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Use IOV_MAX and UIO_MAXIOV constants in limit vectored I/O

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Also updates the libc dependency to 0.2.77 (from 0.2.74) as the
constants were only recently added.
This commit is contained in:
Thomas de Zeeuw 2020-09-10 11:35:25 +02:00
parent 88197214b8
commit f7b6ace029
2 changed files with 28 additions and 18 deletions
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2
library/std/Cargo.toml
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@ -16,7 +16,7 @@ cfg-if = { version = "0.1.8", features = ['rustc-dep-of-std'] }
panic_unwind = { path = "../panic_unwind", optional = true }
panic_abort = { path = "../panic_abort" }
core = { path = "../core" }
libc = { version = "0.2.74", default-features = false, features = ['rustc-dep-of-std'] }
libc = { version = "0.2.77", default-features = false, features = ['rustc-dep-of-std'] }
compiler_builtins = { version = "0.1.35" }
profiler_builtins = { path = "../profiler_builtins", optional = true }
unwind = { path = "../unwind" }

44
library/std/src/sys/unix/fd.rs
View file

@ -7,7 +7,6 @@
use crate::io::{self, Initializer, IoSlice, IoSliceMut, Read};
use crate::mem;
#[cfg(not(any(target_os = "redox", target_env = "newlib")))]
use crate::sync::atomic::{AtomicUsize, Ordering};
use crate::sys::cvt;
use crate::sys_common::AsInner;
@ -31,24 +30,35 @@ pub struct FileDesc {
#[cfg(not(target_os = "macos"))]
const READ_LIMIT: usize = libc::ssize_t::MAX as usize;
#[cfg(not(any(target_os = "redox", target_env = "newlib")))]
fn max_iov() -> usize {
static LIM: AtomicUsize = AtomicUsize::new(0);
let mut lim = LIM.load(Ordering::Relaxed);
if lim == 0 {
let ret = unsafe { libc::sysconf(libc::_SC_IOV_MAX) };
// 16 is the minimum value required by POSIX.
lim = if ret > 0 { ret as usize } else { 16 };
LIM.store(lim, Ordering::Relaxed);
}
lim
#[cfg(any(
target_os = "dragonfly",
target_os = "freebsd",
target_os = "ios",
target_os = "macos",
target_os = "netbsd",
target_os = "openbsd",
))]
const fn max_iov() -> usize {
libc::IOV_MAX as usize
}
#[cfg(any(target_os = "redox", target_env = "newlib"))]
fn max_iov() -> usize {
#[cfg(any(target_os = "android", target_os = "emscripten", target_os = "linux"))]
const fn max_iov() -> usize {
libc::UIO_MAXIOV as usize
}
#[cfg(not(any(
target_os = "android",
target_os = "dragonfly",
target_os = "emscripten",
target_os = "freebsd",
target_os = "ios",
target_os = "linux",
target_os = "macos",
target_os = "netbsd",
target_os = "openbsd",
)))]
const fn max_iov() -> usize {
16 // The minimum value required by POSIX.
}