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| 1 | +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT |
| 2 | +// file at the top-level directory of this distribution and at |
| 3 | +// http://rust-lang.org/COPYRIGHT. |
| 4 | +// |
| 5 | +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| 6 | +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| 7 | +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| 8 | +// option. This file may not be copied, modified, or distributed |
| 9 | +// except according to those terms. |
| 10 | + |
| 11 | +//! Android ABI-compatibility module |
| 12 | +//! |
| 13 | +//! The ABI of Android has changed quite a bit over time, and libstd attempts to |
| 14 | +//! be both forwards and backwards compatible as much as possible. We want to |
| 15 | +//! always work with the most recent version of Android, but we also want to |
| 16 | +//! work with older versions of Android for whenever projects need to. |
| 17 | +//! |
| 18 | +//! Our current minimum supported Android version is `android-9`, e.g. Android |
| 19 | +//! with API level 9. We then in theory want to work on that and all future |
| 20 | +//! versions of Android! |
| 21 | +//! |
| 22 | +//! Some of the detection here is done at runtime via `dlopen` and |
| 23 | +//! introspection. Other times no detection is performed at all and we just |
| 24 | +//! provide a fallback implementation as some versions of Android we support |
| 25 | +//! don't have the function. |
| 26 | +//! |
| 27 | +//! You'll find more details below about why each compatibility shim is needed. |
| 28 | +
|
| 29 | +#![cfg(target_os = "android")] |
| 30 | + |
| 31 | +use libc::{c_int, sighandler_t}; |
| 32 | + |
| 33 | +use io; |
| 34 | +use sys::cvt_r; |
| 35 | + |
| 36 | +// The `log2` and `log2f` functions apparently appeared in android-18, or at |
| 37 | +// least you can see they're not present in the android-17 header [1] and they |
| 38 | +// are present in android-18 [2]. |
| 39 | +// |
| 40 | +// [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms |
| 41 | +// /android-17/arch-arm/usr/include/math.h |
| 42 | +// [2]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms |
| 43 | +// /android-18/arch-arm/usr/include/math.h |
| 44 | +// |
| 45 | +// Note that these shims are likely less precise than directly calling `log2`, |
| 46 | +// but hopefully that should be enough for now... |
| 47 | +// |
| 48 | +// Note that mathematically, for any arbitrary `y`: |
| 49 | +// |
| 50 | +// log_2(x) = log_y(x) / log_y(2) |
| 51 | +// = log_y(x) / (1 / log_2(y)) |
| 52 | +// = log_y(x) * log_2(y) |
| 53 | +// |
| 54 | +// Hence because `ln` (log_e) is available on all Android we just choose `y = e` |
| 55 | +// and get: |
| 56 | +// |
| 57 | +// log_2(x) = ln(x) * log_2(e) |
| 58 | + |
| 59 | +#[cfg(not(test))] |
| 60 | +pub fn log2f32(f: f32) -> f32 { |
| 61 | + f.ln() * ::f32::consts::LOG2_E |
| 62 | +} |
| 63 | + |
| 64 | +#[cfg(not(test))] |
| 65 | +pub fn log2f64(f: f64) -> f64 { |
| 66 | + f.ln() * ::f64::consts::LOG2_E |
| 67 | +} |
| 68 | + |
| 69 | +// Back in the day [1] the `signal` function was just an inline wrapper |
| 70 | +// around `bsd_signal`, but starting in API level android-20 the `signal` |
| 71 | +// symbols was introduced [2]. Finally, in android-21 the API `bsd_signal` was |
| 72 | +// removed [3]. |
| 73 | +// |
| 74 | +// Basically this means that if we want to be binary compatible with multiple |
| 75 | +// Android releases (oldest being 9 and newest being 21) then we need to check |
| 76 | +// for both symbols and not actually link against either. |
| 77 | +// |
| 78 | +// [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms |
| 79 | +// /android-18/arch-arm/usr/include/signal.h |
| 80 | +// [2]: https://chromium.googlesource.com/android_tools/+/fbd420/ndk_experimental |
| 81 | +// /platforms/android-20/arch-arm |
| 82 | +// /usr/include/signal.h |
| 83 | +// [3]: https://chromium.googlesource.com/android_tools/+/20ee6d/ndk/platforms |
| 84 | +// /android-21/arch-arm/usr/include/signal.h |
| 85 | +pub unsafe fn signal(signum: c_int, handler: sighandler_t) -> sighandler_t { |
| 86 | + weak!(fn signal(c_int, sighandler_t) -> sighandler_t); |
| 87 | + weak!(fn bsd_signal(c_int, sighandler_t) -> sighandler_t); |
| 88 | + |
| 89 | + let f = signal.get().or_else(|| bsd_signal.get()); |
| 90 | + let f = f.expect("neither `signal` nor `bsd_signal` symbols found"); |
| 91 | + f(signum, handler) |
| 92 | +} |
| 93 | + |
| 94 | +// The `ftruncate64` symbol apparently appeared in android-12, so we do some |
| 95 | +// dynamic detection to see if we can figure out whether `ftruncate64` exists. |
| 96 | +// |
| 97 | +// If it doesn't we just fall back to `ftruncate`, generating an error for |
| 98 | +// too-large values. |
| 99 | +pub fn ftruncate64(fd: c_int, size: u64) -> io::Result<()> { |
| 100 | + weak!(fn ftruncate64(c_int, i64) -> c_int); |
| 101 | + |
| 102 | + extern { |
| 103 | + fn ftruncate(fd: c_int, off: i32) -> c_int; |
| 104 | + } |
| 105 | + |
| 106 | + unsafe { |
| 107 | + match ftruncate64.get() { |
| 108 | + Some(f) => cvt_r(|| f(fd, size as i64)).map(|_| ()), |
| 109 | + None => { |
| 110 | + if size > i32::max_value() as u64 { |
| 111 | + Err(io::Error::new(io::ErrorKind::InvalidInput, |
| 112 | + "cannot truncate >2GB")) |
| 113 | + } else { |
| 114 | + cvt_r(|| ftruncate(fd, size as i32)).map(|_| ()) |
| 115 | + } |
| 116 | + } |
| 117 | + } |
| 118 | + } |
| 119 | +} |
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