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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 | ||
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31 | use libc::{c_int, c_void, sighandler_t, size_t, ssize_t}; |
32 | use libc::{ftruncate, pread, pwrite}; | |
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33 | |
34 | use io; | |
c30ab7b3 | 35 | use super::{cvt, cvt_r}; |
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36 | |
37 | // The `log2` and `log2f` functions apparently appeared in android-18, or at | |
38 | // least you can see they're not present in the android-17 header [1] and they | |
39 | // are present in android-18 [2]. | |
40 | // | |
41 | // [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms | |
42 | // /android-17/arch-arm/usr/include/math.h | |
43 | // [2]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms | |
44 | // /android-18/arch-arm/usr/include/math.h | |
45 | // | |
46 | // Note that these shims are likely less precise than directly calling `log2`, | |
47 | // but hopefully that should be enough for now... | |
48 | // | |
49 | // Note that mathematically, for any arbitrary `y`: | |
50 | // | |
51 | // log_2(x) = log_y(x) / log_y(2) | |
52 | // = log_y(x) / (1 / log_2(y)) | |
53 | // = log_y(x) * log_2(y) | |
54 | // | |
55 | // Hence because `ln` (log_e) is available on all Android we just choose `y = e` | |
56 | // and get: | |
57 | // | |
58 | // log_2(x) = ln(x) * log_2(e) | |
59 | ||
60 | #[cfg(not(test))] | |
61 | pub fn log2f32(f: f32) -> f32 { | |
62 | f.ln() * ::f32::consts::LOG2_E | |
63 | } | |
64 | ||
65 | #[cfg(not(test))] | |
66 | pub fn log2f64(f: f64) -> f64 { | |
67 | f.ln() * ::f64::consts::LOG2_E | |
68 | } | |
69 | ||
70 | // Back in the day [1] the `signal` function was just an inline wrapper | |
71 | // around `bsd_signal`, but starting in API level android-20 the `signal` | |
72 | // symbols was introduced [2]. Finally, in android-21 the API `bsd_signal` was | |
73 | // removed [3]. | |
74 | // | |
75 | // Basically this means that if we want to be binary compatible with multiple | |
76 | // Android releases (oldest being 9 and newest being 21) then we need to check | |
77 | // for both symbols and not actually link against either. | |
78 | // | |
79 | // [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms | |
80 | // /android-18/arch-arm/usr/include/signal.h | |
81 | // [2]: https://chromium.googlesource.com/android_tools/+/fbd420/ndk_experimental | |
82 | // /platforms/android-20/arch-arm | |
83 | // /usr/include/signal.h | |
84 | // [3]: https://chromium.googlesource.com/android_tools/+/20ee6d/ndk/platforms | |
85 | // /android-21/arch-arm/usr/include/signal.h | |
86 | pub unsafe fn signal(signum: c_int, handler: sighandler_t) -> sighandler_t { | |
87 | weak!(fn signal(c_int, sighandler_t) -> sighandler_t); | |
88 | weak!(fn bsd_signal(c_int, sighandler_t) -> sighandler_t); | |
89 | ||
90 | let f = signal.get().or_else(|| bsd_signal.get()); | |
91 | let f = f.expect("neither `signal` nor `bsd_signal` symbols found"); | |
92 | f(signum, handler) | |
93 | } | |
94 | ||
95 | // The `ftruncate64` symbol apparently appeared in android-12, so we do some | |
96 | // dynamic detection to see if we can figure out whether `ftruncate64` exists. | |
97 | // | |
98 | // If it doesn't we just fall back to `ftruncate`, generating an error for | |
99 | // too-large values. | |
c30ab7b3 | 100 | #[cfg(target_pointer_width = "32")] |
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101 | pub fn ftruncate64(fd: c_int, size: u64) -> io::Result<()> { |
102 | weak!(fn ftruncate64(c_int, i64) -> c_int); | |
103 | ||
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104 | unsafe { |
105 | match ftruncate64.get() { | |
106 | Some(f) => cvt_r(|| f(fd, size as i64)).map(|_| ()), | |
107 | None => { | |
108 | if size > i32::max_value() as u64 { | |
109 | Err(io::Error::new(io::ErrorKind::InvalidInput, | |
110 | "cannot truncate >2GB")) | |
111 | } else { | |
112 | cvt_r(|| ftruncate(fd, size as i32)).map(|_| ()) | |
113 | } | |
114 | } | |
115 | } | |
116 | } | |
117 | } | |
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118 | |
119 | #[cfg(target_pointer_width = "64")] | |
120 | pub fn ftruncate64(fd: c_int, size: u64) -> io::Result<()> { | |
121 | unsafe { | |
122 | cvt_r(|| ftruncate(fd, size as i64)).map(|_| ()) | |
123 | } | |
124 | } | |
125 | ||
126 | #[cfg(target_pointer_width = "32")] | |
127 | pub unsafe fn cvt_pread64(fd: c_int, buf: *mut c_void, count: size_t, offset: i64) | |
128 | -> io::Result<ssize_t> | |
129 | { | |
130 | use convert::TryInto; | |
131 | weak!(fn pread64(c_int, *mut c_void, size_t, i64) -> ssize_t); | |
132 | pread64.get().map(|f| cvt(f(fd, buf, count, offset))).unwrap_or_else(|| { | |
133 | if let Ok(o) = offset.try_into() { | |
134 | cvt(pread(fd, buf, count, o)) | |
135 | } else { | |
136 | Err(io::Error::new(io::ErrorKind::InvalidInput, | |
137 | "cannot pread >2GB")) | |
138 | } | |
139 | }) | |
140 | } | |
141 | ||
142 | #[cfg(target_pointer_width = "32")] | |
143 | pub unsafe fn cvt_pwrite64(fd: c_int, buf: *const c_void, count: size_t, offset: i64) | |
144 | -> io::Result<ssize_t> | |
145 | { | |
146 | use convert::TryInto; | |
147 | weak!(fn pwrite64(c_int, *const c_void, size_t, i64) -> ssize_t); | |
148 | pwrite64.get().map(|f| cvt(f(fd, buf, count, offset))).unwrap_or_else(|| { | |
149 | if let Ok(o) = offset.try_into() { | |
150 | cvt(pwrite(fd, buf, count, o)) | |
151 | } else { | |
152 | Err(io::Error::new(io::ErrorKind::InvalidInput, | |
153 | "cannot pwrite >2GB")) | |
154 | } | |
155 | }) | |
156 | } | |
157 | ||
158 | #[cfg(target_pointer_width = "64")] | |
159 | pub unsafe fn cvt_pread64(fd: c_int, buf: *mut c_void, count: size_t, offset: i64) | |
160 | -> io::Result<ssize_t> | |
161 | { | |
162 | cvt(pread(fd, buf, count, offset)) | |
163 | } | |
164 | ||
165 | #[cfg(target_pointer_width = "64")] | |
166 | pub unsafe fn cvt_pwrite64(fd: c_int, buf: *const c_void, count: size_t, offset: i64) | |
167 | -> io::Result<ssize_t> | |
168 | { | |
169 | cvt(pwrite(fd, buf, count, offset)) | |
170 | } |