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Commit 34392f72 authored by Ady Abraham's avatar Ady Abraham
Browse files

SurfaceFlinger: add a backdoor to override display config 

To generate a config change (and override all other config changes):
    adb shell service call SurfaceFlinger 1035 i32 <config_id>
To disable backdoor override:
    adb shell service call SurfaceFlinger 1035 i32 -1

Test: change configs from backdoor
Fixes: 130044117
Change-Id: Iab5a4ca4866139946ca3f8a6ac78fa9e13fe6d00
parent 75bc57b2

services/surfaceflinger/SurfaceFlinger.cpp

+19 −1
Original line number Diff line number Diff line
@@ -5007,7 +5007,7 @@ status_t SurfaceFlinger::CheckTransactCodeCredentials(uint32_t code) { 
    }

    // Numbers from 1000 to 1034 are currently used for backdoors. The code

    // in onTransact verifies that the user is root, and has access to use SF.

    if (code >= 1000 && code <= 1034) {

    if (code >= 1000 && code <= 1035) {

        ALOGV("Accessing SurfaceFlinger through backdoor code: %u", code);

        return OK;

    }
@@ -5330,6 +5330,19 @@ status_t SurfaceFlinger::onTransact(uint32_t code, const Parcel& data, Parcel* r 
                }

                return NO_ERROR;

            }

            case 1035: {

                n = data.readInt32();

                mDebugDisplayConfigSetByBackdoor = false;

                if (n >= 0) {

                    const auto displayToken = getInternalDisplayToken();

                    status_t result = setAllowedDisplayConfigs(displayToken, {n});

                    if (result != NO_ERROR) {

                        return result;

                    }

                    mDebugDisplayConfigSetByBackdoor = true;

                }

                return NO_ERROR;

            }

        }

    }

    return err;
@@ -5846,6 +5859,11 @@ status_t SurfaceFlinger::setAllowedDisplayConfigs(const sp<IBinder>& displayToke 
        return BAD_VALUE;

    }



    if (mDebugDisplayConfigSetByBackdoor) {

        // ignore this request as config is overridden by backdoor

        return NO_ERROR;

    }



    postMessageSync(new LambdaMessage([&]() NO_THREAD_SAFETY_ANALYSIS {

        const auto display = getDisplayDeviceLocked(displayToken);

        if (!display) {

services/surfaceflinger/SurfaceFlinger.h

+3 −0
Original line number Diff line number Diff line
@@ -1148,6 +1148,9 @@ private: 
    Hwc2::impl::PowerAdvisor mPowerAdvisor;



    std::unique_ptr<RefreshRateOverlay> mRefreshRateOverlay;



    // Flag used to set override allowed display configs from backdoor

    bool mDebugDisplayConfigSetByBackdoor = false;

};



} // namespace android