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use core::slice::memchr;
pub use super::common::Env;
use crate::ffi::{CStr, OsStr, OsString};
use crate::io;
use crate::os::wasi::prelude::*;
use crate::sys::common::small_c_string::run_with_cstr;
use crate::sys::pal::os::{cvt, libc};
cfg_if::cfg_if! {
if #[cfg(target_feature = "atomics")] {
// Access to the environment must be protected by a lock in multi-threaded scenarios.
use crate::sync::{PoisonError, RwLock};
static ENV_LOCK: RwLock<()> = RwLock::new(());
pub fn env_read_lock() -> impl Drop {
ENV_LOCK.read().unwrap_or_else(PoisonError::into_inner)
}
pub fn env_write_lock() -> impl Drop {
ENV_LOCK.write().unwrap_or_else(PoisonError::into_inner)
}
} else {
// No need for a lock if we are single-threaded.
pub fn env_read_lock() -> impl Drop {
Box::new(())
}
pub fn env_write_lock() -> impl Drop {
Box::new(())
}
}
}
pub fn env() -> Env {
unsafe {
let _guard = env_read_lock();
// Use `__wasilibc_get_environ` instead of `environ` here so that we
// don't require wasi-libc to eagerly initialize the environment
// variables.
let mut environ = libc::__wasilibc_get_environ();
let mut result = Vec::new();
if !environ.is_null() {
while !(*environ).is_null() {
if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
result.push(key_value);
}
environ = environ.add(1);
}
}
return Env::new(result);
}
// See src/libstd/sys/pal/unix/os.rs, same as that
fn parse(input: &[u8]) -> Option<(OsString, OsString)> {
if input.is_empty() {
return None;
}
let pos = memchr::memchr(b'=', &input[1..]).map(|p| p + 1);
pos.map(|p| {
(
OsStringExt::from_vec(input[..p].to_vec()),
OsStringExt::from_vec(input[p + 1..].to_vec()),
)
})
}
}
pub fn getenv(k: &OsStr) -> Option<OsString> {
// environment variables with a nul byte can't be set, so their value is
// always None as well
run_with_cstr(k.as_bytes(), &|k| {
let _guard = env_read_lock();
let v = unsafe { libc::getenv(k.as_ptr()) } as *const libc::c_char;
if v.is_null() {
Ok(None)
} else {
// SAFETY: `v` cannot be mutated while executing this line since we've a read lock
let bytes = unsafe { CStr::from_ptr(v) }.to_bytes().to_vec();
Ok(Some(OsStringExt::from_vec(bytes)))
}
})
.ok()
.flatten()
}
pub unsafe fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
run_with_cstr(k.as_bytes(), &|k| {
run_with_cstr(v.as_bytes(), &|v| unsafe {
let _guard = env_write_lock();
cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(drop)
})
})
}
pub unsafe fn unsetenv(n: &OsStr) -> io::Result<()> {
run_with_cstr(n.as_bytes(), &|nbuf| unsafe {
let _guard = env_write_lock();
cvt(libc::unsetenv(nbuf.as_ptr())).map(drop)
})
}
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