

    AIBinder_forceDowngradeToVendorStability(binder);

}



#else  // defined(__ANDROID_VENDOR__)



enum {
@@ -62,6 +74,18 @@ static inline void AIBinder_markCompilationUnitStability(AIBinder* binder) { 
    AIBinder_markSystemStability(binder);

}



/**

 * Given a binder interface at a certain stability, there may be some

 * requirements associated with that higher stability level. For instance, a

 * VINTF stability binder is required to be in the VINTF manifest. This API

 * can be called to use that same interface within the system partition.

 */

void AIBinder_forceDowngradeToSystemStability(AIBinder* binder);



static inline void AIBinder_forceDowngradeToLocalStability(AIBinder* binder) {

    AIBinder_forceDowngradeToSystemStability(binder);

}



#endif  // defined(__ANDROID_VENDOR__)



/**

libs/binder/ndk/libbinder_ndk.map.txt

+3 −0
Original line number Diff line number Diff line
@@ -127,6 +127,9 @@ LIBBINDER_NDK31 { # introduced=31 
    AServiceManager_tryUnregister; # llndk

    AServiceManager_reRegister; # llndk



    AIBinder_forceDowngradeToSystemStability; # apex

    AIBinder_forceDowngradeToVendorStability; # llndk



    AIBinder_Class_getDescriptor;

    AIBinder_Weak_clone;

    AIBinder_Weak_lt;

libs/binder/ndk/stability.cpp

+10 −1
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ using ::android::internal::Stability; 
#error libbinder_ndk should only be built in a system context

#endif



// explicit extern because symbol is only declared in header when __ANDROID_VNDK__

// explicit extern because symbol is only declared in header when __ANDROID_VENDOR__

extern "C" void AIBinder_markVendorStability(AIBinder* binder) {

    Stability::markVndk(binder->getBinder().get());

}
@@ -43,3 +43,12 @@ void AIBinder_markSystemStability(AIBinder* binder) { 
void AIBinder_markVintfStability(AIBinder* binder) {

    Stability::markVintf(binder->getBinder().get());

}



// explicit extern because symbol is only declared in header when __ANDROID_VENDOR__

extern "C" void AIBinder_forceDowngradeToVendorStability(AIBinder* binder) {

    Stability::forceDowngradeToVendorStability(binder->getBinder());

}



void AIBinder_forceDowngradeToSystemStability(AIBinder* binder) {

    Stability::forceDowngradeToSystemStability(binder->getBinder());

}