platform_bionic/libc/include/android/dlext.h
Elliott Hughes 655e430b28 Remove the always-true __INTRODUCED_IN() annotations.
The NDK no longer supports API levels earlier than 21.

This *doesn't* include <ctype.h> because I have a separate change
rewriting that (that's blocked on the upcoming libc++ update).

Test: treehugger
Change-Id: I53e915f27011dfc0513e0c78d8799377e183ceca
2023-06-16 12:39:33 -07:00

187 lines
7 KiB
C

/*
* 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* _Nullable 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* _Nullable 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`.
*/
void* _Nullable android_dlopen_ext(const char* _Nullable __filename, int __flags, const android_dlextinfo* _Nullable __info);
__END_DECLS
/** @} */
#endif