191 lines
7.0 KiB
C
191 lines
7.0 KiB
C
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef __ANDROID_DLEXT_H__
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#define __ANDROID_DLEXT_H__
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <sys/cdefs.h>
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#include <sys/types.h> /* for off64_t */
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/**
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* @addtogroup libdl Dynamic Linker
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* @{
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*/
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/**
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* \file
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* Advanced dynamic library opening support. Most users will want to use
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* the standard [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html)
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* functionality in `<dlfcn.h>` instead.
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*/
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__BEGIN_DECLS
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/** Bitfield definitions for `android_dlextinfo::flags`. */
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enum {
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/**
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* When set, the `reserved_addr` and `reserved_size` fields must point to an
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* already-reserved region of address space which will be used to load the
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* library if it fits.
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*
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* If the reserved region is not large enough, loading will fail.
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*/
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ANDROID_DLEXT_RESERVED_ADDRESS = 0x1,
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/**
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* Like `ANDROID_DLEXT_RESERVED_ADDRESS`, but if the reserved region is not large enough,
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* the linker will choose an available address instead.
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*/
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ANDROID_DLEXT_RESERVED_ADDRESS_HINT = 0x2,
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/**
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* When set, write the GNU RELRO section of the mapped library to `relro_fd`
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* after relocation has been performed, to allow it to be reused by another
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* process loading the same library at the same address. This implies
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* `ANDROID_DLEXT_USE_RELRO`.
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*
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* This is mainly useful for the system WebView implementation.
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*/
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ANDROID_DLEXT_WRITE_RELRO = 0x4,
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/**
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* When set, compare the GNU RELRO section of the mapped library to `relro_fd`
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* after relocation has been performed, and replace any relocated pages that
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* are identical with a version mapped from the file.
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*
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* This is mainly useful for the system WebView implementation.
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*/
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ANDROID_DLEXT_USE_RELRO = 0x8,
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/**
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* Use `library_fd` instead of opening the file by name.
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* The filename parameter is still used to identify the library.
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*/
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ANDROID_DLEXT_USE_LIBRARY_FD = 0x10,
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/**
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* If opening a library using `library_fd` read it starting at `library_fd_offset`.
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* This is mainly useful for loading a library stored within another file (such as uncompressed
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* inside a ZIP archive).
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* This flag is only valid when `ANDROID_DLEXT_USE_LIBRARY_FD` is set.
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*/
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ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET = 0x20,
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/**
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* When set, do not use `stat(2)` to check if the library has already been loaded.
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*
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* This flag allows forced loading of the library in the case when for some
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* reason multiple ELF files share the same filename (because the already-loaded
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* library has been removed and overwritten, for example).
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*
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* Note that if the library has the same `DT_SONAME` as an old one and some other
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* library has the soname in its `DT_NEEDED` list, the first one will be used to resolve any
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* dependencies.
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*/
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ANDROID_DLEXT_FORCE_LOAD = 0x40,
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// Historically we had two other options for ART.
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// They were last available in Android P.
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// Reuse these bits last!
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// ANDROID_DLEXT_FORCE_FIXED_VADDR = 0x80
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// ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100
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/**
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* This flag used to load library in a different namespace. The namespace is
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* specified in `library_namespace`.
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*
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* This flag is for internal use only (since there is no NDK API for namespaces).
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*/
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ANDROID_DLEXT_USE_NAMESPACE = 0x200,
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/**
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* Instructs dlopen to apply `ANDROID_DLEXT_RESERVED_ADDRESS`,
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* `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`, `ANDROID_DLEXT_WRITE_RELRO` and
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* `ANDROID_DLEXT_USE_RELRO` to any libraries loaded as dependencies of the
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* main library as well.
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*
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* This means that if the main library depends on one or more not-already-loaded libraries, they
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* will be loaded consecutively into the region starting at `reserved_addr`, and `reserved_size`
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* must be large enough to contain all of the libraries. The libraries will be loaded in the
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* deterministic order constructed from the DT_NEEDED entries, rather than the more secure random
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* order used by default.
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*
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* Each library's GNU RELRO sections will be written out to `relro_fd` in the same order they were
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* loaded. This will mean that the resulting file is dependent on which of the libraries were
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* already loaded, as only the newly loaded libraries will be included, not any already-loaded
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* dependencies. The caller should ensure that the set of libraries newly loaded is consistent
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* for this to be effective.
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*
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* This is mainly useful for the system WebView implementation.
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*/
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ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE = 0x400,
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/** Mask of valid bits. */
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ANDROID_DLEXT_VALID_FLAG_BITS = ANDROID_DLEXT_RESERVED_ADDRESS |
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ANDROID_DLEXT_RESERVED_ADDRESS_HINT |
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ANDROID_DLEXT_WRITE_RELRO |
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ANDROID_DLEXT_USE_RELRO |
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ANDROID_DLEXT_USE_LIBRARY_FD |
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ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET |
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ANDROID_DLEXT_FORCE_LOAD |
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ANDROID_DLEXT_USE_NAMESPACE |
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ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE,
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};
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struct android_namespace_t;
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/** Used to pass Android-specific arguments to `android_dlopen_ext`. */
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typedef struct {
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/** A bitmask of `ANDROID_DLEXT_` enum values. */
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uint64_t flags;
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/** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
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void* reserved_addr;
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/** Used by `ANDROID_DLEXT_RESERVED_ADDRESS` and `ANDROID_DLEXT_RESERVED_ADDRESS_HINT`. */
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size_t reserved_size;
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/** Used by `ANDROID_DLEXT_WRITE_RELRO` and `ANDROID_DLEXT_USE_RELRO`. */
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int relro_fd;
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/** Used by `ANDROID_DLEXT_USE_LIBRARY_FD`. */
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int library_fd;
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/** Used by `ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET` */
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off64_t library_fd_offset;
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/** Used by `ANDROID_DLEXT_USE_NAMESPACE`. */
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struct android_namespace_t* library_namespace;
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} android_dlextinfo;
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/**
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* Opens the given library. The `__filename` and `__flags` arguments are
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* the same as for [dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html),
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* with the Android-specific flags supplied via the `flags` member of `__info`.
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*
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* Available since API level 21.
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*/
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void* android_dlopen_ext(const char* __filename, int __flags, const android_dlextinfo* __info)
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__INTRODUCED_IN(21);
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__END_DECLS
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/** @} */
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#endif
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