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Revert "Revert "use RWlock when accessing os::env #81850""

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This reverts commit acdca316c3.
This commit is contained in:
The8472
2021-03-14 19:10:34 +01:00
parent 9320b121b5
commit e22143c075
3 changed files with 72 additions and 12 deletions
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19
library/std/src/sys/unix/os.rs
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@@ -22,6 +22,7 @@ use crate::str;
use crate::sys::cvt;
use crate::sys::fd;
use crate::sys_common::mutex::{StaticMutex, StaticMutexGuard};
use crate::sys_common::rwlock::{RWLockReadGuard, StaticRWLock};
use crate::vec;
use libc::{c_char, c_int, c_void};
@@ -490,20 +491,20 @@ pub unsafe fn environ() -> *mut *const *const c_char {
extern "C" {
static mut environ: *const *const c_char;
}
&mut environ
ptr::addr_of_mut!(environ)
}
pub unsafe fn env_lock() -> StaticMutexGuard {
// It is UB to attempt to acquire this mutex reentrantly!
static ENV_LOCK: StaticMutex = StaticMutex::new();
ENV_LOCK.lock()
static ENV_LOCK: StaticRWLock = StaticRWLock::new();
pub fn env_read_lock() -> RWLockReadGuard {
ENV_LOCK.read_with_guard()
}
/// Returns a vector of (variable, value) byte-vector pairs for all the
/// environment variables of the current process.
pub fn env() -> Env {
unsafe {
let _guard = env_lock();
let _guard = env_read_lock();
let mut environ = *environ();
let mut result = Vec::new();
if !environ.is_null() {
@@ -540,7 +541,7 @@ pub fn getenv(k: &OsStr) -> io::Result<Option<OsString>> {
// always None as well
let k = CString::new(k.as_bytes())?;
unsafe {
let _guard = env_lock();
let _guard = env_read_lock();
let s = libc::getenv(k.as_ptr()) as *const libc::c_char;
let ret = if s.is_null() {
None
@@ -556,7 +557,7 @@ pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
let v = CString::new(v.as_bytes())?;
unsafe {
let _guard = env_lock();
let _guard = ENV_LOCK.write_with_guard();
cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(drop)
}
}
@@ -565,7 +566,7 @@ pub fn unsetenv(n: &OsStr) -> io::Result<()> {
let nbuf = CString::new(n.as_bytes())?;
unsafe {
let _guard = env_lock();
let _guard = ENV_LOCK.write_with_guard();
cvt(libc::unsetenv(nbuf.as_ptr())).map(drop)
}
}