Merge "Add api-level.h to dac, improve docs." am: a4110def5c

Original change: https://android-review.googlesource.com/c/platform/bionic/+/1393882

Change-Id: Ic1e5243c2dfcfa59edb9e68579e56002348d7523
This commit is contained in:
Dan Albert 2020-08-11 23:32:23 +00:00 committed by Automerger Merge Worker
commit 37b3e85a9d

View file

@ -28,6 +28,13 @@
#pragma once
/**
* @defgroup apilevels API Levels
*
* Defines functions and constants for working with Android API levels.
* @{
*/
/**
* @file android/api-level.h
* @brief Functions and constants for dealing with multiple API levels.
@ -50,9 +57,40 @@ __BEGIN_DECLS
/* This #ifndef should never be true except when doxygen is generating docs. */
#ifndef __ANDROID_API__
/**
* `__ANDROID_API__` is the API level being targeted. For the OS,
* this is `__ANDROID_API_FUTURE__`. For the NDK, this is set by the
* compiler system based on the API level you claimed to target. See
* `__ANDROID_API__` is the [API
* level](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
* this code is being built for. The resulting binaries are only guaranteed to
* be compatible with devices which have an API level greater than or equal to
* `__ANDROID_API__`.
*
* For NDK and APEX builds, this macro will always be defined. It is set
* automatically by Clang using the version suffix that is a part of the target
* name. For example, `__ANDROID_API__` will be 24 when Clang is given the
* argument `-target aarch64-linux-android24`.
*
* For non-APEX OS code, this defaults to __ANDROID_API_FUTURE__.
*
* The value of `__ANDROID_API__` can be compared to the named constants in
* `<android/api-level.h>`.
*
* The interpretation of `__ANDROID_API__` is similar to the AndroidManifest.xml
* `minSdkVersion`. In most cases `__ANDROID_API__` will be identical to
* `minSdkVersion`, but as it is a build time constant it is possible for
* library code to use a different value than the app it will be included in.
* When libraries and applications build for different API levels, the
* `minSdkVersion` of the application must be at least as high as the highest
* API level used by any of its libraries which are loaded unconditionally.
*
* Note that in some cases the resulting binaries may load successfully on
* devices with an older API level. That behavior should not be relied upon,
* even if you are careful to avoid using new APIs, as the toolchain may make
* use of new features by default. For example, additional FORTIFY features may
* implicitly make use of new APIs, SysV hashes may be omitted in favor of GNU
* hashes to improve library load times, or relocation packing may be enabled to
* reduce binary size.
*
* See android_get_device_api_level(),
* android_get_application_target_sdk_version() and
* https://android.googlesource.com/platform/bionic/+/master/docs/defines.md.
*/
#define __ANDROID_API__ __ANDROID_API_FUTURE__
@ -114,9 +152,9 @@ __BEGIN_DECLS
#define __ANDROID_API_S__ 31
/**
* Returns the `targetSdkVersion` of the caller, or `__ANDROID_API_FUTURE__`
* if there is no known target SDK version (for code not running in the
* context of an app).
* Returns the `targetSdkVersion` of the caller, or `__ANDROID_API_FUTURE__` if
* there is no known target SDK version (for code not running in the context of
* an app).
*
* The returned values correspond to the named constants in `<android/api-level.h>`,
* and is equivalent to the AndroidManifest.xml `targetSdkVersion`.
@ -148,3 +186,5 @@ int android_get_device_api_level() __INTRODUCED_IN(29);
#endif
__END_DECLS
/** @} */