libc/include/android/dlext.h - android_bionic - Gitiles

 /*
  * Copyright (C) 2014 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.
  */

 #ifndef __ANDROID_DLEXT_H__
 #define __ANDROID_DLEXT_H__

 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <sys/cdefs.h>
 #include <sys/types.h>  /* for off64_t */

 /**
  * @addtogroup libdl Dynamic Linker
  * @{
  */

 /**
  * \file
  * Advanced dynamic library opening support. Most users will want to use
  * the standard [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html)
  * functionality in `<dlfcn.h>` instead.
  */

 __BEGIN_DECLS

 /** Bitfield definitions for `android_dlextinfo::flags`. */
 enum {
   /**
    * When set, the `reserved_addr` and `reserved_size` fields must point to an
    * already-reserved region of address space which will be used to load the
    * library if it fits.
    *
    * If the reserved region is not large enough, loading will fail.
    */
   ANDROID_DLEXT_RESERVED_ADDRESS      = 0x1,

   /**
    * Like `ANDROID_DLEXT_RESERVED_ADDRESS`, but if the reserved region is not large enough,
    * the linker will choose an available address instead.
    */
   ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2,

   /**
    * When set, write the GNU RELRO section of the mapped library to `relro_fd`
    * after relocation has been performed, to allow it to be reused by another
    * process loading the same library at the same address. This implies
    * `ANDROID_DLEXT_USE_RELRO`.
    *
    * This is mainly useful for the system WebView implementation.
    */
   ANDROID_DLEXT_WRITE_RELRO           = 0x4,

   /**
    * When set, compare the GNU RELRO section of the mapped library to `relro_fd`
    * after relocation has been performed, and replace any relocated pages that
    * are identical with a version mapped from the file.
    *
    * This is mainly useful for the system WebView implementation.
    */
   ANDROID_DLEXT_USE_RELRO             = 0x8,

   /**
    * Use `library_fd` instead of opening the file by name.
    * The filename parameter is still used to identify the library.
    */
   ANDROID_DLEXT_USE_LIBRARY_FD        = 0x10,

   /**
    * If opening a library using `library_fd` read it starting at `library_fd_offset`.
    * This is mainly useful for loading a library stored within another file (such as uncompressed
    * inside a ZIP archive).
    * This flag is only valid when `ANDROID_DLEXT_USE_LIBRARY_FD` is set.
    */
   ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET    = 0x20,

   /**
    * When set, do not use `stat(2)` to check if the library has already been loaded.
    *
    * This flag allows forced loading of the library in the case when for some
    * reason multiple ELF files share the same filename (because the already-loaded
    * library has been removed and overwritten, for example).
    *
    * Note that if the library has the same `DT_SONAME` as an old one and some other
    * library has the soname in its `DT_NEEDED` list, the first one will be used to resolve any
    * dependencies.
    */
   ANDROID_DLEXT_FORCE_LOAD = 0x40,

   // Historically we had two other options for ART.
   // They were last available in Android P.
   // Reuse these bits last!
   // ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80
   // ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100

   /**
    * This flag used to load library in a different namespace. The namespace is
    * specified in `library_namespace`.
    *
    * This flag is for internal use only (since there is no NDK API for namespaces).
    */
   ANDROID_DLEXT_USE_NAMESPACE = 0x200,

   /**
    * Instructs dlopen to apply `ANDROID_DLEXT_RESERVED_ADDRESS`,
    * `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`, `ANDROID_DLEXT_WRITE_RELRO` and
    * `ANDROID_DLEXT_USE_RELRO` to any libraries loaded as dependencies of the
    * main library as well.
    *
    * This means that if the main library depends on one or more not-already-loaded libraries, they
    * will be loaded consecutively into the region starting at `reserved_addr`, and `reserved_size`
    * must be large enough to contain all of the libraries. The libraries will be loaded in the
    * deterministic order constructed from the DT_NEEDED entries, rather than the more secure random
    * order used by default.
    *
    * Each library's GNU RELRO sections will be written out to `relro_fd` in the same order they were
    * loaded. This will mean that the resulting file is dependent on which of the libraries were
    * already loaded, as only the newly loaded libraries will be included, not any already-loaded
    * dependencies. The caller should ensure that the set of libraries newly loaded is consistent
    * for this to be effective.
    *
    * This is mainly useful for the system WebView implementation.
    */
   ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE = 0x400,


   /** Mask of valid bits. */
   ANDROID_DLEXT_VALID_FLAG_BITS       = ANDROID_DLEXT_RESERVED_ADDRESS |
                                         ANDROID_DLEXT_RESERVED_ADDRESS_HINT |
                                         ANDROID_DLEXT_WRITE_RELRO |
                                         ANDROID_DLEXT_USE_RELRO |
                                         ANDROID_DLEXT_USE_LIBRARY_FD |
                                         ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET |
                                         ANDROID_DLEXT_FORCE_LOAD |
                                         ANDROID_DLEXT_USE_NAMESPACE |
                                         ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE,
 };

 struct android_namespace_t;

 /** Used to pass Android-specific arguments to `android_dlopen_ext`. */
 typedef struct {
   /** A bitmask of `ANDROID_DLEXT_` enum values. */
   uint64_t flags;

   /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
   void*   reserved_addr;
   /** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
   size_t  reserved_size;

   /** Used by `ANDROID_DLEXT_WRITE_RELRO` and `ANDROID_DLEXT_USE_RELRO`. */
   int     relro_fd;

   /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD`. */
   int     library_fd;
   /** Used by `ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET` */
   off64_t library_fd_offset;

   /** Used by `ANDROID_DLEXT_USE_NAMESPACE`. */
   struct android_namespace_t* library_namespace;
 } android_dlextinfo;

 /**
  * Opens the given library. The `__filename` and `__flags` arguments are
  * the same as for [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html),
  * with the Android-specific flags supplied via the `flags` member of `__info`.
  *
  * Available since API level 21.
  */
 void* android_dlopen_ext(const char* __filename, int __flags, const android_dlextinfo* __info)
   __INTRODUCED_IN(21);

 __END_DECLS

 /** @} */

 #endif
	/*
	* Copyright (C) 2014 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.
	*/

	#ifndef __ANDROID_DLEXT_H__
	#define __ANDROID_DLEXT_H__

	#include <stdbool.h>
	#include <stddef.h>
	#include <stdint.h>
	#include <sys/cdefs.h>
	#include <sys/types.h> /* for off64_t */

	/**
	* @addtogroup libdl Dynamic Linker
	* @{
	*/

	/**
	* \file
	* Advanced dynamic library opening support. Most users will want to use
	* the standard [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html)
	* functionality in `<dlfcn.h>` instead.
	*/

	__BEGIN_DECLS

	/** Bitfield definitions for `android_dlextinfo::flags`. */
	enum {
	/**
	* When set, the `reserved_addr` and `reserved_size` fields must point to an
	* already-reserved region of address space which will be used to load the
	* library if it fits.
	*
	* If the reserved region is not large enough, loading will fail.
	*/
	ANDROID_DLEXT_RESERVED_ADDRESS = 0x1,

	/**
	* Like `ANDROID_DLEXT_RESERVED_ADDRESS`, but if the reserved region is not large enough,
	* the linker will choose an available address instead.
	*/
	ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2,

	/**
	* When set, write the GNU RELRO section of the mapped library to `relro_fd`
	* after relocation has been performed, to allow it to be reused by another
	* process loading the same library at the same address. This implies
	* `ANDROID_DLEXT_USE_RELRO`.
	*
	* This is mainly useful for the system WebView implementation.
	*/
	ANDROID_DLEXT_WRITE_RELRO = 0x4,

	/**
	* When set, compare the GNU RELRO section of the mapped library to `relro_fd`
	* after relocation has been performed, and replace any relocated pages that
	* are identical with a version mapped from the file.
	*
	* This is mainly useful for the system WebView implementation.
	*/
	ANDROID_DLEXT_USE_RELRO = 0x8,

	/**
	* Use `library_fd` instead of opening the file by name.
	* The filename parameter is still used to identify the library.
	*/
	ANDROID_DLEXT_USE_LIBRARY_FD = 0x10,

	/**
	* If opening a library using `library_fd` read it starting at `library_fd_offset`.
	* This is mainly useful for loading a library stored within another file (such as uncompressed
	* inside a ZIP archive).
	* This flag is only valid when `ANDROID_DLEXT_USE_LIBRARY_FD` is set.
	*/
	ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET = 0x20,

	/**
	* When set, do not use `stat(2)` to check if the library has already been loaded.
	*
	* This flag allows forced loading of the library in the case when for some
	* reason multiple ELF files share the same filename (because the already-loaded
	* library has been removed and overwritten, for example).
	*
	* Note that if the library has the same `DT_SONAME` as an old one and some other
	* library has the soname in its `DT_NEEDED` list, the first one will be used to resolve any
	* dependencies.
	*/
	ANDROID_DLEXT_FORCE_LOAD = 0x40,

	// Historically we had two other options for ART.
	// They were last available in Android P.
	// Reuse these bits last!
	// ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80
	// ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100

	/**
	* This flag used to load library in a different namespace. The namespace is
	* specified in `library_namespace`.
	*
	* This flag is for internal use only (since there is no NDK API for namespaces).
	*/
	ANDROID_DLEXT_USE_NAMESPACE = 0x200,

	/**
	* Instructs dlopen to apply `ANDROID_DLEXT_RESERVED_ADDRESS`,
	* `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`, `ANDROID_DLEXT_WRITE_RELRO` and
	* `ANDROID_DLEXT_USE_RELRO` to any libraries loaded as dependencies of the
	* main library as well.
	*
	* This means that if the main library depends on one or more not-already-loaded libraries, they
	* will be loaded consecutively into the region starting at `reserved_addr`, and `reserved_size`
	* must be large enough to contain all of the libraries. The libraries will be loaded in the
	* deterministic order constructed from the DT_NEEDED entries, rather than the more secure random
	* order used by default.
	*
	* Each library's GNU RELRO sections will be written out to `relro_fd` in the same order they were
	* loaded. This will mean that the resulting file is dependent on which of the libraries were
	* already loaded, as only the newly loaded libraries will be included, not any already-loaded
	* dependencies. The caller should ensure that the set of libraries newly loaded is consistent
	* for this to be effective.
	*
	* This is mainly useful for the system WebView implementation.
	*/
	ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE = 0x400,


	/** Mask of valid bits. */
	ANDROID_DLEXT_VALID_FLAG_BITS = ANDROID_DLEXT_RESERVED_ADDRESS \|
	ANDROID_DLEXT_RESERVED_ADDRESS_HINT \|
	ANDROID_DLEXT_WRITE_RELRO \|
	ANDROID_DLEXT_USE_RELRO \|
	ANDROID_DLEXT_USE_LIBRARY_FD \|
	ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET \|
	ANDROID_DLEXT_FORCE_LOAD \|
	ANDROID_DLEXT_USE_NAMESPACE \|
	ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE,
	};

	struct android_namespace_t;

	/** Used to pass Android-specific arguments to `android_dlopen_ext`. */
	typedef struct {
	/** A bitmask of `ANDROID_DLEXT_` enum values. */
	uint64_t flags;

	/** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
	void* reserved_addr;
	/** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
	size_t reserved_size;

	/** Used by `ANDROID_DLEXT_WRITE_RELRO` and `ANDROID_DLEXT_USE_RELRO`. */
	int relro_fd;

	/** Used by `ANDROID_DLEXT_USE_LIBRARY_FD`. */
	int library_fd;
	/** Used by `ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET` */
	off64_t library_fd_offset;

	/** Used by `ANDROID_DLEXT_USE_NAMESPACE`. */
	struct android_namespace_t* library_namespace;
	} android_dlextinfo;

	/**
	* Opens the given library. The `__filename` and `__flags` arguments are
	* the same as for [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html),
	* with the Android-specific flags supplied via the `flags` member of `__info`.
	*
	* Available since API level 21.
	*/
	void* android_dlopen_ext(const char* __filename, int __flags, const android_dlextinfo* __info)
	__INTRODUCED_IN(21);

	__END_DECLS

	/** @} */

	#endif