rustld 0.1.55

A modern ELF loader (static & dynamic linker + compatible glibc & musl) written in Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40

use core::sync::atomic::{AtomicBool, Ordering};
use std::{ffi::CStr, mem::MaybeUninit};

use crate::start::environment_variables::EnvironmentIter;

#[allow(non_upper_case_globals)]
static mut environ: MaybeUninit<*mut *mut u8> = MaybeUninit::uninit();
static ENVIRON_INITIALIZED: AtomicBool = AtomicBool::new(false);

unsafe extern "C" {
    #[link_name = "__environ"]
    static mut host_environ: *mut *mut i8;
}

pub unsafe fn host_environment_pointer() -> *mut *mut u8 {
    core::ptr::read_volatile(core::ptr::addr_of!(host_environ)).cast()
}

pub unsafe fn get_environ_pointer() -> *mut *mut u8 {
    if !ENVIRON_INITIALIZED.load(Ordering::Acquire) {
        return host_environment_pointer();
    }
    #[allow(static_mut_refs)]
    environ.assume_init_read()
}

pub(crate) unsafe fn getenv(variable_name_pointer: *const u8) -> *const u8 {
    let variable_name = CStr::from_ptr(variable_name_pointer.cast())
        .to_str()
        .unwrap();
    EnvironmentIter::new(get_environ_pointer())
        .find_map(|(name, value)| {
            if name == variable_name {
                Some(value.as_ptr())
            } else {
                None
            }
        })
        .unwrap_or_default()
}