opengl/libs/EGL/egl_layers.cpp - LeafOS-Project/android_frameworks_native - Gitiles

 /*
  ** Copyright 2018, 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.
  */

 #include "egl_layers.h"

 #include <EGL/egl.h>
 #include <android-base/file.h>
 #include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <android/dlext.h>
 #include <dlfcn.h>
 #include <graphicsenv/GraphicsEnv.h>
 #include <log/log.h>
 #include <nativebridge/native_bridge.h>
 #include <nativeloader/native_loader.h>
 #include <sys/prctl.h>

 namespace android {

 // GLES Layers
 //
 // - Layer discovery -
 // 1. Check for debug layer list from GraphicsEnv
 // 2. If none enabled, check system properties
 //
 // - Layer initializing -
 // - AndroidGLESLayer_Initialize (provided by layer, called by loader)
 // - AndroidGLESLayer_GetProcAddress (provided by layer, called by loader)
 // - getNextLayerProcAddress (provided by loader, called by layer)
 //
 // 1. Walk through defs for egl and each gl version
 // 2. Call GetLayerProcAddress passing the name and the target hook entry point
 //   - This tells the layer the next point in the chain it should call
 // 3. Replace the hook with the layer's entry point
 //    - All entryoints will be present, anything unsupported by the driver will
 //      have gl_unimplemented
 //
 // - Extension layering -
 //  Not all functions are known to Android, so libEGL handles extensions.
 //  They are looked up by applications using eglGetProcAddress
 //  Layers can look them up with getNextLayerProcAddress

 const int kFuncCount = sizeof(platform_impl_t) / sizeof(char*) + sizeof(egl_t) / sizeof(char*) +
         sizeof(gl_hooks_t) / sizeof(char*);

 typedef struct FunctionTable {
     EGLFuncPointer x[kFuncCount];
     EGLFuncPointer& operator[](int i) { return x[i]; }
 } FunctionTable;

 // TODO: Move these to class
 std::unordered_map<std::string, int> func_indices;
 // func_indices.reserve(kFuncCount);

 std::unordered_map<int, std::string> func_names;
 // func_names.reserve(kFuncCount);

 std::vector<FunctionTable> layer_functions;

 const void* getNextLayerProcAddress(void* layer_id, const char* name) {
     // Use layer_id to find funcs for layer below current
     // This is the same key provided in AndroidGLESLayer_Initialize
     auto next_layer_funcs = reinterpret_cast<FunctionTable*>(layer_id);
     EGLFuncPointer val;

     ALOGV("getNextLayerProcAddress servicing %s", name);

     if (func_indices.find(name) == func_indices.end()) {
         // No entry for this function - it is an extension
         // call down the GPA chain directly to the impl
         ALOGV("getNextLayerProcAddress - name(%s) no func_indices entry found", name);

         // Look up which GPA we should use
         int gpaIndex = func_indices["eglGetProcAddress"];
         ALOGV("getNextLayerProcAddress - name(%s) gpaIndex(%i) <- using GPA from this index", name,
               gpaIndex);
         EGLFuncPointer gpaNext = (*next_layer_funcs)[gpaIndex];
         ALOGV("getNextLayerProcAddress - name(%s) gpaIndex(%i) gpaNext(%llu) <- using GPA at this "
               "address",
               name, gpaIndex, (unsigned long long)gpaNext);

         // Call it for the requested function
         typedef void* (*PFNEGLGETPROCADDRESSPROC)(const char*);
         PFNEGLGETPROCADDRESSPROC next = reinterpret_cast<PFNEGLGETPROCADDRESSPROC>(gpaNext);

         val = reinterpret_cast<EGLFuncPointer>(next(name));
         ALOGV("getNextLayerProcAddress - name(%s) gpaIndex(%i) gpaNext(%llu) Got back (%llu) from "
               "GPA",
               name, gpaIndex, (unsigned long long)gpaNext, (unsigned long long)val);

         // We should store it now, but to do that, we need to move func_idx to the class so we can
         // increment it separately
         // TODO: Move func_idx to class and store the result of GPA
         return reinterpret_cast<void*>(val);
     }

     int index = func_indices[name];
     val = (*next_layer_funcs)[index];
     ALOGV("getNextLayerProcAddress - name(%s) index(%i) entry(%llu) - Got a hit, returning known "
           "entry",
           name, index, (unsigned long long)val);
     return reinterpret_cast<void*>(val);
 }

 void SetupFuncMaps(FunctionTable& functions, char const* const* entries, EGLFuncPointer* curr,
                    int& func_idx) {
     while (*entries) {
         const char* name = *entries;

         // Some names overlap, only fill with initial entry
         // This does mean that some indices will not be used
         if (func_indices.find(name) == func_indices.end()) {
             ALOGV("SetupFuncMaps - name(%s), func_idx(%i), No entry for func_indices, assigning "
                   "now",
                   name, func_idx);
             func_names[func_idx] = name;
             func_indices[name] = func_idx;
         } else {
             ALOGV("SetupFuncMaps - name(%s), func_idx(%i), Found entry for func_indices", name,
                   func_idx);
         }

         // Populate layer_functions once with initial value
         // These values will arrive in priority order, starting with platform entries
         if (functions[func_idx] == nullptr) {
             ALOGV("SetupFuncMaps - name(%s), func_idx(%i), No entry for functions, assigning "
                   "(%llu)",
                   name, func_idx, (unsigned long long)*curr);
             functions[func_idx] = *curr;
         } else {
             ALOGV("SetupFuncMaps - name(%s), func_idx(%i), Found entry for functions (%llu)", name,
                   func_idx, (unsigned long long)functions[func_idx]);
         }

         entries++;
         curr++;
         func_idx++;
     }
 }

 LayerLoader& LayerLoader::getInstance() {
     // This function is mutex protected in egl_init_drivers_locked and eglGetProcAddressImpl
     static LayerLoader layer_loader;

     if (!layer_loader.layers_loaded_) layer_loader.LoadLayers();

     return layer_loader;
 }

 const char kSystemLayerLibraryDir[] = "/data/local/debug/gles";

 std::string LayerLoader::GetDebugLayers() {
     // Layers can be specified at the Java level in GraphicsEnvironment
     // gpu_debug_layers_gles = layer1:layer2:layerN
     std::string debug_layers = android::GraphicsEnv::getInstance().getDebugLayersGLES();

     if (debug_layers.empty()) {
         // Only check system properties if Java settings are empty
         debug_layers = base::GetProperty("debug.gles.layers", "");
     }

     return debug_layers;
 }

 EGLFuncPointer LayerLoader::ApplyLayer(layer_setup_func layer_setup, const char* name,
                                        EGLFuncPointer next) {
     // Walk through our list of LayerSetup functions (they will already be in reverse order) to
     // build up a call chain from the driver

     EGLFuncPointer layer_entry = next;

     layer_entry = layer_setup(name, layer_entry);

     if (next != layer_entry) {
         ALOGV("We succeeded, replacing hook (%llu) with layer entry (%llu), for %s",
               (unsigned long long)next, (unsigned long long)layer_entry, name);
     }

     return layer_entry;
 }

 EGLFuncPointer LayerLoader::ApplyLayers(const char* name, EGLFuncPointer next) {
     if (!layers_loaded_ || layer_setup_.empty()) return next;

     ALOGV("ApplyLayers called for %s with next (%llu), current_layer_ (%i)", name,
           (unsigned long long)next, current_layer_);

     EGLFuncPointer val = next;

     // Only ApplyLayers for layers that have been setup, not all layers yet
     for (unsigned i = 0; i < current_layer_; i++) {
         ALOGV("ApplyLayers: Calling ApplyLayer with i = %i for %s with next (%llu)", i, name,
               (unsigned long long)next);
         val = ApplyLayer(layer_setup_[i], name, val);
     }

     ALOGV("ApplyLayers returning %llu for %s", (unsigned long long)val, name);

     return val;
 }

 void LayerLoader::LayerPlatformEntries(layer_setup_func layer_setup, EGLFuncPointer* curr,
                                        char const* const* entries) {
     while (*entries) {
         char const* name = *entries;

         EGLFuncPointer prev = *curr;

         // Pass the existing entry point into the layer, replace the call with return value
         *curr = ApplyLayer(layer_setup, name, *curr);

         if (prev != *curr) {
             ALOGV("LayerPlatformEntries: Replaced (%llu) with platform entry (%llu), for %s",
                   (unsigned long long)prev, (unsigned long long)*curr, name);
         } else {
             ALOGV("LayerPlatformEntries: No change(%llu) for %s, which means layer did not "
                   "intercept",
                   (unsigned long long)prev, name);
         }

         curr++;
         entries++;
     }
 }

 void LayerLoader::LayerDriverEntries(layer_setup_func layer_setup, EGLFuncPointer* curr,
                                      char const* const* entries) {
     while (*entries) {
         char const* name = *entries;
         EGLFuncPointer prev = *curr;

         // Only apply layers to driver entries if not handled by the platform
         if (FindPlatformImplAddr(name) == nullptr) {
             // Pass the existing entry point into the layer, replace the call with return value
             *curr = ApplyLayer(layer_setup, name, *prev);

             if (prev != *curr) {
                 ALOGV("LayerDriverEntries: Replaced (%llu) with platform entry (%llu), for %s",
                       (unsigned long long)prev, (unsigned long long)*curr, name);
             }

         } else {
             ALOGV("LayerDriverEntries: Skipped (%llu) for %s", (unsigned long long)prev, name);
         }

         curr++;
         entries++;
     }
 }

 bool LayerLoader::Initialized() {
     return initialized_;
 }

 void LayerLoader::InitLayers(egl_connection_t* cnx) {
     if (!layers_loaded_) return;

     if (initialized_) return;

     if (layer_setup_.empty()) {
         initialized_ = true;
         return;
     }

     // Include the driver in layer_functions
     layer_functions.resize(layer_setup_.size() + 1);

     // Walk through the initial lists and create layer_functions[0]
     int func_idx = 0;
     char const* const* entries;
     EGLFuncPointer* curr;

     entries = platform_names;
     curr = reinterpret_cast<EGLFuncPointer*>(&cnx->platform);
     SetupFuncMaps(layer_functions[0], entries, curr, func_idx);
     ALOGV("InitLayers: func_idx after platform_names: %i", func_idx);

     entries = egl_names;
     curr = reinterpret_cast<EGLFuncPointer*>(&cnx->egl);
     SetupFuncMaps(layer_functions[0], entries, curr, func_idx);
     ALOGV("InitLayers: func_idx after egl_names: %i", func_idx);

     entries = gl_names;
     curr = reinterpret_cast<EGLFuncPointer*>(&cnx->hooks[egl_connection_t::GLESv2_INDEX]->gl);
     SetupFuncMaps(layer_functions[0], entries, curr, func_idx);
     ALOGV("InitLayers: func_idx after gl_names: %i", func_idx);

     // Walk through each layer's entry points per API, starting just above the driver
     for (current_layer_ = 0; current_layer_ < layer_setup_.size(); current_layer_++) {
         // Init the layer with a key that points to layer just below it
         layer_init_[current_layer_](reinterpret_cast<void*>(&layer_functions[current_layer_]),
                                     reinterpret_cast<PFNEGLGETNEXTLAYERPROCADDRESSPROC>(
                                             getNextLayerProcAddress));

         // Check functions implemented by the platform
         func_idx = 0;
         entries = platform_names;
         curr = reinterpret_cast<EGLFuncPointer*>(&cnx->platform);
         LayerPlatformEntries(layer_setup_[current_layer_], curr, entries);

         // Populate next function table after layers have been applied
         SetupFuncMaps(layer_functions[current_layer_ + 1], entries, curr, func_idx);

         // EGL
         entries = egl_names;
         curr = reinterpret_cast<EGLFuncPointer*>(&cnx->egl);
         LayerDriverEntries(layer_setup_[current_layer_], curr, entries);

         // Populate next function table after layers have been applied
         SetupFuncMaps(layer_functions[current_layer_ + 1], entries, curr, func_idx);

         // GLES 2+
         // NOTE: We route calls to GLESv2 hooks, not GLESv1, so layering does not support GLES 1.x
         // If it were added in the future, a different layer initialization model would be needed,
         // that defers loading GLES entrypoints until after eglMakeCurrent, so two phase
         // initialization.
         entries = gl_names;
         curr = reinterpret_cast<EGLFuncPointer*>(&cnx->hooks[egl_connection_t::GLESv2_INDEX]->gl);
         LayerDriverEntries(layer_setup_[current_layer_], curr, entries);

         // Populate next function table after layers have been applied
         SetupFuncMaps(layer_functions[current_layer_ + 1], entries, curr, func_idx);
     }

     // We only want to apply layers once
     initialized_ = true;
 }

 void LayerLoader::LoadLayers() {
     std::string debug_layers = GetDebugLayers();

     // If no layers are specified, we're done
     if (debug_layers.empty()) return;

     // Only enable the system search path for non-user builds
     std::string system_path;
     if (android::GraphicsEnv::getInstance().isDebuggable()) {
         system_path = kSystemLayerLibraryDir;
     }

     ALOGI("Debug layer list: %s", debug_layers.c_str());
     std::vector<std::string> layers = android::base::Split(debug_layers, ":");

     // Load the layers in reverse order so we start with the driver's entrypoint and work our way up
     for (int32_t i = layers.size() - 1; i >= 0; i--) {
         // Check each layer path for the layer
         std::vector<std::string> paths =
                 android::base::Split(android::GraphicsEnv::getInstance().getLayerPaths().c_str(),
                                      ":");

         if (!system_path.empty()) {
             // Prepend the system paths so they override other layers
             auto it = paths.begin();
             paths.insert(it, system_path);
         }

         bool layer_found = false;
         for (uint32_t j = 0; j < paths.size() && !layer_found; j++) {
             std::string layer;

             ALOGI("Searching %s for GLES layers", paths[j].c_str());

             // Realpath will return null for non-existent files
             android::base::Realpath(paths[j] + "/" + layers[i], &layer);

             if (!layer.empty()) {
                 layer_found = true;
                 ALOGI("GLES layer found: %s", layer.c_str());

                 // Load the layer
                 //
                 // TODO: This code is common with Vulkan loader, refactor
                 //
                 // Libraries in the system layer library dir can't be loaded into
                 // the application namespace. That causes compatibility problems, since
                 // any symbol dependencies will be resolved by system libraries. They
                 // can't safely use libc++_shared, for example. Which is one reason
                 // (among several) we only allow them in non-user builds.
                 auto app_namespace = android::GraphicsEnv::getInstance().getAppNamespace();
                 if (app_namespace && !android::base::StartsWith(layer, kSystemLayerLibraryDir)) {
                     char* error_message = nullptr;
                     dlhandle_ = OpenNativeLibraryInNamespace(app_namespace, layer.c_str(),
                                                              &native_bridge_, &error_message);
                     if (!dlhandle_) {
                         ALOGE("Failed to load layer %s with error: %s", layer.c_str(),
                               error_message);
                         android::NativeLoaderFreeErrorMessage(error_message);
                         return;
                     }

                 } else {
                     dlhandle_ = dlopen(layer.c_str(), RTLD_NOW | RTLD_LOCAL);
                 }

                 if (dlhandle_) {
                     ALOGV("Loaded layer handle (%llu) for layer %s", (unsigned long long)dlhandle_,
                           layers[i].c_str());
                 } else {
                     // If the layer is found but can't be loaded, try setenforce 0
                     const char* dlsym_error = dlerror();
                     ALOGE("Failed to load layer %s with error: %s", layer.c_str(), dlsym_error);
                     return;
                 }

                 // Find the layer's Initialize function
                 std::string init_func = "AndroidGLESLayer_Initialize";
                 ALOGV("Looking for entrypoint %s", init_func.c_str());

                 layer_init_func LayerInit = GetTrampoline<layer_init_func>(init_func.c_str());
                 if (LayerInit) {
                     ALOGV("Found %s for layer %s", init_func.c_str(), layer.c_str());
                     layer_init_.push_back(LayerInit);
                 } else {
                     ALOGE("Failed to dlsym %s for layer %s", init_func.c_str(), layer.c_str());
                     return;
                 }

                 // Find the layer's setup function
                 std::string setup_func = "AndroidGLESLayer_GetProcAddress";
                 ALOGV("Looking for entrypoint %s", setup_func.c_str());

                 layer_setup_func LayerSetup = GetTrampoline<layer_setup_func>(setup_func.c_str());
                 if (LayerSetup) {
                     ALOGV("Found %s for layer %s", setup_func.c_str(), layer.c_str());
                     layer_setup_.push_back(LayerSetup);
                 } else {
                     ALOGE("Failed to dlsym %s for layer %s", setup_func.c_str(), layer.c_str());
                     return;
                 }
             }
         }
     }
     // Track this so we only attempt to load these once
     layers_loaded_ = true;
 }

 } // namespace android
	/*
	** Copyright 2018, 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.
	*/

	#include "egl_layers.h"

	#include <EGL/egl.h>
	#include <android-base/file.h>
	#include <android-base/properties.h>
	#include <android-base/strings.h>
	#include <android/dlext.h>
	#include <dlfcn.h>
	#include <graphicsenv/GraphicsEnv.h>
	#include <log/log.h>
	#include <nativebridge/native_bridge.h>
	#include <nativeloader/native_loader.h>
	#include <sys/prctl.h>

	namespace android {

	// GLES Layers
	//
	// - Layer discovery -
	// 1. Check for debug layer list from GraphicsEnv
	// 2. If none enabled, check system properties
	//
	// - Layer initializing -
	// - AndroidGLESLayer_Initialize (provided by layer, called by loader)
	// - AndroidGLESLayer_GetProcAddress (provided by layer, called by loader)
	// - getNextLayerProcAddress (provided by loader, called by layer)
	//
	// 1. Walk through defs for egl and each gl version
	// 2. Call GetLayerProcAddress passing the name and the target hook entry point
	// - This tells the layer the next point in the chain it should call
	// 3. Replace the hook with the layer's entry point
	// - All entryoints will be present, anything unsupported by the driver will
	// have gl_unimplemented
	//
	// - Extension layering -
	// Not all functions are known to Android, so libEGL handles extensions.
	// They are looked up by applications using eglGetProcAddress
	// Layers can look them up with getNextLayerProcAddress

	const int kFuncCount = sizeof(platform_impl_t) / sizeof(char) + sizeof(egl_t) / sizeof(char) +
	sizeof(gl_hooks_t) / sizeof(char*);

	typedef struct FunctionTable {
	EGLFuncPointer x[kFuncCount];
	EGLFuncPointer& operator[](int i) { return x[i]; }
	} FunctionTable;

	// TODO: Move these to class
	std::unordered_map<std::string, int> func_indices;
	// func_indices.reserve(kFuncCount);

	std::unordered_map<int, std::string> func_names;
	// func_names.reserve(kFuncCount);

	std::vector<FunctionTable> layer_functions;

	const void* getNextLayerProcAddress(void* layer_id, const char* name) {
	// Use layer_id to find funcs for layer below current
	// This is the same key provided in AndroidGLESLayer_Initialize
	auto next_layer_funcs = reinterpret_cast<FunctionTable*>(layer_id);
	EGLFuncPointer val;

	ALOGV("getNextLayerProcAddress servicing %s", name);

	if (func_indices.find(name) == func_indices.end()) {
	// No entry for this function - it is an extension
	// call down the GPA chain directly to the impl
	ALOGV("getNextLayerProcAddress - name(%s) no func_indices entry found", name);

	// Look up which GPA we should use
	int gpaIndex = func_indices["eglGetProcAddress"];
	ALOGV("getNextLayerProcAddress - name(%s) gpaIndex(%i) <- using GPA from this index", name,
	gpaIndex);
	EGLFuncPointer gpaNext = (*next_layer_funcs)[gpaIndex];
	ALOGV("getNextLayerProcAddress - name(%s) gpaIndex(%i) gpaNext(%llu) <- using GPA at this "
	"address",
	name, gpaIndex, (unsigned long long)gpaNext);

	// Call it for the requested function
	typedef void* (PFNEGLGETPROCADDRESSPROC)(const char);
	PFNEGLGETPROCADDRESSPROC next = reinterpret_cast<PFNEGLGETPROCADDRESSPROC>(gpaNext);

	val = reinterpret_cast<EGLFuncPointer>(next(name));
	ALOGV("getNextLayerProcAddress - name(%s) gpaIndex(%i) gpaNext(%llu) Got back (%llu) from "
	"GPA",
	name, gpaIndex, (unsigned long long)gpaNext, (unsigned long long)val);

	// We should store it now, but to do that, we need to move func_idx to the class so we can
	// increment it separately
	// TODO: Move func_idx to class and store the result of GPA
	return reinterpret_cast<void*>(val);
	}

	int index = func_indices[name];
	val = (*next_layer_funcs)[index];
	ALOGV("getNextLayerProcAddress - name(%s) index(%i) entry(%llu) - Got a hit, returning known "
	"entry",
	name, index, (unsigned long long)val);
	return reinterpret_cast<void*>(val);
	}

	void SetupFuncMaps(FunctionTable& functions, char const* const* entries, EGLFuncPointer* curr,
	int& func_idx) {
	while (*entries) {
	const char* name = *entries;

	// Some names overlap, only fill with initial entry
	// This does mean that some indices will not be used
	if (func_indices.find(name) == func_indices.end()) {
	ALOGV("SetupFuncMaps - name(%s), func_idx(%i), No entry for func_indices, assigning "
	"now",
	name, func_idx);
	func_names[func_idx] = name;
	func_indices[name] = func_idx;
	} else {
	ALOGV("SetupFuncMaps - name(%s), func_idx(%i), Found entry for func_indices", name,
	func_idx);
	}

	// Populate layer_functions once with initial value
	// These values will arrive in priority order, starting with platform entries
	if (functions[func_idx] == nullptr) {
	ALOGV("SetupFuncMaps - name(%s), func_idx(%i), No entry for functions, assigning "
	"(%llu)",
	name, func_idx, (unsigned long long)*curr);
	functions[func_idx] = *curr;
	} else {
	ALOGV("SetupFuncMaps - name(%s), func_idx(%i), Found entry for functions (%llu)", name,
	func_idx, (unsigned long long)functions[func_idx]);
	}

	entries++;
	curr++;
	func_idx++;
	}
	}

	LayerLoader& LayerLoader::getInstance() {
	// This function is mutex protected in egl_init_drivers_locked and eglGetProcAddressImpl
	static LayerLoader layer_loader;

	if (!layer_loader.layers_loaded_) layer_loader.LoadLayers();

	return layer_loader;
	}

	const char kSystemLayerLibraryDir[] = "/data/local/debug/gles";

	std::string LayerLoader::GetDebugLayers() {
	// Layers can be specified at the Java level in GraphicsEnvironment
	// gpu_debug_layers_gles = layer1:layer2:layerN
	std::string debug_layers = android::GraphicsEnv::getInstance().getDebugLayersGLES();

	if (debug_layers.empty()) {
	// Only check system properties if Java settings are empty
	debug_layers = base::GetProperty("debug.gles.layers", "");
	}

	return debug_layers;
	}

	EGLFuncPointer LayerLoader::ApplyLayer(layer_setup_func layer_setup, const char* name,
	EGLFuncPointer next) {
	// Walk through our list of LayerSetup functions (they will already be in reverse order) to
	// build up a call chain from the driver

	EGLFuncPointer layer_entry = next;

	layer_entry = layer_setup(name, layer_entry);

	if (next != layer_entry) {
	ALOGV("We succeeded, replacing hook (%llu) with layer entry (%llu), for %s",
	(unsigned long long)next, (unsigned long long)layer_entry, name);
	}

	return layer_entry;
	}

	EGLFuncPointer LayerLoader::ApplyLayers(const char* name, EGLFuncPointer next) {
	if (!layers_loaded_ \|\| layer_setup_.empty()) return next;

	ALOGV("ApplyLayers called for %s with next (%llu), current_layer_ (%i)", name,
	(unsigned long long)next, current_layer_);

	EGLFuncPointer val = next;

	// Only ApplyLayers for layers that have been setup, not all layers yet
	for (unsigned i = 0; i < current_layer_; i++) {
	ALOGV("ApplyLayers: Calling ApplyLayer with i = %i for %s with next (%llu)", i, name,
	(unsigned long long)next);
	val = ApplyLayer(layer_setup_[i], name, val);
	}

	ALOGV("ApplyLayers returning %llu for %s", (unsigned long long)val, name);

	return val;
	}

	void LayerLoader::LayerPlatformEntries(layer_setup_func layer_setup, EGLFuncPointer* curr,
	char const* const* entries) {
	while (*entries) {
	char const* name = *entries;

	EGLFuncPointer prev = *curr;

	// Pass the existing entry point into the layer, replace the call with return value
	curr = ApplyLayer(layer_setup, name, curr);

	if (prev != *curr) {
	ALOGV("LayerPlatformEntries: Replaced (%llu) with platform entry (%llu), for %s",
	(unsigned long long)prev, (unsigned long long)*curr, name);
	} else {
	ALOGV("LayerPlatformEntries: No change(%llu) for %s, which means layer did not "
	"intercept",
	(unsigned long long)prev, name);
	}

	curr++;
	entries++;
	}
	}

	void LayerLoader::LayerDriverEntries(layer_setup_func layer_setup, EGLFuncPointer* curr,
	char const* const* entries) {
	while (*entries) {
	char const* name = *entries;
	EGLFuncPointer prev = *curr;

	// Only apply layers to driver entries if not handled by the platform
	if (FindPlatformImplAddr(name) == nullptr) {
	// Pass the existing entry point into the layer, replace the call with return value
	curr = ApplyLayer(layer_setup, name, prev);

	if (prev != *curr) {
	ALOGV("LayerDriverEntries: Replaced (%llu) with platform entry (%llu), for %s",
	(unsigned long long)prev, (unsigned long long)*curr, name);
	}

	} else {
	ALOGV("LayerDriverEntries: Skipped (%llu) for %s", (unsigned long long)prev, name);
	}

	curr++;
	entries++;
	}
	}

	bool LayerLoader::Initialized() {
	return initialized_;
	}

	void LayerLoader::InitLayers(egl_connection_t* cnx) {
	if (!layers_loaded_) return;

	if (initialized_) return;

	if (layer_setup_.empty()) {
	initialized_ = true;
	return;
	}

	// Include the driver in layer_functions
	layer_functions.resize(layer_setup_.size() + 1);

	// Walk through the initial lists and create layer_functions[0]
	int func_idx = 0;
	char const* const* entries;
	EGLFuncPointer* curr;

	entries = platform_names;
	curr = reinterpret_cast<EGLFuncPointer*>(&cnx->platform);
	SetupFuncMaps(layer_functions[0], entries, curr, func_idx);
	ALOGV("InitLayers: func_idx after platform_names: %i", func_idx);

	entries = egl_names;
	curr = reinterpret_cast<EGLFuncPointer*>(&cnx->egl);
	SetupFuncMaps(layer_functions[0], entries, curr, func_idx);
	ALOGV("InitLayers: func_idx after egl_names: %i", func_idx);

	entries = gl_names;
	curr = reinterpret_cast<EGLFuncPointer*>(&cnx->hooks[egl_connection_t::GLESv2_INDEX]->gl);
	SetupFuncMaps(layer_functions[0], entries, curr, func_idx);
	ALOGV("InitLayers: func_idx after gl_names: %i", func_idx);

	// Walk through each layer's entry points per API, starting just above the driver
	for (current_layer_ = 0; current_layer_ < layer_setup_.size(); current_layer_++) {
	// Init the layer with a key that points to layer just below it
	layer_init_[current_layer_](reinterpret_cast<void*>(&layer_functions[current_layer_]),
	reinterpret_cast<PFNEGLGETNEXTLAYERPROCADDRESSPROC>(
	getNextLayerProcAddress));

	// Check functions implemented by the platform
	func_idx = 0;
	entries = platform_names;
	curr = reinterpret_cast<EGLFuncPointer*>(&cnx->platform);
	LayerPlatformEntries(layer_setup_[current_layer_], curr, entries);

	// Populate next function table after layers have been applied
	SetupFuncMaps(layer_functions[current_layer_ + 1], entries, curr, func_idx);

	// EGL
	entries = egl_names;
	curr = reinterpret_cast<EGLFuncPointer*>(&cnx->egl);
	LayerDriverEntries(layer_setup_[current_layer_], curr, entries);

	// Populate next function table after layers have been applied
	SetupFuncMaps(layer_functions[current_layer_ + 1], entries, curr, func_idx);

	// GLES 2+
	// NOTE: We route calls to GLESv2 hooks, not GLESv1, so layering does not support GLES 1.x
	// If it were added in the future, a different layer initialization model would be needed,
	// that defers loading GLES entrypoints until after eglMakeCurrent, so two phase
	// initialization.
	entries = gl_names;
	curr = reinterpret_cast<EGLFuncPointer*>(&cnx->hooks[egl_connection_t::GLESv2_INDEX]->gl);
	LayerDriverEntries(layer_setup_[current_layer_], curr, entries);

	// Populate next function table after layers have been applied
	SetupFuncMaps(layer_functions[current_layer_ + 1], entries, curr, func_idx);
	}

	// We only want to apply layers once
	initialized_ = true;
	}

	void LayerLoader::LoadLayers() {
	std::string debug_layers = GetDebugLayers();

	// If no layers are specified, we're done
	if (debug_layers.empty()) return;

	// Only enable the system search path for non-user builds
	std::string system_path;
	if (android::GraphicsEnv::getInstance().isDebuggable()) {
	system_path = kSystemLayerLibraryDir;
	}

	ALOGI("Debug layer list: %s", debug_layers.c_str());
	std::vector<std::string> layers = android::base::Split(debug_layers, ":");

	// Load the layers in reverse order so we start with the driver's entrypoint and work our way up
	for (int32_t i = layers.size() - 1; i >= 0; i--) {
	// Check each layer path for the layer
	std::vector<std::string> paths =
	android::base::Split(android::GraphicsEnv::getInstance().getLayerPaths().c_str(),
	":");

	if (!system_path.empty()) {
	// Prepend the system paths so they override other layers
	auto it = paths.begin();
	paths.insert(it, system_path);
	}

	bool layer_found = false;
	for (uint32_t j = 0; j < paths.size() && !layer_found; j++) {
	std::string layer;

	ALOGI("Searching %s for GLES layers", paths[j].c_str());

	// Realpath will return null for non-existent files
	android::base::Realpath(paths[j] + "/" + layers[i], &layer);

	if (!layer.empty()) {
	layer_found = true;
	ALOGI("GLES layer found: %s", layer.c_str());

	// Load the layer
	//
	// TODO: This code is common with Vulkan loader, refactor
	//
	// Libraries in the system layer library dir can't be loaded into
	// the application namespace. That causes compatibility problems, since
	// any symbol dependencies will be resolved by system libraries. They
	// can't safely use libc++_shared, for example. Which is one reason
	// (among several) we only allow them in non-user builds.
	auto app_namespace = android::GraphicsEnv::getInstance().getAppNamespace();
	if (app_namespace && !android::base::StartsWith(layer, kSystemLayerLibraryDir)) {
	char* error_message = nullptr;
	dlhandle_ = OpenNativeLibraryInNamespace(app_namespace, layer.c_str(),
	&native_bridge_, &error_message);
	if (!dlhandle_) {
	ALOGE("Failed to load layer %s with error: %s", layer.c_str(),
	error_message);
	android::NativeLoaderFreeErrorMessage(error_message);
	return;
	}

	} else {
	dlhandle_ = dlopen(layer.c_str(), RTLD_NOW \| RTLD_LOCAL);
	}

	if (dlhandle_) {
	ALOGV("Loaded layer handle (%llu) for layer %s", (unsigned long long)dlhandle_,
	layers[i].c_str());
	} else {
	// If the layer is found but can't be loaded, try setenforce 0
	const char* dlsym_error = dlerror();
	ALOGE("Failed to load layer %s with error: %s", layer.c_str(), dlsym_error);
	return;
	}

	// Find the layer's Initialize function
	std::string init_func = "AndroidGLESLayer_Initialize";
	ALOGV("Looking for entrypoint %s", init_func.c_str());

	layer_init_func LayerInit = GetTrampoline<layer_init_func>(init_func.c_str());
	if (LayerInit) {
	ALOGV("Found %s for layer %s", init_func.c_str(), layer.c_str());
	layer_init_.push_back(LayerInit);
	} else {
	ALOGE("Failed to dlsym %s for layer %s", init_func.c_str(), layer.c_str());
	return;
	}

	// Find the layer's setup function
	std::string setup_func = "AndroidGLESLayer_GetProcAddress";
	ALOGV("Looking for entrypoint %s", setup_func.c_str());

	layer_setup_func LayerSetup = GetTrampoline<layer_setup_func>(setup_func.c_str());
	if (LayerSetup) {
	ALOGV("Found %s for layer %s", setup_func.c_str(), layer.c_str());
	layer_setup_.push_back(LayerSetup);
	} else {
	ALOGE("Failed to dlsym %s for layer %s", setup_func.c_str(), layer.c_str());
	return;
	}
	}
	}
	}
	// Track this so we only attempt to load these once
	layers_loaded_ = true;
	}

	} // namespace android