From 9c462b84c8e15c3b33229a2604b273fc58acf60a Mon Sep 17 00:00:00 2001 From: Alex Crichton Date: Mon, 21 Mar 2016 16:54:53 -0700 Subject: [PATCH] std: Fix linking against `signal` on Android Currently the minimum supported Android version of the standard library is API level 18 (android-18). Back in those days [1] the `signal` function was just an inline wrapper around `bsd_signal`, but starting in API level android-20 the `signal` symbols was introduced [2]. Finally, in android-21 the API `bsd_signal` was removed [3]. Basically this means that if we want to be binary compatible with multiple Android releases (oldest being 18 and newest being 21) then we need to check for both symbols and not actually link against either. This was first discovered in rust-lang/libc#236 with a fix proposed in rust-lang/libc#237. I suspect that we'll want to accept rust-lang/libc#237 so Rust crates at large continue to be compatible with newer releases of Android and crates, like the standard library, that want to opt into older support can continue to do so via similar means. Closes rust-lang/libc#236 [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms/android-18/arch-arm/usr/include/signal.h [2]: https://chromium.googlesource.com/android_tools/+/fbd420/ndk_experimental/platforms/android-20/arch-arm/usr/include/signal.h [3]: https://chromium.googlesource.com/android_tools/+/20ee6d/ndk/platforms/android-21/arch-arm/usr/include/signal.h --- src/liblibc | 2 +- src/libstd/sys/unix/mod.rs | 36 +++++++++++++++++++++++++++++++++- src/libstd/sys/unix/process.rs | 2 +- src/libstd/sys/unix/weak.rs | 8 +------- 4 files changed, 38 insertions(+), 10 deletions(-) diff --git a/src/liblibc b/src/liblibc index 2278a549559..7265c17d184 160000 --- a/src/liblibc +++ b/src/liblibc @@ -1 +1 @@ -Subproject commit 2278a549559c38872b4338cb002ecc2a80d860dc +Subproject commit 7265c17d1845354f979a39b4ceb3a6934025b2ab diff --git a/src/libstd/sys/unix/mod.rs b/src/libstd/sys/unix/mod.rs index c332d6035ee..f8b2d4dd232 100644 --- a/src/libstd/sys/unix/mod.rs +++ b/src/libstd/sys/unix/mod.rs @@ -85,12 +85,46 @@ pub fn init() { #[cfg(not(target_os = "nacl"))] unsafe fn reset_sigpipe() { - assert!(libc::signal(libc::SIGPIPE, libc::SIG_IGN) != !0); + assert!(signal(libc::SIGPIPE, libc::SIG_IGN) != !0); } #[cfg(target_os = "nacl")] unsafe fn reset_sigpipe() {} } +// Currently the minimum supported Android version of the standard library is +// API level 18 (android-18). Back in those days [1] the `signal` function was +// just an inline wrapper around `bsd_signal`, but starting in API level +// android-20 the `signal` symbols was introduced [2]. Finally, in android-21 +// the API `bsd_signal` was removed [3]. +// +// Basically this means that if we want to be binary compatible with multiple +// Android releases (oldest being 18 and newest being 21) then we need to check +// for both symbols and not actually link against either. +// +// Note that if we're not on android we just link against the `android` symbol +// itself. +// +// [1]: https://chromium.googlesource.com/android_tools/+/20ee6d20/ndk/platforms +// /android-18/arch-arm/usr/include/signal.h +// [2]: https://chromium.googlesource.com/android_tools/+/fbd420/ndk_experimental +// /platforms/android-20/arch-arm +// /usr/include/signal.h +// [3]: https://chromium.googlesource.com/android_tools/+/20ee6d/ndk/platforms +// /android-21/arch-arm/usr/include/signal.h +#[cfg(target_os = "android")] +unsafe fn signal(signum: libc::c_int, + handler: libc::sighandler_t) -> libc::sighandler_t { + weak!(fn signal(libc::c_int, libc::sighandler_t) -> libc::sighandler_t); + weak!(fn bsd_signal(libc::c_int, libc::sighandler_t) -> libc::sighandler_t); + + let f = signal.get().or_else(|| bsd_signal.get()); + let f = f.expect("neither `signal` nor `bsd_signal` symbols found"); + f(signum, handler) +} + +#[cfg(not(target_os = "android"))] +pub use libc::signal; + pub fn decode_error_kind(errno: i32) -> ErrorKind { match errno as libc::c_int { libc::ECONNREFUSED => ErrorKind::ConnectionRefused, diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs index 6f56f3ade06..270c2096b2c 100644 --- a/src/libstd/sys/unix/process.rs +++ b/src/libstd/sys/unix/process.rs @@ -393,7 +393,7 @@ impl Command { t!(cvt(libc::sigemptyset(&mut set))); t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &set, ptr::null_mut()))); - let ret = libc::signal(libc::SIGPIPE, libc::SIG_DFL); + let ret = super::signal(libc::SIGPIPE, libc::SIG_DFL); if ret == libc::SIG_ERR { return io::Error::last_os_error() } diff --git a/src/libstd/sys/unix/weak.rs b/src/libstd/sys/unix/weak.rs index e6f85c08d12..99ab8741159 100644 --- a/src/libstd/sys/unix/weak.rs +++ b/src/libstd/sys/unix/weak.rs @@ -75,11 +75,5 @@ unsafe fn fetch(name: &str) -> usize { Ok(cstr) => cstr, Err(..) => return 0, }; - let lib = libc::dlopen(0 as *const _, libc::RTLD_LAZY); - if lib.is_null() { - return 0 - } - let ret = libc::dlsym(lib, name.as_ptr()) as usize; - libc::dlclose(lib); - return ret + libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) as usize }