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khanhduytran0/dlopen.cpp

Created August 23, 2020 00:10
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  1. @twaik twaik revised this gist Mar 17, 2019. No changes.
  2. @twaik twaik created this gist Mar 17, 2019.
    100 changes: 100 additions & 0 deletions dlopen.cpp
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,100 @@
    #include <dlfcn.h>
    #include <cstring>
    #include <android/dlext.h>

    #include "log.h" // LOGE, LOGW, etc...

    bool (*_android_init_namespaces)(const char* public_ns_sonames, const char* anon_ns_library_path) = nullptr;
    bool __unused android_init_namespaces(const char* public_ns_sonames, const char* anon_ns_library_path) {
    if (!_android_init_namespaces) {
    void *libdl_handle;
    char *error;
    libdl_handle = dlopen ("libdl.so", RTLD_NOW);
    if (!libdl_handle) {
    LOGE ("%s", dlerror());
    return false;
    }
    _android_init_namespaces = (bool (*)(const char*, const char*))
    dlsym(libdl_handle, "android_init_namespaces");
    if ((error = dlerror()) != nullptr) {
    LOGE ("%s", error);
    return false;
    }
    }
    return _android_init_namespaces(public_ns_sonames, anon_ns_library_path);
    }

    static struct android_namespace_t* (*_create_namespace)(const char* name,
    const char* ld_library_path,
    const char* default_library_path,
    uint64_t type,
    const char* permitted_when_isolated_path,
    struct android_namespace_t* parent_namespace) = nullptr;
    static struct android_namespace_t* create_namespace(const char* name,
    const char* ld_library_path,
    const char* default_library_path,
    uint64_t type,
    const char* permitted_when_isolated_path,
    struct android_namespace_t* parent_namespace) {
    if (!_create_namespace) {
    void *libdl_handle;
    char *error;
    libdl_handle = dlopen ("libdl.so", RTLD_NOW);
    if (!libdl_handle) {
    LOGE ("error opening libdl.so: %s", dlerror());
    return nullptr;
    }
    _create_namespace = (struct android_namespace_t* (*)(const char*, const char*, const char*,
    uint64_t, const char*, struct android_namespace_t* ))
    dlsym(libdl_handle, "android_create_namespace");
    if (_create_namespace == nullptr) {
    if ((error = dlerror()) != nullptr && strcmp(error, "undefined symbol") < 0)
    LOGE("error opening android_create_namespace in libdl.so: %s\n", error);
    else LOGE("error opening android_create_namespace in libdl.so");
    return nullptr;
    }
    }
    LOGV("Creating namespace");
    return _create_namespace(name, ld_library_path, default_library_path, type, permitted_when_isolated_path, parent_namespace);
    }

    static char *ld_library_path = (char*)"/system/lib:/vendor/lib:/system/vendor/lib/hw/:/vendor/lib/hw";
    static struct android_namespace_t *ns = nullptr;
    static void* (*_dlopen_ext)(const char* filename, int flags, const android_dlextinfo* extinfo) = nullptr;
    void* dlopen_ext(const char* filename, int flags) {
    if (!_dlopen_ext) {
    void *libdl_handle;
    char *error;
    libdl_handle = dlopen ("libdl.so", RTLD_NOW);
    if (!libdl_handle) {
    LOGE ("Error dlopening libdl.so: %s", dlerror());
    LOGV("Dlopening using default dlopen");
    return dlopen (filename, flags);
    }
    _dlopen_ext = (void* (*)(const char*, int, const android_dlextinfo*)) dlsym(libdl_handle, "android_dlopen_ext");
    if (!_dlopen_ext) {
    error = dlerror();
    LOGE ("Error opening dlopen_ext in libdl.so ( %s )", (error)?error:"");
    LOGV("Dlopening using default dlopen");
    return dlopen (filename, flags);
    }
    }

    if (ns == nullptr) {
    // Not needed in JNI
    // android_init_namespaces("", ld_library_path);
    ns = create_namespace("system-namespace",ld_library_path, ld_library_path,0,ld_library_path,
    nullptr);
    }

    if (ns != nullptr && _dlopen_ext != nullptr) {
    android_dlextinfo ext = {0};
    ext.flags = ANDROID_DLEXT_USE_NAMESPACE;
    ext.library_namespace = ns;
    LOGV("Dlopening using default dlopen_ext");
    return _dlopen_ext (filename, flags, &ext);
    }

    LOGV("Dlopening using default dlopen");
    return dlopen (filename, flags);
    }