opengl/libs/EGL/Loader.cpp

/*
 ** Copyright 2007, 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_NDEBUG 0
#define ATRACE_TAG ATRACE_TAG_GRAPHICS

#include "Loader.h"

#include <string>

#include <dirent.h>
#include <dlfcn.h>

#include <android/dlext.h>
#include <cutils/properties.h>
#include <log/log.h>

#ifndef __ANDROID_VNDK__
#include <graphicsenv/GraphicsEnv.h>
#endif
#include <vndksupport/linker.h>

#include "egl_platform_entries.h"
#include "egl_trace.h"
#include "egldefs.h"
#include <EGL/eglext_angle.h>

extern "C" {
  android_namespace_t* android_get_exported_namespace(const char*);

  typedef enum ANGLEPreference {
      ANGLE_PREFER_DEFAULT = 0,
      ANGLE_PREFER_NATIVE = 1,
      ANGLE_PREFER_ANGLE = 2,
  } ANGLEPreference;

  // TODO(ianelliott@): Get the following from an ANGLE header:
  // Version-1 API:
  typedef bool (*fpANGLEGetUtilityAPI)(unsigned int* versionToUse);
  typedef bool (*fpAndroidUseANGLEForApplication)(int fd, long offset, long length,
                                                  const char* appName, const char* deviceMfr,
                                                  const char* deviceModel);
  // Version-2 API:
  typedef bool (*fpANGLEGetFeatureSupportUtilAPIVersion)(unsigned int* versionToUse);
  typedef bool (*fpANGLEAndroidParseRulesString)(const char *rulesString,
                                                 void** rulesHandle, int* rulesVersion);
  typedef bool (*fpANGLEGetSystemInfo)(void** handle);
  typedef bool (*fpANGLEAddDeviceInfoToSystemInfo)(const char* deviceMfr,
                                                   const char* deviceModel,
                                                   void* handle);
  typedef bool (*fpANGLEShouldBeUsedForApplication)(void* rules_handle,
                                                    int rules_version,
                                                    void* system_info_handle,
                                                    const char *appName);
  typedef bool (*fpANGLEFreeRulesHandle)(void* handle);
  typedef bool (*fpANGLEFreeSystemInfoHandle)(void* handle);

}

// ----------------------------------------------------------------------------
namespace android {
// ----------------------------------------------------------------------------


/*
 * EGL userspace drivers must be provided either:
 * - as a single library:
 *      /vendor/lib/egl/libGLES.so
 *
 * - as separate libraries:
 *      /vendor/lib/egl/libEGL.so
 *      /vendor/lib/egl/libGLESv1_CM.so
 *      /vendor/lib/egl/libGLESv2.so
 *
 * The software renderer for the emulator must be provided as a single
 * library at:
 *
 *      /system/lib/egl/libGLES_android.so
 *
 *
 * For backward compatibility and to facilitate the transition to
 * this new naming scheme, the loader will additionally look for:
 *
 *      /{vendor|system}/lib/egl/lib{GLES | [EGL|GLESv1_CM|GLESv2]}_*.so
 *
 */

Loader& Loader::getInstance() {
    static Loader loader;
    return loader;
}

/* This function is called to check whether we run inside the emulator,
 * and if this is the case whether GLES GPU emulation is supported.
 *
 * Returned values are:
 *  -1   -> not running inside the emulator
 *   0   -> running inside the emulator, but GPU emulation not supported
 *   1   -> running inside the emulator, GPU emulation is supported
 *          through the "emulation" host-side OpenGL ES implementation.
 *   2   -> running inside the emulator, GPU emulation is supported
 *          through a guest-side vendor driver's OpenGL ES implementation.
 */
static int
checkGlesEmulationStatus(void)
{
    /* We're going to check for the following kernel parameters:
     *
     *    qemu=1                      -> tells us that we run inside the emulator
     *    android.qemu.gles=<number>  -> tells us the GLES GPU emulation status
     *
     * Note that we will return <number> if we find it. This let us support
     * more additionnal emulation modes in the future.
     */
    char  prop[PROPERTY_VALUE_MAX];
    int   result = -1;

    /* First, check for qemu=1 */
    property_get("ro.kernel.qemu",prop,"0");
    if (atoi(prop) != 1)
        return -1;

    /* We are in the emulator, get GPU status value */
    property_get("qemu.gles",prop,"0");
    return atoi(prop);
}

static void* do_dlopen(const char* path, int mode) {
    ATRACE_CALL();
    return dlopen(path, mode);
}

static void* do_android_dlopen_ext(const char* path, int mode, const android_dlextinfo* info) {
    ATRACE_CALL();
    return android_dlopen_ext(path, mode, info);
}

static void* do_android_load_sphal_library(const char* path, int mode) {
    ATRACE_CALL();
    return android_load_sphal_library(path, mode);
}

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

Loader::driver_t::driver_t(void* gles)
{
    dso[0] = gles;
    for (size_t i=1 ; i<NELEM(dso) ; i++)
        dso[i] = nullptr;
}

Loader::driver_t::~driver_t()
{
    for (size_t i=0 ; i<NELEM(dso) ; i++) {
        if (dso[i]) {
            dlclose(dso[i]);
            dso[i] = nullptr;
        }
    }
}

int Loader::driver_t::set(void* hnd, int32_t api)
{
    switch (api) {
        case EGL:
            dso[0] = hnd;
            break;
        case GLESv1_CM:
            dso[1] = hnd;
            break;
        case GLESv2:
            dso[2] = hnd;
            break;
        default:
            return -EOVERFLOW;
    }
    return 0;
}

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

Loader::Loader()
    : getProcAddress(nullptr)
{
}

Loader::~Loader() {
}

static void* load_wrapper(const char* path) {
    void* so = do_dlopen(path, RTLD_NOW | RTLD_LOCAL);
    ALOGE_IF(!so, "dlopen(\"%s\") failed: %s", path, dlerror());
    return so;
}

#ifndef EGL_WRAPPER_DIR
#if defined(__LP64__)
#define EGL_WRAPPER_DIR "/system/lib64"
#else
#define EGL_WRAPPER_DIR "/system/lib"
#endif
#endif

static void setEmulatorGlesValue(void) {
    char prop[PROPERTY_VALUE_MAX];
    property_get("ro.kernel.qemu", prop, "0");
    if (atoi(prop) != 1) return;

    property_get("ro.kernel.qemu.gles",prop,"0");
    if (atoi(prop) == 1) {
        ALOGD("Emulator has host GPU support, qemu.gles is set to 1.");
        property_set("qemu.gles", "1");
        return;
    }

    // for now, checking the following
    // directory is good enough for emulator system images
    const char* vendor_lib_path =
#if defined(__LP64__)
        "/vendor/lib64/egl";
#else
        "/vendor/lib/egl";
#endif

    const bool has_vendor_lib = (access(vendor_lib_path, R_OK) == 0);
    if (has_vendor_lib) {
        ALOGD("Emulator has vendor provided software renderer, qemu.gles is set to 2.");
        property_set("qemu.gles", "2");
    } else {
        ALOGD("Emulator without GPU support detected. "
              "Fallback to legacy software renderer, qemu.gles is set to 0.");
        property_set("qemu.gles", "0");
    }
}

void* Loader::open(egl_connection_t* cnx)
{
    ATRACE_CALL();

    void* dso;
    driver_t* hnd = nullptr;

    setEmulatorGlesValue();

    dso = load_driver("GLES", cnx, EGL | GLESv1_CM | GLESv2);
    if (dso) {
        hnd = new driver_t(dso);
    } else {
        // Always load EGL first
        dso = load_driver("EGL", cnx, EGL);
        if (dso) {
            hnd = new driver_t(dso);
            hnd->set( load_driver("GLESv1_CM", cnx, GLESv1_CM), GLESv1_CM );
            hnd->set( load_driver("GLESv2",    cnx, GLESv2),    GLESv2 );
        }
    }

    LOG_ALWAYS_FATAL_IF(!hnd, "couldn't find an OpenGL ES implementation");

    cnx->libEgl   = load_wrapper(EGL_WRAPPER_DIR "/libEGL.so");
    cnx->libGles2 = load_wrapper(EGL_WRAPPER_DIR "/libGLESv2.so");
    cnx->libGles1 = load_wrapper(EGL_WRAPPER_DIR "/libGLESv1_CM.so");

    LOG_ALWAYS_FATAL_IF(!cnx->libEgl,
            "couldn't load system EGL wrapper libraries");

    LOG_ALWAYS_FATAL_IF(!cnx->libGles2 || !cnx->libGles1,
            "couldn't load system OpenGL ES wrapper libraries");

    return (void*)hnd;
}

void Loader::close(egl_connection_t* cnx)
{
    driver_t* hnd = (driver_t*) cnx->dso;
    delete hnd;
    cnx->dso = nullptr;

    if (cnx->featureSo) {
        dlclose(cnx->featureSo);
        cnx->featureSo = nullptr;
    }

    cnx->angleDecided = false;
    cnx->useAngle = false;

    if (cnx->vendorEGL) {
        dlclose(cnx->vendorEGL);
        cnx->vendorEGL = nullptr;
    }
}

void Loader::init_api(void* dso,
        char const * const * api,
        char const * const * ref_api,
        __eglMustCastToProperFunctionPointerType* curr,
        getProcAddressType getProcAddress)
{
    ATRACE_CALL();

    const ssize_t SIZE = 256;
    char scrap[SIZE];
    while (*api) {
        char const * name = *api;
        if (ref_api) {
            char const * ref_name = *ref_api;
            if (std::strcmp(name, ref_name) != 0) {
                *curr++ = nullptr;
                ref_api++;
                continue;
            }
        }

        __eglMustCastToProperFunctionPointerType f =
            (__eglMustCastToProperFunctionPointerType)dlsym(dso, name);
        if (f == nullptr) {
            // couldn't find the entry-point, use eglGetProcAddress()
            f = getProcAddress(name);
        }
        if (f == nullptr) {
            // Try without the OES postfix
            ssize_t index = ssize_t(strlen(name)) - 3;
            if ((index>0 && (index<SIZE-1)) && (!strcmp(name+index, "OES"))) {
                strncpy(scrap, name, index);
                scrap[index] = 0;
                f = (__eglMustCastToProperFunctionPointerType)dlsym(dso, scrap);
                //ALOGD_IF(f, "found <%s> instead", scrap);
            }
        }
        if (f == nullptr) {
            // Try with the OES postfix
            ssize_t index = ssize_t(strlen(name)) - 3;
            if (index>0 && strcmp(name+index, "OES")) {
                snprintf(scrap, SIZE, "%sOES", name);
                f = (__eglMustCastToProperFunctionPointerType)dlsym(dso, scrap);
                //ALOGD_IF(f, "found <%s> instead", scrap);
            }
        }
        if (f == nullptr) {
            //ALOGD("%s", name);
            f = (__eglMustCastToProperFunctionPointerType)gl_unimplemented;

            /*
             * GL_EXT_debug_label is special, we always report it as
             * supported, it's handled by GLES_trace. If GLES_trace is not
             * enabled, then these are no-ops.
             */
            if (!strcmp(name, "glInsertEventMarkerEXT")) {
                f = (__eglMustCastToProperFunctionPointerType)gl_noop;
            } else if (!strcmp(name, "glPushGroupMarkerEXT")) {
                f = (__eglMustCastToProperFunctionPointerType)gl_noop;
            } else if (!strcmp(name, "glPopGroupMarkerEXT")) {
                f = (__eglMustCastToProperFunctionPointerType)gl_noop;
            }
        }
        *curr++ = f;
        api++;
        if (ref_api) ref_api++;
    }
}

static void* load_system_driver(const char* kind) {
    ATRACE_CALL();
    class MatchFile {
    public:
        static std::string find(const char* kind) {
            std::string result;
            int emulationStatus = checkGlesEmulationStatus();
            switch (emulationStatus) {
                case 0:
#if defined(__LP64__)
                    result = "/vendor/lib64/egl/libGLES_android.so";
#else
                    result = "/vendor/lib/egl/libGLES_android.so";
#endif
                    return result;
                case 1:
                    // Use host-side OpenGL through the "emulation" library
#if defined(__LP64__)
                    result = std::string("/vendor/lib64/egl/lib") + kind + "_emulation.so";
#else
                    result = std::string("/vendor/lib/egl/lib") + kind + "_emulation.so";
#endif
                    return result;
                case 2:
                    // Use guest side swiftshader library
#if defined(__LP64__)
                    result = std::string("/vendor/lib64/egl/lib") + kind + "_swiftshader.so";
#else
                    result = std::string("/vendor/lib/egl/lib") + kind + "_swiftshader.so";
#endif
                    return result;
                default:
                    // Not in emulator, or use other guest-side implementation
                    break;
            }

            std::string pattern = std::string("lib") + kind;
            const char* const searchPaths[] = {
#if defined(__LP64__)
                    "/vendor/lib64/egl",
                    "/system/lib64/egl"
#else
                    "/vendor/lib/egl",
                    "/system/lib/egl"
#endif
            };

            // first, we search for the exact name of the GLES userspace
            // driver in both locations.
            // i.e.:
            //      libGLES.so, or:
            //      libEGL.so, libGLESv1_CM.so, libGLESv2.so

            for (size_t i=0 ; i<NELEM(searchPaths) ; i++) {
                if (find(result, pattern, searchPaths[i], true)) {
                    return result;
                }
            }

            // for compatibility with the old "egl.cfg" naming convention
            // we look for files that match:
            //      libGLES_*.so, or:
            //      libEGL_*.so, libGLESv1_CM_*.so, libGLESv2_*.so

            pattern.append("_");
            for (size_t i=0 ; i<NELEM(searchPaths) ; i++) {
                if (find(result, pattern, searchPaths[i], false)) {
                    return result;
                }
            }

            // we didn't find the driver. gah.
            result.clear();
            return result;
        }

    private:
        static bool find(std::string& result,
                const std::string& pattern, const char* const search, bool exact) {
            if (exact) {
                std::string absolutePath = std::string(search) + "/" + pattern + ".so";
                if (!access(absolutePath.c_str(), R_OK)) {
                    result = absolutePath;
                    return true;
                }
                return false;
            }

            DIR* d = opendir(search);
            if (d != nullptr) {
                struct dirent* e;
                while ((e = readdir(d)) != nullptr) {
                    if (e->d_type == DT_DIR) {
                        continue;
                    }
                    if (!strcmp(e->d_name, "libGLES_android.so")) {
                        // always skip the software renderer
                        continue;
                    }
                    if (strstr(e->d_name, pattern.c_str()) == e->d_name) {
                        if (!strcmp(e->d_name + strlen(e->d_name) - 3, ".so")) {
                            result = std::string(search) + "/" + e->d_name;
                            closedir(d);
                            return true;
                        }
                    }
                }
                closedir(d);
            }
            return false;
        }
    };


    std::string absolutePath = MatchFile::find(kind);
    if (absolutePath.empty()) {
        // this happens often, we don't want to log an error
        return nullptr;
    }
    const char* const driver_absolute_path = absolutePath.c_str();

    // Try to load drivers from the 'sphal' namespace, if it exist. Fall back to
    // the original routine when the namespace does not exist.
    // See /system/core/rootdir/etc/ld.config.txt for the configuration of the
    // sphal namespace.
    void* dso = do_android_load_sphal_library(driver_absolute_path,
                                              RTLD_NOW | RTLD_LOCAL);
    if (dso == nullptr) {
        const char* err = dlerror();
        ALOGE("load_driver(%s): %s", driver_absolute_path, err ? err : "unknown");
        return nullptr;
    }

    ALOGD("loaded %s", driver_absolute_path);

    return dso;
}

static void* load_angle_from_namespace(const char* kind, android_namespace_t* ns) {
    const android_dlextinfo dlextinfo = {
            .flags = ANDROID_DLEXT_USE_NAMESPACE,
            .library_namespace = ns,
    };

    std::string name = std::string("lib") + kind + "_angle.so";

    void* so = do_android_dlopen_ext(name.c_str(), RTLD_LOCAL | RTLD_NOW, &dlextinfo);

    if (so) {
        ALOGD("dlopen_ext from APK (%s) success at %p", name.c_str(), so);
        return so;
    } else {
        ALOGE("dlopen_ext(\"%s\") failed: %s", name.c_str(), dlerror());
    }

    return nullptr;
}

static ANGLEPreference getAngleDevOption(const char* devOption) {
    if (devOption == nullptr)
        return ANGLE_PREFER_DEFAULT;

    if (strcmp(devOption, "angle") == 0) {
        return ANGLE_PREFER_ANGLE;
    } else if (strcmp(devOption, "native") == 0) {
        return ANGLE_PREFER_NATIVE;
    }
    return ANGLE_PREFER_DEFAULT;
}

static bool check_angle_rules(void* so, const char* app_name) {
    bool use_angle = false;
    const int rules_fd = android::GraphicsEnv::getInstance().getAngleRulesFd();
    const long rules_offset = android::GraphicsEnv::getInstance().getAngleRulesOffset();
    const long rules_length = android::GraphicsEnv::getInstance().getAngleRulesLength();

    std::string app_name_str = app_name ? app_name : "";
    char manufacturer[PROPERTY_VALUE_MAX];
    char model[PROPERTY_VALUE_MAX];
    property_get("ro.product.manufacturer", manufacturer, "UNSET");
    property_get("ro.product.model", model, "UNSET");

    fpANGLEGetFeatureSupportUtilAPIVersion ANGLEGetFeatureSupportUtilAPIVersion =
            (fpANGLEGetFeatureSupportUtilAPIVersion)dlsym(so, "ANGLEGetFeatureSupportUtilAPIVersion");

    if (ANGLEGetFeatureSupportUtilAPIVersion) {

        // Negotiate the interface version by requesting most recent known to the platform
        unsigned int versionToUse = 2;
        if ((ANGLEGetFeatureSupportUtilAPIVersion)(&versionToUse)) {

            // Add and remove versions below as needed
            switch(versionToUse) {
            case 2: {
                ALOGV("Using version 2 of ANGLE feature-support library");
                void* rules_handle = nullptr;
                int rules_version = 0;
                void* system_info_handle = nullptr;

                // Get the symbols for the feature-support-utility library:
#define GET_SYMBOL(symbol)                                               \
    fp##symbol symbol = (fp##symbol)dlsym(so, #symbol);                  \
    if (!symbol) {                                                       \
        ALOGW("Cannot find "#symbol" in ANGLE feature-support library"); \
        break;                                                           \
    }
                GET_SYMBOL(ANGLEAndroidParseRulesString);
                GET_SYMBOL(ANGLEGetSystemInfo);
                GET_SYMBOL(ANGLEAddDeviceInfoToSystemInfo);
                GET_SYMBOL(ANGLEShouldBeUsedForApplication);
                GET_SYMBOL(ANGLEFreeRulesHandle);
                GET_SYMBOL(ANGLEFreeSystemInfoHandle);

                // Read the contents of the file into a string:
                off_t fileSize       = rules_length;
                off_t startOfContent = rules_offset;
                lseek(rules_fd, startOfContent, SEEK_SET);
                char *buffer                   = new char[fileSize + 1];
                ssize_t numBytesRead           = read(rules_fd, buffer, fileSize);
                if (numBytesRead < 0) {
                    ALOGW("Cannot read rules file");
                    break;
                }
                if (numBytesRead == 0) {
                    ALOGW("Empty rules file");
                    break;
                }
                buffer[numBytesRead]           = '\0';
                std::string rule_file_contents = std::string(buffer);
                delete[] buffer;

                // Parse the rules, obtain the SystemInfo, and evaluate the
                // application against the rules:
                if (!(ANGLEAndroidParseRulesString)(rule_file_contents.c_str(),
                                                    &rules_handle, &rules_version)) {
                    ALOGW("ANGLE feature-support library cannot parse rules file");
                    break;
                }
                if (!(ANGLEGetSystemInfo)(&system_info_handle)) {
                    ALOGW("ANGLE feature-support library cannot obtain SystemInfo");
                    break;
                }
                if (!(ANGLEAddDeviceInfoToSystemInfo)(manufacturer, model, system_info_handle)) {
                    ALOGW("ANGLE feature-support library cannot add device info to SystemInfo");
                    break;
                }
                use_angle = (ANGLEShouldBeUsedForApplication)(rules_handle, rules_version,
                                                              system_info_handle, app_name_str.c_str());
                (ANGLEFreeRulesHandle)(rules_handle);
                (ANGLEFreeSystemInfoHandle)(system_info_handle);
            }
            break;
            default:
                ALOGW("Cannot find supported version of ANGLE feature-support library, found version %u", versionToUse);
            }
        } else {
            ALOGW("Cannot use ANGLE feature-support library, it is older than supported by EGL, requested version %u", versionToUse);
        }
    } else {
        ALOGW("Cannot find ANGLEGetFeatureSupportUtilAPIVersion function");
    }

    ALOGV("Close temporarily-loaded ANGLE opt-in/out logic");
    return use_angle;
}

static void* load_angle(const char* kind, android_namespace_t* ns, egl_connection_t* cnx) {
    // Only attempt to load ANGLE libs
    if (strcmp(kind, "EGL") != 0 && strcmp(kind, "GLESv2") != 0 && strcmp(kind, "GLESv1_CM") != 0)
        return nullptr;

    std::string name;
    char prop[PROPERTY_VALUE_MAX];

    const char* app_name = android::GraphicsEnv::getInstance().getAngleAppName();
    const char* developer_opt_in = android::GraphicsEnv::getInstance().getAngleDeveloperOptIn();

    // Determine whether or not to use ANGLE:
    ANGLEPreference developer_option = getAngleDevOption(developer_opt_in);
    bool use_angle = (developer_option == ANGLE_PREFER_ANGLE);

    if (use_angle) {
        ALOGV("User set \"Developer Options\" to force the use of ANGLE");
    } else if (cnx->angleDecided) {
        use_angle = cnx->useAngle;
    } else if (developer_option == ANGLE_PREFER_NATIVE) {
        ALOGV("User set \"Developer Options\" to force the use of Native");
        use_angle = false;
    } else {
        // The "Developer Options" value wasn't set to force the use of ANGLE.  Need to temporarily
        // load ANGLE and call the updatable opt-in/out logic:

        // Check if ANGLE is enabled. Workaround for several bugs:
        // b/119305693 b/119322355 b/119305887
        // Something is not working correctly in the feature library
        property_get("debug.angle.enable", prop, "0");
        if (atoi(prop)) {
            cnx->featureSo = load_angle_from_namespace("feature_support", ns);
        }
        if (cnx->featureSo) {
            ALOGV("loaded ANGLE's opt-in/out logic from namespace");
            use_angle = check_angle_rules(cnx->featureSo, app_name);
        } else {
            // We weren't able to load and call the updateable opt-in/out logic.
            // If we can't load the library, there is no ANGLE available.
            use_angle = false;
            ALOGV("Could not load the ANGLE opt-in/out logic, cannot use ANGLE.");
        }
        cnx->angleDecided = true;
    }
    void* so = nullptr;
    if (use_angle) {
        so = load_angle_from_namespace(kind, ns);
    }

    if (so) {
        ALOGV("Loaded ANGLE %s library for %s (instead of native)",
              kind, app_name ? app_name : "nullptr");
        property_get("debug.hwui.renderer", prop, "UNSET");
        ALOGV("Skia's renderer set to %s", prop);
        cnx->useAngle = true;

        EGLint angleBackendDefault = EGL_PLATFORM_ANGLE_TYPE_VULKAN_ANGLE;

        char prop[PROPERTY_VALUE_MAX];
        property_get("debug.angle.backend", prop, "0");
        switch (atoi(prop)) {
            case 1:
                ALOGV("%s: Requesting OpenGLES back-end", __FUNCTION__);
                angleBackendDefault = EGL_PLATFORM_ANGLE_TYPE_OPENGLES_ANGLE;
                break;
            case 2:
                ALOGV("%s: Requesting Vulkan back-end", __FUNCTION__);
                angleBackendDefault = EGL_PLATFORM_ANGLE_TYPE_VULKAN_ANGLE;
                break;
            default:
                break;
        }

        cnx->angleBackend = angleBackendDefault;
        if (!cnx->vendorEGL && (cnx->angleBackend == EGL_PLATFORM_ANGLE_TYPE_OPENGLES_ANGLE)) {
            // Find and load vendor libEGL for ANGLE's GL back-end to use.
            cnx->vendorEGL = load_system_driver("EGL");
        }
        return so;
    } else {
        ALOGV("Loaded native %s library for %s (instead of ANGLE)",
              kind, app_name ? app_name : "nullptr");
    }

    return nullptr;
}

static const char* HAL_SUBNAME_KEY_PROPERTIES[2] = {
    "ro.hardware.egl",
    "ro.board.platform",
};

static void* load_updated_driver(const char* kind, android_namespace_t* ns) {
    ATRACE_CALL();
    const android_dlextinfo dlextinfo = {
        .flags = ANDROID_DLEXT_USE_NAMESPACE,
        .library_namespace = ns,
    };
    void* so = nullptr;
    char prop[PROPERTY_VALUE_MAX + 1];
    for (auto key : HAL_SUBNAME_KEY_PROPERTIES) {
        if (property_get(key, prop, nullptr) > 0) {
            std::string name = std::string("lib") + kind + "_" + prop + ".so";
            so = do_android_dlopen_ext(name.c_str(), RTLD_LOCAL | RTLD_NOW, &dlextinfo);
            if (so) {
                return so;
            }
        }
    }
    return nullptr;
}

void *Loader::load_driver(const char* kind,
        egl_connection_t* cnx, uint32_t mask)
{
    ATRACE_CALL();

    void* dso = nullptr;
    android_namespace_t* ns = android::GraphicsEnv::getInstance().getAngleNamespace();
    if (ns) {
        dso = load_angle(kind, ns, cnx);
    }
#ifndef __ANDROID_VNDK__
    if (!dso) {
        android_namespace_t* ns = android::GraphicsEnv::getInstance().getDriverNamespace();
        if (ns) {
            dso = load_updated_driver(kind, ns);
        }
    }
#endif
    if (!dso) {
        dso = load_system_driver(kind);
        if (!dso)
            return nullptr;
    }

    if (mask & EGL) {
        getProcAddress = (getProcAddressType)dlsym(dso, "eglGetProcAddress");

        ALOGE_IF(!getProcAddress,
                "can't find eglGetProcAddress() in EGL driver library");

        egl_t* egl = &cnx->egl;
        __eglMustCastToProperFunctionPointerType* curr =
            (__eglMustCastToProperFunctionPointerType*)egl;
        char const * const * api = egl_names;
        while (*api) {
            char const * name = *api;
            __eglMustCastToProperFunctionPointerType f =
                (__eglMustCastToProperFunctionPointerType)dlsym(dso, name);
            if (f == nullptr) {
                // couldn't find the entry-point, use eglGetProcAddress()
                f = getProcAddress(name);
                if (f == nullptr) {
                    f = (__eglMustCastToProperFunctionPointerType)nullptr;
                }
            }
            *curr++ = f;
            api++;
        }
    }

    if (mask & GLESv1_CM) {
        init_api(dso, gl_names_1, gl_names,
            (__eglMustCastToProperFunctionPointerType*)
                &cnx->hooks[egl_connection_t::GLESv1_INDEX]->gl,
            getProcAddress);
    }

    if (mask & GLESv2) {
        init_api(dso, gl_names, nullptr,
            (__eglMustCastToProperFunctionPointerType*)
                &cnx->hooks[egl_connection_t::GLESv2_INDEX]->gl,
            getProcAddress);
    }

    return dso;
}

// ----------------------------------------------------------------------------
}; // namespace android
// ----------------------------------------------------------------------------